Rectifier Testing Question

So after doing some restoration work on my ST70 and replacing the rectifier tube, the new one seems to be glowing very bright. Down at bottom area of the heater I guess is where I would say it is from. I have not worked with tubes enough to say better.

I want to test things before I run it as it is. What are some specific tests I should make sure I do related to the rectifier? Some tests I may do with my multimeter. Other test requiring additional equipment I will leave to my tech. I did just do the Diode mod. I read a little about filament voltage?

Thanks guys.

Drugolf wrote:So after doing some restoration work on my ST70 and replacing the rectifier tube, the new one seems to be glowing very bright.  Down at bottom area of the heater I guess is where I would say it is from.  I have not worked with tubes enough to say better.

I want to test things before I run it as it is.  What are some specific tests I should make sure I do related to the rectifier?  Some tests I may do with my multimeter.  Other test requiring additional equipment I will leave to my tech.  I did just do the Diode mod.  I read a little about filament voltage?

Thanks guys.  

what model rectifier tube are you using? Different manufacturers of the same model tube can 'look' different....even 'act' different...some are a little brighter than others, quite normal. Apart from the brightness, everything else is working OK?, sound is good, no hum etc.?
All voltages meter out OK?

Japanese mullard.
I recall everything testing okay but I want to go back and check with a focus on that area. It was working when tested but the tube seemed bright throughout that process. It was just bench test speakers so I have not got to quality of sound. I want to test more before running this tube much.

I am using a JJ GZ34 in my VTA ST-120. The heaters in this tube are considerably brighter than either the KT-120 power tubes or the JJ ECC82 drivers. I wouldn't worry if things sound good.

Can someone describe for me how to correctly test/check the filament voltage?

Drugolf wrote:Can someone describe for me how to correctly test/check the filament voltage?

Any decent voltmeter with an AC range.

Note that the filaments on the GZ34 is elevated to +500V DC be very careful!
You could connect the voltmeter ( on pin 2 and 8 on the GZ34 ) in advance before powering up.
When powered up it should have 5VAC +-10%

Filaments on other tubes (in a st70) should be at 6.3VAC , these are located on pin 2 and 7
on the octals and 4,5 to 9 on the novals ( see tube data for the specific tube).
There is two 6.3 V windings on ST70, one for each side. On the original st70
those were connected in the octal sockets on the front, thus it was very easy to measure.
( from another post )
I have found no layout of the front octal sockets however,this is extracted from the build instructions
( it might be in error )
1 and 2 _might_ be 6.3V
3 is ground
5 B+
8 bias test

Thanks guys! Right on at 5.
Tube burned out. I went out of teh room for 2 minutes, came back in and the heater was no longer aglow. Must have been bad. Put in a new one (Groove tube) works fine.