How to use these huge caps in PSU for F5?

[Hubba]

I've got my hands on some really huge 68000uF/40V caps, or rather four of them (may get an additional two), and I'm thinking about doing a PSU for my F5 using them as I kind of like the look of them.

However, my skills in the PSU domain are limited at best, so I would appreciate some help. Using the standard Pass F5 PSU schematic, is it possible to simply replace C1&C2, C3&C4...with one of the caps, or would that mess things up?

Thanks,
Fredrik

 

[aspringv]

No reason you can't swap them straight in frankly. There's no penalty of any form, and macho manly sized power supply's are all the range here at diyaudio

I've a set of 8 100000uF 30V caps here somewhere, that i'd intended to use in a similar amp. However they're too big for the largest heatsink cases I could make sooo... they've remained unused!

 

[Hubba]

Thanks for the reply Aspringv,

So, if I would get my hand on two additional caps (having in total 6 available for use) could I throw them into the mix as well? What I'm thinking is that the amount of uF will be different before and after the R in the CRC circuit. (i.e 1x68000-R-2x68000).

Is that "unbalance" a bad thing?

Thanks,
Fredrik

 

[Zen Mod]

with that much , no need for CRC , go with simple C

though, use space and put (at least) 50uF motor runs in parallel

 

[KatieandDad]

You might need to consider a slow-start circuit as the in-rush current might be quite high.

 

[Soundhappy]

On the PSU schematic CL-60 thermistors do slow-start work, so no worry about in-rush current.
Try first time Your new PSU with cheap speakers.
If you need buy components or have 15000 uF ~ 25000 uF then configuration
can be CRC first cap ~ 20KuF + 4x 0.47R | 3watt's metal oxide
( or 1x 0.1R | 20 watt's wirewound ) power resistor :
50W/100W 0.01-5k Ohm Watt Shell Power Aluminum Housed Case Wirewound Resistor | eBay
+ second cap 68KuF.
Some Diyer use choke in place of resistor in CLC configuration

 

[Dennis Hui]

When I built my A30 years, I also used 68000uF caps in a CRC configuration.
The transformer was 500VA and only a single CL60 were used. I used the
spec'ed size slow blow fuse and have not had issues over the years.

 

[gadut]

I used 8pcs and it's 50V which is bigger than yours. no issue at all with CLC

 

[Itsmee]

I have a stereo F5 work horse with 4x 100,000uF Kendeil (CRC), total bias is 2.8A, 500VA transformer with 2x CL60's, and a 2A fuse (230V mains), never had any startup issues with it.

 

[AudioSan]

I would use a overkill transformer with those caps. And a 2x series connected CL60 based softstart that bypass the thermistors after a little while. Do not use a softstart with parallell connected CL60.

 

[gadut]

I would use a overkill transformer with those caps. And a 2x series connected CL60 based softstart that bypass the thermistors after a little while. Do not use a softstart with parallell connected CL60.

my scheme is that softstart before transformer, CL60 is on DC side. they serve different purpose

 

[Hikari1]

I've got my hands on some really huge 68000uF/40V caps, or rather four of them (may get an additional two), and I'm thinking about doing a PSU for my F5 using them as I kind of like the look of them.

However, my skills in the PSU domain are limited at best, so I would appreciate some help. Using the standard Pass F5 PSU schematic, is it possible to simply replace C1&C2, C3&C4...with one of the caps, or would that mess things up?

Thanks,
Fredrik

That’s totally fine to do, just put R (resistor) or L (choke) between the two caps. You won’t need more than a single cl60 most likely. I use 6x33,000uf with a single cl60. Be aware that the stud on that capacitor may be connected to ground and will need to be isolated.

 

[AudioSan]

my scheme is that softstart before transformer, CL60 is on DC side. they serve different purpose

You are looking at the wrong CL60.

 

[Hubba]

Thank you for all the input!

Thank you all who has helped answering my questions, as well as pointing out potential problems.

I'm going for a standard CRC setup using in total 4 of the caps.

As some of you have pointed out the in rush current may be an issue, but I have a separate soft start Circuit (with 4xCL60 and a by pass relay) which takes care of that...

Once again, thank you all for valuable input!

Cheers,
Fredrik

 

[AudioSan]

Thank you all who has helped answering my questions, as well as pointing out potential problems.

I'm going for a standard CRC setup using in total 4 of the caps.

As some of you have pointed out the in rush current may be an issue, but I have a separate soft start Circuit (with 4xCL60 and a by pass relay) which takes care of that...

Once again, thank you all for valuable input!

Cheers,
Fredrik

That is just the kind of softstart you never should use. They have parallell connected thermistors. two and two in parallell and the two couples are series connected. Or all 4 are in parallell.

 

[Hubba]

@AudioSan

Why is that a problem?

/Fredrik

 

[AudioSan]

Thermistors change impedance with current draw. And current takes the path of least resistance. So you will get current hog on one of the thermistors (or two if the are two and two in parallell).

 

[Hubba]

ah, yes..ok

The thermistors are only in play for a couple of seconds, after that a relay closes and the transformer is fed from that path instead.

/F

 

[aspringv]

Hi Hubba, is it one of these by chance?

Just be aware that I think theres some pretty reasonable leakage current through this item. I used on on an aleph build and the led's on the amp boards would never quite go off... concerning enough that I unplugged it.

I should really open that guy up and do some checking actually!

 

[dazed2]

No problem at all!
Go CRC

But I do think you need a slow charge circuit.