Brian E. Brzezicki
Copyright 2015
Version 1.00 12/24/2015

Disclaimer
Use this at your OWN risk, do NOT sue me if it breaks your board... if your doing this your board is probably already broken though ;)

Game Board #1 October 2014

Problem:

  • Game not working, junk on screen

Troubleshooting/dianosis steps:

  1. With Fluke 9010A Getting all kinds of memory errors that change
  2. Tried putting in all new RAM, no changes, put back original RAM
  3. still getting fluxuating errors, looping read shows both bytes changing, something is messed up with the data bus
  4. Found a big solder glob under U17, removed. RAM now passes long tests
  5. Game is booting up now, but won't coin up
  6. Found issues with coin up transistors, Q1 and Q2, replaced both
  7. Game works!
Game Board #2 October 29 2014

Problem:

  • Game not working

Troubleshooting/dianosis steps:

  1. Replaced CPU socket which had a piece of metal stuck in it
  2. Noticed 7404 @ U54 was pulled and missing, replaced
  3. CPU clock is good @ 2Mhz
  4. Attached the Fluke 9010A and did a BUS check - OK
  5. Did a RAM long of the RAM region (0xC000 - 0xCFFF), immediately got BTS error 0x80 on the first address which corresponds to data bit D7
  6. Data bit D7 comes from the 4027 RAM @ 56, swapped it with the RAM for D0 (U63), was expeciting to see errors on D0 (BTS 0x01 error) but there was no change
  7. DB7 is buffered by 8216 @ u33, try swapping u33 and u34, still getting BTS 0x80 errors
  8. there is a 74LS125 that buffers the RAM reads @u46, probed around that with the o-scope during looping reads and writes, nothing out of the ordinatry
  9. Noticed that there is a 74LS244 @ U19 that buffers the ROMs to the main data bus which is socketed, pulled it just for fun and re-ran the RAM long, it did not error out
  10. Stopped the RAM long, replaced the 74LS244 @ U19
  11. Ran Fluke long RAM test @ 0xC000 - 0xCFFF - OK
  12. Still working on board
Game Board #2 October 5/22/2016

Problem:

  • Game not working

Troubleshooting/dianosis steps:

  1. ram long 0x8000 BTS errors 0xFF
  2. verified 74LS08 @ u37 - u39 (address bus buffers)
  3. pulled 8216s (data buffers) and put in known good ones - no change
  4. tested 74ls42 @ u40 (address selection) looks ok
  5. not getting a video read signal on pin #8 of u52 (74LS10) when reading 0x8000
  6. wait according to schematics video RAM starts @ 0xC000 not 0x8000!!!
  7. did a ram long got a DCD error bit 12 and 13
  8. verified c000 writes to d0000
  9. whoops ram range is only vrom 0xc000 - 0xcFFF - RAM ok
  10. Moral of the Story. make sure you know what your testing/read the schematics don't assume you know the info off the top of your head!!!
  11. Game still doesn't work
  12. Testing ROM ranges 
    testing ranges
0x0000 - 0x03FF        0x0530
0x0400 - 0x07FF        0x0530
0x0800 - 0x0BFF        0x0530
0x0c00 - 0x0FFF

0x1000 - 0x03FF        0x0530
0x1400 - 0x07FF
0x1800 - 0x0BFF
0x1c00 - 0x0FFF
  13. WTF? replaced 74LS02 @ U36 now getting actual values
  14. Try again 
    
0x0000 - 0x03FF        0x49e5	WRONG
0x0400 - 0x07FF        0x25fd
0x0800 - 0x0BFF        0x559e
0x0c00 - 0x0FFF

0x1000 - 0x03FF        0x0530
0x1400 - 0x07FF
0x1800 - 0x0BFF
0x1c00 - 0x0FFF
  15. individual reads show all 4 high bits are set! (0x0000 should be 0xC3 getting 0xF3 etc...)
  16. ugg u19 SHOULD Be a 74ls244 I had in a 74ls245!!!
  17. replaced U19 with a 74LS244 game works.
  18. Trying my SRPB..now why isn't my SRPB working.. wait it is, just had to git reset twice
Game Board #3 5/28/2016

Problem:

  • Game not working

Troubleshooting/dianosis steps:

  1. 10uf tant cap caught on fire, replaced
  2. no clock on CPU
    1. no clock on pin #2 of u54 74ls04 (input)
    2. clock is on pin #4 (input) of 74LS175 @ u49
    3. pin broken off U49, replaced now have output, clock seems high though
    4. U49 is driven by PROM @ 316-0043 @ U65, replaced with another from another board - OK
  3. getting constant resetting POD timeout,
  4. verified power - ok
  5. constant resets are gone, now just a single reset and clock is deal again.
  6. PROM at U65 messed up again.
  7. replacing with 82S123 replacement. clock is twice what it should be (should be about 2mhz) it's 4Mhz
  8. tried replaceing 75S175 @ U67 with ls175 now nothing.
  9. pulled sockets, replaced, put back original chips. 1.9Mhz signal back including original prom
  10. pod back to resetting
  11. replaced CPU socket, it was a mess - no chnage
  12. ok disabled some of the POD errors from the setup on the fluke, can not pass pod test will have to look later
  13. what is causing that. error seems to be set enable wait
  14. verified proms
    316-42
    316-43
    316-0138
  15. no sync on pin #15 of ustom chip, custom chip is ok though, tested in other game
  16. traced signals back to 75LS175s U50 - 52, found one bad with broken pins, fixed sync issues
  17. doing RAM long test - OK
  18. game won't boot
  19. pulled ROMS - one was messed up put in single ROM kit, game works!
  20. pulled bad ROM @ 27 don't have any 2708 used 24U replacement - still won't boot
  21. tested ROM u27 - u23 all bad, stopped testing
  22. put my known good ROM in different spots a couple times, tested fine each time.
  23. went back though it was wierd NO roms worked, found -5V was missing, the -5 test point had come lose ripping the trace in 2
  24. put ROMs back in, game works!
Game Board #4 5/28/2016

Problem:

  • Game not working, junk on screen

Troubleshooting/dianosis steps:

  1. short between -12 and GND
  2. removed 7905 @u73 no change
  3. cap at C23 is bad/shorted
  4. on MK4027 has bad/broke pin
  5. fluke RAM long 0xc000 - 0xcfff BTS error 0x20 that's RAM u58, swap with another see if the BTS error changes, it did
  6. replace RAM, getting BTS 01 errors
  7. screen is highly unstable
  8. another bad ram
  9. replaced all Ram sockets and socket @ U65
  10. replaced all 18 pin and below sockets
    verified 316-0138
    verified 316-0043
  11. everything still a mess
  12. replaced 555
  13. replaced 2 2n4401
  14. replaced 74ls10 @ u52 (was getting errors)
  15. pod keeps resetting
  16. replaced 74ls02 @ U36
  17. replaced 3 74ls08s @ U37,38, 39
  18. oh clock is wrong!!! very wrong!!! how did I miss this?
  19. had a bad connection on a socket, resoldered
  20. game plays with some graphics instability
  21. pulled a 27LS244 @ u1 and U19, issue went away put back in U1 ok tried other one - still OK @ u1
  22. put one back @ U19 messed up, tried other at U19 messed up, ROM select must be off or back socket, replaced, many pins fell off
  23. replacing socket @ U1 too for good measure, still bad.
  24. replaced 27LS244 with new one - ok
  25. put in other 74ls244 and it's bad again, going to replace that one too, replaced - OK
  26. doing fluke long RAM test - ok
  27. will need to make sure coin up circuit works too - confirmed
  28. there is noise on the blue gun - replaced Q6 and Q7 nope
  29. found another RAM with a weak/broken pin, replaced
  30. still getgting static issues, problem build up and get worse eventually crash
    • it's 316-042 as it stays on it gets hotter and problems get worse, putting a finger on it lightly cases the problems to fade slowly till they are goine, and they'll start again once f inger is lifted. putting a quarter on it helps delay on onset of issues. odd putting in a new one did not fix the problem.
    • tried a 82S123 replacement, that seems to stop the "snow" problem. been running for about 1 hour ok. will leave running. Many hours now - OK
  31. Game works!
Game Board #5 May 30 2015

Problem:

  • Game not working
  • Power supply will not power on when hooked up

Troubleshooting/dianosis steps:

  2. replaced 2 10uf 25V tantalum caps near +12 and -12 voltage input
  3. power now works
  4. bad d 316-042 prom @ u66, replace with another I had
  5. still getting POD resets
  6. no signal on video
  7. found I had a 74LS161 where a 75LS175 should have been (u50)
  8. now pod is no longer resetting
  9. do a Fluke RAM short 0xc000 - 0xcfff - ok
  10. doing a fluke RAM long 0xc000 0xcfff - ok
  11. odd, not seeing any video
  12. I had accidentally plugged the power into the coin counter spot, maybe I fried a chip will wait till the RAM long is done
  13. a signal is coming out of the custom chip on pin 28 (video) need to replace the chip after that (u41) and perhaps the 2n4401 @ q7 and q6
  14. darn it now I plugged the power into the video output
  15. replaced q6 and q7 - no change
  16. replacing 74LS08 @ U29, fixed that problem
  17. game boots, OK
  18. tried the coin up, smelled burning plastic, it's not working
  19. will replace U12 (75ls00) and U13 (74ls125) since I probably broken them when I plugged things in wrong
  20. U12 is defintely not working
  21. actually u13 is probably ok, those pins where just ground pins
  22. now U12 is working but coin up still is not
  23. replacing 2n4401 @ Q1, the leg on the collector acutally was broken
  24. wierd are we getting the same problem with U42 again? noise? I think so
  25. Game starts up but starts crashing with stuff on screen randomly
  26. hmm that same -5 test point is broken touching it immediately messes things up.
  27. Game now doesn't crash right away, but eventually screen goes off
  28. touched 316-0042 @U66 it was hot after having a finger on the chip a few seconds the screen came back
  29. removed U66 and replaced with 82S123 replacement
  30. that fixed the problem
Game Board #6 9/2021

Problem:

Troubleshooting/diagnosis steps:

  1. tested custom on another board - OK
  2. replaced sockets
  3. Pulled ROMS, tested all- OK.
  4. RAM long 0xC000 - 0xCFFF DCD error bit 4
  5. inputs are fine to custom
  6. outputs are WRONG on 0xc010 (low for bit 4) however it's not low on 0xcFFF
  7. going to test PROMS - tested ok
  8. replaced PROM sockets for good measure, that was the issue