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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
jea48
4,446 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.....
meisterfloh OP
15 posts
 
I guess you guys are right (and I was wrong), the actual potential on the filament is quite high. Of course, it is still not a big deal to measure, but one shall be careful and not get fooled by the 5V specs :)

Anyways, I guess I have no reason to worry as long as everything sounds as perfect as it does, thanks for your answers!
hifihvn
943 posts
 
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.....

Jea48 (Threads | Answers | This Thread)

That's what I was missing. When I type, I loose my train of thought. And I'm lousy at typing.
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