Bottlehead Forum

Bottlehead Kits => Mainline => Topic started by: Bourney on November 14, 2021, 09:04:24 PM

Title: Mainline voltage checks
Post by: Bourney on November 14, 2021, 09:04:24 PM

Hi there, first time post from me.

Just finished the build, all resistance checks are OK, but I have 3 out of spec voltages:
BREG (B) = 272v (BREG A is 218v)
KREG (A) = 1.1v
KREG (B) = 2.0v

All other voltages within spec.

I notice I have 2 LED not lit on the A side of the chassis C4S board on the B side of that C4S board. The other 6 LED are lit.

Thanks for any help you can offer.

Title: Re: Mainline voltage checks
Post by: Paul Birkeland on November 15, 2021, 04:38:24 AM

Are you able to perform the 6C45P biasing procedures with all these issues?

Can you post some build photos?

What are the OB/OA voltages on the center PC board?

Title: Re: Mainline voltage checks
Post by: Bourney on November 15, 2021, 09:41:12 AM

Hi Paul,

I can bias the A side 6C45P to 145v no problem.
The B side will not come down below ~212v.

OB voltage = 0.97v
OA voltage = 1.19v

Thanks

Title: Re: Mainline voltage checks
Post by: Paul Birkeland on November 15, 2021, 09:54:13 AM

I would carefully review the wiring on the 6C45P sockets, paying careful attention that the unpopulated pins are the correct ones in your build. 

Title: Re: Mainline voltage checks
Post by: Bourney on November 15, 2021, 05:27:19 PM

Thanks again Paul,

Checked all the wiring to the sockets, all looked fine.

I pulled the 6C45P tubes out, swapped them between sockets, and magically everything tests within spec.

Possibly one tube has a bad leg which is used on one socket but not the other? Otherwise its a mystery.

All good now. Sounds great.

Title: Re: Mainline voltage checks
Post by: Paul Birkeland on November 15, 2021, 06:05:57 PM

That is a possibility, or there's a loose connection that was jostled into making proper contact.