problem in solod state amp. Any ideas?

[billstets]

I've had this little Randall RG-12-110 practice amp sitting around since about 1987, but I haven't even turned it on for about 15 years. I just saw one go on Ebay for a nice price, so I thought I'd sell it.

But I turned it on and it's making ghost notes in high frequency single note lines. Also when I play high notes, there's a faint hum/hiss that gets louder momentarily as the note starts, and then goes away immediately. It's almost like the sound single coil pickups make with gain when you have them quiet while standing in one position, but then turn your body 90 degrees.

Anybody have any idea how serious this might be? I think it may be worth fixing, as these seem to be somewhat in demand as solid state amps go. But I don't want to spend more than it's worth. Too bad I don't know how to fix them though! :(

[TheAmpNerd]

Thinking,

Silicon typically doesn't go bad over time.

Resistors typically don't either.

Plastic can deteriorate but probably not that.


Scratching head....


might have some dry electrolytics;
i.e., time for a cap job. : )


My have some dry grease in the pots
and general corrosion.

[John Phillips]

I'd guess electrolytic caps too. Solid-state amps have them as well, both filter caps and in the audio path for cathode-bypass, just like tube amps.

[billstets]

Thanks guys. I have hardly ever used this amp. I have a Kingsley for playing out (and of course other tube amps before that) and a POD for home use, so this pretty much sat unused for 15 years. When I fired it up to list it on Ebay, I was surprised at how good this little amp sounds, other than the high frequency problem. It was made in 1986.

I have a friend who knows some things about electronics, though not amps per se. I am going to rule out the speaker first, and then look att he caps with him. He mentioned the caps as well, and when I looked at the chassis, it seems pretty straightforward. I can see the caps. It would be pretty cheap to change those. He also mentioned the "op amp"? I don't know too much about what that is and how hard it would be to replace. Is that the part that does what tubes do?