Brian E. Brzezicki
Copyright 2014
Version 1.00 06/30/2014

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 June 30 2014

Problem:

  • All game boots to is this screen of yellow blocks. Owner said game was working, then one day he just got yellow blocks.

Troubleshooting/diagnosis steps:

  1. Did Fluke 9010a long ROM test of RAM range 0x8000 - 0x8FFF got BTS error 80.
  2. Swapped the RAM that corresponds to data bit 0x80. When swapped the suspectd bad RAM with a known good RAM the error moved too
  3. RAM was a MK4015/MK4027 a 4116 should have worked.. it did not. ordered NOS MK4027s.
  4. Replaced bad RAM with a MK4027
  5. Game works!
Game Board #2 1/24/2015

Problem:

  • All game boots to is a blue grid.

Troubleshooting/diagnosis steps:

  1. Did Fluke 9010a long RAM test of RAM range 0x8000 - 0x8FFF got BTS error FF, this means ALL RAM are bad or soemthign else in the memory circuit is bad, which is more likely.
  2. Pulled one 4027 RAM and replaced it with a known good one, reran Fluke long RAM test, surprised to find that the Fluke responded with BTS error indicating that all RAMs were bad EXCEPT that one!
  3. Looked and RAMS and found they were the wrong type! (actually they should be acceptible replacments, but I learned before that those RAMs will not work on a carnival, for reasons that I'm not sure of.)
  4. Replaced with the proper RAMs from a secondary board as well as a few NOS RAMS.
  5. Reran RAM long test, OK!
  6. Game now has different pattern, but will not reboot (Note on carnival to get the CPU working on a JAMMA test bench you need to make a custom reset circuit (pin 26 on Z80 -> 10K Ohm resistor -> +5) then ground that pin once. That said the game would not boot
  7. Verified all ROMS worked OK
  8. noticed that CPU socket was lose, removed, found at least 2 pins seemed to fall off as desoldering them, not sure how the Fluke passed the test, but after replacing socket game booted fine.
  9. Game works!
Game Board #3 2/9/2015

Problem:

  • All game boots to is a blue line pattern

Troubleshooting/diagnosis steps:

  1. Did Fluke 9010a long RAM test of RAM range 0x8000 - 0x8FFF got BTS erron bits 0. This means that writes to address 8000 and 8001 are colliding in some way. read from 8000 and found data bit D6 was stuck.
  2. replaced the 4027 RAM corresponding to Data bit 6 (4027 @ U70)
  3. Fluke passes ROM test, but game will not boot, have colored pattern.
  4. Tested ROM range 0x0000 - 0x1FFF - OK
  5. Tested ROMs - 0x0000 - 0x3FFF Fluke Signature 271A - OK
  6. Game works!
Game Board #4 2/9/2015

Problem:

  • All game boots to is a blue line pattern

Troubleshooting/diagnosis steps:

  1. Did Fluke 9010a long RAM test of RAM range 0x8000 - 0x8FFF got BTS erron bits 4. This should correspond to addresses 0x8000 and 0x8010.
  2. Read 0x8000 and x8010 both FF
  3. wrote 0x00 to 0x8000 noticed that 0x8010 also became 0x00
  4. Wrote 0xff to 0x8010 noticed that 0x8000 also became 0xff
  5. Looks like something is permanently stuck on address line 4 (which makes sense for a BTS error on address bit 4)
  6. did a loop read on address 0x8000 and 0xFFFF, used osciliscope to test output of 74LS08 @ U11 pin #8, looks good
  7. looked at next chip in circuit, custom chip @ U57 notied output wierd on A4, tried with another U57 from another board, still same problem.
  8. Traced address line A4 to next chip, the program ROMS, followed continuity from ROM to rom, notice from from row to back row, lost continuity.
  9. Found cut trace on Address line #4 from one row of ROMs to the next
  10. Repaired traced
  11. Tested ROMs - 0x0000 - 0x3FFF Fluke Signature 271A - OK
  12. Game works!
Game Board #5 2/9/2015

Problem:

  • Game is dead, no video at all

Troubleshooting/diagnosis steps:

  1. Did fluke long RAM test on 0x8000 - 0x8FFF - OK
  2. Did fluke ROM - 0x0000 - 0x3FFF - FAILED
  3. Tried upper half or ROMS 0x2000 - 0x3FFF - OK
  4. Tested 2708 individually from 0x0000 - 0x1FFF, found that the ROM in range 0x1300 - 0x17FF read bad, switched to another socket/range and it read OK
  5. Replaced the physical socket
  6. Retested - all ROMs OK
  7. Not getting any video still
  8. Replaced 40 pin socket U 57
  9. Found pin #15 (COMPSYNC) is dead, switched with known good one - OK
  10. Game works!
Game Board #6 2/10/2016

Problem:

  • Game is dead,blue pattern on monitor
  • Game is missing some ROMs and RAMs

Troubleshooting/diagnosis steps:

  1. Replaced missing RAMs
  2. Ran Fluke long RAM test on 0x8000 - 0x8FFF - BTS 1 error
  3. Replaced RAM associated with data bit 1 (4027 @ U76), when pulling noted that pin was broken off of the original
  4. Failed ROM test, noticed on reading some addresses the data values were rapidly flipping on a loop
  5. Removed all ROMS but u33 (address range 0x0000 - 0x03FF), but problem still occurred
  6. Replaced socket for u33 as all sockets looked bad, transitioning values went away.
  7. did Fluke ROM long test on range 0x0000 - 0x03FF - Failed
  8. read some values from addresses 0x0000 - 0x0007 and compared them against the known values, bit 3 (4th) bit was always set low
  9. using multimeter found continuity between ground and data output and bit 3 (4th bit)
  10. removed 74LS125 @ u51 (and 74LS125 @ u52, by accident) and replaced socket, no change
  11. Pulled ALL 16 rusty ROM sockets from the ROM location. Problem went away
  12. While replacing sockets, found some bad ROMS, replaced with ROM from another board.
  13. Did a ROM test on all ROM locations, all passed except the ROM associated with 0x2400 - 0x27FF, Fluke was giving address error.
  14. replaced with another ROM, same problem.
  15. verified physical ROM in another slot - OK
  16. Replaced corroded CPU socket
  17. Board works
Game Board #7 3/12/2016

Problem:

  • Game is dead,blue pattern on monitor

Troubleshooting/diagnosis steps:

  1. Plugged in Fluke 9010A with z80 pod, did bus test, all kinds of failures on databus, looks like high 4 bits are bad
  2. removed one of the 8216s (1/2 of the data bus driver) and tried again, same problem
  3. removed the current 8216 and placed back in the pulled 8216, no issues
  4. did not have any new 8216s so pulled one from a old Galaxian board and replaced the one that seemed bad
  5. Ran RAM test on 0x8000-0x8FFF - OK
  6. Ran ROM test on ROM RANGE - OK
  7. Booted game up
  8. Board works
Game Board #8 3/14/2016

Problem:

  • Game is dead,blue pattern on monitor

Troubleshooting/diagnosis steps:

  1. Plugged in Fluke 9010A with z80 pod, did bus test - OK
  2. Ran RAM long ROM test on 0x8000-0x8FFF - got DCD error on Bit 3.
  3. Noticed that all 16 ROMs sockets were replaced with machined sockets, the soldering on some looks questionable.
  4. Found a bridged trace, verified bridge between 2 pins, address line a2 and another pin, found bridge and removed
  5. Ran RAM long ROM test on 0x8000-0x8FFF - more errors
  6. Ran ROM signature check on ROM test on 0x0000-0x3FFF - more errors
  7. Ended up finding 3 more bridges underneath sockets, fixed those 3
  8. Ran RAM test on RAM RANGE - OK
  9. Ran ROM test on ROM RANGE - OK
  10. Game will still not boot up
  11. Replaced Z80 with new Z80
  12. Board works!
Game Board #9 5/21/2016

Problem:

  • Game works, but won't coin up

Troubleshooting/diagnosis steps:

  1. Using Oscilloscope verified that pin #6 on U62 transitioned as coin switch was pressed.
  2. measured pin #2 on U35 (74LS08) that triggers the CPU reset, noted that that pin 2 (coin up input) was always low (it should be high except when a coin is inserted)
  3. measured transistor at Q4, found at base, collector and emitter voltage difference to ground was always 0.
  4. Pulled transistor, found all pins shorted
  5. Replaced with a new 4401 transistor
  6. Game works!
Game Board #10 6/22/2016

Problem:

  • Game does not work, pure blue screen

Troubleshooting/diagnosis steps:

  1. extended ROM video logic board
  2. fluke z80 bus test OK
  3. RAM long 0x8000 - 0x8FFF BTS 0xFF pulled a RAM and replaced no change
  4. looping write test pin #3 it goes low as expected
  5. replaced 8216s "@ u47 and u48 with known good ones, no change, put back originals
  6. pulled 82S123 @ U14 (316-0206) and tested - OK
  7. pulled 82S123 @ u49 (316 - 0633) - OK
  8. looping read test on address 0x8000 to see if buffer read is happening used pin #4 on 74LS125 @ u54 - read signal OK
  9. test 8216s data buffers to make sure they are getting the signal pin #15 on either, there is a signal, not sure if its OK
  10. signal is controlled by 74LS04 @u25 - tested OK
  11. 74LS08 @ U35 looks good
  12. 74LS04 @ U68 looks good Checking address buffers
  13. 74LS08 @ a10 - OK
  14. 74LS08 @ a11 - OK
  15. 74LS08 @ a12 - OK
  16. started tested random chips since I had my logic comparator out, this was probably silly as it just distracted by from "good" diagnosis, still that board has so few chips.
  17. 74LS175 @ u19 - OK
  18. 74LS175 @ u20 - OK
  19. 74LS10 @ u77 - OK
  20. 74LS10 @ u39 - OK
  21. output of RAMs is always floating
  22. correct data signal seems to get through when writing to RAM
  23. VRAS/CAS last chip 74LS04 @ U68 is OK
  24. 74LS163 @ u15 - OK
  25. Tested pins 5 and 6 of u13 - OK
  26. 74LS74 @ u22 - OK
  27. 74LS74 @ u43 OK
  28. OK need to get back on track, let's use a ROM read/checksum to validate address buffers, and data buffers
  29. replaced U33 with known good ROM, read 0x0000 - OK
  30. did fluke checksum on 0x0000 - 0x03FF (u33) got back correct signature,
  31. address lines at least out of the first address buffer are working at least A0 - A9
  32. data bus is working
  33. now we know the RAMs out is floating on read, why?
  34. power to RAMs is good
  35. RAS and CAS are always low on reads that's not correct
  36. vcas and rras are coming from U19 and U20, those have been checked
  37. signal coming into U20 is really dirty let's put in a replacement for the bipolar@u14
  38. socket came off when removing the chip at u14
  39. CPU socket also came off
  40. will need to replace both of these
  41. replaced U14 socket, I now have vRAS ans vCAS on the RAM but still rams not working on all bits @ 0x8000 :(
  42. replaced 40 pin CPU socket no change
  43. replaced a 4027 again, I get valid output on this new one, now that VRAS and VCAS is good, so ,all rams must be bad
  44. swapped in new rams - getting good read/writes - doing long FLUKE ram 0x8000 - 0x8FFF
  45. Put in single ROM kit - OK
  46. Low ROMS test OK, top row not testing OK, sockets are horrible.
  47. removed ROMs installed single ROM kit
  48. Game works!
Game Board #11 2/25/2018

Problem:

  • Game does not work, vertical blue lines every other line on screen
  • Repair Video here

Troubleshooting/diagnosis steps:

  1. Checked voltage - OK
  2. Checked CPU clock signal - OK
  3. Checked /RESET - OK
  4. Fluke Bus test - OK
  5. Fluke RAM long - 0x8000 - 0x8FFF - OK
  6. Did a fluke ROM test on each individual ROM - OK
  7. Huh this should work
  8. Replaced ROMs with my single ROM kit
  9. It worked!
  10. Moved CPU then it started acting up again
  11. jiggled CPU was able to get it to stop working and start working
  12. Removed CPU socket, pins were falling out as I de-soldered them
  13. Installed new CPU socket, game works great with my kit, no issues
  14. Installed the original ROMS, game works great
  15. Just for preventative measurement installed new sockets for all sockets EXCEPT the ROM sockets (since the owner is going to use my single ROM kit)
  16. Game works
Game Board #12 3/12/2018

Problem:

  • Game works but has yellow garbage on the screen in various places.

Troubleshooting/diagnosis steps:

  1. Fluke bus test - ok
  2. Fluke RAM long 0x8000 - 0x8FFF - BTS error 0x80
  3. pulled and replaced MK4027 RAM @ U73
Game Board #13 3/16/2018

Problem:

  • Game does not work, "checkered screen"
  • Board has had alot of work done, all chips seem to be removed and socketed

Troubleshooting/diagnosis steps:

  1. Voltage - OK
  2. u49 looked wierd, pushed on it and colors on screen changed, pulled old socket and replaced
  3. Fluke bus test, address bit 11 stuck high
  4. It was not stuck high but did have a square wave pattern
  5. Found continuity with chip at u48, a tiny bridge under the CPU socket
  6. Cut the bridge and replaced the CPU socket
  7. Fluke bus test - OK
  8. Fluke RAM long 0x8000 - 0x8FFF BTS C0
  9. Swapped 8216 @ u47 and u48, ran test again, this time BTS error 0C
  10. Pulled bad 8216, replaced with another
  11. RAM now ok
  12. Game works!