using a 100uF 240Vac motor run

[pro_crip]

As a goof I bought a pair of GE 100uF 240Vac motor run caps as outputs for my crack. I got an idea. What if I pulled out that 270 ohm resistor and the last electrolytic and replaced them with a triad c7x and one of those motor runs? One of those caps should fit under the chassis. Is this doable or even worth doing? Thanks for listening.

Rich

[Paul Joppa]

You mention a Crack, but have posted in the Paramount forum. If you are going to use it as the last cap in a Paramount, it should be rated for 600 volts DC.

Many people on the forums will try to tell you with great authority how to calculate the DC rating from the AC rating, but only the manufacturer knows for sure!. Many things go into that calculation, and most of them are not specified even if you knew what they were and how to use them in the calculation. Find the specification for that capacitor and see what the DC rating is. If the manufacturer will not provide a DC rating, I would advise not to use it in a DC power supply.

As to effect, I never met a power supply improvement that was not an audible improvement, so this (if it's safe and reliable) would probably be an improvement. Not as large an improvement as it would with a series feed amp, but probably audible.

[pro_crip]

Sorry for the confusion Paul, the caps were bought for the crack output but they're too large to fit in the crack and instead of letting them go to waste I thought I could use them in the power supply of the paramount. Is that 600 volt rating due to power-up conditions? Because I was planning on building my Paramount with the soft-start upgrade and thought that the cap wouldn't see 600v, even on power-up. I multiplied 240 by the square root of 2 to get 360. It doesn't look like I'll be able to do that. At least I can do the choke swap. At the very least let me see if I can find the specs. Thanks.

edit: Now I'm confused, I wanted to pull the last panasonic electrolytic in the power supply and that's rated at 350V in the materials list. Did I cross wires with unclear writing on my part? The output caps are rated at 600v.


Rich

[Paul Joppa]

There are two Panasonic 350v caps in series on the power supply board as the last capacitor; they have equalizing resistors to ensure that each sees half the voltage so the result is a 700 volt rating.

The soft start only applies to the driver section of the 5670, it is NOT an overall power supply soft start. The initial voltage can be in the range of 550-600 volts, until the power tube begins to conduct.

[pro_crip]

I went to GE's page on the cap, ge97F8052, but couldn't find anything about a dc rating. That idea goes in the circular file, except for the choke. Everything I'm building uses that 270 ohm resistor so I''m buying some chokes. Thanks anyway.


Rich

[pro_crip]

How about replacing that last panasonic electrolytic in the power supply with one of these: http://www.surpluscenter.com/item.asp?item=22-1120&catname=electric? Will that 88 uF be enough or at that price should I get two to parallel? Sorry, long day and feeling a little punchy. Thanks for listening.

Rich

[2wo]

Well, the price and voltage rating are good. Pretty big though. And you can recycle them when you build your 1KV 845 amp;).

Look for Motor RUN caps with a 440VAC rating, ASC and others make them. I got mine off the bay.

 You didn't hear it from me but many use this specific type of cap at 600VDC without trouble...John