Pumpkin preamp - ordered by Steen , official making thread

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#2,723
This is probably obvious for everybody here but me (so please be patient with Gruenschnabel) - the diode testing is also good to find out whether it is an npn or pnp pair, right? I did literally glue them together the first time (heat conductive adhesive) and the writing is really hard to read on some pairs...

Q4/5/6/7 = NPN

An externally hosted image should be here but it was not working when we last tested it.


Q4A/5A/6A/7A = PNP


An externally hosted image should be here but it was not working when we last tested it.


Correct?

Sven
 
#2,733
Abraxas336 said:
Annoying, nevertheless. I just realized that the Shunty that works on both channels does not have JP2/JP2A set (somebody told me to take it out).
An externally hosted image should be here but it was not working when we last tested it.
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maybe you have shortie between some part and upper groundplane ; if you remove JP2 then upper copper plane isn't anymore connected to gnd , so shortie is harmless .

try that with other Shunty too , as Metaldanske wrote already

edit:

I think I wrote in Cookbook - use either JP2 OR JP2A ;

not both ,, or you are risking hum
 
#2,735
Abraxas336 said:
I'm not using both. Good news: using JP2 on the working Shunty does not change anything, it keeps working fine. Confusing: cutting the jumper on the other one (one channel fine, one always @ 40.5V ) makes both channels go to 12.1V and no reaction to trimmer.
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take day or two pause ;

then recheck all visually , using magnifier and good light .

sometimes that route is good , not because you are going to find shorts or breaks , but you are also checking parts and values ....
 
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