New build, OD problem, Pics added

[Bob-I]

Tony, maybe I was misunderstood. I was not trying to be critical of the idea of replacing components or doing some rebuilding. I just wanted to suggest that Bob I might feel a little better about doing that after he figured out what the issue is.
CW

It's all good kids, everyone's input is valuable.

[talbany]

Charlie..
Hey we are cool.. Sometimes it's hard to cover everything you want to say in a single post..My intent was to reiterate what you were saying about jumping the gun and automatically assuming it was component choice or failure before exhausting other possible causes which you appropriately pointed out and I totally agree with your post..Perhaps I should have chosen my words more carefully to reflect that..Sorry for any misunderstandings!!.. Judging by his last post I think Bob got the idea..

Tony

[talbany]

My biggest concern is for the filter caps. I've never seen these little stubby radial caps before.

I'm going to try to find the source of the oscillation. If I can resolve that I'll bet the OD will sound much better, then I can address the components.

I'll bet it will sound better too..

Keep us posted and good luck!!

Tony

[Bob-I]

This one is tuff. I'm seeing HF oscillation from V1b and on. I've had issues with PO before but never this early in the gain structure.

I suspect something in the tone stack so I'll be ripping that apart. Damnit, why did I decide to squeeze this into a Princeton reverb chassis, oh yea, portability.

[Bob-I]

Ok, I give up. I re-worked the tone stack to solve the HF oscillation, now I have motorboating.

These filter caps will go so I'm looking at building a new filter board.

[dcribbs1412]

Ok, I give up. I re-worked the tone stack to solve the HF oscillation, now I have motorboating.

These filter caps will go so I'm looking at building a new filter board.

Hi Bob
not much room in that chassis
not sure what cap values you are using in your PS...47uf's?
if possible maybe build a classic PS and use some axial caps (2x100uf and 22ufs) easier to replace anyways. Are the 2 radial caps down stream for reverb?
I believe you will get this amp up and rockin soon

D

[Bob-I]

Ok, I give up. I re-worked the tone stack to solve the HF oscillation, now I have motorboating.

These filter caps will go so I'm looking at building a new filter board.

Hi Bob
not much room in that chassis
not sure what cap values you are using in your PS...47uf's?
if possible maybe build a classic PS and use some axial caps (2x100uf and 22ufs) easier to replace anyways. Are the 2 radial caps down stream reverb?
I believe you will get this amp up and rockin soon

D

yes, they're 47u and yes, those down stream are for the reverb node.

What you can't see in the pics is the can cap that's in the rectifier hole so I have the first node covered. I'll be ordering some 22s and fabricating a new board.

[Charlie Wilson]

Hello Bob, just a thought but I remember reading a post where Brandon said he had an oscillation issue with the tone stack wires being too close to the input. It looks like yours are pretty close.
Good luck,
CW

[Bob-I]

Hello Bob, just a thought but I remember reading a post where Brandon said he had an oscillation issue with the tone stack wires being too close to the input. It looks like yours are pretty close.
Good luck,
CW

Yes, and they were causing a high frequency oscillation. I redressed the wires, in fact rewired the TS completely. Now it's motorboating, at maybe 8-10Hz.

[Charlie Wilson]

Hello Bob, just a thought but I remember reading a post where Brandon said he had an oscillation issue with the tone stack wires being too close to the input. It looks like yours are pretty close.
Good luck,
CW

Yes, and they were causing a high frequency oscillation. I redressed the wires, in fact rewired the TS completely. Now it's motorboating, at maybe 8-10Hz.

OK, but it wasn't motorboating before you made the tone stack changes. Making changes to your filter board may not be a bad idea but it seems like you still have some unwanted coupling or maybe a ground got lifted when you made the tone stack changes?
CW

[Bob-I]

Hello Bob, just a thought but I remember reading a post where Brandon said he had an oscillation issue with the tone stack wires being too close to the input. It looks like yours are pretty close.
Good luck,
CW

Yes, and they were causing a high frequency oscillation. I redressed the wires, in fact rewired the TS completely. Now it's motorboating, at maybe 8-10Hz.

OK, but it wasn't motorboating before you made the tone stack changes. Making changes to your filter board may not be a bad idea but it seems like you still have some unwanted coupling or maybe a ground got lifted when you made the tone stack changes?
CW

Honestly, I don't know if it was motorboating because the HF oscillation was eating up the power. Once I solved that the voltages stay higher and it doesn't cut out.

[Charlie Wilson]

Ok, maybe you had multiple issues and the second one just revealed itself. You seem to have solved one of them, so that is good news. Reworking the filter board may solve the problem or at least rule that out. I like the idea of maybe trying a old school filter board for simplicity. Once you get this issue solved we can go back to talking about those nasty Xicons (Tony I'm trying to be funny).
CW

[Bob-I]

Ok, maybe you had multiple issues and the second one just revealed itself. You seem to have solved one of them, so that is good news. Reworking the filter board may solve the problem or at least rule that out. I like the idea of maybe trying a old school filter board for simplicity. Once you get this issue solved we can go back to talking about those nasty Xicons (Tony I'm trying to be funny).
CW

That's what I'm thinking. Unfortunately I don't have much time to put into this.

[titser_marco]

I have a feeling that the harsh OD tone I'm getting might be due to some PO. I used shielded wires for everything EXCEPT the connections to the tone stack. Do you reckon I should try that instead?