SSL 4000 power supply Rebuild ( Large 100,000uf replacement?)

[jwhmca]

Hi guys,

Any first hand experience replacing the large filter caps in the SSL CF661 power supplies? Like maybe a known good replacement etc...?

I can sure find the values needed okay at Mouser, but just concerned the unknown specs of the original cap... ripple current ESR etc..

 

[audiomixer]

any modern cap will be 'better', probably....... you will need to fix the physical details first (size, mounting, lead attachment) so that will narrow your choices.

- Michael

 

[jwhmca]

Yeah, that's the easy stuff... It's more about the ripple current and maybe some other hidden details that SSL may have used and needed and generics don't....

First hand experience or "proven" subs would be best......

 

[pucho812]

Any reason why you wish to replace those in the first place? Is something not working as it should?

 

[SSLtech]

Modern day advances in Electolytic capacitor technology (thanks to switch mode complexity and the need for super-performance capacitors far-exceeding devices from even 20 years ago) mean that pretty much ANY capacitor you get of the required value and working voltage will outperform the original caps... so don't sweat it.

In addition, the raw rectified/smoothed voltage is so far above the regulated output voltage that sags and ripples simply wouldn't be an issue, even if the caps were ripply, high ESR or whatever.

The issues you SHOULD probably concern yourself "while you're in there" that a lot of people overlook are the condition of the fans, cleanliness of the heatsinks, and condition of the thermal compound. Refresh that stuff, clean the dust and "fug" off the heatsinks, and make sure the fans are in good shape.... not too much lateral "play" on the shaft bearings, spinning freely, and not rubbing/catching.

If one of the rotors has more axial loose play than the others... replace it. If one of them stops spinning a significant time before the others when they 'coast' to a stop after power-off... replace it. Dust and clean them. A dying fan now means a dead fan alter, and a dead fan means BIG repairs.

Use a decent cap, and don't sweat it. Higher ESR caps may ripple a little more, and may also run a little warmer, but it's HIGHLY doubtful that you will find caps of that size and working voltage which don't nowadays comfortably exceed the required spec from back in 1977, or whenever that supply was originally designed.

 

[joaquins]

If ESR is much lower than original, wouldn't be inrush current a problem? Or in the original the ESR was already much lower than the winding resistance?

JS

 

[PRR]

In audio power supplies, capacitor ripple current rating is "rarely" an issue. We need so many uFd to get ripple voltage down, that the physical size ensures adequate ripple current handling. While physical size has been going down, ESR (part of the ripple current problem) has also gone down, so we are not falling behind.

The nature of the beasts and the relative importance of things in power supplies makes it pretty-sure that winding resistance far exceeds cap ESR, so a change of cap does not mean higher peak currents.

Cap makers make caps in these sizes FOR power supplies. And for things like welders which are much more abusive than supplies for audio. If you are building a welder with 30% ripple, rip-current becomes an issue. If you try to run audio on 30% ripple you get just buzz, and even with regulators 30% ripple is just a bad idea, we up-size the caps for 3%-10% ripple.

It would be good to have someone's endorsement for a specific cap that "worked" in a CF661, but without any tips I would just dart-toss the catalogs for a good quality cap with enuff uFd and not too many inches.

 

[jwhmca]

I have a client that "wants to replace everything..." type trip. I could recommend NOT replace the large caps if you guys think it's a total waste of money.

Does anybody have the specs on the rest of the caps in there? it looks like there are 3 other large "screw terminal" caps and it seems like there are a couple axial caps on the mother board behind the REG Cards?

 

[mjrippe]

I have a client that "wants to replace everything..." type trip. I could recommend NOT replace the large caps if you guys think it's a total waste of money.

If they want to replace "everything", why not buy the Atomic Instruments supply?  (http://www.atomicinstrument.com/products/)  We have one here and it is truly amazing.

 

[bruno2000]

For the main filter caps, I used these.
http://www.mouser.com/Search/ProductDetail.aspx?R=PEH200KO6100MB2virtualkey64620000virtualkey80-PEH200KO6100MB2
Slid right in, no muss, no fuss........
Best,
Bruno2000

 

[David Kulka]

That supply is old, and has been running hot for ages. I would definitely replace all the electrolytic caps. It's "penny wise, pound foolish" not to.

 

[sodderboy]

Agreed.  All electrolytic caps get replaced, including the axials under the loom in the back and the caps on the regulator cards.  Label the cards for their positions when you remove them, and take good pics of the pots on the motherboard just in case a vigorous vac moves things.  You could up the voltage rating just to get the physical size closer to original, but it's not critical.

Is it really grimy inside?  You should try to remove as much as possible using dry methods like a toothbrush and a vac.  I liked to keep a foam AC filter at the fan intake just to keep them clean.

Inspect all crimp connectors and connections, both the crimp and screws.  Re-seat everything and look for any kind of dirt or "coppering" on the spades.  Any kind of browning of insulation points to a failing crimp or dirty connection.  Clean the spades with the smallest bit of alcohol on a swab.