ppluis0 wrote:Hi Dan,
You're right: 12AX7 and 12AU7 has the same pinout, so both types can be employed in this project but with sonically differences.
I forgot to say that the numbering of a tube pins is viewed from bottom and counting clockwise.
It's OK to have 0 volts at pins 2 and 7 in each tube, but 0 volts at pin 6 is wrong. Missing connection perhaps ?
At firs sight, at the pin 5 of V2 you must read 12Vdc instead of zero volts, but that tube appears to be active...
(Coincidentally V1 looks as if be cold. There is a chance that the value of 12Vdc belongs to pin 5 of V2 ? )
Are you build the same PSU proposed in this link ? download/file.php?id=31987 or are you using the voltage multiplier topology included in the original PCB ?
I re read again the entire thread, and looks as nobody complete one of the PCB's provided for this project...it's it true ??
Keep in contact,
Jose
To be clear - this is a PCB purchased from PDF Electronics back in the day.
And yes. That is the frustration.
As far as I know - no one else has populated and tested the PCB.