Spencerleehorton
Well-known member
I’ll change the 12ax7 tubes first before I start taking things apart.
Last edited:
JTM45 Build with 6P3P output tubes and GZ34
- Thread starter Spencerleehorton
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Spencerleehorton
Well-known member
Took all tubes out apart from GZ34 and checked voltages, B+ 460v.
Turned on standby and dropped a bit to 457v.
Then put OT in and 12ax7s.
Power on B+ 460v as soon as standby turned on B+ drops to 403v!!
Bias was set at 43ma.
I then dropped bias to 36ma (el34)
This then put B+ to 414v from 403v
Checked out other voltages across the tubes and although they looked low it all looked consistent.
I wonder whether the GZ34 is damaged?
Turned on standby and dropped a bit to 457v.
Then put OT in and 12ax7s.
Power on B+ 460v as soon as standby turned on B+ drops to 403v!!
Bias was set at 43ma.
I then dropped bias to 36ma (el34)
This then put B+ to 414v from 403v
Checked out other voltages across the tubes and although they looked low it all looked consistent.
I wonder whether the GZ34 is damaged?
Spencerleehorton
Well-known member
I think what I will try is to revert back to the original way that B+ was connected and see if it is the same.
