Fender Acoustisonic 150 Qs

I bought this amp at an auction so I have no idea of the prior history. It appears to have very little, if any, wear. I wonder if there might be some corrosion from simply sitting unused for a long period of time. Here are some things I have noticed:

A noticeable hum occurs when it is switched on. Changing out cables has had some effect but the hum persists, just quieter.
When switched off there is a loud pop.
The Mic/Inst channel seems to lack volume.

I have thought about dismantling the cabinet to take a look at the electronics. If there is some corrosion will it be obvious? What other things might I look at? I have only a limited amount of electronic knowledge.

Hi, have you connected it to an earthed socket ? … I have a new one and it hums out of the house on an ungrounded socket … and now he is very quiet…
I don’t know any more about it,…have fun with it :sunglasses:

Hey, Rogier. Yes, the outlet is grounded (earthed). Thanks for the quick reply.

Aaaa, too bad for you, that would have been an easy solution … well hope there is a loose ground wire inside … can also be a simple one … good luck for chasing this dream :grin:

Robert, after my amp had been standing for a while I found things were better after I’d taken the knobs off and sprayed in some contact cleaner.

I took the back off and there was nothing visible to clean and tighten up. Yours may be different.

And I sometimes get the pop when I switch off, sometimes not. And I do the same routine of turning down the knobs on the amp and guitar each time.

It may not be the amp you could have a ground loop caused by fluorescent lights or other electronics in the house. If you eliminate any amp problems and still have a buzz you can buy a filter for the plug. Do a search for Hum X.

Any idea how old it is? Older amps sometimes need to have capacitors replaced.

No, I don’t. Do you know how I can tell?

Maybe this will help. You’d need someone with test equipment to be certain.

There is a certain amount of hum that is inherent, depending on the settings. An amp set to produce clean tones for example will be quieter than one set with high gain.

It is possible that lowering the gain could reduce the noise and that is worth a try.

Interesting read, Mark. I need to do a bit more research and determine the age of the amp.

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