Bottlehead Finished Products > Legacy Products

Extended FP III Shunt Reg problem

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pdxgrampa:
Doesn't look like picture made it .

I'll try again

Paul Birkeland:
Pull the outer two 12AU7s and retest the center PC board.

(Also, the MJE340 tabs should be a volt or two higher than the MJE350 tabs on the outer PC boards when all the tubes are plugged in and running)

pdxgrampa:


Ok tubes out:

 A side                                 B Side                              Shunt Reg
350: 146.8 volts                  350: 146.8                        A side 350: 149
340: 150.9                          340: 150.0                        B side 350: 148.5
                                                                                  A side Kreg; 0
                                                                                  B side Kreg: 8.72
                                                                               

Paul Birkeland:

--- Quote from: pdxgrampa on November 05, 2017, 07:28:57 AM ---                                                                                  A side Kreg; 0
                                                                                  B side Kreg: 8.72
                                                                               

--- End quote ---
It's odd that the A side Kreg is stuck at 0V but the regulator appears to work.  With 0V available for the TL431 to operate, I would expect your regulated voltage to be just a volt or two less than your unregulated voltage. 

pdxgrampa:

PB,

Unless there is something else to measure/try

Should I just contact the Queen on Monday for a board and Parts?

Thanks for your help

Greg

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