Help with old silvertone solid state please..internal feedback?

[junkbones]

 Ok so when I plug the amp up and play a few chords its fine.... if I turn the bass up or hit a power chord (G does it everytime) it starts sounding like really low toned feedback starts. It will not stop regardless of me unplugging the guitar from the amp or turning all the volumes down to 0.  This is a Silvertone 1464 SolidState 100. If someone could point me in the right direction Id appreciate it. Thanks!

[junkbones]

just would like to add that you can play over the hum. Thanks

[Casey4s]

Does it have all the original power supply caps?

[J M Fahey]

What Casey means is that the power supply caps must be certainly dry by now, replace them with fresh ones, and since sizes have shrunk along the time, you probably can easily fit at least 2 X as much capacitance in the same board, which is good.
The hum is a symptom , and the sputtering low frequency sound is motorboating, both caused by dying filter caps.

[Casey4s]

What Casey means is that the power supply caps must be certainly dry by now, replace them with fresh ones, and since sizes have shrunk along the time, you probably can easily fit at least 2 X as much capacitance in the same board, which is good.
The hum is a symptom , and the sputtering low frequency sound is motorboating, both caused by dying filter caps.

Thanks Mr Fahey  :tu:

I guess I didn't say enough for a change...

[junkbones]

Ill check all this out and replace as requested but its not "humming" and its not a sputtering low frequency.. its low end feedback, steady and long. Sounds exactlly the same as if you put a bass guitar in front of a bass amp plugged in and turned up. Its for sure feedback, im positive of that.

[Casey4s]

It's really not that expensive to just replace all the electrolytics at once.


Just my opinion...

[J M Fahey]

Its for sure feedback, im positive of that.

Ok, maybe, no stone should be left unturned. :tu:
To check for actual (physical) feedback, open the chassis and *lightly* tap everywhere with a chopstic or plastic ball point pen.
I mean everywhere, from input jack to speaker out and everything in between.
Anyway, electrolytic caps, as well as any non-soldered connection remain prime suspects; the first ones for age-old dryness and the second ones for rust/grime.
An electrolytic cap may still have *capacitance*, but have also developed high internal resistance , called ESR, which is "asyntomatic" until it starts to really hurt (think diabetes / high blood pressure as a "human machine" equivalent concept).
Consider replacing them something to do on an otherwise a boring evening.
PS: post a couple pictures too, at least one from its guts.

[teemuk]

Does it have a spring reverb?