Bottlehead Forum

General Category => Technical topics => Topic started by: Strikkflypilot on July 13, 2014, 12:23:42 AM

Title: High plate voltage
Post by: Strikkflypilot on July 13, 2014, 12:23:42 AM
Hi.
Would loss of current i.e. bad solder to a grid connector result in high plate voltage?
I seem to have a bad contact for the left channel on my crack.
A3 led out and terminal 5/ plate power in the 170v range. Wiggling the input tube fixes it. 
I know if I am right, all i need to do is resolder or there is something wrong with the tube socket

But what do you think?
Title: Re: High plate voltage
Post by: Paul Birkeland on July 13, 2014, 09:02:09 AM
Poke around with a wooden chopstick and see which component is causing the issue, then replace/resolder that component.
Title: Re: High plate voltage
Post by: Strikkflypilot on July 13, 2014, 11:08:22 AM
Wood chopsticks, check.

I assume i Wont do major damage on the live circuit that way, or on myself for that matter...
Title: Re: High plate voltage
Post by: Paul Birkeland on July 13, 2014, 01:22:09 PM
The wood will protect you, and tubes are durable enough to tolerate some abuse.
Title: Re: High plate voltage
Post by: Strikkflypilot on July 14, 2014, 07:51:04 AM
So Ive isolated the issue to socket 3 of the noval tube socket. Its one of those teflon sockets like on the picture. Got in there with an awl, power cord out of course, and made the socket a tight fit. Now fixed. So the cathode was not connected at all. How that caused the voltage jump, I still dont understand, however.
Title: Re: High plate voltage
Post by: Grainger49 on July 15, 2014, 01:59:46 AM
When the cathode doesn't conduct, it acts like it is open, no connection to ground.  So all the voltage "piles up" on the plate.   At least that is the way I like to describe it.  It is pretty accurate to what is happening.
Title: Re: High plate voltage
Post by: Strikkflypilot on July 15, 2014, 04:36:09 AM
I see, and it flows current only when the meter is connected, I guess.
It will take some time before I really understand these things.
Thanks for enlightening me!