Left channel is a lot weaker than Right channel

bskahj · 1823

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Offline bskahj

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on: December 22, 2018, 01:11:32 AM
Hi

//So this is my first build, and its probably just a fault from my side.

The left channel is a lot weaker than the right, I measured 0.221 VAC @ 60Hz at Tip, vs 2.031 VAC @ 59.9Hz at R1 (sleeve). (run test with 60Hz Sinewave)

after seeing the others with the same problem ive both twisted the volume knobs alot and no difference. but therefore did these measurements as the others:

A side:
at the 10uF - 24.45VAC @ 50Hz
Center lug   - 1 VAC @ 60Hz

C side
at the 10uF - 6.647VAC @ 50Hz
Center lug  - 1 VAC @ 60Hz

* both tubes have been switched around and rebiased to 145VDC. have still not found any cold solder or miswired leads, any help would be greatly appreciated  ;D
- BS
« Last Edit: December 22, 2018, 01:13:06 AM by bskahj »


Offline Paul Birkeland

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Reply #1 on: December 22, 2018, 07:04:52 AM
This may be something we can see if you post some photos of your build.  How are the rest of your voltages? 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline bskahj

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Reply #2 on: December 22, 2018, 11:08:01 AM
More DATA!:
+275 VDC PSB - 263VDC
+ 6.3 VDC PSB - 6.26VDC
AI  - 260VDC both sides
Breg - 219 VDC both sides
-reg - 000.4mV both sides
Kreg A - 11.85 VDC
Kreg B - 10.93 VDC

Resistance check:
where either chassis or ground is connected  i get around 0.30 Ohms..

also 35KOhms on T1 and T5.
220KOhms on T19 and T21
T20 and T30 suddenly got 4.4MOhms

seems like i have a serious grounding issue?, any tips?
- I have a lot to do dont I?  :-[


Offline Paul Birkeland

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Reply #3 on: December 22, 2018, 11:11:18 AM
Can you get a close up on the C side 9 pin socket?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline bskahj

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Reply #4 on: December 22, 2018, 11:15:37 AM
Here it is!


Offline Paul Birkeland

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Reply #5 on: December 22, 2018, 11:22:33 AM
That's the A socket.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline bskahj

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Reply #6 on: December 22, 2018, 11:26:48 AM
yeah, my bad, here is the real C socket


Offline Paul Birkeland

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Reply #7 on: December 22, 2018, 11:28:17 AM
I would apply a little more solder the joints on either side of the 10uF cap.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline bskahj

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Reply #8 on: December 22, 2018, 11:49:53 AM
I did add some solder to the uF 10 cap, unfortunately when i powered up the amp, a pop came from the amp, and now the +275 is into the 320..
so I think it might be time to send the amp in for the pros?


Offline Paul Birkeland

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Reply #9 on: December 22, 2018, 06:20:27 PM
There will be other voltages that aren't correct.  Things that "pop" are generally small resistors and occasionally LEDs.  You are also more than welcome to take advantage of the repair service.
-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline bskahj

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Reply #10 on: December 22, 2018, 10:46:14 PM
then I´ll go for the safest option trough the repair service. But again, thank you so very much for your assistance and have a great christmas


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