What fixed your game today / general repair log

jacklick

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Donor 9 years: 2013, 2016-2021, 2023-2024
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Hopefully a similar thread doesn't already exist. Thought something constant, quick and referable might be worth while and encourage some posts on fixes.

Open to suggestions on format but lets keep it to just the repairs. If you have questions PM someone or open a new thread for your specific problem.

or maybe this dies a quick death like most of my threads :)

Suggested post format.
Game PCB:
Symptom:
Steps:
Repair:
 
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Game PCB: Pac-Man or Ms. Pac-Man
Symptom: No Sound
Steps: Quickly tested capacitors with ESR. C51 and C29 out of spec
Repair: Replaced C51 and C29.
 
Game/PCB: MCR 90412 Power Supply board
Background: Bought board off of ebay assumed not working. Had replace TIP31 written on side in marker.
Symptom: +5v not adjustable reading 3.3 volts.
Steps:
1) Inspected board. Noticed tantalum cap at c107 was missing (Likely blown off due to voltage spike) Q105 2n2905 (amplifier) U2 LM305 (regulator) and Q104 TIP31 (transistor) all appeared to have been replaced. Also had a weird VR at vr102
2) replaced c107 with electrolytic cap and vr102
3) Pulled and tested TIP31 good
4) checked fuse F1 and it was blown. remembered this fuse powers/protects the +5 regulation ckt
https://forums.arcade-museum.com/showpost.php?p=3511552&postcount=19
5) replaced fuse and retested board good. +5 adjustable.
Repair: replaced fuse F1 with 3/8 amp fuse.
 
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Game PCB: Legend of Kage
Symptom: Certain player inputs weren't working (p1 start, p1-ButtonA, p1-ButtonB)
Steps:
1. ohm'd out swtich to insure it was closing on button press
2. ohm'd out wires back to edge connector pins, insuring continuity
3. manually jumpered gnd and pcb finger for p1, jump, fire...all were recognized by game pcb.
4. ohm'd out edge connector to pcb finger trace = Tested Bad
Repair: Cleaned pcb fingers with pencil eraser and then some contact cleaner. Retested Good.
 
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Game PCB: Midway Mortal Komabt Y Unit
Symptom: U99 Error

Steps
To rule out a bad U99 replace with a known good one no change
Metered out all pins of U99 found one intermittent jumped intermittent connection fixed issue
 
Game PCB: Midway Y Unit Sound PCB
Symptom: Staic Noise/No Sound Seems Dead
Steps

Repalced faulty crystal got sound CPU running
Replace capacitors around AMP the worse one that was leaking underneath was a 2200UF restored sound and clear
 
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Game PCB: Snow Brothers
Symptom: Would start off as normal boot up screens with no ram/rom test text then go to solid black screen. Looking closely with brightness fully up you can just make out Color Ram Error

Steps
Found a failed 74LS158 replaced bought back video but all GFX flashing and incorrect color

Replaced/socket 4 X 41464 rams repaired GFX issues
 
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Game PCB: Street Fighter 2 WW Bootleg
Symptom: Game would start off fine but leaving on for about a good 10 mins all text and main GFX would start being mixed up turning voltage up slowly to just over 5.4 would make the game run correct with no issues.

Steps
This one was tricky to find but after feeling around the PCB and finding nothing getting hot i noticed one of the PALs with static from my hand would change the screen, Repalced PAL off a parts PCB fixed the issue. Tried to dump the good PAL but sadly is locked read protected

These PCBs are not made very well quite cheap so if i couldnt find the issue quickly would of been a parts PCB
 
Game PCB: Golden Axe Bootleg
Symptom: Game runs missing Player 1 and 2 magic and attack buttons

Steps
Was told this PCB was plugged in backwards and blew some of the input buffers

Replaced 4 X 74LS245s repaired all inputs told owner to check all connections before applying power
 
Game PCB: Atari Anti-Aircraft
Symptom: Game appeard dead nothing on screen

Steps: Started by looking at the timing
1. Crystal was good and so were the horizontal counters
2 checked the 74107 next for 256H and output was static this chip also feed 256V

Repair:replaced J6 a 74107 and board came back to life
 
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Game PCB: Crazy Kong Falcon PCB with Crazy Kong PT2 Rom Mod
Symptom: Watchdog Reset/Random Garbage on screen

Steps: Found a broken pin/bad socket at 7B repaired 7B MB7052 Ground Pin/replaced socket got game to displaying Insert Coin Credit and demo high score table screen but kept resetting, found broken connection on a piggy backed 74LS32 at 5E got the game up and running but no spites

Symption No Sprites

Checking on bottom PCB i found that all sprite ram Hm2511 was running expect A3 was sitting stuck on scope. Traced that back to 9H 74LS86 replaced and all sprites were restored
 
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Game PCB: Marval VS Capcom CPS2
Symptom: Game runs battery OK but text/player GFX all messed up

Steps: Replaced 2 X HM6264 SMD Object Rams on B board repaired issue, Replaced Battery also as it was look like the original one from factory

Game PCB: DarkStalkers Capcom CPS2
Symptom: Dead
Steps: Battery was dead removed battery reprogrammed eprom for decryption version all good again
 
Game PCB: Super Bug
Symptom: Text and car were OK but playfield was scrolling by. Gas pedal was unresponsive.

Steps: there are counters (74191) in the playfield logic that scrolls the playfield horizontal and vertical so I started there. Found F8 to be bad and replaced it which fixed the playfield issue. I also replaced the multiplexer (74151) at E9 that was connected to the gas switch and it started working.

Repair: Replaced F8 and E9
 

Attachments

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Game PCB: Atari Basketball

Symptom: nothing on the screen but some jagged lines up and down the screen. Game reseting in game mode

Steps: Checked CPU and it appeared to be working. I entered self test mode and self test ran but it still had the vertical lines. The self test mode said RAM OK ROM BAD B. B corresponded to the 82s137 at L2, it's was a REV 1 PCB with 16 proms. I ended up removing all 16 proms and replaced with 4 newly programed 2716 EPROMs. Test mode now said RAM OK ROM OK but still nothing on the screen except the lines in game mode. I was going to swap the graphics ROM (A/B6 and C6) with known good to see if it made a difference but I noticed A/B6 had pin 9 bent under itself so I straighted it out put the ROMs back and the game booted.

Repair:Removed old program PROMs and burned new Program EPROMs. Straighted the bent leg of A/B6.
 
Game PCB: Canyon Bomber

Symptom:Just garbage on the screen. later found one sound channel dead

Steps:Checked CPU and it had no sign of life. I swapped it with a new 6502. Address and data lines were now moving but no change to screen (pic 1). Seen something like this before and it usually ends up being R/W line to the memory. R/W line good at CPU but stops after C6 (74174). Replaced C6 and got Pic 2, looks like a playfield RAM issue. Game plays but has graphic errors and no sound from Audio 1 (Left? side). Piggy back the 2102 RAM and playfield improved when I got to L2. Replaced L2 and playfield looked good. On to sound, using my audio tracer I picked up sound before the TDA1004 amp but nothing on the output. amp voltage was good so I replaced C11 (TDA1004) which brought audio 1 back. I thought it was all fixed but well playing I noticed the white plane's sound would cut out some times. I finally traced it back to R38. It was suposed to be a 2.2 M resister but it was a 1.6k. Factory error? I'm not sure, didn't look like it had ever been replaced. I replaced it and now I had all sounds and a working PCB.

Repair:New 6502 CPU. new 74174 @ C6. new 2102 RAM @ L2. new TDA1004A @ C11 and replaced R38 with a 2.2M resistor





 
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Hope this one isn't to long. I don't own the cabinet so I had to do it all on my bench. I hooked up a couple 25k pots and switches and had a go. I ran into an issue with the the MAME ROM set. ROM E would not pass the self test. I was able to pulll a good image off the originals and send it off to the MAME devs. So if any of you are working on this board the good ROM will be in MAME release .189

Game PCB: Midway Road Runner 8080

Symptoms: nothing on the screen, ROM/RAM issues, missing sound and gun positioning

Steps:

To start with I removed Road Runner daughter board and used my known good Space Invader daughter board and test rom. which allows me just to focus on the mainboard


Issue 1: blank screen
When I first powered it on I saw nothing on the screen, no sounds, it seemed dead. The first thing I usually check in this situation is the timing. Using my oscilloscope I made sure the CPU was getting a clock on pin 22, it was. Then I went through the counters 9316/74161, they looked fine. I had good signals going into A5 and it seemed a valid sync signal coming out so I looked at the video side of the signal out of C4. C4's output was not moving and while checking the inputs I noticed pin 15 (load) was not changing so the RAM data was loading into the chip. I followed it back to A7 and D6 those chips seem to be acting correctly for the signals they were receiving. I moved on to B4. The inputs were good but no output. I replaced and got a screen with white vertical lines.
UaNq40vm.jpg


Issue 2: White vertical lines
You see these lines when you remove all ROMs. I had a Space Invaders test ROM in there so it they should not have been there. Seems like I should start looking at the ROMs. The address lines going in to the ROMs looked good and so did the data lines coming out. Followed the instruction bus from the ROMs to the 74153's (A2, B2, C2 and D2) There was no output at A2 so I replaced it and my test rom started working and displayed a RAM error at G14

Issue 3: RAM error
Replaced G14 with a new RAM and the motherboard booted to the test screen. On to the Road runner daughterboard.

I removed the Space Invaders parts and installed Road Runner ROMs and daughterboard.
xdtQCram.jpg


Daughterboard
Issue: moving Graphics were missing
When I had it all set up for Road Runner I noticed all moving graphics were white squares. Not uncommon to have white lines running through the graphics but when everything is missing it usually is A4 (74175) I tested using my logic comparator and it did come up as bad. I replaced A4 and I had the moving animals.
MMybdRZm.jpg


Issue 4: no sound
There was no sound at all so I started working backwards from the speakers starting at P1 (LM377) the final amp. Using my signal tracer I was able to hear all the game sounds at pin 7 (input) of P1 but nothing was coming out of pin 2 (output). Voltage was good so it looks like I need to replace the chip. Hate replacing this chip there is such a big ground plane and heat sink it's hard to melt the solder unless you cut off the heat sink. Bought new amp and heat sink and replaced it. Sound came back.

Issue5: gun tracking

Everything is working now except when I go into test mode the marker for the gun location is travailing diagonally across the screen/ the control pots make some change to the location but it is always moving. Using my oscilloscope, I trace the signals from the pots back. Ever thing looks good until I get to B1 (LM324) pin 6. The signal is not reading any higher than about 2 volts. Looks like it is either B1 (LM324) or C1 (ZN425E) messing up. I had a LM324 but not the ZN425E so I replaced the B1 and there was no difference so I ordered the ZN425E and replaced it and the aiming worked. everything seems to be working

Repair: replaced on motherboard 7420 @ B4, 74153 @ A2, 2107 RAM @ G14
on daughterboard 74175 @ A4, LM377 @ P1, ZN425E @ C1
 
Thought I had a bad AR2 in Pole Position so ended up testing like 5 of them on bench. Only one (non PP) had an issue.

PCB: AR2 power supply
Symptom: -6.3v on -5v line.
Steps: none really
Repair: replaced 7905 at Q9

PCB: Pole Position CPU board
Symptom: Powers on to blank blue screen
Steps:
1) checked voltage (note only +5v required on PP)
2) shotgunned z80 and it worked.
3) replaced original z80 and it still works
Repair: reseated z80 at 7d? I think the jury is still out here. Could have questionable socket.

While I had various things out, tested another PP board I have.

PCB: Pole Position Video PCB
Symptom: Boots to screen showing RAM 30 error
Steps:Read diagnostic screen
Repair:replaced ram at 3E with HM6116LP-4 (200ns)
200ns or faster required according to manual

Have one working PP CPU and two working PP video boards now but really need to address my hacked harness.
 
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Not a "classic" but will be some day:

Time Crisis 4 IO PCB

Single LED blinking by CPU. Activity on the data lines but computer doesn't
see IO board. Only thing it really can be since I'm sure the CPU is running:

Replaced the serial transceiver labeled SP485ECN (8 pin SOIC chip)

Digikey part # ISL8485EIBZ-TCT-ND $1.49
 
Recently had a Konami Violent Storm PCB that had missing sprites and a color palate issue. Located some damage to the legs on the sprite generator at 7K, removed the chip and replaced with a donor. Everything is working as it should.

nWXEvJEl.jpg
 
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