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-   -   F5 increased capacitance (http://www.diyaudio.com/forums/pass-labs/231157-f5-increased-capacitance.html)

Hikari1 2nd March 2013 06:14 AM

F5 increased capacitance
 
I am in the beginning stages of an F5 build, next up is power caps.

I have a 600va transformer, any harm in bumping the 8 x 15,000uf caps to say 8 x 22,000uf? the cost difference is not much and they will fit on the board. The caps I am looking at are Panasonic TSUP 35v.

ECO-S1VP223DA Panasonic Electronic Components | Mouser

Will the CL-60 thermistors still be enough or do I need to look at soft start? Planning on running a 35amp bridge.

Also, the Pass schematic specifies 25 volt caps. There's 24 volts on the rails. Wouldn't 35v be a better choice?

Zen Mod 2nd March 2013 08:42 AM

with 18Vac secondaries , you'll have aroundish 22Vdc under load

if you are not sure how to maintain voltage under 25Vdc during setup procedure , then buy 35Vdc caps

22mF isn't critical ; I'm having 33mF-0R1-33mF on each rail in FW based sort of monoblock (common 800VA xformer , with 4x18Vac )

WalterW 2nd March 2013 10:48 AM

Hikari no problem at all, i used the exact same capacitors, see here:

http://www.diyaudio.com/forums/pass-...ml#post3358959

danny_66 2nd March 2013 12:25 PM

You're better off with a softstart that bypasses the CL60 after some seconds.
Plenty of those can be found on ebay

Andersonix 2nd March 2013 05:56 PM

1 Attachment(s)
ApexJr has these 33mF 50V caps for $4 each. Get some Teflon coated wire and some big rubber feet while you're ordering.

For soft start, next time I want to try something with an AC relay like 'Fig. 2' in the attached article.

Zen Mod 2nd March 2013 06:02 PM

CL60 alone is perfect

Andersonix 2nd March 2013 06:44 PM

Quote:

Originally Posted by Zen Mod (Post 3392744)
CL60 alone is perfect

For a normal amount of PS capacitance, I agree.

Zen Mod 2nd March 2013 07:34 PM

it's covering fine 800VA Donut , 8x33mF , all that on 220Vac

4A fuse

Hikari1 2nd March 2013 10:23 PM

Zen: That's good to know. I'd rather user the Cl-60 than a softstart board.

Apex Jr. looks like a great shop. I may order some wire from them. Don't know if I am ready to point to point a power supply yet though.

I know it's been done to death but you guys have any opinions on IRF vs Fairchild vs Toshiba outputs? It will be a standard F5, One pair N/P per channel.

I am leaning towards IRFs becasue they are easy to get. The Fairchilds seen to be unobtainium and the Toshibas scare me with the different pin out and possible resistor change needed.

Zen Mod 2nd March 2013 10:27 PM

best thing after wheel is - soft start circuit but filled with series NTCs , instead of fixed resistors

that will give you really soft start

whatever - that's better in just one instance - behavior in case of mains blackout - when you'll need maybe every 10-th time to change fuse

which Toshibas exactly ?


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