Macintosh Color Classic Sound Issue

[AlexTheCat123]

Hello!

I recently purchased a broken Color Classic off of eBay and it arrived in the mail a few days ago. The capacitors on the logic board are leaky and I ran the board through the dishwasher to get all of the goo off. After doing this, I managed to get the computer to work and I plan to recap the logic board in the next few weeks. However, the sound suddenly stopped working when I booted it up today and at first I thought that the volume was just turned down. After turning it up, there was still no boot chime or any audio of any sort. Then I realized that the Color Classic was producing sound, but it was so quiet that even the case fan in the computer overpowered it. Trying to narrow down the cause of the problem, I plugged headphones into the machine and powered it up, hoping for the best. I got a perfect boot chime at normal volume! This leads me to believe that the logic board is not the culprit, although I still plan to recap it since the capacitors were leaky. I have a suspicion that the analog board is causing the problem and that it needs a recap. Can someone confirm this before I order a bunch of capacitors and start the painstaking process of replacing all of the caps on the analog board? It would be great if someone could point out the capacitors on the analog board that deal with the audio so that I would only have to replace those. Also, if I am on the wrong track and the problem is something totally different, please let me know!

Thanks!

Alex

 

[sigtau]

Capacitor issues around the audio DAC chips in anything from the II, LC, or (Color) Classic series' usually results in dead, or very faint, sound.  That would be my first suspect too.

To test it out, you can first desolder and replace the caps around the TI amp/dac chip, which should be labeled 343S0129, and then try powering it on to see if you get sound.

Warning: If you go with tantalum chip capacitors like most of the people around here do, note that the polarity stripe on tantalums denotes positive, and not negative.  Certain tants can be quite explosive if connected backwards.  Make sure the stripe side is positive.  If you do replacement aluminum can caps, this is a non-issue.

 

[AlexTheCat123]

Thanks you for your suggestion! I'll look and see if I have any capacitors lying around that will do the job after I get home from school. If not, I'll order some today or tomorrow.