Pwr Supply Cap upgrade question.....

[DIYIdaho]

I am removing 55v 15000 uF electrlytics and want to put back 63v 18000 uF's because current 15000's are too short to reach the upper stabilizing bracket.

I have two simalar amps, and when I power them, the lights flicker slightly from initial surge (15000 uF caps [2 per amp]).

Are the 18000 uF replacements advisable? And should I put a 1.5 mH inductor (.048 oms DCR, 700 watt 14 gauge) between the FW bridge rect and the new caps to soften the start up surge?

Thanx much for any help, Chuch.......and Merry Christmas

[Conrad Hoffman]

IMO, the difference between the two caps is negligible and I wouldn't hesitate to replace them. The inductor is probably a bad idea. Live with the power-on surge or design a time delay relay and parallel resistor. Even a few ohms of resistance between the bridge and caps might not be a bad idea just to limit the current a bit.

CH

[DIYIdaho]

I have one of those bridge rectifiers that look like a T-o3 power transister mounted on a flt aluminum heat sink

[AndrewT]

a slow charge circuit would help to reduce the current surge into the capacitors and through the rectifier, but 18mF is not that much to warrant Thermistors in the secondary circuit.

A soft start to reduce the surge into the transformer is more likely to remove/lessen the mains sag at start up. This will also allow a much lower value mains fuse to be used to power the amplifier.