left channel suddenly out of balance [resolved]

kill_surf_city · 3549

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Offline Paul Birkeland

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Reply #45 on: July 24, 2022, 11:42:34 AM
With one probe on each of the 6.3V terminals, what DC voltage do you see?  It occurs to me that it's possible that your 6.3V regulated DC supply may not be putting out sufficient voltage for proper tube emission, so that's worth looking into (or there's something in the heater circuit consuming extra current).

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline kill_surf_city

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Reply #46 on: July 24, 2022, 12:12:07 PM
With one probe on each of the 6.3V terminals, what DC voltage do you see?  It occurs to me that it's possible that your 6.3V regulated DC supply may not be putting out sufficient voltage for proper tube emission, so that's worth looking into (or there's something in the heater circuit consuming extra current).

Okay, I'm getting 6.25v on the 6.3 V terminals on the PSU board.



Offline kill_surf_city

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Reply #47 on: July 24, 2022, 03:31:54 PM
With one probe on each of the 6.3V terminals, what DC voltage do you see?  It occurs to me that it's possible that your 6.3V regulated DC supply may not be putting out sufficient voltage for proper tube emission, so that's worth looking into (or there's something in the heater circuit consuming extra current).

Hey PB, I noticed that one of the screws that is supposed to secure the PSU board just wasn't there, found it and screwed it in. I decided to go ahead and connect everything and redo my voltage tests. Everything was well within range on all boards. The Kreg on the shunt regulator is still showing me ~1.9v  on both sides but I went ahead and turned it on and everything sounds perfect to me. No balance issue. No hum. Do I still need to worry about that Kreg value on the shunt regulator?



Offline Paul Birkeland

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Reply #48 on: July 24, 2022, 04:08:20 PM
If the front C4S board is hooked up and you still see 1.9V at each of the Kreg pads on the board above the D socket, what's the DC voltage at the +275V pad on the power supply board above the power transformer?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline kill_surf_city

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Reply #49 on: July 24, 2022, 04:32:21 PM
If the front C4S board is hooked up and you still see 1.9V at each of the Kreg pads on the board above the D socket, what's the DC voltage at the +275V pad on the power supply board above the power transformer?

With the C4S board connected I'm getting 5.94v on side A and 5.92v on side b. DC voltage on the +275 pad is 265v.



Offline kill_surf_city

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Reply #50 on: July 24, 2022, 04:33:41 PM
I do also have the step up transformers installed if that makes any difference.



Offline Paul Birkeland

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Reply #51 on: July 24, 2022, 06:52:20 PM
Those Kreg voltages are more reasonable and should be sufficient for the circuit to operate properly. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline kill_surf_city

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Reply #52 on: July 25, 2022, 02:56:19 AM
Those Kreg voltages are more reasonable and should be sufficient for the circuit to operate properly.

Awesome. Thanks for you help Paul.