Help With Pioneer SA-9800 Please

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With no sources connected I have a fairly loud hum on both channels which does not change with volume setting. Occasionally there is also a hiccup/thump on both channels whether source connected or not. Apart from this the amp sounds fantastic and plays perfectly. The sound recovers immediatly after the interruption. With the pre/power amps links removed there is no thump and very little hum.

Grateful for any advice please.
 
It sounds to me like a bad solder connection somewhere. If removing the pre/power links "fixes" the hum/thump issue, then it's most likely in the preamp section, after the volume control. I'd try wiggling the components, especially capacitors, and see if anything changes there. Could also be the filter caps in the power supply going south.... You shouldn't really hear any hum. If you turn off the speakers and use headphones, are the symptoms the same? If it sounds OK on 'phones, then the filter caps are a good bet.

sherlock
 
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