Sceptre PT voltages

[Adamn]

Been looking around for a while and I guess I'm not alone in seeing a bit higher B+ than on the schematic. The PT puts out 444 VAC.  Does anyone know if that's right?  After the Recto I get 539 VDC with no tubes in.  

Been trying to quiet this thing down and I thought all the high B+ voltages may have been the problem, but now I suspect not.

[mckinnon audio]

   Hi there,remember,the old Sunn's are looking for 117 VAC,these days it's normal to see 120 - 125 VAC coming down the line.Also,with the tubes pulled,the power supply is unloaded and the volts will be a little higher,good luck Mel.

[Adamn]

So I'm getting a lot of white noise from the first stage, even with all four grid stoppers disconnected and just the grid to ground resistor connected to the first gain stage.  The schem gives Vdc at the pin as 165, and I'm getting 245.  That seems a bit too high, yeah? 

[mckinnon audio]

  Hi there,yeah that's 80 volts over,check your power supply feed resistors,(plate resistors) they might have drifted a bit,good luck,Mel.

[Adamn]

Seems the MV pot had been replaced with an Alpha, so maybe that's a bit noisy, but the B+ just seems too wacky.


          Actual      Schematic
Recto   556          500
A         551          485
B         436          385
C         339.5       295
D         297.3       260
pin 1    192          165
pin 6    235          165

I also don't know why the plate voltages would be different in this first 12AX7.  I replaced both plate resistors with 100k 1/2 watters.

[George Snyder]

Did you try replacing the 12AX7? What is the voltage at cathode? Since the plate res isn't dropping much voltage the tube is not conducting much current. Either the tube is bad or the bias is off.

HTH, George