12-30-2015, 09:05 PM
Hi Mike and Seasons greetings, (Both Mikes)
> with tube in socket I get 262v. ac and 261v. ac on each plate to chassis ground.
That's good.
> But the filament I only get .oo5 dc to chassis ground.
The heaters are powered by AC current, if you measure it with a DC meter you will get an inaccurate reading.
> I'm asking this because I have no plate voltage on any of the tubes
Well strictly speaking you do have plate voltage on the 5Y4 tube. Like Mike sez R-7 or 8 could be open (he types faster that me)
Just for grins you could ground to the chassis the minis side of C-10. This will restore the HV but you won't have negative bias for the audio tubes if R7 or 8 are open. You don't want the leave it like that but just to see if you have HV.
> One question, I get 195v if I test from the center tap to the chassis.
That's way high. Should be 20v or so. Something is open between the HV ct and the chassis .
Terry
> with tube in socket I get 262v. ac and 261v. ac on each plate to chassis ground.
That's good.
> But the filament I only get .oo5 dc to chassis ground.
The heaters are powered by AC current, if you measure it with a DC meter you will get an inaccurate reading.
> I'm asking this because I have no plate voltage on any of the tubes
Well strictly speaking you do have plate voltage on the 5Y4 tube. Like Mike sez R-7 or 8 could be open (he types faster that me)
Just for grins you could ground to the chassis the minis side of C-10. This will restore the HV but you won't have negative bias for the audio tubes if R7 or 8 are open. You don't want the leave it like that but just to see if you have HV.
> One question, I get 195v if I test from the center tap to the chassis.
That's way high. Should be 20v or so. Something is open between the HV ct and the chassis .
Terry
