Help sought for an 8K7A+ with bad caps

Hi All,
I want to fix at minimum cost and trouble an 8K7A+ which seems to have
developed bad capacitors (some look quite bad and it's started random
reboots and lock-ups -- see thread *Spontaneous reboots* in alt.windows98).
I'm looking for somone who can supply a good replacement similar model board
or who can replace the caps for me (I'm in France).
I found another board on E-Bay but as it's in the US and described as
"refurbished" I'm a little leery of paying so much carriage for that one.
Help or ideas, anyone?
Thanks in advance,
Michael Anders

Could you not replace the caps.... should be easy enough do with a
small 15 Watt soldering iron.

If you should take this route use LOW ESR (Effective Series
Resistance), or low impedance 105 deg. C types, do not use standard
capacitors...!

Obviously it's pointless if the capacitors have leaked and damaged the
board, the gunge they spew 'could' eat away at the protective PCB
lacquer then eat away the copper tracks.

Davy

Actually, I've solved the spontaneous rebooting problem for the moment by
changing the PSU, notwithstanding the dodgy-looking caps, thanx !

"Davy" <> a écrit dans le message de news:
...
> Could you not replace the caps.... should be easy enough do with a
> small 15 Watt soldering iron.
>
> If you should take this route use LOW ESR (Effective Series
> Resistance), or low impedance 105 deg. C types, do not use standard
> capacitors...!
>
> Obviously it's pointless if the capacitors have leaked and damaged the
> board, the gunge they spew 'could' eat away at the protective PCB
> lacquer then eat away the copper tracks.
>
> Davy
>

Sometimes the caps can look bad and the board will still work. I have two
8RDA+ systems. One began not booting up or having a hard time booting. It
usually would boot after several attempts. I replaced the bad caps and that
did cure it. The other 8RDA+ also has bad looking caps but continues to
function properly to this day. Maybe the power supply in this machine is of
better quality and gives better voltages so the bad caps aren't as big a
problem. So for this reason I can see why the caps and the power supply are
related. So the question is, did you really fix the problem with a new
power supply? Maybe. Then again you may only have bandaided it.

Replacing caps easy enough to do? No, not so easy. I have 22 years
experience in electronics soldering and I struggled. It could have been
easier if I had specialized tools. It's not a job for a novice.

As to the job requiring special low esr, high temp caps? Not so. I used
standard electrolytics of 85c temp and have absolutely no problems.

DaveL


"Leachim Sredna" <> wrote in message
news:45bc6d35$0$5086$...
> Actually, I've solved the spontaneous rebooting problem for the moment by
> changing the PSU, notwithstanding the dodgy-looking caps, thanx !
>
> "Davy" <> a écrit dans le message de news:
> ...
>> Could you not replace the caps.... should be easy enough do with a
>> small 15 Watt soldering iron.
>>
>> If you should take this route use LOW ESR (Effective Series
>> Resistance), or low impedance 105 deg. C types, do not use standard
>> capacitors...!
>>
>> Obviously it's pointless if the capacitors have leaked and damaged the
>> board, the gunge they spew 'could' eat away at the protective PCB
>> lacquer then eat away the copper tracks.
>>
>> Davy
>>
>
>

> [quote="dave"]
> As to the job requiring special low esr, high temp caps? Not so. I
used
> standard electrolytics of 85c temp and have absolutely no problems.
>

Don't think I'll be doing the same in a warm environment and where
high frequency ripple is concerned.

It's not a good idea to replace 105 deg. C caps with 85 deg.C types
but it does make sense to replace 85 deg.C
caps with 105 deg. C superior ones with better current ripple ratings
as you should know being in the trade and that caps can look ok n'
still can be bad. It's the ESR..... as
the ESR rises so does the internal heating... and if the vent can't
cope they pop or swell.

High ESR (effective series resistance) will also cause the capacitor
not to decouple the supply lines allowing HF ripple on them from the
clocking pulses and the switch-mode ripple frequency, hence the use of
hi-temp low impedance devices....

....and caps can be easily replaced by anyone with some soldering
ability and a little knowledge of mobo construction, the only tools
required are a small soldering iron and a pair of mini side cutters,
what specialized tools are they..?

> [quote="dave"] Replacing caps easy enough to do? No, not
so easy. I have 22 years
> experience in electronics soldering and I struggled. It could have
been
> easier if I had specialized tools. It's not a job for a novice.

[b:864825d93d][i:864825d93d]If I had been in the trade 22 years and
struggled to replace a capacitor.... I'd have given up or been fired a
long long time ago.. and that includes surface mounted capacitors,
which is not relevant here.. ![/i:864825d93d][/b:864825d93d]

Davy

"Davy" <> wrote in message
news:...
>> [quote="dave"]
>> As to the job requiring special low esr, high temp caps? Not so. I
> used
>> standard electrolytics of 85c temp and have absolutely no problems.
>>
>
> Don't think I'll be doing the same in a warm environment and where
> high frequency ripple is concerned.
>
> It's not a good idea to replace 105 deg. C caps with 85 deg.C types
> but it does make sense to replace 85 deg.C
> caps with 105 deg. C superior ones with better current ripple ratings
> as you should know being in the trade and that caps can look ok n'
> still can be bad. It's the ESR..... as
> the ESR rises so does the internal heating... and if the vent can't
> cope they pop or swell.
>
> High ESR (effective series resistance) will also cause the capacitor
> not to decouple the supply lines allowing HF ripple on them from the
> clocking pulses and the switch-mode ripple frequency, hence the use of
> hi-temp low impedance devices....
>
> ...and caps can be easily replaced by anyone with some soldering
> ability and a little knowledge of mobo construction, the only tools
> required are a small soldering iron and a pair of mini side cutters,
> what specialized tools are they..?
>
>> [quote="dave"] Replacing caps easy enough to do? No, not
> so easy. I have 22 years
>> experience in electronics soldering and I struggled. It could have
> been
>> easier if I had specialized tools. It's not a job for a novice.
>
> [b:864825d93d][i:864825d93d]If I had been in the trade 22 years and
> struggled to replace a capacitor.... I'd have given up or been fired a
> long long time ago.. and that includes surface mounted capacitors,
> which is not relevant here.. ![/i:864825d93d][/b:864825d93d]
>
> Davy
>

How many motherboards have you done with only a soldering iron and side
cutters? I don't think you know what you are talking about. You normally
would need something to remove the old solder. I have done this job with
basic capacitors and can report no lockups. On top of that, the system is
overclocked. My experience is cold hard fact. Nothing you can say can
dispute it.

DaveL

I think it is you who dosen't know what you are talking about and you
must be the only person what does such things...!

Why do all mobo manufacturers not use standard 85 deg. C caps, they
will sure save some cash, also why is it that you see 105 deg C low
ESR caps in mobos... to make them look pretty? Please explain.

It is clear if you are replacing these with standard types you are
doing a sub-standard repair.... wonder what the manufacturer would
think let alone your customers? It could be you are doing this so that
the mobo keeps coming back for repair.... instead of doing a quality
job.

It is plainly obvious that a 85deg C component ain't
gonna last as long as a 105 deg C type in a warm environment... you
also can't see the reason for using low ESR types.... I doubt you even
take their current ripple rating into consideration...

.... you have been in the trade 22 years and can not see this point.


Your gonna tell me you even use them in power supplies as well.. ?

Oh... and to remove solder from a plated through hole in a multilayer
board is easy.... [b:67d6a17884]and no [/b:67d6a17884]it's not trying
to force the component leads through the holes which can do damage,
you gotta clean the hole first and it ain't with a hot air tool, and
desoldering braid is useless.


Davy

I'm sorry, but all the hype is interesting read. I replaced all the caps on
"my" computer [8K7A with 85 degree C caps [which by the way if your board is
running over 185 degrees F., you got other problems] and have had no ill
effects. I replaced them several years ago, and the board's been fine... no
hiccups or BSOD.

--
Zyp
"dave" <nospam> wrote in message
news:_. ..
>
> "Davy" <> wrote in message
> news:...
> >> [quote="dave"]
> >> As to the job requiring special low esr, high temp caps? Not so. I
> > used
> >> standard electrolytics of 85c temp and have absolutely no problems.
> >>
> >
> > Don't think I'll be doing the same in a warm environment and where
> > high frequency ripple is concerned.
> >
> > It's not a good idea to replace 105 deg. C caps with 85 deg.C types
> > but it does make sense to replace 85 deg.C
> > caps with 105 deg. C superior ones with better current ripple ratings
> > as you should know being in the trade and that caps can look ok n'
> > still can be bad. It's the ESR..... as
> > the ESR rises so does the internal heating... and if the vent can't
> > cope they pop or swell.
> >
> > High ESR (effective series resistance) will also cause the capacitor
> > not to decouple the supply lines allowing HF ripple on them from the
> > clocking pulses and the switch-mode ripple frequency, hence the use of
> > hi-temp low impedance devices....
> >
> > ...and caps can be easily replaced by anyone with some soldering
> > ability and a little knowledge of mobo construction, the only tools
> > required are a small soldering iron and a pair of mini side cutters,
> > what specialized tools are they..?
> >
> >> [quote="dave"] Replacing caps easy enough to do? No, not
> > so easy. I have 22 years
> >> experience in electronics soldering and I struggled. It could have
> > been
> >> easier if I had specialized tools. It's not a job for a novice.
> >
> > [b:864825d93d][i:864825d93d]If I had been in the trade 22 years and
> > struggled to replace a capacitor.... I'd have given up or been fired a
> > long long time ago.. and that includes surface mounted capacitors,
> > which is not relevant here.. ![/i:864825d93d][/b:864825d93d]
> >
> > Davy
> >
>
> How many motherboards have you done with only a soldering iron and side
> cutters? I don't think you know what you are talking about. You normally
> would need something to remove the old solder. I have done this job with
> basic capacitors and can report no lockups. On top of that, the system
is
> overclocked. My experience is cold hard fact. Nothing you can say can
> dispute it.
>
> DaveL
>

It's not just the ambient, ever thought what effect the ripple current
has on a capacitor - especially if it's not low ESR.. ever wondered
what made them go in the first place?

They go even in a very cool environment not just computers and it
ain't the age.

So, it's ok then to swap a 105 deg. C hf type cap for a plain ol'
standard 85 deg C. - sorry, I don't think so.

Maybe you'll explain why they use them in the first place?

Davy

Davy,

Here is the REAL reason they went bad:

"The cause...
This inferior and flawed electrolyte formula was used by a number of
component manufacturers that sold to many different, reputable, and well
known motherboard manufacturers. This problem isn't isolated to one
particular brand of motherboard, and not even isolated to motherboards
alone. I won't mention brands, but a VERY popular monitor manufacturer has
been plagued with RMA's on some of their monitors that were built using
these inferior capacitors. This problem has been reported in computer
motherboards, monitors, televisions, radios, and stereo equipment. Through
my experiences owning a service center, I've personally seen and serviced a
large number of 'high-end' equipment that had prematurely failed
capacitors."

http://www.badcaps.net/causes/

Read the above web page. It explains the "large-scale industrial espionage
foul-up".

DaveL


"Davy" <> wrote in message
news:...
> It's not just the ambient, ever thought what effect the ripple current
> has on a capacitor - especially if it's not low ESR.. ever wondered
> what made them go in the first place?
>
> They go even in a very cool environment not just computers and it
> ain't the age.
>
> So, it's ok then to swap a 105 deg. C hf type cap for a plain ol'
> standard 85 deg C. - sorry, I don't think so.
>
> Maybe you'll explain why they use them in the first place?
>
> Davy
>