B+ dropping resistors, concerning heat and electrolyics...

[eddie25]

Should I be concerned about having a large electrolytic filter cap basically resting on top of a 10k B+ dropping resistor? I think I've read that they get hot (the resistor), but haven't had the balls to stick my hand near one to see.

[novosibir]

Don't place a electrolytic too close to a power resistor!
The heat of the resistor dries out the electrolytic quickly and it looses its capacitance.

The only exception is(are) the 10K power resistor(s) on the preamp side on the board, because this(these) R('s) doesn't(don't) have much load and only become(s) hand warm.

Larry

[eddie25]

Thanks Larry. That's actually the one in question. I'm using two Sprague 40uf's on the preamp part of the board and they are pretty big so the 10k dropping resistor is slightly more under the cap then when I used the dual 33uf axial like my last build.

Once again, I appreciate the help.

[Structo]

If at all possible mount the resistor above the cap, heat rises so it would help a little.
Probably not a viable solution for the dual cap used in some Marshall.

[eddie25]

Yeah, I would have put it more to the side, or even above the cap, but these 2 watt resistors I use have really short leads and I can barely get it bent into the eyelets in the first place, even if it goes straight across the board.

[eddie25]

Had a 'duh' moment that the resistor will actually be on top of the cap when the amp is all set up. Plus, there are holes in the board every centimeter so hopefully all will be good.