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|21st April 2017, 04:09 AM||#1|
Join Date: Aug 2009
Wanted - Electrolytic caps. ~25,000uf 100v. Pin or tag.
I'm after a supplier for 4 off the following.
Termination can be; Pin, Snap in, Tag. Not screw.
Pitch of 10mm to 28mm
Normal two pin. Not multi pin. (double sided board with tracks under the cap)
Maximum diameter of 53mm
Hight up to 140mm
I've tried; rs, e14, digikey, mouser, dalbani, hifi collective.
Any other suggestions or links appreciated.
Last edited by Old'n'Cranky; 21st April 2017 at 04:11 AM. Reason: Title clarification
|21st April 2017, 10:56 AM||#3|
Join Date: Aug 2009
The original is 25,000uf 80v.
But they run right on 80v.
If (when) the mains goes up obviously they'll be over stressed.
So I'd really prefer to replace them with a higher voltage.
But it looks like I'm trying to find unicorn tears.
I don't want to go to screw terminals as that means a whole lot of lateral thinking to make them fit.
But I may be forced down that road yet.
|21st April 2017, 03:44 PM||#4|
Join Date: Sep 2004
Location: Lansing, Michigan
Still, whatever you do, 22000 will be easier to find. OEMs can have any value they want made up for their production, but we rely on off the shelf products.
Caps have "working voltage" ratings, so an 80v cap is OK at 80v. They also all have a surge rating, which is higher. Often that is to cover momentary higher voltage as circuits warm up, but running slightly over would fall under that.
|21st April 2017, 04:34 PM||#5|
Join Date: Jul 2004
Location: Scottish Borders
I would be happy running a smoothing capacitor at 99.9% of it's rated maximum voltage.
I would not operate it at 101% of maximum rated voltage.
I consider the openers concern at using 80V caps at >80Vdc when the mains voltage is high to be worthy. The overvoltage could last many hours and in exceptional circumstances maybe even exceed days.
regards Andrew T.
Sent from my desktop computer using a keyboard
|21st April 2017, 11:35 PM||#7|
Join Date: Aug 2009
Yes I may have to resort to a lower capacity.
I'd rather not if I can help it though.
It's a nice amp designed by a great designer so I'd like to it justice.
But the reality of physical size, mounting restrictions, and what can be bought for realistic sums will all determine what actually gets installed.
The caps in question are ps filter caps in an amplifier.
The owner (a friend) asked me to investigate several faults.
When I opened it up I saw the caps bulging. (Not the main issue, but still need to be fixed in my opinion)
He and I are a bit ocd so I need to replace them for my own sanity
Note that I have Not measured the secondary or filtered voltages.
These are from the schematic, and I have no reason to doubt them.
Heres an excerpt from an email I sent him about the caps.
amp is supposed to be 230vac.
transformer out to board is listed as 55vac.
then shows the main supply rail listed as 80vdc.
so with some quick maths and generalizations applied.
230vac input -> 55vac x 1.4 (rectification and filtering factor) = 77vdc
Thats to close to the 80v cap rating for my liking.
If we throw in the fact of it being on 240vac into the mix.
230vac + 4.5% = 240.35vac
55vac + 4.5% = 57.5vac x 1.4 = 80.4vdc
Thats right on the edge of what the cap is rated for.
Now, caps can, and will, survive with higher voltages.
But, they will run hotter and their life will be reduced.
If for fun we now look at what I would allow for as 'normal'.
230vac + 9% = 250vac
55vac + 9% = 60vac x 1.4 = 84vdc
Ok so thats survivable. Albeit with a shorter life span.
I have an article on an amp i built many years ago.
The designer did his research and came up with this..
His office in waroonga sydney ranged from 245-255vac.
and various councils he contacted said he should allow for 265vac.
230vac + 15% = 264.5vac (pretty common for w.a.)
55vac + 15% = 63.25vac x 1.4 = 88.55vdc
As a side note.
Where he and I live the mains is normally around 245vac
This kit amp I refer to (AEM6000), I built it in 1988 using caps with a higher voltage than specified.
I have never needed to repair it.
And it still has the original caps in it.
Obvious solution is to use higher voltage caps.
which means lower capacitance units.
which means more of them to get the capacitance needed.
which means more space to fit them.
which means more cost at production.
The amp has outlived it's warranty period.
Thats all that matters.
Last edited by Old'n'Cranky; 21st April 2017 at 11:40 PM.
|21st April 2017, 11:42 PM||#8|
Join Date: Dec 2008
Location: Portland, OR
Realistically, 22000 vs 25000 with a 20% tolerance on these caps mean they're essentially fungible. And very very doubtful to materially change anything about the PSU performance. Possibly beneficial if you have a modern electrolytic capacitor with a bit lower ESL ESR. And who knows how much the value of your old cap has changed over its lifetime.
Happy DIYing, Daniel
(This space is occupied by the artist formerly known as Derfnofred)
|22nd April 2017, 12:19 AM||#9|
Join Date: Aug 2009
ooh yes ta for reminding me about that.
I did have super quick search and couldn't find anything about the original caps.
I'll have another better search when I get home tonight.
Old caps are Elna CE-W 85 Degree
Sadly none of my meters are able to measure the old ones so I can't say just how close or far out they now are.
|22nd April 2017, 12:39 AM||#10|
Join Date: Jan 2017
While 25m (25,000uF) isn't a standard value, 33m (33,000uF) should be. Not sure how old your chassis is, but chances are that if it's 20yrs or more, a modern 33m would easily fit where an old 25m did. And 33m shouldn't be all that much more than 22m.
I'm currently fluffing-up a 35yrs old Hafler DH-200, which uses 2" (51mm) computer-grade cans rated 10m @ 75V. After some searching, it seems the sweet spot for price / quality is Nichicon 10m @ 100V, in a much smaller 1-3/8" (35mm) snap-cap package. Sure, I'll have to adapt the to the mounting clamps with shims, but hey - why not? Sure, I could use 1-3/8" clamps, but that would require drilling holes.. and that's always to be avoided.
The pair of 10m cost $17US shipped, and the 22m @ 100V were only about 50% more in price..
Last edited by legendre; 22nd April 2017 at 12:41 AM.
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