lcd panel driver board repair free sample

Here is a Toshiba C655D-S5200 that had a broken case. It had severe water damage and the case was broken at the hinges. I salvaged as many parts as possible and wanted to use the LCD panel for a project. Over the last few years that I have been a member of iFixit, we had a couple of questions about what to do with spare panels. So, I figured I"d spend $32 and purchase a LCD controller board and investigate how difficult it would be. The trickiest part was to find a controller board that matches the panel.The LCD panel in this Toshiba is a LTN156AT05-U09. I contacted a couple of vendors on Ebay and found one that was very responsive and accommodating. I ordered the controller board and it arrived in 2 weeks from China.

25-40W Pencil Soldering Iron with pointed cone tip ($8.99 at Radio Shack - don"t use soldering guns or higher heat soldering irons! If tip of the iron isn"t clean, smooth and tinned, don"t use it - you"ll damage the circuit boards)

Sunlight causes the LCD polarizing filters to fade, which causes the information on the cluster to disappear. The LCD panels should appear black while the cluster is off. If you can see the colored info when the cluster is off, the polarizing film has faded and should be replaced. Click Here to buy.

When soldering, heat the connector lead and the solder pad on the circuit board (simultaneously). Once these two locations are sufficiently heated, feed fresh solder into the joint.

Over time, heat, vibration and bad design cause the board connectors or their solder joints to fail. Not all look as bad as the one in Figure 1, but they almost always need to be replaced.

3) On the bottom circuit board (the one you took out last), remove the old connector using a soldering iron and desoldering braid or another desoldering method of your choice. When the solder has been removed and the connector is ready to be removed, you should be able to pull it away from the board by hand. Don"t use force to remove the connector, as the hole plating (which connects top traces to bottom traces) can be damaged! See Figure 2.

4) The connector will tend to warp when resoldered, which results in unevenly spaced pins. You can prevent this by temporarily installing the top board connector onto the pins of the bottom board connector.

6) Using a soldering iron and desoldering braid (or a desoldering method of your choice), remove the old white connector from the top board. When the solder has been removed and the connector is ready to be removed, you should be able to pull it away from the board by hand. Don"t use force to remove the connector, as the hole plating (which connects top traces to bottom traces) can be damaged!

12) Heat from the factory bulbs causes the riveted connection of the dimmer transistor to become loose over time. Scrape the sides of the heat sink tab (opposite end from the three leads) and then solder it to the large heat sink pad on the bottom board. See Figure 7.

13) Inspect the polarizing filters on the LCD panels. If you see a fade ring around the edges, consider replacing the polarizing filters on the LCD panels. Now is the time to do that repair.  Click Here to purchase.

15) If the black paint on the back of the LCD panels has worn through, light will shine through the panel in areas other than the places it should. Use black enamel acrylic paint designed for glass and a small paint brush to repaint that area. Note that we supply the correct paint and a brush if you purchase our LCD Polarizing Film kit. Be careful to avoid areas near the factory graphics, and in the areas of the LCD segments!

If your cluster displays randomly flickering LCD segments along with intermittent backlighting, the onboard power supply (Fig 1) may need to be rebuilt. We sell a kit of parts to replace commonly needed components - Click Here

Ever had your TV showing nothing but a black screen even if the audio was working? Unfortunately, that’s a common issue with low/middle-end LCD/LED TVs these days… Even more frustrating, this issue often comes from a rather tiny and cheap component that can be easily replaced. Most common issues are:

One of my relatives had this exact symptom happening all of a sudden. This problem on low-end TVs often occurs within the first couple years. As the repair costs for that kind of TV is pretty low, considering repairing it yourself might be a good idea!

The first step into repair is to find the root cause of the issue. As backlight failure is a very common issue, this is the first thing to test. To do so, the easiest way is to power on your screen, put a flashlight very close to it and check if you can see the image through. The image would be very dark, like turning the brightness of the screen very very low.

That implies disassembling the TV to access the backlight which is between the LCD screen in the front and the boards in the rear. In my case, with a Samsung F5000, I had to process as follows:

First we have to remove the back housing to reveal the boards (from left to right: main board, T-CON, power supply) and disconnect the LCD panel from the T-CON board.

Note: Older TVs have neon tubes for backlight, which is thicker and less exposed to this kind of failure. LED backlight is the most common thing these days, but do not mistake an LED TV with an OLED TV. The first one is a classic LCD panel with a LED backlight, whereas the second is an OLED panel that doesn’t need any backlight as it is integrated in each pixels (making the spare parts much more expensive by the way).

There might be a lot of other root causes for similar symptoms, a black screen often looks like something very serious and therefore expensive to repair, but this case is the perfect example that taking some time to look for the root cause can sometime lead to a good surprise: here a 1$ fix!

TV repair costs between $60 and $350 with most spending $207 on average for LCD, LED, plasma, and 4K TVs; costs are higher if repairing older DLP, projection, and HD TVs. TV problems like display issues, powering-on problems, or sound issues can be fixed. Pickup and delivery fees may apply.

The cost to repair a TV will include the price of parts and labor costs, plus other associated costs. Additional charges include a trip fee for a technician to come to your home, a fee to transport your TV to and from a repair shop, and the diagnostic fee to determine what needs to be replaced.

The cost to repair a TV screen can be significantly more than the cost of purchasing a new TV. For this reason, replacing or repairing a broken TV screen is not considered feasible.

For example, the price of a new Samsung 40-inch LED TV is about $400, yet the cost of a replacement display panel for this model is about $380. This price is only for the replacement part and does not cover diagnostic costs, labor costs, or travel or shipping fees.

Broken TV screen repair is not a service offered by most TV or electronics repair companies. For example, BestBuy"s 90-day warranty, does not list broken TV screen repair as one of the problems they service.

Unless you are trying to fix a TV from the ’80s or earlier, cracked TV screen repair is not feasible; the entire display panel must be replaced instead. The cost of a replacement TV display panel is more than the cost of buying a new TV, and that’s before labor and other service costs.

TV manufacturers do keep replacement TV screen panels on hand to support products under warranty in case the screen malfunctions, due to manufacturer defect.

If you still want to replace a damaged or malfunctioning TV screen, your best option is to find a used replacement panel or a broken TV of the same model on which the screen is still functional. You might find one on eBay, and you can hire a technician to change out the panel.

The cost of a used replacement TV panel ranges from $50 to $350 or more, excluding shipping, depending on the brand and size. Note that the chances of finding exactly the part you need in excellent condition are slim, and the cost excludes the cost of installation by a repair shop.

Whether your TV is LCD, LED, plasma screen, or 4K (Ultra HD), the cost to fix common problems ranges from $60 to $350, depending on the repair type and the brand of TV being repaired.

These repair problems could have more than one possible source, so a technician should take time to narrow down the exact problem. TVs are repaired by replacing faulty components.

TV motherboard replacement costs between $200 and $350, including parts and labor, or about $275 on average. Motherboard replacement parts range from $35 to $199and labor costs from $60 to $125.

A TV inverter repair costs $104 to $171, including parts and labor, with an average cost of $138 for a TV with one inverter board or $178 for two. Parts range from $7 to $74, and the average labor cost for TV inverter repair is $97 per hour.

The function of an inverter board in a TV is to power the backlight of the screen. The inverter board requires a few hundred volts of power. If the inverter board goes bad, this would cause the TV to power on and have sound but no picture.

When an inverter component goes bad, it is usually replaced rather than repaired. In some cases, the capacitors on a converter board fail, and a technician can fix it by replacing the capacitors rather than replacing the entire inverter component. However, if an entire inverter board replacement is not available for the model of TV being repaired, replacing the capacitors may be the only option for TV inverter repair.

If an older model LCD TV or projection TV powers on and has sound but no picture, this may be due to lamp burnout, which is both common and expected. In this case, replacing the bulb will fix the problem. An experienced technician should be able to replace the bulb quickly and easily.

TV backlight repair costs $100 to $122, including replacement parts and labor, at a repair shop. In-house repair costs are more due to trip fees. The price of backlight replacement parts averages around $2.50for each LED and between $20 and $25 for each CCFL strip.

A new inverter may be needed to power the LEDs, costing between $7 and $74before labor, or an average of $40. In some cases, a repair shop can convert a CCFL backlight to LED without installing a new inverter.

Repairing a TV power supply board costs $23 to $234 for parts alone. Completely replacing the power supply board costs $250 for parts and labor. If one capacitor has failed, the cost for replacement capacitors is low. However, it’s more cost-effective for the technician to replace the entire board rather than spend time trying to diagnose and replace faulty capacitors one by one.

The cost to fix an HDMI port on a TV is $93 to $302. In some cases, the input circuit board that the HDMI port connects to may be damaged and need to be replaced. The cost for replacing this input circuit board, including labor, ranges from $200 to $350.

TV capacitor repair costs $60 to $129, including parts and labor. The cost for the replacement part ranges from $0.06 to $14, with the labor portion ranging from $60 to $125 per hour. TV capacitors protect the circuit from getting too much power, filter signals, and facilitate changing channels.

Flat screen replacement glass is not available. The only option for flat-screen TV glass repair is to try optical glass glue, which costs $1.70 for a 5-ml. tube. This may be an option for TV glass repair if the crack is only a few inches or less. TV panels are built as one unit at the factory, with the glass adhered to the display panel.

In-home CRT repair ranges from $199 to $249. The cost of repairing a CRT picture tube ranges from $199 for a TV that is 27 inches or smaller to $249 for a TV that is 28 inches or larger.

A TV fuse repair costs between $61 and $136, with most spending $99 on average. The cost of the replacement fuse itself is $1.50 to $11, while labor ranges from $60 to $125 per hour. Additional fees may apply.

LCD flat-panel repair is not considered cost-effective. If the glass is cracked or the display is physically damaged, it is cheaper to replace the entire TV than to repair or replace the display panel.

Estimating TV repairs costs by brand is not something TV repair shops offer, however, there are general prices by type. When looking for specific repair costs for your TV, you’ll find them in the common repairs price list above. Pricing applies to brands such as Samsung, LG, Sanyo, TCL, Insignia, HiSense, Sony, Toshiba, Pioneer, and Vizio.

More popular TVs are usually less expensive to repair because repair shops order replacement parts for them in bulk, which allows them to buy those parts at a lower cost.

The cost of flat-screen TV repair ranges from $42 to $359. You cannot fix a broken screen, but the price of a new flat-panel TV starts from around $249 for a 1080-mp (non-4K) LED TV from LG to as much as $14,999 for an 85-inch 8K LED TV from Samsung. A TV referred to as a “flat TV” or “flat-screen” TV might be any of the following:

LCD TV repair typically costs $60 to $85 for diagnostics testing, and $200 to $300 to perform repairs. LCD TVs use backlighting, which may fail. Newer LCD TVs use LED strips for backlighting. Older ones might use CCFL. If CCFL backlighting fails, a technician can replace it with LED backlighting.

An LED TV is just an LCD TV that uses LED backlighting, which all newer models do (older models use CCFL backlighting). The cost to replace one LED backlighting strip ranges from $100 to $122, including parts and labor.

The cost to replace the motherboard, inverter, or LED"s in a 4K TV ranges from $100 to $275 or more depending on the brand and model. The cost for screen repair for a 4K TV is irrelevant because it cannot be fixed or replaced at a cost that is lower than the cost of a new 4K TV.

Digital light processing (DLP) TVs are also known as projection TVs. DLP big screens have not been made since 2012, and DLP TV repair is usually not worth the cost except for a lamp burnout, in which the bulb can be replaced. The cost to replace bulbs ranges from $60 to $115.

TV repair shops charge an average $60 to $125 per hour, or a flat rate of $50 to $250, which includes the diagnostic fee. Additional costs after that depend on the repairs needed and the brand and type of TV. However, most stores will have a minimum charge of about $90.

Best Buy TV repair is provided through the Geek Squad TV & home theater service. Geek Squad TV repair starts at a base cost of $100 for a diagnostic fee. TV repair is covered under Best Buy’s protection plan, which costs $280 per year when you purchase a TV from Best Buy at the time of purchase, or within the return period printed on your receipt.

The brand and model of your TV will dictate the final repair cost, with more expensive brands and larger TVs costing more to repair. Consider the remaining lifespan of the TV before paying for repairs. You can now buy bigger TVs with more features and better displays for a TV that won’t need repairs for a while and probably comes with a warranty.

The cost of labor to fix a TV ranges from $60 to $125 per hour, or a flat rate of $90 to $299. If the work is performed in your home, the cost ranges from $25 to $125 per hour plus the trip fee. Most TV repairs take 1 to 3 hours if the repair specialist has the parts already.

If you live in a remote area, you may need to ship your TV to a repair facility, costing $99 to $175. Be sure to choose a delivery service that allows you to track the shipment and confirm delivery. When sending your TV into a service center for repair, you will be contacted regarding the associated costs and asked to process payment before the repair is completed, which usually takes two weeks including the shipping time.

Many TV repair shops charge a diagnostic fee that ranges from $20 to $60, depending on whether it is done in your home or the repair shop. Some shops charge a flat fee that ranges from $50 to $250that covers both the diagnostic cost and labor cost. In many cases, the initial diagnostic fee will be applied to the repair cost if you have the shop do the repair.

The more expensive a TV is, the more sense it makes to purchase an additional warranty to defray the potential for costly repairs. Best Buy offers an $89 five-year extended warranty for entry-level TVs. On larger TVs such as the 85-inch Samsung QLED 8K TV, which costs $14,998, the five-year warranty from Geek Squad costs an additional $1,699—11.33% of the cost of the TV.

With modern TVs, repair entails component replacement or replacement of capacitors, for which high levels of certification are not necessary. Generally, TV repair shops will let you know if their employees have certification.

Satellite dish repair is either covered by your satellite service company or the cost for a technician to fix it ranges from $80 to $150. Repairs may also be billed at an hourly rate of $50 to $65.

There are various ways you might be able to save money on TV repair. These include transporting your TV to a repair shop, using a shop that charges in 15- or 30-minute increments, diagnosing the problem yourself, using salvaged parts, and doing the repair work on your own.

You can also consider the cost of TV repair when purchasing a new TV. More popular TV models are less expensive to repair because repair shops buy parts for the most common TVs in bulk and are therefore able to get them at lower prices.

Circuit breaker - Check the circuit breaker for the power outlet that the TV plugs into. You can check the breakers by opening the door to your breaker panel and looking for circuit breakers that are in the OFF position.

Lamp burnout -In a projection TV or older LCD TV, no picture may be caused by lamp burnout. In this case, a technician can replace the bulb quickly and easily.

If the picture is displaying but there are problems such as vertical lines, a double picture, or a white display, this could indicate a faulty motherboard or mainboard.

The primary way to save money on TV repair would be to perform the work yourself. This may require you to purchase and get familiar with various tools such as soldering tools, and methods for replacing a capacitor or some other component.

The right parts - It can be complicated to determine which component of a TV is failing and causing the TV not to work correctly. If you buy a replacement part and perform the repair yourself, the TV may still not work, either because you replaced the wrong part, the part was old and not working properly to begin with, or you did not perform the work correctly. Buying multiple replacement parts can become costly.

The cost of repairing a TV could be as much as $500 if multiple repairs are needed. Consumer Reports recommends not to spend more than 50% of the cost of a new TV repairing the old one.

If you have a newer TV that cost thousands of dollars, having it repaired would most likely be cost-effective. If the TV only cost a few hundred dollars to begin with, replacing the TV is more likely to be the best option.

In most cases, a flat-screen TV can be fixed. The exception is a physically damaged display panel or screen. Most other issues including failing speakers, backlights, or power supply. Burned out fuses and damaged input ports can also be repaired.

If the screen is not physically damaged but is not showing a picture or is displaying “snow’” or vertical or horizontal lines, a technician can repair the TV by replacing failed components. If the screen is physically damaged, it cannot be repaired.

If you live in a remote area, you may need to ship your TV to a repair facility, costing $99 to $175. Be sure to choose a delivery service that allows you to track the shipment and confirm delivery.

Note: If your MacBook Pro has any damage which impairs the service, that issue will need to be repaired first. In some cases, there may be a cost associated with the repair.

TFT LCD image retention we also call it "Burn-in". In CRT displays, this caused the phosphorus to be worn and the patterns to be burnt in to the display. But the term "burn in" is a bit misleading in LCD screen. There is no actual burning or heat involved. When you meet TFT LCD burn in problem, how do you solve it?

When driving the TFT LCD display pixels Continously, the slightly unbalanced AC will attract free ions to the pixels internal surface. Those ions act like an addition DC with the AC driving voltage.

For normal white TFT LCD, white area presenting minimal drive, black area presenting maximum drive. Free ions inside the TFT may are attracted towards the black area (maximum drive area)

This instructable came about from a broken LCD control module out of a modern VW Camper Van. The LCD module is part of a control unit which was virtually unreadable and a replacement for a new unit was £400+. It really was a no lose option, either have a go at fixing it or end up buying a new unit.

The fault of the LCD was that it only displayed a couple lines of output on the LCD. The symptoms are caused by poor location of the LCD ribbon in manufacture and also the poor position of the whole module in the vehicle which exposes it to heat and is subject to vibration within the vehicle. This causes the ribbon to fail eventually and is a known common fault.

The ribbon in this display actually controls the Rows of the LCD matrix and the Columns were handled by a rubber standoff connection on the longest side of the LCD. There were no problems with the rubberized connection.

Some re-work on the LCD ribbon had already been tried with a little improvement but the poor registration of the ribbon pushed me to try a new attachment.

From the photos below you can see the LCD control unit and the state of the LCD ribbon before repair. You can just make out the offset placement and poor registration of the ribbon before repair.

Do not under estimate the patience required for this repair as some delicate and nimble work is required and i cannot stress how important it is to take your time and not rush.  You may only get one chance with this sort of repair.

The registrations of the LCD ribbon in this repair was difficult. It took me and my friend 20 minutes just to line up the ribbon for re-attachment. The ribbon in this case is sub 1mm pitch OR less than 25.4 thousands of an inch. You may want to try a simpler ribbon repair on an old LCD clock for example before jumping in head first with fine pitch.

Also the removal of the LCD ribbon is a delicate process as you do not want to tear what is a good ribbon or damage the carbon printed lines. Also the PCB must be respected to avoid introducing other faults and the the re-attachment may need an extra pair of hands.

You may also want to review the last step for results and lessons learned from this instructable before jumping in head first but i believe this will give a you a good insight to some important factors of LCD ribbons and possible success.

Other favorites of reworking the LCD connection that i have read here are the tinfoil on a heat gun. This has good temperature management but not so good in tight spaces. The solder iron with flat blade and tin foil is more precise but a 25 Watt iron can be too brutal on the ribbon.

In the photos below you can see the available ribbon length was generous enough but do watch for mechanical constraints. In some cases you could find yourself not being able to lay down the LCD back down as it is too tight a radius to sit down.

You do not want to pull at the ribbon as you will most likely damage what you already have. In my instance it was best to cut the ribbon free as close to the PCB pads as possible.I used a scalpel to slice parallel to the PCB board to remove the ribbon. Do make a good job of this as you may need to preserve as much extra ribbon to re-attach the LCD module.

The LCD assembly was lifted off and put in safe place to avoid damage. The ribbon was then gently lifted and peeled back with tweezers to remove the bulk. You must not use force to remove the remainder ribbon especially if your PCB is off a cheap quality OR single sided cardboard type variety. The PCB pads can come off with the ribbon! If you have a double sided PCB of FR4

The trick to get good alignment is to allow some the gold pad fingers toes of  the PCB to be visible just beyond the carbon lines of the ribbon. You then get the pads toes to line up with the carbon lines of the LCD ribbon.

The photos below show how i handled the PCB and LCD and clamped the ribbon in place. The LCD display is being held by a plastic clamp above the PCB assembly. The PCB below which has components both sides is laying on some foam (try polystyrene). This allowed me to nudge the PCB under the ribbon into position. The plastic ruler acts as a LCD ribbon clamp. When you have got the registration get a steady handed friend to hold the ruler as a ribbon clamp in place so you can then apply the heat to stick the ribbon back down.

In our case the LCD ribbon was not only glued to the PCB pads but there was some additional tape at the heel of the ribbon to hold the ribbon in place. By holding at the heel the ribbon you get some good extra mechanical support.

I did not go further with more re-work as the VW LCD module was considered a good enough result and some other time pressures intervened. It was concluded that we could read the display well enough and operate items from the controller. It was also considered as one of those quit while your ahead things!

The technique for LCD ribbon removal and re-attachment are achievable certainly on simpler ribbons and fine pitch ribbons with careful preparation and thought. I hope this instructable is comprehensive enough for people to get some good results.

The other end of the ribbon that joins to the LCD is terminated on the glass on Indium tin oxide (ITO) which is one of the most widely used transparent conducting oxides.

If you want more information there are many different types of LCM assemby (LCD Display plus it driving chips) to look at but these are the main ones (increasing in density):

In manufacture of these modules a machine is used for assembly which would compress HSC to the LCD Or the PCB and then apply the correct amount of heat.

very nice and complicated work but...my question is, where can I find a ribbon cable like this? I have a keyboard Technics KN2000 with a display not working because the cable was disconnected from both the glass display and the circuit board. Thank You!

Attached is a picture of a screen from a Brookstone clock. I think it may be an LCD. The black pads show where a ribbon cable was connected and I see not transmission paths from the pads into the screen. How does this work? Is it really an LCD?

Are the paths in this ribbon cable covered on both sides as mine is and can you adhere the ribbon without removing any covering by applying heat? And what do I do on the LCD side where there appears to be no pads on the LCD but the ribbon cable was apparently applied in this manner?0

I have two items to add, kapton tape and sil-pads used to isolate heat-sinks from semiconductor devices. With kapton tape it brings the means to secure the ribbon to the board, place the tape over the whole connection area, and kapton resists heat very well, ( try and melt it with your soldering iron). This means an average soldering iron turned down will allow heat to be applied to each joint. With experience a rework can be done in a few minutes. The bond can also be renewed on the LCD glass as well, kapton also works here. Sil-pads allow heat to be passed to the joint with some pressure applied at the same time. The sil-pad can be dragged up and down all the ribbon connections allowing uniform heating. Once the bond is resurrected the sil-pad is discarded. http://goo.gl/mpZNkm0

Sorry, the connector on the link doesn"t match the board design... you must search for FFC, FPC connectors with the number of vias of your cable and look for the real dimensions on the datasheet.

I just thought the same way, adding aLCD flat connector... then you can swap chinese or VDO oem screens. Seems the VDO LCD(as for Audi A3-Vw golf/jetta4) have 50 pins and the ribbons is 48mm width. Then you have to look to modify the metal bracket to avoid pressure on ribbon.

i have an alarm clock which doesn"t have a ribbon, but instead some sort of rubbery contact strip against which the display should be pressed. You can find pics of it on google images for "lcd rubber contact strip", it seems to be called a zebra rubber. Any idea on how to glue/solder the display to that rubbery contact strip?More CommentsPost Comment

The White Star System board set consists of three boards mounted to the the back box, but four boards total. The CPU / Sound board, I/O Power Driver board and the Display Power supply. Additionally, there is a dot matrix display controller mounted to the backside of the dot matrix display. On some games, the dot matrix display controller is mounted to the backbox instead.

The first two White Star games, Apollo 13 and Goldeneye, both used an additional solid state flipper control board. Starting with Twister, the solid state flipper board was abandoned, and flipper control became an additional duty for the I/O power driver board.

In addition to pinball machines, the White Star board set was used in several redemption games made by Sega and Stern. Some of the games are Wack-A-Doodle-Doo, Sega Sports, Titanic, and Monopoly redemption.

Stern White Star CPU/Sound Board II 520-5300-00 (LOTR and forward). U201, U213, and U413 are socketed on this board as a result of alkaline damage abatement.

The board used in Sega machines starting with Apollo 13 (A13) and Stern machines up to Terminator 3 (T3) are the standard version as shown above with the BSMT2000. There were different revisions of this board, which included slight component changes and modifications. However, there were some distinct changes to the board from revision D to revision E. The Q9 transistor located just below U212 (RAM memory) was removed, and a two pin jumper (JP1) was added. Additional circuitry allowed for increased RAM memory from 8K to 32K. Jumper JP1 is used to select between use of a 6264 or a 62256 RAM. Note: While a 62256 RAM can be used in any game MPU, Sharkey"s Shootout specifically requires a 62256 RAM.

Stern machines starting from Lord of the Rings (LOTR) used a different version of the White Star CPU/Sound board called White Star CPU/Sound Board II or more commonly WhiteStar (modified), part #520-5300-00. Stern had this in-between version made because the BSMT2000 audio chip wasn"t available anymore and having it reproduced was too expensive. The White Star II therefore uses an BSMT2000 emulation circuit consisting of an Atmel AT91R40008 microcontroller and an Atmel AT49BV1614-11TC 16Mbit flash memory. Later boards use a AT49BV162AT-70TI flash memory chip. Both flash chips are obsolete now. The boards are known for sudden sound failures sometimes because of a bad flash chip and it is advisable to buy a spare. If the amplifier section is good the most common cause for sound failures is the U414 Xilinx CPLD. This chip is a programmed by Stern via the JTAG connector. While some repairmen have the skill to replace the chip, only Stern can "flash" the code into the chip.

Note:Stern states that the Atmel version board is backwards compatible with the standard (BSMT2000) version, so it can be used in *some* White Star based games (in most cases, Stern branded White Star games only - including South Park and Harley Davidson) prior to LOTR as well. However, the only games which the board can be installed in must use 8mb EPROMs for the sound section versus the 4mb EPROMs more commonly found on Sega White Star based games. If the CPU/Sound board II is used in early games, Starship Troopers for instance, some sounds may not render correctly.

The BSMT2000 based White Star sound system is nearly identical to the sound circuitry found on Data East/Sega soundboards 5020-5050-0x, 5020-5077-00 and 5020-5126-02.

The board uses TIBPAL16L8 PAL ICs. These are programmable logic chips Stern used to condense a great deal of TTL logic into a single chip. Each PAL is marked with a colored dot for identification and configuration management. U213 is one of these PALs that is within the battery corrosion area. It is readily available, already programmed under part number 965-6504-00 (blue dot), the only exceptions to the blue dot being Sharkey"s Shootout which uses part number 965-5023-00 (gold dot) and Lord of the Rings LE with a shaker motor installed which uses a different part number (the standard LOTR without a shaker motor uses the standard 965-6504-00 but the software version supporting the shaker motor will only run on the alternative U213).

There are two more PAL chips on the board at U19 (yellow dot, 965-0136-00) and U20 (white dot, 965-0137-00). These aren"t needed very often for repair of the sound section but they do fail now and then.

Sega first used standard TIBPAL chips and later switched to reprogrammable PALCE devices. The latest boards from Stern use GAL chips. In the old PAL chips, fuses are burned so they do not have a data retention period. For the programmable logic chips the data retention period is generally specified at 20 years or more at operating temperature. The first White Star boards are from 1995 Beginning in 2015, all with reprogrammable chips begin to exceed the data retention period and although big problems are not to be expected, it wouldn"t be surprising if these parts begin to fail.

The programmable logic in the board design makes it harder to repair the boards because of the grey area it causes in the schematics as there aren"t any logic diagrams of these available. In short; you don"t know what they do so you don"t know what the output should be.

"Blink Codes" do not exist for the 68B09E or the Atmel based MPU. With one exception (Atmel based board) anything blinking is a side-effect of improper board operation. The blinking may help you diagnose the actual board problem, but blinking LEDs are not driven with intent by the processors. i.e. There are no "Bally -17-like Blink Codes".

The single exception to this is LED1 on the Atmel based MPU. LED1 on this board will blink anywhere from 5 to 8 times to indicate the sound operating system version contained in the flash memory at U8. Stern has provided a good explanation within Service Bulletin # 157. This service bulletin also describes the process to update flash memory to a newer version of the sound operating system (which is not recommended unless you encounter sound issues after moving an MPU from one game to another).

There are two JTAG (Joint Test Action Group) connectors available on the Atmel based board. One connects to the Xilinx CPLD (Complex Programmable Logic Device). The other connects to the Atmel R40008 processor. The JTAG interfaces to this board and their use have not been documented publicly.

Like the earlier Data East boards, the first White Star generation uses a TI DSP for sound processing. The chip is just a relabeled mask programmed stock Texas Instruments TMS320C15NL-25 DSP. The 8K mask programmed ROM is custom programmed during manufacturing and can not be read out, reprogrammed, or altered in any way. Only the ones labeled BSMT2000 will work in a pinball. For prototyping, the TMS320P15NL-25 and TMS320E15NL-25 were available which included a more-or-less standard 27C64 EPROM. The pictures on the left shows a BSMT2000 and a TMS320P15NL-25 out of a Sega board. The hand labeled chips are rare but if you have one in your pin, you can read it out. The security fuse was not set on the device in the picture. If you build an adapter using a 27C64 and some logic which puts the DSP in microprocessor mode and does the address decoding it might even be possible to use the C10 and C15 devices because the internal ROM is not used in this mode.

Both versions of rhe WhiteStar CPU/Sound board employ an 8 by 8 (8 switch columns, 8 switch rows) switch matrix. In addition to the typical switch matrix, an extra column of switches, which are dedicated to specific functions like coin door switches, appear on all WhiteStar games.

The Power Driver board supplies fused power, GI power and fusing, lamp matrix circuitry as well as coil and flash lamp drivers. A watchdog circuit also must communicate with the MPU periodically to allow the MPU to boot and operate properly.

Please be advised that four revisions of these board exist. The letter after the number indicates the revision. See below. All existing Stern schematics are wrong.

The most obvious change to the Rev G driver board is the addition of eight 100 ohm resistors under the J2 aux out connector (R258-260, R273-277). This board is backwards compatible with all machines that use the I/O Power Driver board. It is possible to add these resistors to the back of J2 for I/O board Rev F, jumping from the connector pins to the capacitors below the J2 connector to make the board compatible with those games that use the J2 connector.

The now defunct Stern web site containing schematics listed a few differences in the I/O Driver Board for Sharkey"s Shootout. Those differences are identified in the image at left.

The RottenDog aftermarket power/driver board uses the voltage regulator shown at left, primarily because the older LM317 voltage regulator has gone obsolete.

Only the latest revision G is compatible with the Stern tournament system (TOPS). With earlier revisions while everything including the tournament sign seem to work ok a tournament can not be started. Pressing the tournament button will result in a "Tournament Game Paused" message displayed on the DMD. The tournament button itself will also not light up during normal operation. The J3 Aux In connector has an additional pin instead of the key pin on these boards. Because of this the LST line to the lamp drivers goes nowhere on this revision.

The display controller board doesn"t contain circuitry to provide the on board 68B09E with a "reset" pulse. The reset signal is provided from the games MPU via a pin at the ribbon cable connection (J1 pin 20). The surface mount version of the board has provisions to provide a reset signal at U10, but the necessary components are not stuffed.

As of April 2014, schematics for the 237-0255-00 DMD controller board (primarily surface mount components) are no longer available from Stern"s website.

The surface mount version of this board sometimes has dubious solder connections at some of the surface mount resistors and capacitors. The picture at left shows a fractured solder joint on the resistor in series with the "power on" LED. The LED would never light. Another fractured solder joint on the same board prevented the reset pulse from the MPU board from ever reaching the on board 68B09E.

This WhiteStar game system high voltage power supply (for displays) is an evolution from the larger Data East power supply. The high voltage section of this board is nearly identical to the high voltage section of Data East power supplies 520-5047-01 and 520-5047-02. Of course, those earlier Data East power supply boards regulate and supply more than display high voltages (i.e. 5VDC). As such, the WhiteStar board could be made more compact while using almost identical parts.

Generally, White Star boards are manufactured quite well. The traces are very fine, making alkaline damage repair difficult. But, those batteries shouldn"t be on the board, should they? The Atmel based MPU board uses a multi-layer PCB, which increases the need for clean component removal and replacement.

By the time White Star boards were being manufactured, improved methods of controlling solder temperature and junction temperature at the through-holes was much better understood. In the picture at left, the "spider" connections at some through-holes, allow less heat to be used to create quality solder joints.

As always, it is highly recommended to possess a game manual. Every game manual is full of detailed information regarding game specific switch, lamp, and coil assignments. Equally, details for maneuvering through test, audit, and bookkeeping screen menus, schematics for all boards used, and game specific mechanical assemblies are included. Hard copy game manuals can be purchased through several of the recommended pinball parts suppliers. Some Stern White Star Game manuals are available in PDF form on the Stern Pinball website. They are on the game specific pages of the Stern website. An index of games can be found in the right margin here.

All White Star Games use trough opto boards at the location of the trough VUK which feeds the ball to the shooter lane. Earlier White Star games (Apollo 13 to Viper Night Drivin") use only a single opto above the VUK plunger. Later White Star games (Lost in Space to NASCAR / Grand Prix) use a two opto system. The lower opto serves a dual purpose. It is the opto just above the VUK plunger like earlier games, but is also designated as trough switch #4. The upper opto is designated as the "stacking opto". Its purpose is to identify when a ball inadvertently gets "stacked" above a ball located at the VUK plunger.

To briefly summarize the operation of White Star VUK opto boards, if an object is blocking the light beam between the transmitter opto LED and the receiver opto LED, the CPU detects this as a switch closure. When an object is not present to break the light beam, the CPU detects this as an open switch. The components used on the opto receiver board are designed to do as such.

This particular system is contrary to how Bally / Williams WPC CPUs handle opto pairs. Equally, WPC games employ infrared (IR) opto switch pairs. If interested in learning the theory of operations for the White Star opto trough upkicker boards, please consult the manual. Sega / Stern have included some excellent, detailed, technical documentation within their manuals.

Only two Sega games used this style of magnet processor board - Twister and Goldeneye. When U1 for Twister is installed in the board, the board"s part number is 520-5143-01. The part number for the board when U1 is written for Goldeneye is 520-5143-02. Difference between the board used on each game is the different custom PIC / GAL chip used at position U1 and the Goldeneye board has R10, R11, R12, R13, D11 and D12 stuffed. This is not always the case with boards for Twister.

All Sega / Stern White Star flipper assemblies are solid state controlled. Apollo 13 and Goldeneye are the only two White Star games which use a separate solid state flipper control board located in the game"s lower cabinet. Starting with Twister, the flipper board was abandoned, and circuitry for the flippers was solely controlled by the FETs on the power driver board.

Solid state pinball machines typically have a built in system for audits and adjustments. All White Star based machines use a system called "Portals". The Portals interface is a carry over from the last two Sega games (Baywatch and Batman Forever) which used the original Data East board set.

The Portals system has a very user friendly, simple navigation system. Unlike previous Data East / Sega games, having to scroll through all of the audits and adjustments is a thing of the past. Diagnostic testing (including game specific assembly tests), audits, and adjustments can all be quickly accessed via the initial display menu graphical interface. The 3-button control panel (in most cases, except some earlier White Star games) used to access Portals is located on the coin door.

Most White Star games have two switches located on a bracket inside the coin door (hinge side). The upper switch is the memory protect switch. This switch is used so that nothing can be written to the memory, unless the coin door is open. The memory protect switch is not part of the switch matrix, nor is it one of the dedicated switches. Although it does connect to the CPU / Sound board via the same connector as the dedicated switches, its state is processed by a different chip (U213) versus the dedicated switches (U206).

If the GI lamps are blinking at about a 1Hz rate, this means that the MPU is not booting and that the I/O Driver board is sending a reset pulse to the 68B09E on the CPU/Sound board.

Inter-board ribbon cable fault inhibiting the reset of the CPU/Sound board watchdog timer DS1232. The timer is reset via signal DRV0, a lamp matrix signal.

Failed ROM. Note that the ICs on WhiteStar CPU/Sound boards are ALL installed notch down. Installing a ROM upsidedown and powering on immediately destroys the ROM.

Relocating the 3xAA batteries off the MPU board or installing other alternatives for memory retention is always a good idea. Leaky alkaline batteries are the #1 killer of pinball boards.

One option is to install a remote battery holder, and place the battery holder somewhere below all the other boards. This ensures that even if the remotely located batteries leak, they won"t leak onto (or even drip onto) components of the MPU board. Use good quality alkaline batteries, mark the date of replacement with a Sharpie, and replace the batteries annually.

Whatever you do, GET THE BATTERIES OFF THE BOARD! It"s not a matter of if they will leak, it"s a matter of when. WhiteStar boards are pricey to replace, and repair is difficult/expensive/even impossible due to the very fine traces used on the board.

A White Star MPU Board with Remote Battery Pack Connected. The Positive (+) terminal is circled. D200 and D201 are highlighted inside the rectangle. Note that the battery installation date is recorded with a Sharpie. Also note the long wires, allowing the holder to hang well below the backbox boards, another precaution for leaky batteries.

Adding a connector between the battery pack and the MPU board is a good idea. In doing this, the battery pack can easily be removed from the MPU board. Plus, if the batteries are forgotten, and do leak, the MPU board may not have to be removed to add another battery pack. A 3 x AA battery holder is the typical recommended replacement. If only a 4 x AA battery holder is available, a jumper can be soldered in the first battery position. Likewise, a diode can be placed in this position instead. Using a diode instead of a jumper will prevent the batteries from being charged and "cooked" by the game if blocking diode D201 on the MPU board fails. Keep in mind that a second (redundant) diode added to the circuit will reduce the backup voltage to the RAM memory by .5 to .7 volts. Install a 1n4001 or 1N4004 diode in the position closest to the last + terminal (where the Red Wire exits). The banded side of the diode must be pointing in the direction of current flow, which is towards the (+) terminal marking on the MPU board, and away from the battery pack.

Since the MPU board is already out, another good practice is to check the D201 blocking diode. An open blocking diode will not allow the battery pack voltage to pass through to the non-volatile memory, and the newly installed battery pack will be ineffective. Conversely, a shorted blocking diode will allow the board"s +5vdc logic power bus to pass through to the battery pack. This in turn, will charge the batteries, while the game is turned on. Alkaline batteries do not like being charged. They will heat up, and fail rather quickly. In worse cases, the new batteries can even leak or explode if charged. Testing the D201 diode is quick and easy, and worth the trouble checking it out. When in doubt, replace the D201 diode with a 1N5817 (a 1N4004 will work in a pinch), or add a redundant 1N4004 to the battery pack. Once again, if a second (redundant) diode is added to the circuit, it will reduce the backup voltage to the RAM memory by .5 to .7 volts

Testing the D200 diode is a good idea too. The D200 (1N5817) diode is used to keep the backup batteries from powering the complete MPU board when the power is off. A symptom of a failed D200 diode are batteries which deplete rapidly.

After adding a remote battery pack, and while the board is still out of the game, it is a good practice to measure the battery pack"s voltage at the VBATT test point on MPU board. All battery packs are pretty cheaply made, and failures "out of the box" are somewhat common. Checking to make certain the battery pack is functioning before reinstalling the MPU board in the game will save some headaches.

It is recommended to use a 1F (Farad) 5.5v memory capacitor. The lead centers on a common, button memory cap are shorter than the "+" and "-" through holes where the factory battery holder was installed. To overcome this, solder a short wire onto the negative lead of the cap. Then, bend the lead at a 90 degree angle, so it is now parallel to the bottom of the memory cap. Place the positive lead of the memory cap into the "+" of the board, and then place the wire from the negative lead into the "-" of the board. Solder both leads in place.

Sega/Stern White Star boards are well known for issues with leaky batteries. This is because the batteries are mounted on the top of the board with plenty of board beneath it for the corrosion to leach onto. Components well below the battery holder are often damaged.

Remember, battery corrosion is alkaline. Harkening back to the dim and distant past, remember your Chemistry 101. Alkaline is neutralized with acid. Most commonly used is vinegar, since it is an acid. Diluting the vinegar to half strength by adding an equal amount of water (50/50) is a good idea to prevent adverse impact to adjacent areas of the board.

Argh! The MPU pictured at left has sustained alkaline damage. In this case, the damage was repairable. Most of the time, alkaline damage to White Star MPUs is more substantial and beyond economical repair.

Just below the battery holder, the CPU EPROM and RAM both reside. Both of these chips and their sockets are susceptible to battery damage. Provided that the alkali damage breached the chip sockets, it is always best to check continuity on the new work performed. Below is a chart of the pin outs between the RAM (U212), EPROM (U210), and CPU (U209) chip. This chart will hopefully come in handy should repair of this area is necessary.

The +5VDC for logic power is sourced from the 8VAC secondary windings on the transformer. The 8VAC is fed to the I/O Power Driver Board, and rectified via bridge rectifier, BRDG21. The rectified DC voltage is regulated via an LM338K adjustable voltage regulator. Logic voltage can be adjusted via R116 on the driver board, which is a 50 ohm adjustment potentiometer.

U413, which is located on the CPU / sound board next to the reset button, is a Dallas Maxim DS1232 monitoring chip. In theory, should the logic voltage dip to less than 5% or +4.75VDC, the DS1232 will force a reset of the CPU. However, it has been determined that most White Star board sets will not function properly below +4.85VDC.

If the voltage on the power I/O driver board is below the +4.85VDC threshold, adjustment can be made via the R116 adjustment pot, until a satisfactory voltage is achieved. The best location to measure the +5VDC is at the bottom leg of resistor R114. R114 is located in the vicinity of the R116 adjustment pot, and just below the +5VDC LED, L2. Another location to measure the +5VDC is right on the metal casing of the LM338K regulator (U19), If a satisfactory voltage cannot be achieved, turn the game off. Remove connector J16, located above the LM338K regulator. Turn the game back on, and measure the +5V again. If a satisfactory voltage can be acquired with J16 disconnected, a board or component which uses the +5VDC is "dragging" it down. Turn the game off, and remove all 5V input connectors on all other boards at this time. Reconnect J16 again, and review the logic voltage on the I/O Power Driver board. Repeat the process of turning off the game, and reinstalling logic power connectors one at a time to determine the suspect board. Keep in mind that all opto switch receivers used throughout the game use the same +5VDC logic lines. If no other boards in the backbox appear to be suspect, an opto transmitter board may be at fault.

Should the game start randomly resetting, the first course of action is to measure the +5VDC on the I/O Power Driver Board. If the logic voltage is within spec., measure the +5VDC on the CPU / sound board. The +5V test point on the CPU / sound board is located just to the left of the 6809EP CPU chip (U209) on the board. If the voltage drastically differs between the measurement of the I/O Power Driver Board and the CPU / sound board, turn the game off. Remove and reseat connections CN2 on the CPU / sound board and J16 on the I/O power driver board.

While this looks to be an error, it"s actually a factory modification to the DS1232 reset generator. While this part is on the CPU/Sound board, there is an identical part on the driver board, which will have pin 3 clipped also. On the CPU pin 2 (Time Delay Set) might also be clipped. Pin 2 and 3 are left unconnected from the factory on the WhiteStar (modified) CPU/Sound board.

Both the WhiteStar MPU and Driver boards employ a DS1232 voltage watchdog. From the Sega and Stern factory, pin 3 is almost always clipped. Pin 3 is used to select the voltage tolerance the chip is to enforce.

An (probably) intentionally created solder bridge on a RottenDog power/driver board, bridging pins 3 and 4 on the DS1232 voltage watchdog, selecting 5% (4.75VDC) tolerance.

RottenDog WhiteStar power/driver boards may have a solder bridge across pins 3 and 4 of the DS1232 voltage watchdog. This is done to prevent pin 3 from "floating" and instead actively select the watchdog voltage.

It appears pin 3 (voltage tolerance pin) was left floating on their (RottenDog) design. That input is supposed to be tied high (reset at 4.5V or 10% VCC tolerance) or tied low (reset at 4.75V or 5% VCC tolerance) and should never be left floating. Adding the jumper from pins 3 to 4 selects the 5% tolerance. If the 5V line dips below 4.75V then your board will reset (which is what it is supposed to do with that setting).

Revision G of the WhiteStar Power/Driver board leaves pin 3 floating even though R257 is provided to jumper the pin to ground. A better option is to jumper pin 3 to 5VDC which configures the DS1232 to trip reset at 4.5V or 10% VCC tolerance. An easy method to achieve this is shown at left. This method uses the available through hole at R257.

This may be a bit of an anomaly, but it is worth mentioning. If when the DMD controller board is connected without the data line ribbon cables, and the game continues to reset, replacement of BRDG21 may be required.

In one particular instance, a game was resetting continually with only the +5v / ground connection connected to the DMD controller board. If the board was not connected, the driver board would output ~+5VDC. If the DMD controller board was connected, the driver board"s logic line would dip down to around +4.85VDC. Logically speaking, this type of symptom somewhat points to the DMD controller board having issue. However, the end result was replacement of BRDG21 per Stern tech support.

If the game is experiencing issues with multiple devices (coils, flashers, controlled lamps) that are controlled by the driver board, and those devices are "separated by 8 bits", there is a good chance that the data bus that connects to each of the 74HCT273s driver chips on the driver board has lost continuity somewhere between the associated MPU board dual row connector and the driver chips.

The Sega/Stern I/O Power Driver Board contains 32 driver transistors on the bottom right of the board. Transistors Q1-Q16 are MOSFETs – either 20N10Ls or P22NEs. These are used to drive high current coils like the flippers and other heavy loads. These are connected to devices through J8 and J9. Transistors Q17-Q32 are TIP 122s and are used for driving low power solenoids such as flash lamps. These are connected to devices through J6 and J7.

All of these drivers are computer controlled directly from the CPU board through a flip-flop on the driver board. Q1-Q8 are controlled through U1 on the driver board, Q9-Q16 are controlled through U2, Q17-Q24 are controlled through U3 and Q25-Q32 are controlled through U4. Each one of these chips is selected by the address decoder at U204. There is another address decoder at U205 and both of these decoders must be working properly for the I/O board to function.

It is possible to test the driver transistor and the solenoid in the circuit from the driver board. Above Q16 on the driver board is a test point marked “TPL1 FET”. Not a lot of people know what this is for. Per the manual: “This will apply 3.4v to the gate of the MOSFET transistor thus switching it on.” You’ll notice that the bank of resistors from R1 to R16 have a white stripe on one side closest to the MOSFETs. By using a jumper wire from TPL1 to the lug of each resistor in the white band, you can fire the coil associated with that resistor/MOSFET. Each resistor number corresponds with the same MOSFET number. So R1 fires Q1, R2 fires Q2, etc, etc. TPL1 is for testing all the FETs from Q1 to Q16.

If you look in that same photo above R302, you will notice “TIP TPL3”. This serves the same purpose as TPL1 except for the TIP transistors on the driver board Q17-Q32. By jumping from TPL3 to the leg of the resistor in the white band, you can test each of the TIP122s and their associated circuitry. This is a useful diagnostic step if the machine will not fire a coil in self-test or during a game. If you can fire the transistor with this test, you know the problem is with the computer control circuitry for the solenoids. However, if it doesn’t fire, it could be a problem with the transistor or the associated components in that solenoid circuit.

You might notice in the photo (prior section) that the white stripe is on the lower leg closest to the transistors of R1-16 and R25-32, but there is no white stripe on R17-24. Instead the stripe is on the lower leg of the resistors R200-R207. This is a screening error on the board but electrically match to the correct legs of resistors R17-24. As an example, if you want to test Q17, touch the leg of resistor R200 that’s in the white strip and Q17 should fire. The same holds true for R201/Q18, R202/Q19, etc etc.

The White Star driver board first used STP20N10L FETs to drive high current circuits, like solenoids. When they were discontinued later boards used the STP22NE10L. Since the 22NE10L is obsolete and even the current replacement, the

Lamp matrix power is derived from 13VAC presented to the I/O Driver board at J17, pins 8 and 9, via the transformer secondary winding. The circuit is fused by F22, an 8ASB fuse. BRDG20, a 35A bridge rectifier creates the 18VDC which is then smoothed by two 15,000uf/25V filter capacitors at C201 and C202. Of interest is the combined filtering of 30,000uf matches the original lamp matrix filtering capacity of old Williams System 3 games. When lit, LED202 indicates the presence of 18VDC power.

Lamp rows are implemented with STP19N06L or STP20NF06L FETs, controlled by the 74HCT273 at U6 on the I/O Driver Board. 39K current limiting resistors protect the 74HCT273 from sinking too much power. The 74HCT273 is strobed (enabled) via the LMPSTB which originates at U205 (a 74LS138 at U205, pin 15).

Lamp columns are implemented by the obsolete VN02N PENTAWATT solid state relay (5 legs). They are controlled by the 74HCT273 at U18 on the I/O Driver Board. 18VDC is "strobed" to the lamp column headers. The 74HCT273 is strobed (enabled) via the LMPDRV which originates at U205 (a 74LS138 at U205, pin 13).

A replacement for the obsolete VN02N has not been identified. In addition to the WhiteStar I/O Driver board, VN02Ns were used on Capcom driver boards.

The four general illumination (GI) strings are turned on and off via the relay on the power driver board. On the White Star board the relay is controlled via transistor Q200 and latch U206. This is more or less the same setup found in earlier Data East and Williams System 11 games where the relay is located on the power supply or PPB board. These relays seldom fail. The part number for the 24VDC relay is any of the following:

If the GI goes out during game play and turns back on when opening the door, check capacitor C32 on the power driver board. It normally has nothing to do with either the GI circuit or the relay voltage but a leaking cap can short the trace coming from Q200 to ground. In this case the relay pulls in and disconnects the GI. When you open the door the game cuts the coil power for the relay coil and the GI turns back on. This has been observed in a Twister game.

Switch columns (strobes) are connected to CN5 on the top edge, left side, of the CPU/Sound board. The columns are controlled by the 74HCT273 at U203 which sequentially controls an array of 8 2N3904 transistors. These transistors switch the 5VDC, normally held high via 560 ohm pull up resistors R423 through R430, to ground.

Switch rows (returns) are connected to CN7 on the top edge, right side, of the CPU/Sound board. 5VDC pull up resistors (560 ohms at R401 through R408) normally hold the switch row high. However, when the ground is presented at the row header of CN7, that 5VDC is pulled to ground. The signal is compared to 5VDC by the LM339 comparators at U400 and U401 with the result presented the the 74HC245 at U205 and then read via the 68B09E"s data bus.

Like most modern game manufacturers, Sega/Stern games employ a switch matrix. The switch matrix circuitry on the CPU/Sound board may be tested (as pictured at left) by jumpering between switch row and switch column header pins while in switch test. This works with all versions of the Whitestar CPU/Sound board.

Sega/White Star Transmitter, Receiver, and Opto "Long Hop" Board Pair, as found on Starship Troopers. Note that the ultra-red LED on the transmitter side is not lit until power is applied. The receiver side never illuminates.

Depending on the exact circumstances, and the era of the White Star game, one or two of these symptoms can occur. The crux of the problem is either one or both of the two trough LED opto transmitters or receivers is failing. Rarely do the components on the trough opto boards other than the red LEDs actually fail though. And in most cases, it is not the LED itself, although, there are some instances when the problem is a failing LED. It is noteworthy that the issue is more common to the opto receiver side more so than the opto transmitter side.

If the any of the previously mentioned symptoms are evident, the best approach is to fi