My Spring Break has missing and weak sounds. When it plays, the sound is really thin and tinny, and there is always background static. It kind of sounds like a stereo recording that is missing one of the sides - you know there is more there but it's not coming through.

Also, when the ball kicks out to the shooter lane, there is no background music - just a bunch of quiet static noise and periodic electronc chirp.

Is this a faulty sound prom issue? Or should I dig deeper into various chips on the board? I was thinking of ordering a new licensed rom set and trying with fresh eproms, but I wonder if the symptoms point to something else?

Thanks,

-Adam

Ordered some caps for the aux board.

I thought the missing sounds might be a bad sound rom, so I burned all 3 new ones, and have the same issues.

I have the same issues with two different mpu s (one is a new swemmer board), and with two different driver boards (one is a new rottendog), so I think I can eliminate any chip problems from those boards.

I'm definitely missing sounds - when you add a coin, all I get is a crackle, there are drum and bass sounds that are completely missing during the music tracks, I never get the surfer drum roll music.

If the caps on the aux board don't solve it, what should I look at next? 6116 ram chips?

Thanks Marco, I got them, I'll try them this week and see how it goes.

Replaced both op amp chips, and also recapped the aux power supply board. Still the same issues.

Going to test and replace the ram chips.

I also noticed that if I put my hand on the ay-3-8913 sound synthesizer/generator chips, that the sound crackles and buzzes a bit. What are those chips? Are they analog? Or could one of those be failing and not generating the proper sounds?

Am also going to get a couple of 74ls374 chips to piggyback and test. A couple of them feel hot to the touch.

Wanted to close this thread out with a resolution.

After struggling to socket and replace the two LM324 chips (broke 3 solder pads, those parts are just jammed in there, the pins are totally pinched into the thru holes), I didn't want to risk any more damage to the board. I sent the board out to Clive at the coinopcauldron, and he repaired the board for me. It had multiple chip failures. Here is the repair log:

Gottlieb MA766 Sound board (SN 24770. Spring Break. Missing sounds. Audio path issues. Prior repairs): All socketed ICs removed and tested, -- 3x NOS 2764 Spring Break sound ROMs (DROM, YROM1, YROM2). 2x 6116 Static RAM ICs and 2x 24-pin chips sockets. AD7528 D to A converter IC and 20-pin chips socket (dead). NOS SP0250 Speech synthesizer IC (feeding constant noise into audio path). Prior repairs checked, -- reworked 3x open traces. Addition open trace to H1 Op-Amp repaired. 2x LM334 Quad Op-Amp ICs. Signal flow analyzed. Edge connector cleaned. Board cleaned up. DIP switch tested. Two-tier full functional testing.

Glad to have everything back working well, and Clive did a really professional repair job.