Kustom Challenger

[Wes]

I've got one of these I'm looking at and it sounds good and strong except that when you hit it hard
there is this sizzling, whistle-y, oscillation that accompanies the notes you've played. It continues as your
notes decay until the level of output gets low enough again.

Any ideas what this could be?

It's got new filter caps in and I don't see any intermittent or weak connections anywhere. Nothing is burnt.

It sounds great until you drive some power into it!

[Enzo]

What are the board numbers on the preamp and power amp?

A common need of these old amps is to rreplace the small electrolytics in the preamp.

[Wes]

It only has one board and the numbers on it are PC5094 REV 2 KEI-1

It's got little black caps in the preamp that are roughly the shape of tantalum caps I've seen. Could these actually be tantalums?

[guitician]

Those sure do look like dipped tantalum caps, like a bigger version on the orange one between the two 12k resistors. That noise could be the speaker, have you tried others?

[Wes]

I've used different speakers. It's in the circuit for sure.

[Wes]

Yeah, that orange one looks like it too.

Might have to cut 'em all out!

Gonna wait to hear from Enzo. Thanks guys!

[guitician]

I've heard bad things about using Tantalum for signal path use in that if they didn't have a dc voltage across them they could distort horribly. The DC bias on the transistors may have drifted, which also could have caused the symptoms you described.