High pitch squeel

[brack23_5]

About 8 years ago I inherited an old 60's AIMS PA head which sounded awesome for just about anything played through it, especially guitar, had amazing reverb and cleans...POwered by two 6550's...Anyway about a year ago I turned it on and there is a high pitched squeel...you can hear some signal coming through but its pretty quiet....anyone know what this may be? Transformer? Caps maybe?

Thanks

[Ronsonic]

Depends on the type of squeal, could be tubes, my money is on caps. Faulty reverb pans and other oddities can do this too.

[donnyjaguar]

It could be half a dozen different things. I know this doesn't help much. Have you tried swapping tubes?

[brack23_5]

Yea we definatelty swapped both the preamp and power tubes...brand new both...still the same problem

[brack23_5]

So I opened it up and turns out about 5 caps are blown....Problem is they are fried beyond recognition....Anyone know how to find a schematic for this, I've not been able to even find info on these things, let alone a schematic.

[roadhog96]

About 8 years ago I inherited an old 60's AIMS PA head which sounded awesome for just about anything played through it, especially guitar, had amazing reverb and cleans...POwered by two 6550's...Anyway about a year ago I turned it on and there is a high pitched squeel...you can hear some signal coming through but its pretty quiet....anyone know what this may be? Transformer? Caps maybe?

Thanks
They show one for AIMS 120, not sure of it's like yours, check it out. http://www.schematicheaven.com/bargainbin.htm