Reissue Deluxe Reverb B+ filter caps

[LooseChange]

Just noticed this while I was poking around in the amp....

The B+ filter caps on the first node are stacked totem pole arrangement with...
220uf - 100v on top of a 47uf - 500v. The resistors are setup to skew the voltages. 100k around the 220uf and 470k around the 47uf.
I find this very strange... The original has two 16uf - 450v in parallel.
Sure looks like a disaster waiting to happen!

What do you think?


Schematic: http://www.el34world.com/charts/Schematics/files/fender/65_deluxe_reverb_manual.pdf

[sluckey]

I think it's a stupid idea! But it may buy a pair of school shoes for your kids one day.  

I'd much rather have two 100@350 stacked up with equal value resistors, or two 20@500 connected parallel. I'm just too symmetrical I guess.

[Tiny_Daddy]

I would put in some higher-wattage resistors and make sure they are well soldered.

[mresistor]

How do they get away with using a 100V rated cap and a 1/2W resistor in that filter?

[John]

If I'm reading the schem right (with my head cocked sideways) you have 396 going in, 325v at the "divider" point, although there's no actual "voltage out", which means you're dropping 71 volts across the top cap. Dissipation should be right at 1/2 watt across that 100k resistor. (IF all my math is right)
Of course, you've already figured that out and like everyone else you're wondering why on earth they did it like that.  I can only guess that at the time of manufacture they saved money?

[sluckey]

71 volts across the top cap. Dissipation should be right at 1/2 watt across that 100k resistor.

No, 71 volts across 100K is .05 watts. The resistor power rating is plenty big.       P = E²/R

[John]

Oops, you're right. When I saw .0497 on my readout I dropped the 0. Thanks for the correction!

[Cups]

Must have already had a boatload of those caps and decided to use what was on hand.