It can be frustrating being an idiot

Soul Tramp

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I'm building a bunch of Tweed 12 amps. The one I finished today failed miserably with a loud hum during testing. This is something that just shouldn't happen as it's an easy circuit and I've built more than I can count. After two hours crawling over it with an o-scope I'm ready to throw it in the trash! It was a text book example of bad filter caps. But they're brand new.

Turns out I left off the ground buss connection on the reservoir cap. The problem was obviously in the filter caps and the missing wire was staring me in the face. But I jumped in too deep with the scope and meters and completely over engineered what should have been simple problem solving. Talk about missing the forest through the trees.

The lesson learned....... Remember the basics and check the obvious things first!
 

goldtop0

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Well I'm in awe of your prowess/patience in building them and agree on the basics.............we all pass by the obvious from time to time :laugh2:
 

bungle

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Happy ending. Its not hard to over think stuff sometimes :squint: Those amps sound interesting.
 

dmac in SC

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You are way better than me.. I don't touch amps...got popped once a long time ago..that shit hurts
 

judson

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thats somewhat normal


walking around looking for my cell phone with a handfull of books ...... i set them down...keep looking

then walk by the books i set down .....and of course sitting on the top of the books i just had in my arms..

my phone..... :doh:

i actually called myself an idiot and walked out the door....
 

CoyotesGator

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I built an experimental amp once. Pretty sure I did everything correctly but it wouldn’t pass signal. Popped good when probing and wanted to work on the bench. Took a good long time of head scratching and cussing to realize the jack on my Tele magically went bad.
 

CB91710

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Hmm.... Looks like a 5E3 with a couple of surprises under the hood!
 

Soul Tramp

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Hmm.... Looks like a 5E3 with a couple of surprises under the hood!

Pretty much. It's the one amp I offer that's based on someone else's design. I wanted a tweed in my lineup and there's nothing better than the 5E3 (with a few mods).
 

The Ballzz

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Just be glad that it wasn't a ZAP to remind you to pay attention to the simple stuff. That is nearly always what bites even the smartest and most skilled folks in the wazoo!

Can you share a bit more info on your Tweed 12? What power tubes? Cathode/fixed bias, phase inverter type, tube/SS rectified, etc? Maybe even a gut shot of your stellarly pristine workmanship?
Thanks & Congrats!
Gene
 

cooljuk

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Didn't that same thing happen recently on a Twin Reverb? ;)
Yes! Exactly the very same thing. I had missed a buss wire in the totem pole.

I hate the feeling of going to bed defeated. I stayed up and found it. :thumb:
 

The Ballzz

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Never mind! I just went to your website as well as checking out the vid you've got for that Tweed 12! :cheers2: Very cool sounds! :thumb: Is that you playing?
Thanks Again,
Gene
 

Soul Tramp

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Just be glad that it wasn't a ZAP to remind you to pay attention to the simple stuff. That is nearly always what bites even the smartest and most skilled folks in the wazoo!

Can you share a bit more info on your Tweed 12? What power tubes? Cathode/fixed bias, phase inverter type, tube/SS rectified, etc? Maybe even a gut shot of your stellarly pristine workmanship?
Thanks & Congrats!
Gene

Gene, it's 6V6 P/P, cathode bias, 5Y3 rectifier, and a pair of 12AX7.






r_DSC01634.jpg


r_DSC01635.jpg


r_DSC01631.jpg
 

cooljuk

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I spent hours yesterday swapping out tubes, looking at the PI and output section, checking grounds, even checking my bench power supply and scope probes, over a Landry LS50 (AMAZING amp!) because I was getting some weird shape shifting on only the top half of a waveform on my scope (even though the amp sounded fine, which was all I should have needed to step away).

Turns out, with the FX send turned down, even with nothing plugged into the send/return, the signal changes. It's another gain stage, always in line. I just never realized that ...having owned the amp for about nine years.

All that time spent, and when I'm slammed busy with other things. ...but at least I learned a few things, in the process of servicing that amp.
 

Soul Tramp

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I spent hours yesterday swapping out tubes, looking at the PI and output section, checking grounds, even checking my bench power supply and scope probes, over a Landry LS50 (AMAZING amp!) because I was getting some weird shape shifting on only the top half of a waveform on my scope (even though the amp sounded fine, which was all I should have needed to step away).

Turns out, with the FX send turned down, even with nothing plugged into the send/return, the signal changes. It's another gain stage, always in line. I just never realized that ...having owned the amp for about nine years.

All that time spent, and when I'm slammed busy with other things. ...but at least I learned a few things, in the process of servicing that amp.

:rofl: :rofl: That's why I have a loop bypass toggle on my amps.
 

CB91710

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Do the volume controls do the interactive thing, or does your channel switching eliminate that?
 


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