SA-8800 Capacitor drain

[QSilver]

I'm working on one of these at the moment - giving it a recap and changing some of the resistors that looked a little stressed. I discovered yesterday while working on it (having left it switched off and unplugged on the bench for two days) that the negative main reserve caps still had -45VDC in them whereas the positive caps were completely drained.

Needless to say, before I did ANY work I drained the caps off safely through a resistor but I wanted to make sure with others here whether this was normal or not? Most amplifiers I get have discharged their caps by themselves within a day but this beast was hanging on to serious charge after two or three days!

Just checking in case there is a fault with a bleed resistor somewhere that I've missed?

 

[rcs16]

Usually they have a bleed R across (~8K) the big ecaps for safety purposes. The bleed R will in effect drain off the voltage in minutes instead of hours/days.
I'd have to check the sch to see if they used bleeder R in this design. if they did not use them you can add them.
Sounds like the -ve side has no bleed R whereas the +ve rail does. You need to check what is going on there.

 

[QSilver]

Looking at the schematic, it seems that the reason the +ve discharge looks to be because they power separate circuits which must drag them down and bleed it off.

The -ve looks to be purely for the output transistors and nothing else so maybe that is why they stay fully charged...?

What sort of 8k resistor would be a good idea? Maybe I could/should remove them after work has been completed?

EDIT: actually after looking again, I see the negative cans supply more than the outputs so I'm not quite sure what is going on with some draining and some not...