RSS

Articles & Guides

Pac-Man / Ms. Pac-Man Repair Log

Spent some time going through the box of broken Pac-Man / Ms. Pac boards we've got kicking around the shop.  Seems like some Pac fixes are very straight forward, others I really struggle with and throw them back in the box. I think part of the problem is the how the boards were stored, some were thrown in a box, might have a scratch or two or some rust some ICs.

These days I tend to only work on cleaner boards, ones that haven't had prior repairs as sometimes the prior repair is botched and makes troubleshooting a PITA. Anyway a few tips for Pac repairs:

  • Check out the repair logs, there are quite a bit of repairs out there as well as some good resources on repairing these boards, I'm too lazy right now to look them, Google is your friend.
  • Check out the two original Midway Pac-man Advance Troubleshooting Manuals, again Google is your friend.
  • As always, inspect the board for damage and other prior repairs.

Here's my basic Pac-Man repair procedure, at the last the beginning, the Midway manuals have additional steps:

Pac-Man / Ms. Pac-Man Board Repair Procedure

  1. See Pac-Man Troubleshooting Manual.
  2. Always use known working satellite boards, usually replace the sockets for the satellite boards right away as they tend to fail.
  3. Always use known working roms on main board. I usually just remove the original proms and burn new 2532 eproms.  For Ms. Pac-Man, make sure 2532 roms at row 6 are 45ns or faster.
  4. Check Ms. Pac-Man ribbon cable, they go bad often.
  5. Test for voltage on large caps, should be 8.0 VDC on these. Test for 5 VDC on boardset.
  6. Check for clock signals at Z-80 and other test point (per manual).
  7. Make sure reset signal at Z-80 is high.

After this I go into using the Fluke 9010a to check that the program roms and program rams are working. After that I usually rely on prior repair logs to narrow the problem down if I don't see anything myself.  Some of my repairs from over the years, I don't usually note as many bad program roms anymore as I usually replace them first as preventative maintenance, hope this helps:

No Video, Deadish (3/28/17) – Board had fresh set of program roms installed, fairly clean boardset.  Voltage was 6.2 VDC on chips, turns out Q6 was shorted together on the back of the board as two traces were touching each other. Replaced Q6 and voltage was back at 5.05 VDC.  Clock and reset line checked out okay, used Fluke 9010a to test Roms and Rams, no problems.  Noticed reset line was not going low when hit the push button switch near the amplifier.  Replacing 74LS161 at 9C fixed this problem, but no change.  Visual inspection showed that 4F was installed backwards, replaced it with a known working Prom and the board fired up.

Board booted to Garbage, pretty much all “P” on the screen with other garbage graphics (3/28/17) – Board had fresh set of program roms installed already, replaced the sockets on the Z-80 and V-Ram board, replaced the Z-80 socket for the heck of it.  

Roms checked out okay on Fluke 9010a, all 2114 ram tests failed. Swapped rams and found 4R to be bad.  Replaced it and board was much closer, playing with wider horizontal red lines across most of the screen (except top and bottom).  Research of other repairs pointed to 2125 rams at 2A to 2D, piggybacked 2D and the problem cleared up. Installed new socket and 2125 ram at 2D to fix the problem.

Game Booted, but Everything was Super Fast, Not Working 100% (3/24/17) – Board looked fairly close to working, it booted up, but attract mode was moving really fast, game didn’t really play when you started, but it was close.  Maze was being redrawn very slowly during game mode.  Checked roms and with 2114 with Fluke 9010a just to be sure (didn’t think they were the problem) and they were fine.  Used Two Bit Diagnostic tool and the board didn’t pass the Interrupt test. Swapped at 74LS74 at 8C as it was already socketed and it fixed the problem.

Slight Hum Bar, Doesn’t work with Jamma Adapter (3/22/17) – Kind of an odd one, board had a very minor vertical hum bar.  Also, would not boot on a Jamma test rig (DC voltage was at 2.3 VDC), only on a original AC harness.  Replaced big filter caps, D6, D7 and D8, voltage regulator and a few other electrolytic caps, but no change.  Turned out Q6 on the heat sink was bad, replaced with a TIP31C and it booted perfectly on both test benches.

Sounds Missing/Scratchy (3/22/17) – Most sounds were missing or barely audible.  Bad prom at 3M.
When converted Pac-man to Ms. Pac-Man (11/24/14): The game comes up and plays fine, but then ghosts start flashing diagonally on the screen. It is not all of time and only when the maze screen is on. After it runs for a little while the ghosts start going through the maze blocks (not the on normal maze path). None of this happens when the board is left as Pac-Man. – Slow 2532 roms at row 5, use 45ns or faster.

Gobbling sounds and dying sounds off (11/18/14) – Bad prom at 3M.

Board would constantly try to boot (1/23/12) – Looked like the game was booting up, but it would never quite get there.  Reset line was going from high to low corresponding to the resetting at booting.  Started pressing on a few sockets and it seem to get further on booting, so I replaced a Z-80 daughterboard socket and rom socket, but no real change.  Finally noticed that if I left the game on for a couple of minutes it would get closer to booting and sometimes boot up fully and work.  Tested voltage on the two large caps and it was 7.0 VDC.  I replaced these caps and it the board booted fine.
Lesson learned: always test power supply voltage first.

Board comes up with “1” on top left corner of screen (3/19/12)  - This board was okay, then started acting up. I replaced a rom socket I thought was bad as well as the Z-80 and Z-80 daughter board sockets, but no luck.  Started pressing on the ribbon cable and the board would boot. Went through about 3 ribbon cables until I found a good one.
Lesson Learned: always check the ribbon cables.

Most Sounds Missing (3/19/12) – Most sounds were missing and those that did play seemed off.  Replaced 1N and socket at 1M as they looked pretty bad (rust). Could see sound signals going to 2M but not coming out, so I replaced 2M to no avail.  Noticed that 3M looked pretty rough and when I pulled it legs fell off of it.  Installed a new socket, but no change.  Checked signals going to 3M and were missing signals and pins 2 and 3, checked for continuity at 3P and 3N and didn’t get any. Ran two jumpers and the sounds came back.

Sounds Off Slightly (3/19/12)  - Everything played,  just seemed a little off. Replaced most caps in audio circuit to no avail. Reseated 1M and they came back.

Board had zeros all over the screen (3/19/12) – This board was working, but just came up with zeros. Self test didn’t show a ram error, but the troubleshooting guides suggested 4K was bad. Replaced 4K and it fixed the problem.

Boots to “1s” on the screen (3/19/12) – Self test didn’t change anything. Reset and clock lines looked okay, checked the bus with the 9010a and found data lines 2 and 7 stuck together.  Found a small socket tail shorting out the two data lines and fixed that problem.  Checked the program roms with the 9010a and found that 6E was bad. Board would now come up with an illegible ram error.  Tried the 9010a and it said ram 4K or 4N was bad.  Replaced 4K and the game now came up with graphics were off. Pulled graphic roms 5E and 5F and they were both bad. Burned new roms and the game works.

Game Plays but characters at bottom of the maze and only move horizontally (3/20/12) – actually a continuation of the last repair, I didn’t notice this until the next day. Game plays fine, but characters were offset low and moved only left and right.  Game seemed fine otherwise, started poking around in the final video output section and found that 1E pin 9 input was stuck high. Traced this back to 4C and found that pin 5 was stuck low. Replaced 4C (74LS00) and the problem was fixed.

Garbage on Screen (3/20/12) – Board was recently repaired as Pac-Man Plus but had Ms. Pac-Man roms and Proms installed. Suspected something with the roms as I knew it was recently working.  Connected 9010a and tested the roms and found 6E was reporting as bad. Pulled 6E and it verified okay with burner, but tried another rom just in case.  Problem was fixed, apparently the original 6E rom had some issue but still verified okay with my burner.

Nothing on Screen (3/20/12) – Board was noted as worked when complete. Installed new roms and it booted with nothing on screen. Connected 9010a and tested the roms and found 6E was reporting as bad. Installed another rom at 6E and the board booted but with horiztonal lines through characters across entire screen. Pushed on graphic roms at 5E and 5F and problem corrected itself so I installed new sockets.

Board would not come up after the new sockets were installed. After a few minutes I found the issue, when replacing the sockets a blob of solder fell out of the desoldering iron. I was able to clean it all up but broke a trace near 4E in the process. Repaired the trace and the board booted fine.

Nothing on Screen (5/16/12) – Tested for voltage and it wasn’t there and I smelled something burning.  Starting rebuilding the power supply for the heck of it and finally realized that two large diodes were worked on before and installed backwards. Replaced these and got my +5VDC back.  Boardset would then come with a out of sync screen, but coin up and play.  Sometimes the game would lock-in and play fine.  Started poking around and tapping on chips and found 3R (74LS161) was the problem.  It was replaced at one point and the socket and chip legs looked beat, so I replaced the socket and IC and the board worked.

White screen (5/17/12) –Board came up with a white screen, clock, reset, program roms and ram checked out okay.  Followed guide in troubleshooting manual and did not see any address signals at pins 5 and 6 at 4A.  Traced this back to 5A and noticed the IC was rusty.  Found about another 10 rusty ICs that I replaced until the board came up.  White screen was caused by bad IC at 3B (74LS157).

White background, red maze, blocks behind characters (5/17/12) – part of the rusty chip repair, bad IC at 5C.

No Sound (5/18/12) – Lost all sounds in testing.  Quick look found that 1L was rusty, so I just replaced that at the sound game back.

Two distorted characters on top right and one "zero” on top left (5/29/12) – Continuation of rusty chip repair.  This corresponds to a Ram 4M error, so I replaced that but not change. Also replaced the socket, no change.  Sometimes board would boot and play fine.  Finally realize Z-80 controller had about four more rusty ICs.

Pac-Man color off and some ghosts off (5/29/12) – broken trace at pin 15 of 2A.

Random Garbage on Screen (5/30/12) – Ms. Pac-Man board that booted with just some random characters and garbage graphics.  Starting swapping daughterboards and the Z-80 controller daughterboard was bad, had a number of rusty ICs.

Horizontal lines in characters (5/30/12) – Character rom at 5F had a bad socket.

0
05 February, 2017

Donkey Kong and DK Jr. Repair Log

Spent a bit of time going through some Donkey Kong and DK Jr. boards I've had sitting for a while.  Not included in these repairs are a few boards that had bad roms and/or bad rom sockets.   Boards with bad roms and/or a bad socket are fairly common in my experience and the first thing you should look at.  Also check the pots on the video boards as they tend to crack if the board has been banged around, the board will look out of sync if the pots are bad.

Donkey Kong Jr. CPU Boards

Jump Sound off Pitch, No Walk Sound (2/8/17) – This was a board I just fixed with the constantly thumping sound. Didn’t notice it had another sound issue until further play testing.  Replaced caps in jump section as well as some other caps in sound section, but no change.  Replacing 4020 IC at 6L fixed the problem, thanks to Scott Brasington for documenting this repair online.

Jump Sound Off Pitch (2/7/17) – Jump sound was out of pitch, just not right.  Replaced C24, C23 and C22 but no change.  Closer inspection showed pin 9 of 8L was never soldered properly through the board. The leg was bent and didn’t make it through the solder hole.  Looked like this was from the factory, the jump sound probably never worked properly. Was able to remove solder from hole, run a small metal lead through the hole and solder it to the leg to fix the problem.

Thump Sound Constantly On, No Music (2/7/17) – The “thump” sound from Donkey Kong jumping at the beginning of stage was constantly playing, no music was present. Initially thought this was a bad transistor as that seems to be common issue when sounds are stuck “on”.  All sound transistors tested good, swapped out the 8035 and sound rom, no change.  Recapped the sound section just in case, but no change.  Grabbed the logic probe and starting probing around before the 8035 and found pin 10 at 74LS04 at 6J was stuck low (it should have been high).  Replaced 74LS04 at 6J to fix the problem.

All Low Sounds (2/7/17) – Sounds were present, but very low.  Noticed R1 was burnt, replaced it, no change. Pulled Q1 and it tested bad, replacing C1815 at Q1 fixed the problem.

Donkey Kong CPU Boards

Garbage on Screen (1/31/17) – CPU boardset booted to garbage, went to pull Z-80 and test roms with Fluke 9010a.  Original Z-80 socket was replaced and the replacement socket didn’t look very high quality and poorly installed. Removed the socket, cleaned up the area as best I could and installed a new socket, board now works.

Garbage on Screen (1/31/17) – Fairly clean CPU boardset, complete, but boots to garbage.  Used Fluke 9010a to test roms and found program roms at 5C and 5F where bad.

One background sound during intro sequence out of pitch (after DK thumps) – recapped entire sound section, but no change.  Replaced LM724 at 8K and that fixed the problem.

Video Boards

Board had Mario Heads and Bottom on Screen (2/6/17) - Kind of an odd problem, it would boot up fine, after a couple minutes Mario's head and bottom would appear on the screen in the four corners (see picture).  Used some freeze spray to hit the chips and after spraying 2148 ram at 6R the picture would clear up again.  Replaced ram at 6R to fix the problem.

Sprites had horizontal lines (2/3/17) – Board looked close, but the sprites had horizontal lines running through them. Also a small horizontal line was on the title screen near the middle left hand-side.  Board had a fresh set of roms, swapping them into a working board, found rom at 7D to be bad.  Rom tested fine in burner, but didn’t work in the board.

No Sprites (5/18/12) – Board came up, but no sprites. Checked outputs at 3E and found a signal missing.  Replaced 74LS163 at 3E to fix the problem.  Thanks to Mike at Mike’s Arcade for this one, he had already documented the problem so it was easy to find.

Taito Stratovox Board Repair Log

Updated 4/28/17 - Added a repair

A few years ago I had a few Stratovox sets, managed to get half of them running fairly quickly by swapping boards or they were already working.  Dug out the other ones this week and picked up one online as well.  Fun game, I'm guessing way back when the speech feature was really impressive.  Anyway, most of these were fairly straightforward repairs, roms falling apart, or other simple things, but figured I'd share anyway.

UPDATE: Had a customer ask me to look at some of his boards and a couple I sold him that died.  Added these repairs.

Stratovox does require a reset signal to boot up, so you're using this on a Jamma test bench or other test bench, make sure you provide it or the board will boot to some vertical lines.

Game Board, No Red (4/28/17) - Board was working, died at customer's location.  Dead output at pin 3 of 74LS32 located 1H, the IC right before the red goes to the pinout.

CPU Board, Garbage on Screen (4/7/17) - Looked like it was trying to run, but would just show some graphics and sometimes some garbled sounds.  Z-80 and program roms checked out okay, swapping 2114 rams into a working board I found 9E to be bad, which fixed the problem.

CPU Board, Horizontal Lines (4/7/17) - Boards had horizontal lines on certain areas, again suspected a bad 4116 ram. They were already socketed, but the clearly the sockets were replaced a long time ago.  Pressing on the ram at 3E cleared things up. Replaced the socket to fix the problem.

CPU Board, Horizontal Lines (4/7/17) - Board booted with horizontal red lines, suspected a bad 4116 ram. Grounded output on 4116 rams and found lines went away when grounding ram at 1F. Replaced 4116 at 1F to fix the problem.

Game Board, Red Heavy (4/7/17) - Game board booted with good video but was very heavy with red, the background was red, not black.  Tried replaced 74LS174 at 1F and 74LS32 at 1H, but not change. Some further digging showed output at pin 10 of 5D was stuck high.  Replaced 74LS95 from 5D to fix the problem.

Game Board, Vertical Lines (4/6/17) - Game board booted but had horizontal lines, suspected a bad 4116 ram. Replace all eight of them, and picture improved but not perfect.  Output at pin 9 on 74LS157 at 4C was high, should have been pulsing, replaced 4C, but no change, replaced 5C as well, no change.  Went back to 4116 ram, found output at 3C (pin 14) was dead. Replaced 3C (again) and board worked, must have used a bad 4116 when I installed them initially.  

CPU Board Locked in Test Mode - Boardset came up with some numbers and characters on the screen. After checking the manual I realized it was booting in test mode.  Figured the test switch in put was stuck, found an IC on the CPU board (10F) that I thought was the cause. While replacing it I noticed a scratch in the traces near it.  Replacing the IC didn't change anything, checked continuity on the damage and three traces were bad. Jumpered them and board came back to life. Should have inspected the board closer initially.

CPU Board Booting to Garbage - Clock signal on Z-80 looked good, while checking the Z-80, I noticed the first program rom (LS01) was installed backwards.  Pulled it, tested it in a working board and rom was bad. Burned new LS01 rom and board worked.

CPU Board Not Working - Didn't even bother testing this one, started by pulled program roms after looking at some of the legs on these roms.  Three roms had very brittle legs, a couple broke off when pulling them. Burned new LS01, LS02, LS03 2716 roms, installed them and board worked.

Game Board, Speech Issues - This one was lacking speech or most of it. Noticed that I listened very closely I could hear a blurb or something that sounded like speech.  Pinched sound pot on the very corner of the board together while game board was on and speech got a little louder.  Replaced 100K speech pot and the speech came back loud and clear.

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.

Quite a Few Konami Classic Board Repairs

Updated: Added Tutankham Sound Board Repair (3/7/17)

Had a free day today and spent some time digging out some Konami boards from the dead pile.  Make some good progress, nothing extremely complex, but always good to get some boards running again. I will update this page as I fix other Konami boards. Here's some of the highlights:

Circus Charlie, Bad ram on boot – Very clean boardset that reported “Ram Bad” when powered on.  Checked manual, but no reference to what ram it is referring to.  

I started by replacing 2128 ram at 3E just for the heck of it, but no change.  There are two more 2128 rams and 2114 rams, moved on to 2114 rams at 2F and 3F, checked the outputs with logic probe and they were dead.  Replaced 3F first, no change, replaced 2F and board booted and played perfectly.  Rechecked both of the 2114 rams that I removed and they were both bad.

Hyper Sports, video issues - Board had noticeable video issues, background was mostly gray, some game play could be seen, but it looked pretty far off.  Starting by reseating roms, found sockets at A12 and A14 to be bad.  Replacing those got board much closer, some sprites had vertical lines, starting by replacing rom sockets at G17, G18, and J17.  Video improved, finally left with one character on the vault stage that had vertical lines, which was due to a bad socket at J19.

Hyper Sports, marked as "touchy" - Board was tagged as OK, but touchy.  Tested it and pressing on the ribbon cable would get it to boot sometimes.  Replaced the ribbon cable, but no change. replaced the bottom connector for the ribbon cable, but no change.  Started pressing on ICs as it was booting and noticed one of the custom ICs was the cause. Removed it, cleaned pins and reseated it to solve the problem.

Hyper Sports, graphic issues - Board had vertical lines on some screens (but not all). Starting pulling socketed chips, they were very clean, just reseated them all and the problem went away.

UPDATE: board didn’t survive burn-in, problem reappeared, found socket at 12C to be bad by pressing on roms when game was on.

Pooyan, Board marked as has graphic issues, had no sound as well.

  1. Pulled custom ICs on the CPU boardset, cleaned legs, reseated them and the video issue was gone.
  2. No Sound, but some amp “buzz”.
  3. Reset line on sound board was stuck low, replaced 74LS02 at D7 and it was high again (more on this later).
  4. Still no sound, removed Z-80 (it was soldered on), installed socket, known working Z-80, no change.
  5. Tried another set of sound roms, no change.
  6. At this point I should have pulled the Fluke 9010a out to test stuff, but removed 2114 rams, installed sockets and tested them, all OK.
  7. Again, should have pulled 9010a out, but replaced a couple more ICs near Z80 thinking it would solve the problem, didn’t really feel like “thinking” today.
  8. Finally pulled Fluke 9010a out, ran Bus test on it reported a CTL Error. 
  9. After poking around for way too long, finally realized I installed a 74LS20 instead of a 74LS02 at D7.
  10. Installed correct 74LS02 at D7 and the sound came back.
  11. Lesson learned: Don’t fix arcade boards after playing two late night hockey games the night before and not getting enough sleep.

Scramble, no sound - Clean boardset, played, but no sound, sometimes a very low pulse or something like it was trying.  Started by swapped out processor and roms and then AY-3-8910s into a working boardset.  Found a bad AY-3-8910 at 3D.  Replaced this and the sound came up but was low. Replaced a couple electrolytic caps in the sound section just in case, but no change.  Noticed that pressing on op-amp at 3A would cause some buzzing and a bump in sound. Found a parts sound board and grabbed another op-amp which fixed the problem.

Scramble, no sound – Very clean boardset tagged as having no sound and “amp broke”.  Sure enough the amplifer was physically broken, grabbed another one from parts board and the sound came back.

Tazz-Mania, CPU Board boots to garbage (2/8/17) – Boardset was tagged as having Rom 2E Error.  Pushing firmly on Z-80 would sometimes get it to show a Rom error, 2E or 2H.  Replaced Z-80 socket and the board would boot now, sometimes come and play with graphic issues, other times Rom Error.  Replaced sockets for Roms at 2C, 2E and 2H and board booted with graphic issues. Pressing on rom at 5F would make things change, replaced socket at 5F and board worked perfectly.  Let it run for two days just in case any other sockets were bad, but seems to be very happy now.

Time Pilot, distorted graphics – Board was working, but in testing developed some distorted graphics, but still played. Starting pressing on custom chips and found IC4 at F12 to have dirty legs.  Cleaned the legs, the problem persisted so I replaced the socket and the problem was fixed.

Track and Field, No Sound (3/3/17) – No sound at all, no amp buzz, suspected a bad amplifier. Recapped sound section and replaced amp, still no sound.   Started checked sound CPU, signals looked good, used scope to see if the board was making sounds before the amp and it appeared to be behaving normally.  I replaced the LM324, LM358 and 4066 ICs in sound section as I wasn’t sure what else to do, but no change. 

Still no change, pulled the amp I installed and noticed it was a LA4460 as indicated in the manual, BUT the board had a LA4461 amp installed, which uses the same pinout, but in reverse. Removed LA4460 and installed it “backwards” and the sound came back. Wish I would have looked closer at the amp I removed, I assumed it was LA4460 as that is what is in the manual. 

Tutankham Sound Board, no Sound (3/7/17) – Removed, checked and socketed Z-80 processor to further troubleshoot with Fluke 9010a. Z-80 and 2114 rams checked out. Rom 7A did not verify with 9010a, grabbed another, but still did not verify. Pressing firmly on it and the sound came back. Replaced rom socket at 7A to fix the problem.

Tutankham, horizontal lines - Video board had lines on boot-up.  Suspected a bad 4116 ram, just wasn't sure which one.  Started replacing a couple and finally spent some time with a logic probe looking at outputs and found two that seemed to be different than the other rams. Replaced these two and board booted.

Yie Ar Kung Fu, graphic issues - Booted with blocks around some graphics.  Started swapping the graphic roms (don't remember location off the top of my head) with a known working board.  All checked out okay. Reinstalled and powered non-working board back up and it worked.  Apparently one rom wasn't seated well or making good contact.