stereo reciever static

Divide and conquer. You need a signal tracer or scope to find out where it begins in the circuit.

If it is independent of the volume control and in both channels, it must be somewhere in the power supply.

H. R.(Bob) Hofmann

On Sat, 03 Feb 2007 01:12:07 +0000, James Sweet Has Frothed:

Well then you've not worked on many amplifiers :)

Take a wooden dowel and tap on some components and the pc board. You might find something that reacts to it. Could be a bad elect cap somewhere. Or a transistor that gets noisy when it warms and might quiet if sprayed with a drop of freeze mist. Would help you narrow it down if you had some test equipment like a scope and either a decent knowledge in the component layout or a schematic.

I've worked on a few amps, probably a dozen or so, but usually the failures I come across are blown output devices.

I like the freeze spray idea, I'm not sure why that escaped me, I even have a can of the stuff. I have a scope too so I can poke around and see what I find. No schematic unfortunately but I suppose the circuit is pretty similar to other receivers of the era.

Sounds like a power supply issue. Replace electrolytic capacitors and reflow the solder joints. Use heat gun and freeze spray to isolate it. Can you poke around with an oscilloscope to see what the static looks like on the power supply rails?

Some of the other suggestions were good, power supply, intermittent connections etc, but how about this - maybe the power switch arcing internally? A quick test for this would be to run a transistor AM radio nearby and see if it picks up the static from the switch radiating. Or, using an AC voltmeter across the switch terminals of course would read zero while the unit is turned on. If voltage appears across the power switch when the problem occurs, the switch is bad.

Mark Z.