Re: Another filter cap discharge question - Plate pins to ground?

On Nov 24, 3:26 pm, "Elvis Kabong" <ampscie...@xxxxxxxxxxxx> wrote:
<agk...@xxxxxxxxx> wrote in message

news:72fed5ca-83b8-46e2-bbc8-d640afee550c@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

On Nov 24, 12:42 pm, mykey <mykeymyke...@xxxxxxxxx> wrote:
Plate to ground could conceivably cause damage to
output transformer windings, use CENTER TAP
of output transformer instead.
This way the DC is discharged BEFORE it has
entered the windings.

So, ground to chasis, then clip to center-tap will drain all the caps?
Can I leave it connected like that, to prevent re-charge?

Never knew there are so many ways to drain the caps!

Yep, and here's another alternative.
Get one clip lead, solder a wire to it, solder a cylindral 100 Ohm
5 Watt resistor, solder another wire to it, cover the resistor and the
solder connections with appropriate sizes of heat shrink, then solder
on a meter probe to the unconnected wire.

Clip the lead to anywhere on a chassis and apply the meter probe to B+.
If caps are fully charged, you'll see a mild spark. Voila, it's done.

Or, if you have a signal generator hooked up to an amp, make sure
the amp is also hooked up to a speaker load or dummy load, while
the amp is fully on, turn the volume up as loud as you can stand it
if you have it connected to a speaker load, then turn the amp to OFF
(NOT to Standby). This will also discharge the caps. Unplug the amp
from the wall outlet and it's ready to be worked on.

I like the idea of using two clips, so that I can keep the connection
hooked up, keeping the caps drained throughout the repair. But I plan
on draining as much as I can by turning the amp off while hitting a
chord. Then, use the drainer I will make, and I should be plenty safe
to change out my Presence pot!

One thing, you mention a 100 ohm 5 watt resistor. Others have said I
need way more than that (5K or even 10K). What gives - can I use a 100
ohm (.1k) and still do what I need to do?
Thanks.
.

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