leaky capacitors

  • Thread starter Thread starter philo
  • Start date Start date
P

philo

I just picked up a free P-III mobo.
It seems to work OK...but I found two capacitors with the dreaded leakage
on top. I could replace them without too much trouble...but is it worth it?
 
I just picked up a free P-III mobo.
It seems to work OK...but I found two capacitors with the dreaded leakage
on top. I could replace them without too much trouble...but is it worth it?
Click to expand...

For me , no.

It depends on your situation though. You know if you have a CPU
already and cant find a cheap board. I think the hassle and finding
the the caps etc if you cant do it for a few bucks or have the caps
sitting around your house then usually you can find an old board some
place for cheap. There are refurbs at Newegg etc.

Abit also has or had reasonable rates for fixing boards even out of
warranty. It wasnt 20 bucks more like 60 I think but better than youd
think with labor costs as they are today. I think the bad caps place
charged 40-50 or something to redo the caps.
 
For me , no.

It depends on your situation though. You know if you have a CPU
already and cant find a cheap board. I think the hassle and finding
the the caps etc if you cant do it for a few bucks or have the caps
sitting around your house then usually you can find an old board some
place for cheap. There are refurbs at Newegg etc.

Abit also has or had reasonable rates for fixing boards even out of
warranty. It wasnt 20 bucks more like 60 I think but better than youd
think with labor costs as they are today. I think the bad caps place
charged 40-50 or something to redo the caps.
Click to expand...


Well since I have all the parts I need to make an entire machine...
I may just do it. I did fire the thing up on my workbench with a 1ghz
cpu and it works fine...
but I don't trust it with those leaky caps.

a few weeks back i tossed a mobo because it had at least 6 or 8 bad caps...
but this one only has 3 bad ones..and I should be able to replace them
fairly easily. I don't do much soldering any more...but still have not
forgotten how
 
philo said:
Well since I have all the parts I need to make an entire machine...
I may just do it. I did fire the thing up on my workbench with a 1ghz
cpu and it works fine...
but I don't trust it with those leaky caps.

a few weeks back i tossed a mobo because it had at least 6 or 8 bad caps...
but this one only has 3 bad ones..and I should be able to replace them
fairly easily. I don't do much soldering any more...but still have not
forgotten how
Click to expand...

If you can do the work, and don't mind the risk then sure, go ahead.

You may mant to check for additional bulging caps, not as bad as a
leak, but ont exactly GOOD.
 
Well since I have all the parts I need to make an entire machine...
I may just do it. I did fire the thing up on my workbench with a 1ghz
cpu and it works fine...
but I don't trust it with those leaky caps.

a few weeks back i tossed a mobo because it had at least 6 or 8 bad caps...
but this one only has 3 bad ones..and I should be able to replace them
fairly easily. I don't do much soldering any more...but still have not
forgotten how
Click to expand...


If you already have the caps, might as well do it. Actually
it's BETTER that way... because after you replace all the
faulty caps with known *very good* ones, you have a much
better expectation that the system has a longer life, that
those weakest points have been replaced.

Unfortunately, unless the board was just running too hot
from limited chassis cooling, IE- if the caps were actually
of the defective variety rather than the
pushed-beyond-their-reasonable-limits, variety, then all of
the same make and model should be replaced, not just those
which are visibly venting at the moment.

socket 370 systems are great for aux. uses though, take one
with a 1GHz CPU, underclock it to 66MHz FSB, put a giant
passive heatsink on it and reduce the CPU voltage a couple
notches and it'll run passively. Grab all those old dimms
out of the drawer and you have a 768MB+ fileserver that is,
as most, bottlenecked by the hard drives and LAN, not the
mobo or CPU.
 
If you already have the caps, might as well do it. Actually
it's BETTER that way... because after you replace all the
faulty caps with known *very good* ones, you have a much
better expectation that the system has a longer life, that
those weakest points have been replaced.

Unfortunately, unless the board was just running too hot
from limited chassis cooling, IE- if the caps were actually
of the defective variety rather than the
pushed-beyond-their-reasonable-limits, variety, then all of
the same make and model should be replaced, not just those
which are visibly venting at the moment.

socket 370 systems are great for aux. uses though, take one
with a 1GHz CPU, underclock it to 66MHz FSB, put a giant
passive heatsink on it and reduce the CPU voltage a couple
notches and it'll run passively. Grab all those old dimms
out of the drawer and you have a 768MB+ fileserver that is,
as most, bottlenecked by the hard drives and LAN, not the
mobo or CPU.
Click to expand...


Well i picked up some new replacements today...(about $4 )
considering that i have all the parts to build another machine ...
the total cost will be just the price of the capacitiors...
so I guess I'll warm up my soldering pencil and see if i still know how to
solder.

this should not be as bad as replacing the smt capacitor on a hardrive that
i did last year!
 
If you can do the work, and don't mind the risk then sure, go ahead.

You may mant to check for additional bulging caps, not as bad as a
leak, but ont exactly GOOD.
Click to expand...


well it looks like the only bad ones are the 100mfd @ 6.3v so i'm going
to go for it...
the board was a freebie anyway so there's not too much risk i guess
 
Well i picked up some new replacements today...(about $4 )
considering that i have all the parts to build another machine ...
the total cost will be just the price of the capacitiors...
so I guess I'll warm up my soldering pencil and see if i still know how to
solder.

this should not be as bad as replacing the smt capacitor on a hardrive that
i did last year!
Click to expand...


I actually prefer surface mount, much easier and quicker to
me. SMT ceramics are a cinch, just take some desoldering
wick with some flux added to it, drape it across the whole
cap and heat the wick and the whole cap lifts off with it.

With a tantalum, take a thin object like an X-Acto knife
blade or a dental pick and gently push under the edge of the
cap while heating one side. With practice this technique
will cause the other end of the cap, the lead at the cap
body to bend rather than pulling the pad up, so the cap is
then sticking up on the end you heated first. Keep the
prying tool under the cap and heat the other side. "Prying"
is really too strong a word, it just needs ever-so-slightly
nudged.

SMT electrolytics are a bit harder, 'tis more important to
have a good hot, fine-tipped iron to heat what little of the
pad is exposed. When there is too little of the pad
exposed, I put in a spare (scrap) tip to melt through the
plastic baseplate of the cap towards the pad, which is a bit
messy but that's why I use the old tip. It'll destroy the
base of the cap but then the new one comes with a base, it's
not like you'd need to reuse it.

I hope you found decent caps for replacement, those
typically found at radio shack aren't even close to low
enough ESR for most motherboard subcircuits, particularly
those in which the typical cap failures are seen. Mostly I
use Panasonic FM or Nichicon H(*) series for those, though a
few others like Rubycon M*C or United Chem-Con are pretty
good too. It's hard to find decent caps though, well not
really hard online but I usually look to major supply houses
like Digikey or Mouser. Bought caps on ebay once-
apparently "brand new" on ebay can mean 10 years old. Not a
problem with foil caps for audio use but for low ESR 'lytics
I'll pass on ebay in the future if there isn't a date
guarantee.
 
I hope you found decent caps for replacement, those
typically found at radio shack aren't even close to low
enough ESR for most motherboard subcircuits, particularly
those in which the typical cap failures are seen. Mostly I
use Panasonic FM or Nichicon H(*) series for those, though a
few others like Rubycon M*C or United Chem-Con are pretty
good too. It's hard to find decent caps though, well not
really hard online but I usually look to major supply houses
like Digikey or Mouser. Bought caps on ebay once-
apparently "brand new" on ebay can mean 10 years old. Not a
problem with foil caps for audio use but for low ESR 'lytics
I'll pass on ebay in the future if there isn't a date
guarantee.
Click to expand...

Glad I did not replace them yet...
I got Radio Shack...
although they are rated at 50 volts
and the originals were just 6.3v so I thought they'd be ok.
 
well it looks like the only bad ones are the 100mfd @ 6.3v so i'm going
to go for it...
the board was a freebie anyway so there's not too much risk i guess
Click to expand...


Seldom do I see 100mfd caps fail, did you mean 1000mfd?
What brand were they, what color sleeving (good to keep
track of these things historically) ?
 
Glad I did not replace them yet...
I got Radio Shack...
although they are rated at 50 volts
and the originals were just 6.3v so I thought they'd be ok.
Click to expand...


Depends a bit on where it is in the circuit, but if it's one
of the 6.3V 1000uF caps in the power regulation (VRM)
subcircuit, you definitely want a very low ESR cap for that.

It'll be handling 5V, so at least 6.3V in a typical 'lytic
will work, but depending on the diameter you can likely
substitute a 10V or 16V part instead.

That's what I usually do, buy mostly 16V caps in quantity so
long as doing so doesn't mean dropping down too much below
the original cap's mfd value. I don't try to match that
value though, instead getting the tallest part that'll fit
in the provided space. Typically that means for 8mm, a
20-25mm tall cap or 25mm tall for 10mm. I don't bother with
more than 25mm for a 12.5mm diameter cap though, the 12.5mm
parts in the same lines have so much better ESR it's not of
much benefit.

That brings me to the other good point, that I'll use the
largest diameter that'll fit in the provided space. Often
they're so crowded together you have to use the same size,
but sometimes not and the 12.5mm typically have the same
lead pitch as the 10mm so they're workable. 8mm has a
narrower pitch though, are more of a pain.

I'll get creative with it sometimes though, back in the slot
1 days a bunch of generic boards used to line up a bunch
(about a dozen) 6 or 8 mm caps behind the socket well, but
with a little distance between themselves and the socket
retention frame. I'd use a 12.5mm cap and put it's positive
lead in the position one of the smaller caps was in, and
it's negative in the ground position for a different cap
(which had been in parallel before they failed).

To buy small quantities of caps, best place online is
probably Mouser, because Digikey has a $25 minimum order
limit (else a $5 handling fee). At mouser the Nichicon HE
(UHE) series in the appropriate size should work, is
somewhere among these results,
http://www.mouser.com/?Ne=100&handl...icon*&terms=Nichicon&crc=true&N=288&Ns=SField
 
Seldom do I see 100mfd caps fail, did you mean 1000mfd?
What brand were they, what color sleeving (good to keep
track of these things historically) ?
Click to expand...


well i am sure glad i posted here and got your advice...

the caps are green and ESR rated...

the way they are labeled...the top of the number is cut off and all i
saw was : 00

the leading 10 was not there...

I should have known something was wrong because the 6.3v caps are about
the same size as the 50v caps i just purchased.

I think I'll find some good ones on a scrapped mobo and use them...
so for now, this project is on hold

thanks for the good info!!!!
 
That brings me to the other good point, that I'll use the
largest diameter that'll fit in the provided space. Often
they're so crowded together you have to use the same size,
but sometimes not and the 12.5mm typically have the same
lead pitch as the 10mm so they're workable. 8mm has a
narrower pitch though, are more of a pain.

I'll get creative with it sometimes though, back in the slot
1 days a bunch of generic boards used to line up a bunch
(about a dozen) 6 or 8 mm caps behind the socket well, but
with a little distance between themselves and the socket
retention frame. I'd use a 12.5mm cap and put it's positive
lead in the position one of the smaller caps was in, and
it's negative in the ground position for a different cap
(which had been in parallel before they failed).

To buy small quantities of caps, best place online is
probably Mouser, because Digikey has a $25 minimum order
limit (else a $5 handling fee). At mouser the Nichicon HE
(UHE) series in the appropriate size should work, is
somewhere among these results,
http://www.mouser.com/?Ne=100&handl...icon*&terms=Nichicon&crc=true&N=288&Ns=SField
Click to expand...



there is enough room to mount larger caps if necessary...
if i can't steal some off a dead board...there is an electronic supply
store not too far from my house...so i'm sure i can get them...


thanks!!!!
 
well i am sure glad i posted here and got your advice...

the caps are green and ESR rated...

the way they are labeled...the top of the number is cut off and all i
saw was : 00

the leading 10 was not there...

I should have known something was wrong because the 6.3v caps are about
the same size as the 50v caps i just purchased.

I think I'll find some good ones on a scrapped mobo and use them...
so for now, this project is on hold

thanks for the good info!!!!
Click to expand...


If you can determine the make and model (perhaps from other
caps still on the board), and supply the can (casing) size,
I can probably figure out what value they were.

Given only 6.3V and "00", many combinations were common.
Seldom in power regulation areas was less than 1000uF used
and those were typically rather small, 8mm diameter and
about 10-12mm tall. Moving upwards (more common on Pentium
2 era and newer boards, especially name-brand boards) it was
more common to have larger values such as 1200uF, 1500uF,
2200uF, or even 3300uF on some of the newer boards for
Athlon and P4 era systems.

However, one of the common telltale signs of a questionable
quality generic capacitor (for the switching power use) is
that for it's can size, it's mfd value is higher than the
same size quality cap from the major manufacturers such as
United Chem-Con, Rubycon, Sanyo/Panasonic, Nichicon et al.

In other words, supposing a spot had room for only a 8mm
diameter part and the original was 20mm tall and rated for
2200uF. That's an unreasonably large value and you would
expect a good quality low-ESR from a major brand to be only
(roughly) 1200uF in their tallest 8mm diameter part.

So it goes with many many caps I've seen failed, not all of
them and it only applies to the wet aluminum electrolytics,
not some of the more exotic caps on some video cards or the
shorter surface mounted ones (more common around socket
areas of newer P4 boards).
 
In other words, supposing a spot had room for only a 8mm
diameter part and the original was 20mm tall and rated for
2200uF. That's an unreasonably large value and you would
expect a good quality low-ESR from a major brand to be only
(roughly) 1200uF in their tallest 8mm diameter part.

So it goes with many many caps I've seen failed, not all of
them and it only applies to the wet aluminum electrolytics,
not some of the more exotic caps on some video cards or the
shorter surface mounted ones (more common around socket
areas of newer P4 boards).
Click to expand...

Ok

I put on my reading glasses and gave the board a good inspection.
the caps are 1500mfd @ 6.3v

the board is an ABIT VH6-II
 
philo said:
Glad I did not replace them yet...
I got Radio Shack...
although they are rated at 50 volts
and the originals were just 6.3v so I thought they'd be ok.
Click to expand...

Don't use regular electrolytics like that or they may run hot and wear
out in just 6 months. I've seen that happen with many power supplies,
and in the case of some heavily-used Citizen impact printers, the same
capacitor would fail every 3-6 months until it was replaced with a
Japanese brand rated for high frequency switching and low ESR.

In addition to Mouser and Digikey, another source of good capacitors is
B&D Enterprises, www.bdent.com, which sells Sanyo OSCON dry capacitors.
 
Don't use regular electrolytics like that or they may run hot and wear
out in just 6 months. I've seen that happen with many power supplies,
and in the case of some heavily-used Citizen impact printers, the same
capacitor would fail every 3-6 months until it was replaced with a
Japanese brand rated for high frequency switching and low ESR.

In addition to Mouser and Digikey, another source of good capacitors is
B&D Enterprises, www.bdent.com, which sells Sanyo OSCON dry capacitors.
Click to expand...


Right!

I'm going to get some good caps. before I do anything
 
Ok

I put on my reading glasses and gave the board a good inspection.
the caps are 1500mfd @ 6.3v

the board is an ABIT VH6-II
Click to expand...


The class action suit settlement period for those boards
ended (submission date elapsed) only a couple months ago.

It looks like that board takes mostly 10mm diameter parts.
There might be some 16V rated (necessary due to being on the
12V rail on the board) caps on it but the majority should be
6.3V, particularly those failing since it used 5V for the
CPU regulation subcircuit.

The typical quality cap in 10mm diameter from the better
manufacturers has a max height of about 25mm (rarely 30mm
but not common and unnecessary to seek). IOW, the best
replacement for that board would be 10 x 25mm sized caps
which are typically about 2200 mfd. Two examples of parts
that should work (considering only those caps rated at 6.3V,
IF you need 16V caps too then see the 3rd link) are,

http://www.digikey.com/scripts/DkSearch/dksus.dll?PName?Name=P12344-ND&Site=US

http://www.mouser.com/index.cfm?han...uctid=496773&e_categoryid=381&e_pcodeid=64712
There are other slightly better caps from Nichicon listed on
Mouser's site but they aren't kept in stock.

Doing only one board, getting the 6.3V parts to replace
currently failed 6.3V parts would be the most obvious
course. Cap prices get significantly lower buying in
volume though, if you just wanted to buy a large quantity of
one part that will service most boards (future boards being
more likely to need caps in 12V subcircuits so a 16V part),
the better option would probably be the Panasonic FMs as
linked through Digikey,
http://www.digikey.com/scripts/DkSearch/dksus.dll?PName?Name=P12367-ND&Site=US

These are considering only the resonably priced low-ESR
caps, there are certainly some exotic formulations that
would work as well but their prices are much higher, and as
such they aren't ever used on motherboards except when there
are significant space constraints. It costs the motherboard
manufacturer much less than an individual buying would pay
though, some are easily over $3 a piece which is far too
expensive to repair an old board, IMO, while the preceeding
parts are just under 50 cents each in volumes of 10 or more.
 
These are considering only the resonably priced low-ESR
caps, there are certainly some exotic formulations that
would work as well but their prices are much higher, and as
such they aren't ever used on motherboards except when there
are significant space constraints. It costs the motherboard
manufacturer much less than an individual buying would pay
though, some are easily over $3 a piece which is far too
expensive to repair an old board, IMO, while the preceeding
parts are just under 50 cents each in volumes of 10 or more.
Click to expand...



well if i can get it repaired for under $5 or $10
it's probably worth it

thanks!
 
Back
Top