Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: pbman1953 on March 15, 2019, 09:43:53 am

Title: Pin 3 measurement
Post by: pbman1953 on March 15, 2019, 09:43:53 am

I just learned that my Bias Rite needs a tweak. The meters' power voltage reading is off compared to a stand alone meter.   The Weber company told me about the  trim pot inside the BR to help me match to the stand alone. What started this is that , on my Traynor, pin 3 was 55 volts higher using a stand alone multi meter. It measured around 609 volts vs. the BR was at 552-554.


Due to this I have to take another look at my Sunn 300.


Here's a couple  questions-


Can I pull one tube on the Sunn to read pin 3?


If yes, should I check each socket, pin 3, to see they are the same.


Thanks

Title: Re: Pin 3 measurement
Post by: sluckey on March 15, 2019, 09:51:45 am

You need the tubes plugged in to get a meaningful voltage reading.

Title: Re: Pin 3 measurement
Post by: pbman1953 on March 15, 2019, 09:59:21 am

ok, good info.


I suppose I can test while plugged in.