Faint, high-pitched noise

Just a thought before you pot it in epoxy and make any subsequent repair impossible, see if any electrolytics are getting warm, it could be an ESR problem - although this normally improves as the unit warms up, still its worth a try.

It could be the other way around...... I think you'll find that electrolytic capacitor ESR goes down as they warm up. If it is a stability problem, which is a good reason for things whining then that is a possibility.

Depending on how 'good' the manufacturer think they designed things it can work the other way around. As electrolytics age their ESR goes up and that might affect stability at the other end of things. Which sounds like a possibility since it is second hand and presumably old. (!)

I assume you did not buy this from a freind or, if you did, they did not hear it themselves.....

Since you are Robert Latest you probably have a scope so it would be worth a prod to see what the supply voltage looks like....

DNA

You obviously have as much difficulty understanding English as you do with washing yourself!

Well, I didn't really want to pot it, like into a whole block of plastic. I have this lacquer-like stuff that I can brush or spray, so it would just soak into the windings of the coil.

Thanks for the electrolytics/ESR tip.

robert

You appear to have used reasonable English to provide a scenario whereby the problem, as described, should in fact go away as the unit warms up. I'm just pointing out that, technically speaking, your argument might be incorrect.

Then again, it's not uncommon for people with a good grasp of English to have difficulty with technical issues. Logic appears to be a problem as well. Still, one out of three isn't bad.

DNA

On a sunny day (1 Mar 2007 14:53:41 GMT) it happened Robert Latest wrote in :

My idea is to locate something that looks like a magnetic

I have use plastic spay in the past on noisy TV magnetics. Worked sometimes, does little harm.

Capacitors with ESR problems typically improve slightly as they warm up, although in my years of experience servicing TVs, monitors & SMPSUs I've seen caps react in a way contrary to usual expectation in this regard, my suggestion to the OP that the fault presenting once the unit had warmed up shouldn't automatically preclude paying attention to the caps, like I said - "still its worth a try".

The Maplin PCB lacquer is even better - the can I bought never sets, it stays gooey forever!

Well, at least my shoes don't smell!

DNA

How could they? - You don't wear any!

Bugger...

Signed, sealed, delivered and slayed.

DNA

I bought it from ebay at a very good price, and if I can't get rid of the noise the thing will have to be move to a back corner. I'm just too lazy to lay the wiring there.

robert