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Midway Rally-X Board Repairs

Picked up a Rally-X boardset last week, spent some time getting it going and a few others from the dead pile. I've always liked this game, something about the Namco designed games that I really like and this is one of them.  I've fixed a few of these sets over the years, some tips, ramblings and previous repair logs, enjoy!

Repair procedure (Stuff that I do before really going much further):

  • Inspect board for any damaged traces, etc.
  • Replace all masked roms with 2532 roms, just good preventative maintenance as the originals fall apart.
  • Make sure ribbon cables are good.
  • Use Fluke 9010a to test roms and 2114 ram on the CPU board (bottom board)
  • Clean legs on socketed ICs on video board.

Performing these steps first seems to solve a lot of problems with the boards I've worked on, similar to other games that use the masked proms where they tend to rust and become very brittle.

Top Board Repairs:

Random garbage on Screen/Video Issues (9/24/15) – Discovered that 9P, pin 3 was stuck low, replaced that, but no change.  Swapped at socket on 9R after confirming 9R was okay, but change.  Then realized that 8M and 8P were swapped and in the wrong place. Swapped them back and video issue cleared up quite a bit, but now a vertical line of cars instead of one car each.

Vertical Lines, no Playfield (9/24/15) – Initially suspected a bad ram, this board had 2147 ram installed, thought 9E might be the problem, but no changed. Noticed output on 9F at pin 15 was stuck low.  Replaced 74163 at 9F to fix the problem.

Playfield Missing (9/24/15) – Right side of screen was okay, but the complete maze/playfield was not visible.  Found 10E (93415 Ram) was stuck high at pin 7. Replaced ram and board worked.

Bottom Board Repairs:

Sound Issues (1/25/17) – Board booted and played, but only the crash sound was running, nothing else.  Outputs at 74LS273 at 1P didn’t look right, replaced it, but no change.  I should have spent more time looking at inputs, after further digging found that outputs at 74LS158 which eventually feeds 1P were dead. Replacing 74LS158 at 1P fixed the problem.

Garbage on Boot (1/23/17) – Not much sign of life, a few sockets were replaced at some point.  Burned new set of roms, installed them and board worked.

Rom 2 Error (9/24/15) – Reported Rom 2 error on boot, used Fluke to confirm rom was bad (it was) and replaced the rom. Board then reported ram “0H” error and failed ram test at 8000-83FF with Fluke which pointed me to 2114 at 6A based on my notes. Replaced 6A and board now works.

Garbage on Boot (9/24/15) – Immediately noticed Ram 6A socket was missing plastic piece, so I replaced and installed a 2114 ram, but no change.  Connected board to Fluke 9010a to test roms and ram and the board came right up. Installed another Z-80 and the board worked fine, so the original Z-80 was bad.

Rom OK Messsage (9/24/15) – Board wouldn’t pass self test. Top board known to be good, used Fluke to test Roms, all of them checked out okay (figured they’d would).  Put game in test mode and it reported bad OH ram, which led me to replace 6A.  Board now passed self test but played with color issues and some graphic issues.  Started pushing on ribbon cables and it would clear up a little, but not completely.  Replaced original cables with SCSI cables and board works fine.

Rom 1 – Rom OK Flashing (2/18/14) – figured this was a dodgy socket or bad mask rom.  First, I replaced all the mask roms as well as a few sockets that looked suspect.  Board booted with Rom OK message, put game in test mode and it reported bad “Rom 5H”.  According to the manual this is a 2114 at location 6E, which I replaced but continued to get the same message. Starting swapping out other 2114 rams and found that 6E was in fact the culprit.  Board booted right up now and works fine.

Graphics Color Issues (3/3/14)  - Game booted and played, but colors were off, car was red, just everything was off on colors and some graphics.  Bad prom at 11N was bad.

Taito's Qix Hardware and Games (Zoo Keeper, Kram, Electric Yo-Yo, Space Dungeon, Complex X)

Last Updated: 2/3/17 - Added a Video Processor and Sound Board repair.

I’ve always been intrigued by Taito’s games running on Qix hardware. Zoo Keeper is one of the best classic games out there and over the years I’ve spent way too much time researching these games messing with these boards, getting to learn a bit about them. 

While Qix and Zoo Keeper were two of Taito’s most popular classic games, Taito also released other games on the hardware, including Electric Yo-Yo, Kram, Space Dungeon and Complex X.  In my years of collecting I’ve owned all but Kram and Complex X. 

I don’t know production numbers but can say from experience (I’ve been collecting games since the late 90s) that Qix and Zoo Keeper are by the far the most common games, Taito probably made more Qixs than any other game as those are the boards I’ve come across the most.  Based on what I’ve seen Zoo Keeper’s production run was fairly high as well, but nowhere near as high as many of the classic arcade games you'll find, I’d probably consider it uncommon.

I have personally owned three Space Dungeons and seen a couple for sale over the last 20 years or so, I would consider it the third most common, but something I’d still classify as rare.  I’ve owned on Electric Yo-Yo and have seen maybe one or two other on the market in the same time.  I have only seen one (maybe two) Kram pop up for sale in the past and would say they are even harder to find that Space Dungeon. At one point I found a NOS Kram control panel overlay as well (I sold it while back). I do own a Kram bezel but it has seen much better days. I have never seen any Complex X games, only heard of a header and manual being found.

Space Dungeon running on a Taito test rig.

Space Dungeon Running on my Qix Test Rig

I’ve written this document to help other collectors preserve and learn more about these games and the boards that are needed to keep them going. 

Quick disclaimer: I have had pretty good success fixing these boards and converting them to the uncommon games over the years.  However if you don't know what you're doing in regards to soldering and working on arcade games find someone who does as you can make things worse.

Finally, this document is a work in progress, I plan to add quite a bit to it as I find the time, but I wanted to get some of this information out there.

Hardware Background

All of these games pretty much use the same boardsets, there are some minor differences but those are all related to Zoo Keeper (I can’t speak for Complex X as I haven’t had that running yet, but do plan to do one day).  I use Qix as a starting point as that was the first game released. Qix includes a Video Processor Board, Data / Sound Board and Rom I/O boardset. 

All later games include these boards as well as a Coin Processor Board.  Zoo Keeper includes one extra board, a Rom Expansion Board.  You can pretty much take a Qix boardset and convert it to any of these games.  You do need the Rom Expansion Board to make a Zoo Keeper boardset, there were reproductions of this board out there last I checked.

The Taito manuals are very good at explaining how these boards function and other details (good schematics, how to run test mode, etc.) so I won’t go into too much detail on each boardset, but here is a quick rundown and some other useful tips:

Video Processor – The largest board in the boardset, it mounts on the top of the metal frame and is probably the most common one to fail or not work when you find it in a game.  According to the manual this board, “performs all screen based functions, such as playfield image motion, line drawing, etc”.

Taito Video Processor Board used in all of these games

This boardset includes one of the 6809 processors (the game uses two to run) as well as two 2114 program rams, 32 4116 video rams and two 2148 rams, among other components.

The most common problem with these boards is that the battery originally mounted leaks corrosive acid which eats up traces and ICs on the boardset.  If you find a “clean” video processor boardset, you’ll have a much easier time getting it run as most other problems are related to the tantalum caps and 4116 rams which are all socketed.

Interesting side note, Slither uses the same video processor boardset as these Taito games, although it is labeled by Century II Corporation. I have personally tested one of these on my test rig and it works fine.  Slither uses a DSR (Data/Sound/Roms) which is different that Taito’s setup.

Century II Video Processor Board from Slither (will work in Taito games though).

Rom I/O – This is the middle board in the set and contains the game’s Program Roms for both the Data, Video and Sound Processors.  This board also includes three 6821 PIAs used to control the coin door and player inputs.  These boards are fairly reliable, assuming no corrosion got to them from the battery on the Video Processor boardset.  I have seen sockets go bad on these and occasionally a 74LS138 used to select the roms. 

Qix Rom / IO Board

The 6821 PIAs do fail from time to time, in which case your inputs will not work properly.  On the earlier versions of these boards they are soldered directly to the board, later versions they were socketed.

Data / Sound Processor – The bottom board used in the boardset and performs two functions, the Data Processor, “which supervises the operation of the entire system” and the Sound Procesor, “which generates sounds under the direct control of the Data Processor”.

Qix Data / Sound Processor Board

Again I find these boards to be pretty reliable, a good chunk of the ones I’ve found work right away, some have had bad 2114 ram or sockets as well as bad processors 6809 for the data side or a 6802 for the sound side.  I have come across a bad amplifier or cap as well related to sound issues in the past.

There are two versions of the Data / Sound Processor, Qix’s board is fully populated (except for U19) while Zoo Keeper used a boardset what didn’t include certain components on the bottom left hand corner of the boardset, include the J9 connector, U21, U25, U22 , SW1 and U26, among other components. 

Zoo Keeper Data / Sound Processor Board (note the empty area on the bottom left hand side).

They are pretty easy to tell apart when side by side.  Note that you can convert Qix Data / Sound boards to Zoo Keeper, the procedure is as follows:

1. Cut trace between TP-5 and U17 pin 6 on the component side

2. Cut trace between U23 pin 13 and feed through hole on solder side.

3. Wire Tp-5 to U23 Pin 13.

4. Wire U17 pin 6 to U23 pin 12

I believe all of the other Taito games (Space Dungeon, Electric Yo-Yo and Kram) use the Qix Data/ Sound board.

Coin Processor – Since all of these games share the same hardware, Taito added a Coin Processor board to all games (except for Qix as it was the first released) to prevent operators from converting one game to another.  Luckily, there is a coin processor bypass rom available for games, which allows you to eliminate the Coin Processor and basically convert Qix boards to any other game out there. 

My Game is Broken. How Do I Fix It?

Probably why you found this article in the first place was to figure out how to fix your Qix or Zoo Keeper. My first word of advice is to be patient, these boards and games can be overwhelming, especially if you don’t have much experience with classic arcade games.  They are probably not a good first choice for a novice, but I’ll do my best to provide some repair tips.

Assuming your monitor is known working, the first thing to suspect is your power supply, the Taito Linear power suppliers are notorious for failing. I highly recommend installing a switching power supply kit sold by Arcadeshop. It replaces the old power supply with a modern power supply and includes a reset circuit board which is needed to have these boards boot-up. 

First check that you have the proper voltages on the boardset (be sure to measure for +5VDC, +12VDC and -5VDC as all of them are used on these boards). Next step is to see what the game does on boot-up, assuming it doesn’t fully boot take a look at the LEDs on the Video Processor board as they may tell you what is wrong.  The manual will walk you through the self test procedure and hopefully point you to a failing IC. I won’t go into too much detail, but will say this isn’t always 100%, it cannot detect every error or problem.

If you don’t get anywhere with the self-test procedure I would do the following, these are things I pretty much to do every boardset I work on and it addresses quite a bit of problems with them:

  1. Check your ribbon cables, reseat them, cross your fingers, ideally just replace them with a new set if possible as they can cause so many problems. I can't emphasize this enough, I've had boards run fine and then not boot 10 minutes later due to touchy ribbon cables.
  2. Check factory jumper wires on the board to be sure they are in place.
  3. Carefully reflow solder joints on header pins on all of the boards.
  4. Check reset circuit, try powering board up a few times. Some seem more touchy with regards to booting and the reset circuit setup.
  5. Replace all 10uf 25V tantalum caps near 4116 rams with electrolytic caps on Video Processor board.
  6. Replace all 4116 ram chips on Video Processor board
  7. Replace 2114 sockets at U3 and U4 on Video Processor board

Rom I/O Board Info

I’ve mentioned all of the Rom boards are the same for all games, Qix Rom boards were shipped with jumper packs for 2716 roms (which Qix uses), most other games use 2732 roms and need 2732 jumper packs, I’ll get to this eventually.  There are multiple rom versions for Qix, I have not seen multiple rom versions for the other Taito games.  I’ve seen Qix boards with at least three different rom set versions:

QQ Rom Set 1 – Consists of 16, 2716 roms at U3 through U19 and one sound rom at U27, all roms are labeled QQ3, QQ4, etc.  For some reason these boards almost never seem to work for me. I’ve seen a bit of these boards in my time.

Qix Rom / IO Board with QQ Rom Set 1 Roms Installed

QQ Rom Set 2 - Consists of 16, 2716 roms at U3 through U19 and one sound rom at U27, all roms are labeled “QQ3 -02”, “QQ4 -02”, etc.  This rom set is common.

Qix Rom / IO Board with QQ Rom Set 2 Roms Installed

QU Rom Set 1 - Consists of 14, 2716 roms at U3 through U19 (except for U6 and U15, they are empty) and one sound rom at U27, all roms are labeled “QU3”, “QU4”, etc. with handwritten labels. This rom set seems to be uncommon. 

Qix Rom / IO Board with QU Rom Set Roms Installed

Qix II: Tournament Rom Set - Don't have one handy, but I've seen this running on some Qix Rom boards as well.  

For some reason almost every board I have with QQ Rom Set 1 does not run on my test rig, I have no idea why, if anybody has some insight let me know.

The biggest issue I've had with rom boards are bad roms and bad rom sockets.  If you're rom board is bad I'd start by pulling and checking the roms, and then move onto the rom sockets and the 74LS138 ICs on the boards. If you're looking enough to have a Fluke 9010a and 6809 pod you can use it test the rom signatures: roms U3 to U10 using 6809 on the Video Board and roms U12 to U19 using the 6809 on the Data / Sound Board.  

There really isn't much else to look at.  Before doing anything check the board for signs of corrosion, I've seen many of these boards with bad traces and sockets from the battery on Video Processor leaking acid on them.  Sometimes they aren't worth the effort to fix if they are badly corroded.  

I would also recommend reflowing the solder joints on the header pins, especially at J11 as that is the power input to the board.  The joints are usually okay on these boards, but it is good preventative maintenance.

If you're having an input issue (start buttons, joystick, buttons or test mode buttons not working), check the 6821 PIA chips on the rom board, there are three of them, the schematics show you which inputs they control.  The 6821 PIA chips are soldered on some boards and socketed on others.

If your having a sound issue and you're certain it is NOT the Data/Sound board, U27 (and U26 on some games) are the sound roms, check those roms as well as the sockets.  

Repair Logs

I've fixed quite a few of these over the years, will add to this list as I have the time and fix some more.  Here goes:

Video Processor Boards

Dead, Nothing on Screen (2/3/17) – This was a board I had repaired for someone, came back to me as not working.  It was dead on boot, all LEDs on, replaced processor socket just for the heck of it.  Used Fluke 9010a to try to test roms, but none were testing properly.  The buffer ICs looked good, noticed some corrosion on the legs of 74LS08 at U101, it wasn’t horrible, but enough to make me want to replace the IC.  Replaced U101 and board booted again and now works.

Dead, Nothing on Screen (1/8/17) – Board didn’t show much signs of life, but hit the test switch and LEDs responded and indicated a bard CMOS ram at U85 or U86.  Tested them in a good board and U86 was bad.  Board now booted with a video issue. Ran self test it reported bad 4116 ram at U26. Pulled it, one leg was out of socket, reseated it and board worked. Replaced tantalum caps near 4116 rams as preventative maintenance and ran board overnight without any issues.

Dead, Nothing on Screen, All LEDs Lit (12/15/16) – This board had no corrosion, but was bounced around a bit as both of the 50 pin connectors had broken and bent pins and it was missing its 2114 rams.  Since the traces were very clean I decided to spend a bit of time rebuilding it, replaced both of the 50 pin connectors (J3 and J6) as well the 2114 ram sockets (u3 and U4) and 6148 ram sockets (U56 and U57).  I also replaced the 6809 socket (U82) and 6845 socket (U18).  Both of those sockets were falling apart as I removed them, the legs were breaking off once I removed some solder, so it was a good call replacing them.  I also gave the board a quick bath and scrub down.

After replacing all of the above, I was optimistic it would be close to working, but it booted with all LEDs on and nothing on screen.  Poking around I noticed the clock signals were missing on the 6809 (pins 34 and 35).  Worked my way backwards and thought the problem was 74LS74 at U36, replaced this but no change.  More poking and I noticed U36, pin 12 was stuck low and shorted to ground on the board.  Traced this back to the large connector that I replaced at J6, pin 27.  When I replaced this connector I shorted this pin to the ground pin right next to it.  Visually it looked fine, but there must have been some solder shorting it out. Removed the solder on those connectors, resoldered and the short went away.

Board now booted with a minor video issue which I found to be a bad 4116 at U30 by using the game’s self test procedure. Replaced the bad ram and board is now working. Will probably hang on to this one for my test board due to the amount of time I have in to it. Always nice knowing having a reliable, rebuilt test board to work from.

Rom Boards

Zoo Keeper Rom, Sound Issue (1/18/17) – Board would spit out some garbled sounds, but definitely not right.  Pulled sound roms, all tested okay in working boardset.  Replaced 74LS138 at U28 since there is much else in the circuit driving sound and sounds came back.  Guess it could have been rom sockets, but all of the other roms had original sockets and the board was otherwise working.

Qix Rom, No Sound (1/11/17) - Board booted up and played fine but no sounds. Pulled the sound rom at U27, tested fine in my rom burner. Swapped the rom in a known working board and I had no sound.  I've seen roms do this a couple times before test fine in my burner but not work in a board, can't really explain this one, but it happens.  Burned new U27 rom to fix the board.

Zoo Keeper Rom, Sound Issue (12/20/16) – Originally thought this was a bad Data/Sound board, as it would just spit out a beep or two, some static and then sound would cut out.  Turned out jumper pack at U29 for sound roms was loose.  Would hold it down and sound would come back.  Replaced socket with machine pin sockets as I was using a custom made jumper pack that wasn’t making the best contact with the original socket.

Qix Rom, Boots to Initial Screen with Languages, but that’s it (12/9/16) – This board seemed closed, would boot to first test setup screen but not go to attract mode.  Ran self test and it gave an error at the U8 rom.  Pulled the rom, it had some corrosion and the socket was corroded. Remove the socket, cleaned up the corrosion, installed new socket and new U8 rom and the board booted fine.

Zoo Keeper, No sound (9/29/14) – Board played fine, but no sound. Pushed hard on rom U27 and the sound came back on. Rom socket solder joints looked iffy, but I just replaced entire socket to fix the problem.

Zoo Keeper, Nothing on Boot (9/29/14) – Board was marked as okay and roms tested okay. Noticed that when I messed with U22 I’d get signs of booting so I replaced that socket, but no change. Replaced 74LS138 at U21 and that fixed most of the problems.  Game came up and played, but would not completely cycle through test mode.  Swapped 6821 PIA at U11 and that solved the problem.

Zoo Keeper, Nothing on Boot (1/30/12) – Board would do nothing on boot-up.  After a quick glance, the jumper packs were installed backwards.  Fixed the jumper pack orientation and the board would boot but in game mode I would only get some stair graphics.  Put board in test mode and it reported a bad rom Z13.  Replaced the rom and the board worked.

Zoo Keeper, Nothing on Boot (12/12/11) – Board would not boot, other boards known good in set.  Tested all of the roms, they were okay, but still no boot. Also tested the jumper chips and they were all fine.  Was real puzzled here, tried the roms in another board just to be sure, and they were fine.  Finally started pushing real hard on the roms and trying to reset board and it came up.  Started replacing rom sockets, about 4 of them were touchy, one was very corroded.  Kind of odd since there was no corrosion signs on the board itself or traces.  Board now booted up but wound up locking up after 10 minutes…

Tried to power it back on and it didn’t come back up. Checked continuity on rom legs and everything was fine.  Checked 74LS138 chip at U2 and noticed the outputs were not correct compared to working a board.  Checked the inputs and they seemed okay. Replaced U2 and the board came up just fine.

Sound / Data Boards

Nothing on Power-Up (2/3/17) – Quick inspection showed that 74LS244 at U1was removed at some point (probably for parts).  Installed new socket and 74LS244 and board booted, but no sound.  Further inspection showed that someone started remove 74LS244 at U12 (guess they gave up and removed U1 instead).  Finished removing it, installed s new socket and another 74LS244 and sounds came back with a minor issue.  

Sound issue was tough to describe, certain sound patterns had a “click”, just something was off, if you didn’t know the game you probably wouldn’t have noticed it.  Replaced a few ICs (U20, U24) but no change, initially my gut told me this was something else (not a bad IC), but tried replacing those chips anyway.  Compared board to another board and noticed C44 was missing, but clearly the board was shipped without it from the factory.  Dug out some other boards and they had C44 installed.  Installed 1uf 50v cap at C44 and the problem was fixed.  Not sure if this was an early board that didn’t have installed or it was just never installed by mistake.

Powered on, locked up almost immediately, initial setup screen issue (1/18/17) – Clean sound board that came up, but at the “This Location” screen the first character was constantly changing, almost like a test switch is toggling.  After going into game mode, board would lock up almost immediately.  Replaced the sockets at 2114 for preventative maintenance, tested 2114 rams, they were okay.  Tested 6809E and it caused the same problem in a working boardset. Replaced 6809E and board is now working.

Sounds would also drop out after a while, sometimes 5 minutes, sometimes 15 minutes.  Initially suspected a bad socket in sound circuit, replaced 6802 socket at U5, but no change. Also replaced socket for 6821 at U7, still not change. Noticed when I pulled U7 with board running, sounds would come back.  Replaced 6821 to fix the problem.

Working, but Sound Would Cut or Not Work sometimes (12/12/16) – Board worked just fine sometimes, other times no sound, sometimes it would cut out after 5 minutes or so.  Replaced the 6802 socket at U5.

Nothing on power on (9/29/14) – Quick visual showed a bent pin on 6809, which I straightened out to fix the problem.

How to Convert your Qix Boards to Another Game

You can fairly easily convert any Qix boardset to EYY, Kram or Space Dungeon by burning a new set of roms and replacing the jumper packs at U1 and U22 on the Rom / IO board.  You’ll need a 12 blank 2732 roms, a blank 2716 and a rom burner in addition to 14 pin sockets to make the jumper packs. Here's a quick summary of the games and what roms they use:

When converting boards from Qix to other games that use 2732 roms, make sure you change the jumper pack at U1 and U22 (and U29 if that game uses 2732 roms  for the sound (U26 and/or U27, Zoo Keeper only).  You can make these jumper packs by hand using 14 pin machine tooled sockets and some light weight wire or thin metal (cuttings from caps work very well for this).  

Just run your jumper leads from pin 2 to pin 14, pin 3 to pin 13, pin 4 to pin 12, pin 5 to pin 11 and pin 6 to pin 10. I use a dab of solder on each pin to hold the jumper in place.  Here’s a visual of what it should look like:

Also make sure you use the coin bypass rom (U14 for all games, I believe).  Space Dungeon will boot without the coin bypass rom and is playable but reverts to the test mode after a game (don’t ask me how I know that). Once you have your new roms burned and jumper packs installed the board should work.

Hopefully this will get closer or up and running.  Eventually I will add some more repair tips, just out of time right now.  Some upcoming topics I’ll be also be adding:

How to Save your Scores

How to Build a Qix/ZK Test Rig

How to Play Zookeeper Like a Pro

Few MCR-II Sound Board Repairs

Updated 4/3/17 - Added a few more repairs.

Been working some MCR boards recently, not my favorite boards to mess with, I probably give up on half of them as my board repair skills aren't quite there yet. I have had decent success with sound boards, just fixed a Domino Man sound issue, figured I'd post it along with a few other sound repairs from a while back. Here goes:

Tron Sound Board, Sounds cut out on MCP Cone Stage (4/3/17)- Board would sometimes report an A9 Sound Rom error, sounds would always cut out during MCP Cone Stage and not come back. Replaced rom socket, no change, it was a newly burned rom, burned another A9 Sound Rom and it worked fine.  The first rom did verify okay in my rom burner, but was apparently not happy when installed, not the first time I’ve seen this.

Tapper Sound Board, caused video issue when going up (6/15/16) – originally thought this was due to a mismatched rom set on the video and CPU board, later realized the issue was only caused when moving up. Replaced 74LS244 IC at E2 where the “Up” input goes through and it fixed the problem.

Domino Man Sound Board, No Sound (5/17/16) – No amp buzz, took me a few minutes to realize the +12 VDC varistor was smoked on the CPU board due to a shorted tantalum cap on the sound board (very common on Super Sound I/O boards).  Replaced both of those and the sound came up but would spit out a nasty buzz during certain sounds. From prior repairs I suspected a 4016, when probing with the scope, the buzz would shut off on the 4016 at D8. Replaced D8 to fix the problem.

Tron Sound Board Interface Error and No Sound (7/13/10) – Bad 2016 Ram at A6 on Super Sound I/O

Tron No Sound with good Sound Board (7/7/10) – noticed no amp buzz, there was no +12 VDC on sound board. The Super CPU board had a bad varistor on the +12 line.

Tron Sound Board Spinner not working right – (1/28/11) – spinner would skip a spot at top of guy.  Small .1 cap (C114) was reading different than all other caps in that row. Replaced it and problem went away.

Distorted Sounds on certain Sound Effects (3/7/12) – some sounds played fine, others were barely audible or very distorted.  Replaced the LM3900 as I could hear some of the sounds but it didn’t fix the issue. Started at the AY-8910 sound IC and found an output of a bad sound.  The sound seemed to be generating there, so I went to 7407 at C6 and found that pin 13 was high, but should have been low.  Replaced the 7407 IC and the signal was now low again, but I still issues although the sounded a little different.  Started comparing signals at the three 4016s and found that D7 at some very high outputs (9 VDC), compared to 1.8 VDC on the other 4016s. Replaced D7 and the problem was fixed.

Missing Sounds 8, 11, 16, 24, 22 and 25 (3/12/12) – some sounds missing, other sounds had a loud pop after they played in test mode. Started at the AY-8910 sound IC and found the sounds were being outputted at this IC  Started comparing signals at the three 4016s and found that D9 at some very high outputs at pins 3 and 9 (9 VDC), compared to 1.8 VDC on the other 4016s. Replaced D9 and the problem was fixed.

Tapper Sound Board (7/20/12) - missing roms, burned new roms, but no sound. Outputs at F6 and F7 were dead, replaced the AY-3-8910s and sound came back.

Tapper Sound board (7/20/12) - same board as above. I was using the ground lead on cap CP1 to add credits and start the game, but noticed it wasn't always working. Turns out the CP1 was not soldered on the ground side.

Minefield Board Repair Log

I've always been a big Stern video game fan, still own a Minefield upright and picked up another Minefield board a month ago. The board was sold as untested, was hopeful it would work, but it came up with video issues as shown below.

The board did appear to play, just  hadscrambled video that was scrolling a bit as well.  Minefield boards are basically modified Scramble boards (and probably other classic Stern games).  Dug out my Scramble schematics and after 10 minutes realized that my VSYNC signal was missing at 8L and 9D, but present at 8L.  Quick visual inspection showed a damaged trace that I jumpered.  The board's video looked much better but was still rolling and not locking in. Tried it on another monitor and it did the same thing.  Checked my work and there was also a second trace that the gouge took out. Fixed this one as well and the board fired up perfectly as you can see.

One of the golden rules of board repair is always do a visual inspection prior to starting work, I did do one, but apparently not well enough as I didn't catch the broken trace until some troubleshooting work.

Mappy Board Repair Log

Spent some time working through a few Mappy circuit boardsets today.  Always loved this game, I still own one, unique cabinet and a pretty fun, quirky game.  Anyway here are some repairs from today and a few from a few years back.  I always recommend carefully removing and cleaning the legs on the custom ICs on this board. As you can see most issues were fairly straightforward, these boards seem to hold up pretty well over time. Enjoy!

Low sound - bad C30 cap.

"MAPPY" logo distorted on title screen - 4M Custom Chip on video board had dirty legs, cleaning them solved the problem.

No text on titles scren, etc. - Rom 3B on video board had a bent leg that was not in the socket.

No sound - amp was humming, so I suspected something else.  Prom at 3M on CPU boardset was bad.

Ram 3 Error - manual pointed to 6116 Ram at 2N, but replacing it didn't help.  Also tried ram next to it at 2M, no change, but sometimes it would boot okay.  Replaced both ram sockets for good measure.  Still booted with Ram error at times.  Kicked up the voltage from about 4.9 VDC to 5.1 VDC and board booted everytime.

Color Issue - Looked prom-ish, sure enough Prom at 5B at one leg out of socket.

No Sound (no hum or "audio pop" on boot) - Replaced by C29 and C30 as one looked iffy and a bit worn. Sound came right back.

That's all I have for now, probably will be some time until I get back to these boards, but hopefully this is of use to somebody someday.