Re: Pignose G60VR Mods


<neilgdsn@xxxxxxxxxxx> wrote in message
news:1131935393.597239.255380@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Phil-
>
> Thanks for the info. I do have a healthy respect for the voltages in
> these things, and I think that I may ultimately shovel this one to a
> qualified amp builder/repairperson.
>
> Nevertheless, I couldn't resist looking at the chassis to see how Pin 8
> of V1 in the preamp (it is a 12ax7 type tube) is currently wired.
> Right now, Pin 8 has an insulated wire running to the mainboard of the
> amp.

If this is a PCB amp, you need to identify the copper trace etched onto the
board and follow it to the first resistor.

>
> I take it that in order to really install this capacitor properly, I'd
> have to divine which resistor on the mainboard corresponds to the wire
> off of the cathode/Pin8 of V1, and that I'd have to wrap the free ends
> of the capacitor wires around the posts of the resistor going into the
> PCB/ mainboard. Then I'd have to do a really neat job of soldering it
> to the posts to cinch it in place. Brain surgery sounds easier!!!!!.
>
That is exactly the task. A schematic would help you locate it. Sometimes
these things are all neatly labeled and cross referenced on both the board
and the schematic, other times the board and/or the schematic has no labels.
>
> Ultimately the resistor and capacitor get grounded to the chassis
> somewhere don't they? Would it be acceptable practice to solder one end
> of the capacitor at Pin 8 and the other directly to the chassis
> somewhere? This would be much easier....
>

While you can put one end of the cap to pin 8, you still need to know where
the other side of the resistor is. A bypass cap is just that...it is in
parallel with the resistor and they share the same ground point. It is
probably easier and better to identify the correct resistor.


.

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