Replace caps?

[pcmacd]

I've been reading about replacing caps in Soundcraftsmen vintage amps.
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I've a ~22 year old PM860 that, after a modest warm up period, simultaneously goes up and down in power (volume) level on both channels simultaneously.
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DC offsets are modest @ output. In the mv range.
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I've not tested the amp at non-idle conditions (need a non-speaker load; thinking about some light bulbs?)

• some 50-100 watt bulbs seem to be about four ohms at thermally stable conditions
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  • Thoughts? If you please?
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  • They are not inductive or capacitive, so they seem to be a good load?
  
  

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At no load, p/s rails are stable at ~70VDC.
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• I presume that this is either a problem with the regulation circuit or, perhaps, the output filter caps?

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I've posted a schematic at http://www.mediafire.com/?fw5oikud3d1az54.
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The original is here: http://www.audioheritage.org/vbullet...4&d=1296216160
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• I presume the regulation circuit is the upper left hand corner of the schematic?
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  • If not, please advise. .
  
  

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I'm an engineer, an ME, and am gasping for air here.

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And, when I read of replacing caps, does this include ALL caps, or just the electrolytics?

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AND, btw, I have ALL manner of test gear at my disposal. LOTS AND LOTS OF STUFF, including:
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• dmms -- some pretty awesome ones
• o'scopes
• power supplies; all manner of such
• low frequency network analyzers -> 50 KHz dual channel, 100 KHz single
• transient capture devices, lots of 'em
• counters
  
  • etc etc etc.
  
  

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Thanks for you help. WE DO appreciate your inputs...
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mac