• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Dynakit ST35

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Netlist

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Translation:

Hi, forgive my English, I'm building a clone of the Dynakit ST 35, I'm having a problem, I can't understand on pin 6 of the 7247 input triode there are 52 VDC while the schematic table shows 112 VDC, thanks for any advice


English please.

Hugo :cop:
Moderation team
 
Last edited:
petertub

petertub

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Joined 2015
tubular-well.se
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This indicates that the first triode draws too much current ( Vcat= 1.8V )
Two reasons : the grid is not grounded but free floating. Check this( you could ground pin 7 to ground )
Or the tube is the 823 model, check by temporarily replacing with a ECC83

If you install a ECC83/12AU7 in the same socket i suspect that the voltages on
plate and catode is according to the dynaco manual ( 112V and 0.8V )
To be gente of the ECC83 you could temporarily disconnect the R7 and R6 resistors.
 
I

isporo

Member
Joined 2009
hello Petertub thank you for the suggestions,you turned on the light bulb.incredible I inverted the 2 triodes contained in the ecc832,After so many years of self-construction I still make these mistakes, unfortunately the years are no longer green Thanks again
 
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