Frogger no sound

Zinfer

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Recently acquired a grail item. Finally! A Frogger. After getting it home and plugging it in however I had trepidations about it. No audio at all. What's a Frogger without sound?
I pulled the old pot off and replaced it with a 2K (had a choice of a 100Ohm or 2k on hand). Not of like kind, and not even close to 200Ohms, but another nonetheless. Still nothing. Checked speaker connections. I'm obviously getting a pop and hum from the speaker at max volume.
Pulled the sound and CPU boards apart. Pulled socketed chips and reseated. Nothing. Pulled the Sound boards Eproms out and double checked them. They're fine. Checked wiring diagrams. Everything appears to be hooked up well. The game plays, no audio at all. Checked all fuses. Fine. Didn't see any broken traces on the boards.
Talked to the guy I bought it from and he said sound was not a problem.
I'm not sure what to check next. Is there an amp or something that could be preventing all audio? I've noticed there are 2 pins at 2P on the audio board that nothing is connected to, but I think that is for some other configuration. The pot is plugged into 6P.
I'm running out of ideas.
 
Dual board

Check the half board (Top one) look at the end of the aluim bar crossing this board by the vol pins. You should see a (IC2) M51516 attached to the heat sink. Bob has the pot and wiring didn't look to see if he had the chip. I do know Mark Cap at Arcade chips had one listed. I requested a few things at the start of the year and damed if I forgot to order a couple 51516 for my boards. Try a search on KLOV for frogger sound and read the posts may help you. You could try reading schmatics and probing with a computer amp speaker setup.

Good Luck.
 
Yea the main and sound board on top. Where is this darned sound amp located? I thought I found the problem last night as Eproms 108 and 110 on the sound board were off on their checksums. But it was fruitless.

Probably a bad sound amp. Is this the two pcb board?
If all else fails I have a couple working boards for sale.
 
Yea I was in process of removing that bar but it looked like an odd transistor was screwed into it, connecting that bar and the sound board. I am going to check this 'ic11' for high/low signals as per the troubleshooting docs today.
I did the Google search many times.

Check the half board (Top one) look at the end of the aluim bar crossing this board by the vol pins. You should see a (IC2) M51516 attached to the heat sink. Bob has the pot and wiring didn't look to see if he had the chip. I do know Mark Cap at Arcade chips had one listed. I requested a few things at the start of the year and damed if I forgot to order a couple 51516 for my boards. Try a search on KLOV for frogger sound and read the posts may help you. You could try reading schmatics and probing with a computer amp speaker setup.

Good Luck.
 
Which - IC2 or IC11?
I saw the M51516 is 6.00 on arcadechips.com but min order is $15.00. So I looked for some 2716's as I had to use one for Eprom 108 last night. Maybe I could get by with ordering 2 of the M51516 plus shipping.
It'd help if I had a known working pcb set to test with. I'll take a second look at the schematics for IC2 to see what readings I should be getting.
I hate ordering parts, installing them, just to find that the original part was fine.
Thats the sound amp IC.
 
Ok, I used a logic probe on IC 11 for high and low signals. I used 2P for the taps. Pin 1 high, 3 low and 6 high, exactly what they should be. I guess just try replacing the amp itself. I'm not sure what is done to test the amp or what readings I should be getting for the amp.
 
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Replaced the amp this evening. Still quiet as a mouse. No audio at all.
Special thanks to Mark Capps, I placed an order for 3 of the amps just to get me over the $15 min order, and he sent me 5.
Striking out alot lately, the sound amp for Frogger, the Keltron/Cinematronics monitor rebuild for Armor Attack. Donkey Kong audio...etc. In a rut on repairs lately. Kind of a hit or miss business, and I'm missing alot. There goes another 'Swish' of the bat.
Maybe this will do it? http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=LM741CNNS-ND
 
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Uh I hate to state the obvious, but you are going to need a scope to track down lost audio signals. A Logic probe isn't going to tell alot about an audio signal. Random replacement of parts isn't very cost effective either.
 
Nice! I'm going to try replacing the audio chip, still waiting on parts. I've replaced the pot, double checked and replaced a couple eproms, replaced the M51516L amp Ordered a few LM741's. After that it's either build yet another harness rig or send it to a pro.
Talons right though, you can only go so far on hunches. I just hate building those harnesses for a single fix.
If there's guys out there that fix them affordably I'll just send it off. If it's something like Berzerk I'm pretty much forced to figure it out for myself; full blown harness rig, on the bench. Wish I had alot more scope knowledge it'd probably be a cinch. I was able to repair berzerk with a logic probe alone.
 
bah! Humbug! I just rechecked the audio boards' Eproms 8,9,10 and threw in a new AY audio IC I recieved today and still nothing. Not wasting anymore time or money on this. Shipping it out for repair at the first available moment.
I hate it when hunches don't pay off.
 
Good to hear. I hope that Eprom isn't flaking out on me. Thanks again for the repair. Looking forward to hearing some tunes.
 
Board recieved and it's playing beautifully. Thanks for everything Riptor. Your amazing.
 
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