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When does a 5V4G/GZ32 have to be replaced?

Hi all, this is my first post here, and I would appreciate some help! :)

I have a custom made pre+amp built on 4 triodes and a 5V4G rectifier. The triodes are relatively easy to keep an eye on (I am measuring the cathode current), but what about the rectifier? How do I test whether it is still in a good shape (preferably, without removing it from the socket)? Would measuring the actual filament voltage (that is directly fed from a secondary winding) tell me whether the tube is still alive?

Thanks!
meisterfloh

Showing 2 responses by jea48

jea48
4,777 posts
 
Meisterfloh,

Get it tested or just buy a new one....

It would seem to me if the tube were to short you could burn out the 5 volt filament winding or possibly the high voltage winding of the power transformer.
The tube is by far the cheaper of the two.

http://www.r-type.org/pdfs/5v4g.pdf

http://www.r-type.org/exhib/aaa0597.htm
.
jea48
4,777 posts
 
I do have schematics of my amp. In particular, unlike the Dynaco, in my case 5V4G has its own secondary that is used just for its filament, so there is no high potential there.
06-21-11: Meisterfloh

If you look at the data sheet for the 5V4 you will see pin 8 of the tube is common to one side of the filament and the cathode. Lethal full wave DC voltage from pin 8 on the tube socket to the metal chassis (B-).

Yes you will measure 5 volts AC across #2 & #8 of the tube socket but if the meter probe was to slip and short 8 to chassis (B-) sparks are going to fly big time.....
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