S.E.X. 3.0 [resolved]

Dana Hinds · 3493

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Offline Dana Hinds

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on: September 05, 2022, 04:09:29 PM
Power and resistance values were all good, finished and powered up.  Heard snapping noise and saw some smoke, only one channel was working.  After looking it over the only problem I found was I missed soldering one resistor to terminal #16U.  Looked like the 680 ohms resistor that goes from 21U-33U was hot.  Looked everything over a hundred times and all else seems ok.  I now do not get proper resistance reading from terminal 17, 18, or 25 to H1.  Not sure what to do next. Any help would be appreciated.
« Last Edit: October 08, 2022, 05:33:52 AM by Paul Birkeland »



Offline Paul Birkeland

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Reply #1 on: September 05, 2022, 06:38:30 PM
Can you post some build photos?

Your voltage checks should have been way off if you ended up with that situation.  If the 680 ohm resistor going to 21 got hot, two component leads on that side of the amp are probably touching that shouldn't be.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Dana Hinds

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Reply #2 on: September 06, 2022, 01:06:26 PM
Here are the pictures. Thank you.
Dana



Offline Dana Hinds

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Reply #3 on: September 06, 2022, 01:26:42 PM
Here are some more pictures.
Dana



Offline Paul Birkeland

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Reply #4 on: September 06, 2022, 02:28:22 PM
Remove the red wire from 21, bend it up into the air, then fire the amp up and check the DC voltage at 21. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Dana Hinds

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Reply #5 on: September 07, 2022, 12:20:38 PM
From terminal 21 to h1 I get 500v



Offline Paul Birkeland

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Reply #6 on: September 08, 2022, 09:57:09 AM
If the amp is happy with this wire disconnected, this tends to mean that something is touching around that socket that shouldn't be.  You may want to remove the Solen parallel feed cap and post more pictures and we might be able to see what's causing the problem.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Dana Hinds

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Reply #7 on: September 09, 2022, 11:50:38 AM
Here are some more.



Offline Paul Birkeland

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Reply #8 on: September 09, 2022, 12:19:10 PM
I still see no issues.  Something else you could try is to put the disconnected wire and cap back, then run the amp with no tube in that side and recheck the voltage at 21 (it should remain high).

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Dana Hinds

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Reply #9 on: September 11, 2022, 11:33:52 AM
Voltage stays at 500



Offline Paul Birkeland

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Reply #10 on: September 11, 2022, 11:35:20 AM
Put the tube from the other channel into that socket and see what happens.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Dana Hinds

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Reply #11 on: September 11, 2022, 04:26:58 PM
I installed both tubes, nothing seemed to overheat and no smoke.Plugged in headphones and only have one channel.I noticed b side plate choke was warm when running and a side plate choke never got warm.



Offline Paul Birkeland

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Reply #12 on: September 12, 2022, 04:33:44 AM
The voltages are of interest here, not attempting to listen to an amp that isn't working yet.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Dana Hinds

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Reply #13 on: September 12, 2022, 06:02:40 AM
Doesn’t seem like a side may be getting power



Offline Paul Birkeland

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Reply #14 on: September 12, 2022, 08:20:56 AM
So the information I'm looking for is something like "The voltage at terminal x is supposed to be y but instead it's z".

Without that kind of information your guess is as as good as mine.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man