Gyruss No Sound!

Joined
Dec 28, 2024
Messages
85
Reaction score
31
So I actually started soldering for the first time and effectively repaired a burnt edge-connector! However, the game has no sound which has left me wondering if a nearby pin had gotten damaged from the burn. Wanted to hear some other perspectives on the subject. I tried cleaning the other pins with alcohol 91% proof but still no change.


Needless details:
Sanded and washed with alcohol, soldered a strip of copper in place, used two-part epoxy resin underneath and clamped down until cured, resoldered, and inserted. #VeryProud

Thanks to Arcade Jason for being an incredible example!

P.S. The PCB was sold to me with a burnt connector. I simply just wanted to make the best of the situation.
 

Attachments

  • 1.jpg
    1.jpg
    269.7 KB · Views: 24
  • 2.jpg
    2.jpg
    232.6 KB · Views: 19
  • 3.jpg
    3.jpg
    198.1 KB · Views: 20
  • 4.jpg
    4.jpg
    250.6 KB · Views: 20
  • 5.jpg
    5.jpg
    356.7 KB · Views: 24
  • 6.jpg
    6.jpg
    164.9 KB · Views: 25
Last edited:
It's just a ground connector. You didn't show the other side, but even if that burned up you still have two ground connectors. Yes it's important you repaired it, but I doubt it has anything to do with your sound.

Did you verify you're getting good 12V from the power supply? Have you audio probed from the sound amp? Verified RAM from the sound board? Verified that AY-3-8910 works?

BTW - congrats on Gyruss. It's always been a favorite of mine.
 
It's just a ground connector. You didn't show the other side, but even if that burned up you still have two ground connectors. Yes it's important you repaired it, but I doubt it has anything to do with your sound.

Did you verify you're getting good 12V from the power supply? Have you audio probed from the sound amp? Verified RAM from the sound board? Verified that AY-3-8910 works?

BTW - congrats on Gyruss. It's always been a favorite of mine.
It definitely has nothing to do with my sound issue. I'm just proud I didn't burn myself. I haven't gone through any troubleshooting because I wasn't sure where to start. I will definitely start looking into some of this that you provided. Thank you, z0ner. :)
 
I'm not sure if this will help or not but some boards I've worked on needed the negative on the speaker to be tied to a cabinet ground. I believe this is the case for at least Konami frogger boards. I love my gyruss as well. High score saves sells a gyruss time pilot and pooyan multi game mod also just fyi.
 
Last edited:
You need to probe the CPU on the sound board and see what it is doing. Is it getting a reset signal on pin 26? Does it have clock on pin 6? What are INT, IOREQ, and M1 doing? Have you tested the sound roms to make sure they are good?

Your problems could be any of the following, in best troubleshooting order:

1. Bad audio amps/caps. While the board is powered, see if you can run your finger and touch the back side pins of the audio amp chips. If you hear buzzing through the speakers, the amps are most likely good and you can move on to other troubleshooting. Do this with volume knobs maxed out. If not, check the caps near the amps. Lightly press or wiggle them and see if any sound or buzzing cuts in or out. Sometimes a leg of a cap has come loose with bad solder joint and prevents sound output.
2. CPU doesn't have clock or reset. If the CPU doesn't have clock, it has no heartbeat and will not run any code. If it doesn't see the RESET signal toggle, it will never wake up and run code. Check those first.
3. Bad sound ROM. If the roms on the top board are bad, the CPU could not be processing the correct sound code and crashing. You need to check these with an eprom reader and verify against known good MAME roms, using tool like web based ROMIdent.
4. Bad sound RAM. There are two 2148/2149 rams on the sound board, if they are bad, the program will crash.
5. Bad CPU. Is the z80 getting really hot? Might be a clue that it is bad.
6. Bad AY3-8910. There are lots of these on the sound board. If yours are socketed, it is easy to swap with a known good chip, otherwise, difficult to remove and socket 40 pin chips. See this thread for an example of this issue: https://forums.arcade-museum.com/threads/gyruss-no-sound-stuck-int-line.514769/
7. Other bad sound chip TTL logic. This would require more extensive troubleshooting of the circuitry on the soundboard, using logic comparator, oscope, and logic probe.
 
You need to probe the CPU on the sound board and see what it is doing. Is it getting a reset signal on pin 26? Does it have clock on pin 6? What are INT, IOREQ, and M1 doing? Have you tested the sound roms to make sure they are good?

Your problems could be any of the following, in best troubleshooting order:

1. Bad audio amps/caps. While the board is powered, see if you can run your finger and touch the back side pins of the audio amp chips. If you hear buzzing through the speakers, the amps are most likely good and you can move on to other troubleshooting. Do this with volume knobs maxed out. If not, check the caps near the amps. Lightly press or wiggle them and see if any sound or buzzing cuts in or out. Sometimes a leg of a cap has come loose with bad solder joint and prevents sound output.
2. CPU doesn't have clock or reset. If the CPU doesn't have clock, it has no heartbeat and will not run any code. If it doesn't see the RESET signal toggle, it will never wake up and run code. Check those first.
3. Bad sound ROM. If the roms on the top board are bad, the CPU could not be processing the correct sound code and crashing. You need to check these with an eprom reader and verify against known good MAME roms, using tool like web based ROMIdent.
4. Bad sound RAM. There are two 2148/2149 rams on the sound board, if they are bad, the program will crash.
5. Bad CPU. Is the z80 getting really hot? Might be a clue that it is bad.
6. Bad AY3-8910. There are lots of these on the sound board. If yours are socketed, it is easy to swap with a known good chip, otherwise, difficult to remove and socket 40 pin chips. See this thread for an example of this issue: https://forums.arcade-museum.com/threads/gyruss-no-sound-stuck-int-line.514769/
7. Other bad sound chip TTL logic. This would require more extensive troubleshooting of the circuitry on the soundboard, using logic comparator, oscope, and logic probe.
It seems both amps are indeed broken. One was working and then stopped. I didn't have time to unscrew the heatsync for the part number but those will be first to replace. Thank you for your insights on this, TimePiloteer
 
So I actually started soldering for the first time and effectively repaired a burnt edge-connector! However, the game has no sound which has left me wondering if a nearby pin had gotten damaged from the burn. Wanted to hear some other perspectives on the subject. I tried cleaning the other pins with alcohol 91% proof but still no change.


Needless details:
Sanded and washed with alcohol, soldered a strip of copper in place, used two-part epoxy resin underneath and clamped down until cured, resoldered, and inserted. #VeryProud

Thanks to Arcade Jason for being an incredible example!

P.S. The PCB was sold to me with a burnt connector. I simply just wanted to make the best of the situation.
Nicely done!
 
By any chance, does anyone know the replacement audio amp chip to gyruss? Or a modern substitute?
 
What about the heat syncs? I can just reuse them? Also, what's the paste that's in between them and the chip?
Clean any gunk off the heat syncs and re-use them. Otherwise you are going to end up having to make your own --see https://forums.arcade-museum.com/threads/gyruss-boardset-rehab.539628/post-4844109 for the set I made for mine. Making a set requires a tap set and a drill press is recommended. So if you have both of the originals, just re-use them. The paste is just plain thermal paste -- https://www.arcadepartsandrepair.co...rts/pinball-parts/thermal-paste-1-gram-packet.

I didn't post it in my thread for some reason, so I'll add it here for people searching. The LA4460 heatsinks I made were 30mm x 20mm x 10mm. https://www.amazon.com/dp/B093V778LH
 
Update: I changed out the amplifier chips but no such luck on any sound. I know the old amp chips burned out so they definitely still needed replacing. I heard it could be CPU2 or any of the following:

"[Gyruss uses] two Z80 microprocessors, one 6809 microprocessor, and one 8039 microprocessor. For sound it uses five AY38910 PSGs and a DAC."

I'm just wondering ways to test these in order to definitively know which ones need replacing.
 

Attachments

  • 20250411_173258.jpg
    20250411_173258.jpg
    384.7 KB · Views: 8
  • 20250411_175019.jpg
    20250411_175019.jpg
    355.6 KB · Views: 8
  • 20250411_201101.jpg
    20250411_201101.jpg
    420.1 KB · Views: 8
Back
Top Bottom