The Amp Garage

The new output transformer showed up in the mail today. I subbed the new transformer in for the old one, and... voila... the champ clone is functional once again. I'm just happy it's fixed as I tend to put other things on hold while troubleshooting. The scope trace with injection of a 1KHz signal we...

Yes, I agree. Adding a grid stopper or small value ceramic cap from the grid to cathode on the 6V6 are things I'm trying before the OT shows up, but I don't have much faith at this point that the issue is an oscillation.

I've been swapping two different 6V6's through the amp. The values are a little piecemeal as I've been going for gross characteristics. Doing all the measurements with the 6V6 in it at the moment, I get: 401V plate to chassis 375V plate to cathode 25.82V cathode to chassis 36.6mA plate current final...

Thanks for pitching in on this. I purchased a new OT a few days ago, but it doesn't show until Saturday, or so. I figure on further testing the old OT by swapping in a new one. In the meantime if someone sees another path to getting this amp back up and running, please chime in.

6V6 cathode is 26.1V (adding it in above -- must have hit some flux first time through).

I just noticed that. In the process of doubling checking that one.

Pin voltages "in process"... just wanted to double check a few values before posting them, which I have done now. I think the 12AX7 ones are moot based on the scope traces, but I'll posted them with the 6V6 data as well. 12Ax7 1) 125V 2) 3) 1.19V 4) 3.3V 5) 3.3V 6) 187V 7) 8. 1.64V 9) 3.3V 6V6 1) 2)...

Here's what V1a and V1b look like:

V1a:
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V1b at low volume:
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edit: reposted the first trace as it some letters superimposed on it somehow in the posting process.

Yes, I've tried a different speaker. I've also tried different guitars, and a different input and output cable. I also replaced the output jack with a new one. Thanks.

Everything I did to the inside of the amp posted above was only after the volume spontaneously diminished in an effort to find out what happened and fix it. There is a negative feed back resistor, and I was careful not to swap the leads during testing to find out what caused the volume issue. Thanks.

I think I may have hexed my recent champ clone acquisition by posting about it, here: https://ampgarage.com/forum/viewtopic.php?f=8&t=35994 It sounded fantastic for about one hour of playing. Then, after a couple of odd muffled static noises, it lost about 90% of its volume. Here's what I've catalog...

My first pass will be to clean up joints as needed and look over the grounds. I'm going to avoid anything intrusive to preserve tone. The frayed wire joint on the fuse holder gets looked after first. It's the first thing I see when looking at the gut shot. Thanks. I did purchase the amp. So I'm movi...

I find interesting how much unique creativity went in to certain elements. I'm not completely opposed to leaving it alone.

If a Champ clone with the following gut shot hypothetically came into your possession, what would you change first and why? I don't own it (yet) but it has a reasonable noise floor and sounds like a Champ should. There are (many) things that bother me about this build, but I can't get away from how ...

Yes, I would short everything. Also, it would be best to solder the shorts rather than use clips as otherwise (more) error is likely to be introduced, see: https://www.voltech.com/support/technic ... nductance/