CD32's sound cracking up

[jaokim]

From time to time my dear CD32 cant play sounds very well. The sound seems garbled (?) and distorted. This happens to both samples an CD-music, ie an ordinary music CD through the earphones gets scrambled. It's very odd. Sometimes its okay.
Could this be due to those capacitors beeing wrongly put?

[Juzz]

Could be the volume slider that needs to be slided up and down a couple of times (to clear out dust etc from the contact).

[jaokim]

No, I dont think so, since the sound coming out from the line is also scrambled. And it seems to be computerized scrambled, ie not that ordinary analog distortion, but a cracked up technoid disturbing sound.

(Kinnda like Cher, but in a non-good way ;-) )

[Juzz]

Hmm... mkay - then I am not so sure what it can be...

[Ami603]

Sometime ago my A1200 Power supply fails to do negative powering, that is, the board was feeded only with +12V and +5V,everything worked fine until i played some sounds.You can check negative powering,maybe it is :-D.

@Juzz: Judging by your signature,A1XE on Denmark.
mmmh.... Nice :-o

[Juzz]

@Juzz: Judging by your signature,A1XE on Denmark.  mmmh.... Nice

Yup :-D
And my A1XE has been travelling about - it's been to Gothenburg and before it transitioned to an XE it had also been to an Amiga Party in another part of DK :-P

[KennyR]

I had the same problem with my A1200 when I removed the -12V power line. It seems to use the audio output as a -12V line instead, totally garbling the sound.

[jaokim]

So, maybe these capacitors that apparently are wrongly soldered (Iv'e read this in a lot of different places) cause this same -12V problem.
So, I'll guess I got some soldering to do.  :-D

[SilvrDrgn]

Check the -12 volt supply to the motherboard first.  The audio out on Amigas is generated by chips called "Op-Amps" (Operational Amplifiers).  These particular ones require both +12 and -12 in order to produce waveforms needed to generate sound for you.  If you only have +12 available to the chips, only the positive side of each waveform can be generated.  Thus, it produces crummy sound as the bottom of each waveform is "clipped" off at zero potential.  That could even cause damage to speakers if played loud enough.

[Stedy]

Don't bother checking the -12V supply of the CD32, it does not have one!
From what I remember it used single rail Op-amps.

I would suggest cleaning the cd-lens in case that causes a problem and spray some contact cleaner on the volume control.

The capacitors referred to were those across the +5V supply, the PCB silkscreen is wrong. If your CD32 was manufactured after October 1993, it should be fine.