500+ no sound

[curtis]

Another day, another snakebite!

Working on a 500+ rig and set up a set of speakers and fired it up.

No sound.

Hmmm, maybe a bad Paula?  Swap with a known good, no joy.  Try original chip in another 500 mobo and it works.

Suggestions?

[Oldsmobile_Mike]

Any other issues or just no sound?  Probably obvious but you've confirmed the speakers and wiring are working, yes?

[Merc]

I seem to remember having audio problems with a bad -12v connection from the power supply on an a500, when you tested with the other machine was it using the same PSU?

[curtis]

Used the same speakers on both units.  

Works on one, but not the other.

No other issues.  Everything else is good.

Any other issues or just no sound?  Probably obvious but you've confirmed the speakers and wiring are working, yes?

[curtis]

Different power supplies.

I seem to remember having audio problems with a bad -12v connection from the power supply on an a500, when you tested with the other machine was it using the same PSU?

[paul1981]

Used the same speakers on both units.  

Works on one, but not the other.

No other issues.  Everything else is good.

If found to not be the psu, then I suppose it must be either a power failure to the op-amps, or faulty op-amps which amplify the signal from Paula. But seems unlikely they'd both die together, so like the other chap said, check the 12v line.

[Blizz1220]

Bad -12V gives "broken" distorted and crackling sound but it can be
heard.If there is no sound check for damage on traces , I (think) that
if Paula was gone it wouldn't boot but never seen that case.

[curtis]

Well, after a good nights sleep and an chance to ponder it a bit, my eyes were opened!

I had forgotten when I picked this up, the previous owner told me there had been some battery damage before he removed the old leaky battery.

So, looking at that area which is where the audio filter circuitry sits, I noticed remains of battery damage that has been cleaned up, but not repaired!

Hmmm.

Yeah, I kinda feel stoopid!

I'm including a picture...

[paul1981]

Well, after a good nights sleep and an chance to ponder it a bit, my eyes were opened!

I had forgotten when I picked this up, the previous owner told me there had been some battery damage before he removed the old leaky battery.

So, looking at that area which is where the audio filter circuitry sits, I noticed remains of battery damage that has been cleaned up, but not repaired!

Hmmm.

Yeah, I kinda feel stoopid!

I'm including a picture...

Erm... Yeah!! Always perform a visual inspection before anything else.

[curtis]

Well, I did have 3 other senses working at the time.

Smell, no burning odor!
Sight, no smoke!
Hearing, no sound!
Why would I need to look at the actual motherboard?

:laughing:

Erm... Yeah!! Always perform a visual inspection before anything else.

[mechy]

Curtis, is that the same board i installed the 68000 socket on? i remember kind of looking at it and thinking the battery damage seemed a bit rought. As for finding faults, i can't count the hours wasted on repairs i looked in the wrong place for the problem.  
hope you get it fixed.

Mech

[curtis]

Yeah mechy, it's the same board.

Actually, I've got a 6a I'll probably use instead and will see if this "silent" partner can find a new home...

[Oldsmobile_Mike]

Maybe you could bypass the audio filter circuitry?

[curtis]

That will be up to the new owner.

Yeah, I've decided to offer it to someone new.

Check out the marketplace forum.

Maybe you could bypass the audio filter circuitry?