Can you guys look at this.....

[C Moore]

The meter might speed up the discharging process.

I am not sure what you are referring to exactly...but when I turn off amps...by the time I get a meter...clip to the chassis...and poke the other probe onto a cap...the VDC is down to 10-30 V.
Maybe 20-30 seconds elapses by the time I clip to ground..... so the meter is only involved for about 2 seconds.

[jelle]

The current that flows through the bleeder resistor(s) effectively discharges the capacitor.

My point is that the Voltmeter, when placed across the charged capacitor, will represent an additional resistive element that is in paralel with the charged capacitor and the bleeder resistor.

This way the value of the resistive element is reduced, and the speed of the discharging process is increased. This effect may be very small, if you have a decent meter, that is.

The observability depends of the voltage; on 500VDC, the effect is easier noticable than on 30VDC.

The problem is that unless you have a high quality meter to compare against, it is hard to see how much your normal meter will have an effect on what you are reading.

And I agree with the others, it is good practice to clip in a bleeder resistor before doing work on these amps.

[rdjones]

I've felt a mild zap from an amp that had been unplugged for 2 days.
Just like a gun should be treated as if "always loaded" a tube amp is "always hot" until known and measured as discharged. ;->

Sometimes I'll stick a bleeder on the far end of the PS string near the preamps.
This has the added protection of preventing overvoltage to (possibly) lower voltage preamp filters when preamp tubes are pulled.

reddog

[C Moore]

As the old saying goes......."A loaded gun never hurt anybody...it is always the unloaded guns that kill people".

[Tillydog]

I cannot tell if you were making a joke or not...

Sorry - No, I wasn't trying to be funny, just applauding your pragmatism!

What I SHOULD have written was.....HOW do you figure for a resistor with a value high enough to render it inconsequential while the amp is being played.?

As already alluded to in previous replies above - if the power amp bias current is going to be 20mA, 50mA, or whatever, then a bleeder resistor drawing 2 or 3 mA from the main reservoir capacitor is going to be 'inconsequential'.

(But proper design is obviously needed to demonstrate compliance with consumer safety regulations, etc. - I didn't know about those.)

The 'gotcha!' on charged capacitors for me is if you're working on an amp where the power section is faulty, with no tubes in, or whatever - where the capacitors take *much* longer to discharge to a safe level than if the tubes were all in, working and drawing current.

[C Moore]

I cannot tell if you were making a joke or not...

Sorry - No, I wasn't trying to be funny, just applauding your pragmatism!

What I SHOULD have written was.....HOW do you figure for a resistor with a value high enough to render it inconsequential while the amp is being played.?

As already alluded to in previous replies above - if the power amp bias current is going to be 20mA, 50mA, or whatever, then a bleeder resistor drawing 2 or 3 mA from the main reservoir capacitor is going to be 'inconsequential'.

(But proper design is obviously needed to demonstrate compliance with consumer safety regulations, etc. - I didn't know about those.)

The 'gotcha!' on charged capacitors for me is if you're working on an amp where the power section is faulty, with no tubes in, or whatever - where the capacitors take *much* longer to discharge to a safe level than if the tubes were all in, working and drawing current.

Hey Tilly -
Hope it did not sound like I was being a dick.
I DID realize I had inadvertently written something intuitive and smart.....but that was purely accidental.
btw...thanks for the additional info.