Pioneer sa-9500 hum?

[Chriswashere]

Hi I have a pioneer sa-9500 that has a horrible non DC related hum out of the speakers. When uncoupling the amp and preamp the amp seems fine but has a faint hum while the preamp is horrendously loud.

Any ideas on where to start? I've been messing with this thing for a couple weeks but haven't had any luck.

 

[jheu02]

Loud hum from preamp could be a loose ground somewhere. Check solder joints, especially in the phono section (most sensitive) and wires to make sure all terminate where they should. With the cover off and it powered up and humming, try carefully moving some of the black wires a little and see if it changes or gets rid of the hum. Only one hand in the amp, other behind your back. It's not tube gear, but good safe practice.

The amp hum could be old mains caps. If you're handy with a soldering iron, and have some 1 or 2 uF film caps you could try adding them as bypass across the terminals to see if it gets rid of the hum. If you have to use electrolytic caps for this, be careful to observe correct polarity when taking them on.