What fixed your game today / general repair log

PCB: Kee Games Super bug

Symptoms: The board had the picture of the car in the middle of the screen but garbage was scrolling across the screen (see Pic)

Steps:
Because I was seeing the car on the screen I assumed the CPU was working, turns out that assumption was wrong. that error had me looking in the timing and playfield section for a bit until I figured out that the car image is placed were it is by the timing not the CPU.

Starting over fresh I checked the timing again and it was good. Then I moved to the CPU and saw that none of the address lines were moving.

I looked at the reset line next and it was stuck low and pushing the reset switch on the board didn't make a change at the cpu. There is a 7496 (shift register) that will kick the cpu reset if the code takes to long or if you hit the reset button. I figured that was bad.

I replaced the 7496 at D4 and the board came back to life. There was no other issues.

Repair: replaced 7496 at D4
 

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PCB: Atari Football

Symptoms: graphic glitches on the playfield and player movement effected. Problem in both test screen and during play. (see pics). The overlays are because the monitor is from a superbug. I throw it in just for testing.

Steps:

Seen something like this a couple times before and it is usually to do with the display RAM 2101s located at F2, H2, J2, K2, F4, H4, J4, K4. I will first try to piggyback the RAM. This doesn't always work but when it does it makes things go pretty quick. It worked for me this time and when I got to H4 the errors cleared up. I replaced H4 and the playfield looked right and the player movement was correct too. There were no other issues.

Repair: Replaced 2101 Ram at H4.
 

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PCB: Taito Marine Date

Symptoms: Missing roms few rom sockets look rusty otherwise complete

Replaced missing roms replaced a few eprom sockets that looked rusty crusty and booted right up No other repairs required

This is one weird game
 
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PCB: Mortal Kombat Bootleg

Symptoms: Game plays fine no sound blown track from 12 to Sound section hmm

Checked why track was blown found a 220uf filter cap from 12+ pad dead shorted to ground removed and replaced, repaired track and short was gone. Applyed power and sound was all working
 
PCB: Space invaders

Garbage on screen, nothing moving.

linear power supply was blowing the 2n4123 transistor in the reset circuit. Reset was reading +3v instead of .05mv. Replaced transistor and it worked a few times. Then blew again. Also could not get the output voltage to go lower than +13.5v, +5.15, and -5.15v.

Ordered replacement transistors (both 2n4125 and the 2n4123) and midway power supply rebuild kit. Installed and all is good. Voltages are able to be adjusted perfectly and no more blown transistors.
 
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pcb: gunfight midway 8080
symptoms ... not working

power up on test bench, screen shows typical ram issue garbage, within 60 seconds one of the 12v line shorts out, blows 3a fuse, damages the 12 reg on power supply pcb & the D3245 is now dead - ugh.
remove caps on 12v line until i find the offending 22uf cap - replace along with all other blow items - i replaced both of the 22uf tant caps with electrolytics

power back up to same garbage screen, poke around a bit and find the LS74 at E4 has a dead output, replace and things are looking better, discovered the LS174 was not working correctly either, replaced and now board passes rom and ram tests and runs somewhat, but random garbage at times appears & disappears on screen ?
suspect that A2 is bad, pull toss in cheap ass ttl tester and it passes test, install back on board and board works correctly for a bit and then after a couple minutes then starts displaying random garbage again but also clears up on its on ...
leave powered on until it completely crashes & does not restart and i now find that yes A2 was bad / going bad the whole time - as i originally thought
replaced and game program is now working

replaced both LM354 sockets on daughter board and sound is back

running on test bench for 5-6 hours straight & i call it done for now - fingers crossed

note to self .. replace both 22uf tants with electrolytics before powering on - they are cheap & the parts they can damage are not, also found a bad 10uf 25v cap on another board and it caused problems with sync, these are very cheap caps and i will start replacing all of them on future 8080 main board repairs - not worth the headaches
 
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PCB Midway Space Invaders

Symptoms: moving garbage on the screen

Steps
Voltages looked correct so I inserted my known good daughterboard and started troubleshooting. Removing ROMS should bring solid lines but there was no change to the display. I also noticed pin 12 (ground) was broken on one of the ROMs. I'm not sure if it was like that or happened then but either way no white lines so I moved on. I inserted my Braze kit it reported different RAM bad every time I restarted so I starting looking at the RAM address circuitry specificly the 74157s. I found F6 (74157) bad and replaced it. That fixed the mainboard.

I inserted the original daughterboard and the game booted but the test screen gave my a bit error and there were lines through the aliens. Most likely one of the chips in the shifting circuit. First suspects are the 74174 and 74175 flip flops. I found D5 (74174) dead so I replaced it and the game looked like it was working.

Tested sound and it was good. Tested controls and while they worked for player 1 they were unresponsive for player 2 also I should mention it was giving 4 lives per credit but was set for 3. Both can be issues with the dip switches. Testing continuity of the dip switches revealed a couple stuck open. Cleaning it with turner cleaner fixed the issue.

Finally I put in the orginal TMS2716 ROMs and soldered a replacement leg to the chip missing one so that way I didn't have to restrap and burn all new 2716 ROMs.

Repair: Replaced 74157 @ F6 (main), 74174 @ D5 (daughter), Cleaned dip swithes and repaired missing leg on the TMS2716 @ E1

Note on the last pic. My SI has a color monitor in it so I had to redirect the video to my Breakout. That is why it probably looks a little strange.
 

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Picked up "The Lost World" super cheap from a guy who got it from a local arcade that was just going to toss it.

He said "screen" was not working at all and he was told he shouldn't mess with CRT's because of the High voltage.

Upon getting it home and powering it up the Nanao ms9-29SU Monitor was in Vertical Collapse. Replaced Vertical deflection IC and recapped because it still had the stock 20 year old caps in it.

Fired right up!

I got my parts from https://www.arcadepartsandrepair.com/

I cannot recommend that shop enough.
 
#1 Pcb: Atari Football

Symptoms: Corruption of graphics on the playfield

Steps:
The text looked fine and it came up with ROM ok and RAM ok in test mode. Since it seemed to be limited to the playfield first suspect is the video RAM (2101 @ F2,H2,J2,K2,F4,H4,J4,K4), see pic 1. I piggybacked the RAM with a known good. This doesn't always work but I've had good luck with it on this board. When I got to F4 the picture changed, see pic 2. I replaced F4 which cleared up a lot of the screen but there was still some coruption, see pic 3. Pic 3 is the test screen and the bottom 2/3rds should look like that but the H's are not supposed to be there. Piggybacked again and when I got to F2 it cleared up so I replaced F2 and the board was fully working.

Repair: Replaced the 2101 RAM @ F2 and F4

#2 PCB: another Atari football
Symptoms: missing crowd sounds

Steps:
All the other sounds were present so I focused before they were combined. starting at the LM324 @ A9. I injected an audio signal on the output and heard it in the game speakers but I couldn't hear it when i put it on the input. Replaced LM324 and the crowd sound was back.

Repair: Replaced LM324 @ A9
 

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Always start with power... right? So I learned more about the Atari power brick, the AR II BOARD, PCB, etc... and finally tested the voltage from the wall...then the switch off, then the switch on... and thought... it CAN'T be this simple...

But it was...and after 3 weeks of troubleshooting... it was a $10 switch.

Centipede and TRON however... still not working...
 

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PCB: Street Fighter Alpha CPS2

Symptoms: Hangs in POST screen at QSound test

I had heard before that QSound issues can hang the whole system and that's exactly what happened here. One of the sound program EPROMs was messed up. Grabbed EPROMs 01 and 02 from another SFA and it booted right up.

-ud
 
Game PCB: Gorf Ram board
Symptom: Wouldn't boot even to test rom.
Steps:
1) Used ESR/DCR meter and found caps reading shorted
2) Narrowed short down to +12v line by continuity testing 4027 ram voltage pins (pin1=-5v, pin8=+12v, pin9=+5v, pin16=gnd) to gnd.
3) removed leg of c2 and verified +12v to gnd short removed
Repair: replaced C2 15uf 20v cap.

Game PCB: Gorf Game Board
Symptom: Strange black lines graphics on scrolling intro and dotted horizontal lines following space invaders and galaxians.
Steps: too many to list but basically involved swapping game boards and x2/x3 I/O Custom chips. Determined one the I/O Customs was causing the problem
Repair: replaced I/O custom at x2.

Made some videos of my learning and getting Gorf back to 100%
https://www.youtube.com/playlist?list=PLI-IyFhSMr12AriWeiYuTyYUNqvmWMAQD
 
Game PCB: Pac-Man
Symptom: Random Garbage on screen looked like cpu was resetting. Video is worth thousand words



Steps: Was about to hookup logic probe but z80 is tucked under that sync controller card. Shotgun replaced z80 and got lucky I guess.
Repair: Replaced z80
 
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Game PCB. Mr. Do's Castle
Symptom: Dead nothing displays.
Steps:
1) visually checked board for damage. was missing c26 (not sure what that does w/ amp), c24 (clock ckt) and a decoupling cap all had some damage.
2) with logic probe checked clock pin #6 on z80 cpu. Not toggling believe it was stuck low.
3) checked z80 reset pin 26 == toggling.
4) replace caps and game booted and played.
Repair:replaced capacitors, in particular c24 220pf. Love the easy ones.
 
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Game PCB: DK Jr

Symptom: Will not Sync

Steps: Checked all ICs. Cleaned and reseated. Confirmed cable connections. Saw no basic issues. Game was playing and coining up. Adjusted Sanyo 20EZ vertical and horizontal hold. No luck.

Repair: Replaced Horizontal and Vertical 50k potentiometers on game PCB. Also adjusted horizontync hold on Sanyo 20EZ. This is located on chassis and not remote video board with pots.
2c8ffa9687a4f2c035be9d361f5bad17.jpg

ecb097da7fbcf3de9c7fcc4970bfae5d.jpg
 
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deoxit on the Sanyo EZV potentiometers. Capkit, and B+ changed out still left a shaky sync. New 200k pot did not help, but man DeoxIt,... Love that stuff. Normal cap kit stuff always brought back a WG 7k that would not show a picture before. It was a good day today :D
 
Game PCB. Super Cobra - Stern
Symptom: graphic issues
Steps:
1) I could tell it was running code so tried both test roms that are out there. Unfortunately it wasn't obvious what they were reporting due to graphic issue and I didn't take a picture. (should have)
2) pulled roms and 2C-2J and verified via romident
3) pulled 2114 rams on main board and tested one bad in Neoloch tester
4) put everything back with one new 2114 ram
Repair:replaced I believe 3L 2114 SRAM but not certain as I pulled them all out at same time.
 

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Game PCB: Defender
Symptom: Not saving settings
Fix: Previous owner had installed the coin cell mod to this PCB. While I've had good luck with this mod on other Williams games, it doesn't seem to work well for Defender. The battery drains out too quickly.
I removed the coin cell mod and wired a remote AA battery box. If these batteries ever leak, they will not damage the PCB.
 

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Game PCB: MK2
Symptom: Kick Harness not working
Steps: looked closely at the board, no pins
Repair: soldered the thing directly to the board
 
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Game PCB. Asteroids Deluxe with HSS Multigame
Symptom: High Score screen flickering & jumbled Alpha-num, self test OK, game plays with 99% OK vectors
Steps:
1) Checked several pathways. No real data issues
2) Changed RAM and tried a good set of ROMS > NO FIX
3) Changed 6502A CPU. BINGO.

Update: I have had 2 failed 6502A's to date now. Some just don't like the multigame mod? A:B tests are 100% reproducible.
 
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