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Old 06 February 2016, 00:11   #3
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Join Date: Feb 2010
Location: SnowLand, Canada
Posts: 74
Originally Posted by alenppc View Post
I have an A600, rev 1.5 motherboard that has recently developed an audio issue. The audio sounds "broken" (scratchy, not all of the frequencies sound quite right, some sound "overamplified" and some underamplified).

Now, short of desoldering every single resistor and capacitor to test them individually, is there any other way to troubleshoot this problem?
I've got 2 Amiga's that both do this.. not sure if they were always like that, or it eventually happened.. haven't got around to working on them yet...

Start with this.. Amiga is ON and no sound playing..

on the L347/TL084
Power Supplies:
Check Pin4 and Pin 11 for +12 and -12V (Main Power)
Check Pin10 and Pin12 for between 2-3V (If bad check AVREF circuit)

OP-AMP: (2nd & 1st Stage)
Check Pin 1 and Pin 7 should be close to 2.5V (2nd stage center output)
Check Pin 8 and Pin 14 should also be close to 2.5V (1st stage center output)

depending what you find... from there I would suspect
C331/C321 and maybe C332/C322..
or the negative feedback R331/R321 on the Rev1.5 are just too high a value of resistor..

Let me know what you find..
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