Power Transformer Secondary test fail 175V [resolved]

evansrt · 684

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Offline evansrt

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on: January 01, 2020, 07:22:13 AM
I had a successful S.E.X. kit 3.0 build (wired for incoming 120V AC) with C4S upgrade.  A couple weeks ago it stopped working, with no tube glow upon energizing.

I started going back through diagnostics tests:
Powerline Voltage test (pg 28) passed with 124V AC.
Power Transformer Secondary Test (pg35) failed.  Terminal 7 to 9 showed 6.5V AC, but terminal 11 to 12 had 0V AC (should be 175V).
Resistance Checks (pg59) passed.

I'm seeking advice on what might be my issue?

Ryan Evans
NC

« Last Edit: January 01, 2020, 09:43:32 AM by Paul Birkeland »



Offline Paul Birkeland

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Reply #1 on: January 01, 2020, 07:31:53 AM
It would be unlikely to have no tube glow and 6.5V AC between terminals 7 and 9.

How are your DC voltages?

With the amp not plugged into the wall, what DC resistance do you get between terminals 11 and 12 on the power transformer?

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline evansrt

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Reply #2 on: January 01, 2020, 09:06:11 AM
Resolved!

I re-soldered some suspicious joints - 36 and transformer terminal 12.  Perhaps I was reading off of a previously cold portion of the joint at terminal 12.  Now resistance between 11 and 12 on the transformer is 43, tubes glow, and speakers sing beautifully.

Thanks for the super fast reply!

Ryan Evans