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Author Topic: Do I have a dead Paula chip in my A1200?  (Read 2747 times)

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Offline shortcircuit

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Re: Do I have a dead Paula chip in my A1200?
« on: June 27, 2010, 10:39:11 AM »
Quote from: tom16mm;567508
Hello all.

My A1200 recently developed an audio issue, where the bottom half of both stereo audio signals are clipped. The following video of my oscilloscope display, taken from the right channel output while playing a mod file in ProTracker, clearly shows what's wrong (sorry, no audio, but it sounds as bad as it looks):

http://www.youtube.com/watch?v=pSqCU4FU_n8

The audio waveform is distorted in the same way all the way back to pins 33 and 34 on Paula/U3. I replaced coupling capacitors C324 and C334 with non-polar ones, and the 470µF electrolytic filter cap (C307) in Paula's power circuit, and the problem persists.

Power in to Paula is close to 5v, and very stable. I also did not detect any leaking/bulged capacitors.

Is Paula really dead, or can something else be at fault?

Check power to U15. Should be +12v at pin 4 & -12v at pin 11.