Gyruss PCB issues

jacklick

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I just picked up a gyruss and it boots but has issues. One amp is out (can see brown discoloration), the cross hatch pattern stays on in upper and lower part of screen, fire button doesn't work, dip switch settings seem to have no effect (stuck on free play).

I removed and reseated all socketed chips and confirmed voltage. There is a small harness hack to bypass/ reinforce one of the grounds that was burned up on edge connector but don't see any other visible damage.

Downloaded and installed shoestring's test rom and get
RAM 3J stack err $97FA

thoughts while I read more threads? Looks like Konami scratched out all the chip model #s or something.
 
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Well that was a quick repair. Thanks Shoestring for making this test rom. Game passed the self test so fast I couldn't read it but game plays fine. Fire button works, dip switches behaving normally, etc.

I don't know what sounds I am missing so am going to jumper, forget name, to mono, to see and then order replacement amp from riptor.
 
Jumpering the audio jumper brought the missing sounds out but only one speaker. I am assuming only the amp is bad.

Dang been a long time since I played this game but lots of fun and cools sounds.
 
I think you'll find that the amp is fine. Jumpering just plays both channels in a mono setup.

Edit:

For my home setup I hooked up speakers via RCA cables I made to channel 1( pin 2 & pin B ) & channel 2 ( pin 15 & pin S ) from the Konami end of the adapter. I also isolated both speaker connections that go to the JAMMA ( by disconnecting pin 15 & pin 2 from the PCB side at the konami edge connector ) end as I didn't want to overload the two amplifiers on the PCB.

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LA4460 Amp question

I am about to install new LA4460. I assume the metal on pcb and metal on back of amp chip is ground and there should be no heat sink compound there?

Going to take a pic the the board part is burnt a bit and doesn't have great continuity in the brown spot.
 
put some compound on heat sink but not on the grounding pad, which I cleaned w/ scotch pad and alcohol.

yes I removed compound from the amp chip :)
 

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Success. The guess of amp being bad worked out. Replaced the caps on the sound board while I was at it. I believe each amp drives a separate speaker, so when you go to mono, if both amps and speakers work, you get all sounds out both speakers. I could be wrong but replacing amp seemed to solve my issue.

Put in Matt's HSS rom w/ 6116 NVRAM module and have HSS now too.

Now to clean this bad boy up and get it ready for basement.
 
Success. The guess of amp being bad worked out. Replaced the caps on the sound board while I was at it. I believe each amp drives a separate speaker, so when you go to mono, if both amps and speakers work, you get all sounds out both speakers. I could be wrong but replacing amp seemed to solve my issue.

Put in Matt's HSS rom w/ 6116 NVRAM module and have HSS now too.

Now to clean this bad boy up and get it ready for basement.

Love to hear stories like this one. Congrats on the repair. Great game, too.
 
Crap...Nevermind I jumped the gun I guess. Maybe replacing the caps made it sound a lot better? No idea.... but after messing w/ vr1 and vr2 it is clear the right speaker, controlled by vr1, has no sound in stereo or mono. I tried a different speaker but no change.

Board is now back out of game.
 
You will only get sound from one speaker in a mono setup ( all sounds play through the left speaker when jumpered ).

Check your harness, wiring and speakers.
 
If I am getting all sounds in Mono then the issue has to be downstream of the mono/stereo jumper. Looking at schematic, there is only the VR, caps, and the LA4460 before leaving the board.

Can I use mini hooks right to pin 7 * 9 of LA4460 to see if I have sound there or should I use logic probe?

While board is out, going to remove VR1 and check that.
 
You will only get sound from one speaker in a mono setup ( all sounds play through the left speaker when jumpered ).

Check your harness, wiring and speakers.

going to do this as well. want to see if I could bypass harness by hooking directly to board kind of like you did but not permanent.
 
You will only get sound from one speaker in a mono setup ( all sounds play through the left speaker when jumpered ).

Check your harness, wiring and speakers.

I had already tested w/ different speaker. Just ohm/continuity checked from edge connector to speaker and it appears good. One wire is near zero ohms and the other changes w/ adjustment of coin door vol pots. Not that those pots are super smooth but they work.

back to board I guess
 
ok. I carefully hooked up my pc test speaker to card edge A/B2 and have no sound. Doing the same with left speaker at A/B15 results in sound. This has to mean the issue is on the board. I pulled VR1 and it tests fine (@200ohms)...

Is my logic correct in thinking the problem has to be down stream of mono jumper? Maybe will check mylar caps c21,c22 and r23, r24 next.

I don't understand how sound isn't sent to both amplifiers with mono jumper in place but I suck at reading these schematics anyway.

**edited** added schematic snapshot for clarity/future refernce. Konami uses different card edge numbering and lettering on sound board schematic vs harness schematic. Also you can see the outputs from 8910s @ 11&12D go to mono jumper.

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ok. I carefully hooked up my pc test speaker to card edge A/B2 and have no sound. Doing the same with left speaker at A/B15 results in sound. This has to mean the issue is on the board. I pulled VR1 and it tests fine (@200ohms)...

Is my logic correct in thinking the problem has to be down stream of mono jumper? Maybe will check mylar caps c21,c22 and r23, r24 next.

I don't understand how sound isn't sent to both amplifiers with mono jumper in place but I suck at reading these schematics anyway.

Getting back to this and finally have it working.
c21,c22, r23, r24 all checked ok. One thing that was somewhat interesting but have no clue if it meant anything... the resistance between a2&b2 (Right speaker vr1 = no sound) was like 50k ohms vs a15/b15 (left speaker vr2 = working) was @ 1.8k ohms

After poking and looking at old amp and schematics and back again and again, I realize I put the replacement 4460 amp in backwards. The metal pad goes to the heat sink. Flip it back right and am now getting audio out of both channels. Resistance between a2&b2 @2k ohms.

Also tested mono jumper and verify I get sound out both speakers and can control it via VR1 (right) or VR2 (left).

Have to read back through to see if I tested it correctly with old amp chip, and if so, that was my issue (beyond being a knuckle head and putting crap in backwards).
**edit** read back through and not 100% if it was the amp chip or not as I did replace the caps as well and likely was at the same time. Oh well it is working.
 
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So you fixed it, then it wasn't working, then magic happened, and now it is.

Gotta love magic.

:)

Good thread. Lots of detail. Fun to read.
 
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