2 Sep
2012
2 Sep
'12
4:24 p.m.
Hi all --
Working on recapping an old (failed) 5V supply in that Microkit machine
I picked up last week; the main filter capacitor is rated at 16,000uF
15V, axial. So far in my searches an exact (or even close) match in an
Axial form-factor seems to be unobtainium. I can find snap-in or
screw-in types but those are going to be clumsy to retro-fit given the
space it has to occupy. (plus they're pretty expensive.)
How far off the original capacitance value can I stray before it
compromises the original design?
Thanks,
Josh
2 Sep
2 Sep
10:28 p.m.
On Sun, 2 Sep 2012, Josh Dersch wrote:
Hi all --
Working on recapping an old (failed) 5V supply in that Microkit machine I
picked up last week; the main filter capacitor is rated at 16,000uF 15V,
axial. So far in my searches an exact (or even close) match in an Axial
form-factor seems to be unobtainium. I can find snap-in or screw-in types
but those are going to be clumsy to retro-fit given the space it has to
occupy. (plus they're pretty expensive.)
How far off the original capacitance value can I stray before it compromises
the original design?
What are the dimensions of the original capacitor (in millimeters)?
If it is being used at 5V then you could go down slightly on the voltage
rating, but I'm not sure I'd want to go up much higher because an even
larger plate surface will result in an even thinner oxide layer being
formed, which isn't optimal for electrolytics. The general rule of thumb
in an application such as this is to use a capacitor that is rated for 2x
the operating voltage.
As far as the capacitance goes, you can probably go a little higher
without too much worry (20% of 16,000uF is 3,200uF, so the original could
have been 19,200uF and still would have been within specs), but I'd keep
it under about 18,000-22,000 unless you know for certain that the existing
regulator(s) and/or reverse biased protection diode can handle it (you
don't want to burn out your regulator when you switch the supply off and
the capacitor still has a charge).
Axial style capacitors are available in that range, but you may not like
the price. They appear to be going for USD ~$10.00-15.00 each in qty of
about 50/pcs.
There are a number of capacitors in Nichicon's VX series that you could
consider. The VX series are general purpose 85c rated parts.
TVX1C153MDD 16V 15000uF 22x52mm
TVX1A153MDD 10V 15000uF 22x40mm
TVX1C223MDD 16V 22000uF 25.4x61mm
TVX1A223MDD 10V 22000uF 22x52mm
Another option worth considering is using a radial mount part. Just attach
it to the board with some silicone (which isn't a bad idea for large
capacitors anyway) and extend and insulate one of the leads with some
small teflon tubing. The Nichicon VY and VZ are 105c rated, and the VK and
VR are 85c rated.
UVY1C153MHD 16V 15000uF 18x40mm
UVY1A153MHD 10V 15000uF 16x35.5mm
UVY1C223MRD 16V 22000uF 22x40mm
UVY1A223MHD 10V 22000uF 18x40mm
UVZ1C153MRD 16V 15000uF 20x40mm
UVZ1A153MHD 10V 15000uF 18x35.5mm
UVZ1C223MRD 16V 22000uF 22x50mm
UVZ1A223MRD 10V 22000uF 20x40mm
UVK1C153MHD 16V 15000uF 18x40mm
UVK1A153MHD 10V 15000uF 16x35.5mm
UVK1C223MRD 16V 22000uF 22x40mm
UVK1A223MHD 10V 22000uF 18x40mm
UVR1C153MRD 16V 15000uF 20x40mm
UVR1C153MRD6 16V 15000uF 25x30mm
UVR1A153MHD 10V 15000uF 18x35.5mm
UVR1C223MRD 16V 22000uF 22x50mm
UVR1C223MRD6 16V 22000uF 25x40mm
UVR1A223MRD 10V 22000uF 20x40mm
UVR1A223MRD6 10V 22000uF 25x30mm
I might also consider using a Nichicon HE, PW, or PS series assuming I
could find a close value (these generally top out at 10,000uF or
15,000uF). These are rated for high ripple and 105c. I use tons of these
in all sorts of values in switching power supplies of all sizes and they
would probably work just fine in a linear supply too.
UPW1A153MHD 10V 15000uF 18x40mm
UPS1A153MHD 10V 15000uF 18x40mm
http://nichicon-us.com/english/products/pdfs/e-vx.pdf
http://nichicon-us.com/english/products/pdfs/e-vy.pdf
http://nichicon-us.com/english/products/pdfs/e-vz.pdf
http://nichicon-us.com/english/products/pdfs/e-vk.pdf
http://nichicon-us.com/english/products/pdfs/e-vr.pdf
http://nichicon-us.com/english/products/pdfs/e-he.pdf
http://nichicon-us.com/english/products/pdfs/e-pw.pdf
http://nichicon-us.com/english/products/pdfs/e-ps.pdf
11:49 p.m.
Hi Josh,
I'm having a real problem. A few months ago you asked about my 6205 /
6210 tek workstation components.
I have about 20 boards CPU, IO serial/scsi/disk/parallel , graphics
engines, frame buffers, and a multibus converter with disk controller
three chassis, an extra backplane, diagnostic card ( fits on the IOP
processor) 3 power supplies and about 100 lbs of
manuals plus the schematics and service manual for the IOP/ I/O processor.
My problem is this,
I 'm between jobs, Difficult to make it.
The chip collector people will pay, A lot.
I sold all my spare chips last month to make my mortgage.
All the boards have engineering sample parts and are quite valuable. To
them.
Software will be really hard to find,. I might have a tape that has the
IOP bootstrap code, but nothing is sure.
With the diagnostic card and the schematics, you might be able to get
the thing running.
Back to the "problem", I can get $1500 for just the chips I can pull
from the boards, I hate junking something so rare, but
times are tough
Are you interested?
Thanks,
Jim.
Josh Dersch wrote:
Hi all --
Working on recapping an old (failed) 5V supply in that Microkit
machine I picked up last week; the main filter capacitor is rated at
16,000uF 15V, axial. So far in my searches an exact (or even close)
match in an Axial form-factor seems to be unobtainium. I can find
snap-in or screw-in types but those are going to be clumsy to
retro-fit given the space it has to occupy. (plus they're pretty
expensive.)
How far off the original capacitance value can I stray before it
compromises the original design?
Thanks,
Josh
3 Sep
3 Sep
8:53 a.m.
At 06:24 PM 9/2/2012, you wrote:
Hi all --
Working on recapping an old (failed) 5V supply
in that Microkit machine I picked up last
week; the main filter capacitor is rated at
16,000uF 15V, axial. So far in my searches an
exact (or even close) match in an Axial
form-factor seems to be unobtainium. I can find
snap-in or screw-in types but those are going to
be clumsy to retro-fit given the space it has to
occupy. (plus they're pretty expensive.)
How far off the original capacitance value can I
stray before it compromises the original design?
Caps THAT big are probably filter caps, yes? In
that case, use anything with MORE capacitance and
the same or somewhat higher voltage-- too much
higher and it won't fit on the board.
900 . "Red meat is NOT bad for you. Now,
blue-green meat, THAT'S bad for you!" -- Tommy Smothers
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10:26 a.m.
On 09/03/2012 11:53 AM, Tom wrote:
At 06:24 PM 9/2/2012, you wrote:
Caps in that range should not be that costly. Axial leads may be scarce
but look harder.
Generally I find if one vendor does not have what I want look at another.
Allied, Digikey, Mouser, Jameco, Advent, MPJA.com and oh so many more.
Values for filter caps are flexible. the typical cap like that has a -20
+80% tolerence.
So anything from 12,000uf and up is fine and not less than 15V but not
higher than 25V
That will fit in the occupied space is fine. Yes, that 12,000uF is not a
typo! You have a fair
amount of latitude in power supplies especially older linear types..
Allison/KB1GMX FN42HH :)
Hi all --
Working on recapping an old (failed) 5V supply in that Microkit
machine I picked up last week; the main filter capacitor is rated at
16,000uF 15V, axial. So far in my searches an exact (or even close)
match in an Axial form-factor seems to be unobtainium. I can find
snap-in or screw-in types but those are going to be clumsy to
retro-fit given the space it has to occupy. (plus they're pretty
expensive.)
How far off the original capacitance value can I stray before it
compromises the original design?
Caps THAT big are probably filter caps, yes? In that case, use
anything with MORE capacitance and the same or somewhat higher
voltage-- too much higher and it won't fit on the board.
NEW: a50mhzham at gmail.com ? N9QQB (amateur radio)
1:57 p.m.
On Mon, 3 Sep 2012, allison wrote:
On 09/03/2012 11:53 AM, Tom wrote:
Axial in that size are very hard to find it seems. The few companies that
do make them (Nichicon doesn't even list them on the datasheet, but they
are available) charge a lot for them. You can get a radial type for as
little as $1.50-$4.00 (for a -good- quality one, no less) if you hunt.
At 06:24 PM 9/2/2012, you wrote:
Caps in that range should not be that costly. Axial leads may be scarce
but look harder. Generally I find if one vendor does not have what I
want look at another.
Allied, Digikey, Mouser, Jameco, Advent, MPJA.com and oh so many more. Hi all --
Working on recapping an old (failed) 5V supply in that Microkit machine I
picked up last week; the main filter capacitor is rated at 16,000uF 15V,
axial. So far in my searches an exact (or even close) match in an Axial
form-factor seems to be unobtainium. I can find snap-in or screw-in types
but those are going to be clumsy to retro-fit given the space it has to
occupy. (plus they're pretty expensive.)
How far off the original capacitance value can I stray before it
compromises the original design?
Caps THAT big are probably filter caps, yes? In that case, use anything
with MORE capacitance and the same or somewhat higher voltage-- too much
higher and it won't fit on the board.
Values for filter caps are flexible. the typical cap
like that has a -20
+80% tolerence. So anything from 12,000uf and up is fine and not less
than 15V but not higher than 25V That will fit in the occupied space is
fine. Yes, that 12,000uF is not a typo! You have a fair amount of
latitude in power supplies especially older linear types..
In this application, if the capacitor is being used on the regulated side
of the 5V supply, I'd even consider a 10V capacitor. On the unregulated
side, 16V would be the logical choice (25V, maybe, but a 25V would be a
no-go for me on the regulated side). If this capacitor is on the regulated
side, I would say that they used a 15V part originally due to
availability. In some switching regulator circuits, I even see 6.3V
capacitors used, although I personally prefer slightly more headroom (10V)
in that application.
A photo of the power board would certainly help.
11:09 a.m.
Hi all --
Working on recapping an old (failed) 5V supply in that Microkit machine
I picked up last week; the main filter capacitor is rated at 16,000uF
15V, axial. So far in my searches an exact (or even close) match in an
Axial form-factor seems to be unobtainium. I can find snap-in or
screw-in types but those are going to be clumsy to retro-fit given the
space it has to occupy. (plus they're pretty expensive.)
How far off the original capacitance value can I stray before it
compromises the original design?
Quite a long way!. +/-20% is regardsd as close-tolerance :-)
Don;t go too low, it'll increase the ripply. I would think that 15
millifarads would be OK< though. Don't go ridiculously high either. but
20 millifarads should be OK.
-tony
11:58 a.m.
Thanks to all for the advice. Looks like at least part of my problem is
I need to look a little harder, but at least now I know what I can get
away with. I'll do a little more searching this evening.
Thanks again!
Josh
2:03 p.m.
On Mon, 3 Sep 2012, Josh Dersch wrote:
Thanks to all for the advice. Looks like at least
part of my problem is I
need to look a little harder, but at least now I know what I can get away
with. I'll do a little more searching this evening.
If you can determine if the capacitor is on the unregulated or regulated
side of the supply and have a photo of the board, it would help narrow it
down a little more.
As I mentioned in another reply, you could go as low as 10V on the
regulated side of the supply, but on the unregulated side, 16V would be
the logical choice (some 25V parts exist, but 25V rated 15000uF and
22000uF are somewhat uncommon).
If you want to stick close to the original 15V 16000uF part, just go with
a 16V 15000uF or 22000uF and you should be fine.
4493
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4494
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8 comments
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