I'm trying to repair an old model Gateway GT5056 Windows XP system. The
symptom is that intermittently it will just freeze up in its tracks or a
BSOD will appear. One of the types of BSOD says, "Machine_Check_Exception."
The other says, "Kernel_Stack_Inpage_Error." I tried updating drivers and
software, removing the DVD burner, and just using the bare minimum of
hardware, but it still was freezing up. Usually, it will happen when
watching a video. On other days, it would happen as soon as the computer
booted to the desktop. Then on some days, it wouldn't freeze-up at all.

Just to make sure the hardware was ok, I ran a RAM test which passed. I
cleaned out the CPU fan and heat sink. Then I visually inspected the
motherboard. Hmmmm. I saw about a half dozen 1,000uF 6.3V capacitors that
were bulging. In fact every capacitor of that particular value was bulging.
I checked ESR and only one was out of tolerance. It measured 6 ohms while
the others were less than 0.2 ohms. I replaced the one that was out of
tolerance thinking I'd go back and do the rest of them if it corrected the
problem but it didn't. It still freezes occasionally.

There was one particular occurrence where right before the system froze, the
CPU fan switched to a very high speed so maybe it is heat related. By the
way, the motherboard is a Foxconn C51GU01.

Thanks for your reply.
--
David Farber
Los Osos, CA

On 17.04.14 0:53, David Farber wrote:
I'm trying to repair an old model Gateway GT5056 Windows XP system. The
symptom is that intermittently it will just freeze up in its tracks or a
BSOD will appear. One of the types of BSOD says, "Machine_Check_Exception."
The other says, "Kernel_Stack_Inpage_Error." I tried updating drivers and
software, removing the DVD burner, and just using the bare minimum of
hardware, but it still was freezing up. Usually, it will happen when
watching a video. On other days, it would happen as soon as the computer
booted to the desktop. Then on some days, it wouldn't freeze-up at all.

Just to make sure the hardware was ok, I ran a RAM test which passed. I
cleaned out the CPU fan and heat sink. Then I visually inspected the
motherboard. Hmmmm. I saw about a half dozen 1,000uF 6.3V capacitors that
were bulging. In fact every capacitor of that particular value was bulging.
I checked ESR and only one was out of tolerance. It measured 6 ohms while
the others were less than 0.2 ohms. I replaced the one that was out of
tolerance thinking I'd go back and do the rest of them if it corrected the
problem but it didn't. It still freezes occasionally.

There was one particular occurrence where right before the system froze, the
CPU fan switched to a very high speed so maybe it is heat related. By the
way, the motherboard is a Foxconn C51GU01.

Thanks for your reply.

Get a second hand pc. I get them offered for free,
the last one a HP 3GHZ 2GB dual core xp pro computer.
I removed all the bloatware and personal data,
and it works like a treat.
People have been scared out of their wits by the
"end of life" commotion.
Then transfer step by step special hardware/software
from the broken one(if any).

An btw, try a number of memtest programs, I had one
computer failing only with one out of four test floppys.
And let those run for several hours, with closed case,
else the temperature will not match with usual use.

If you HAVE to use the old board, replace ALL bulging
caps, they are broken, even if they seem to work.

Replace some of the ones that read 0.2. They are probably a bank of caps. The common thing is to use a bunch of them in parallel. You can confirm this by meter. Of course all the negatives will read continuity, but in a bank of caps, both leads will read continuity.

If you have a bank of five caps, 0.2 ohms ESR is too high and that's one of the reasons they used so many. Another is ripple current.

When you have this, you can just replace a couple in a bank to see if it cures the problem. In fact when it gets to that point I don't even clip the leads off, I just let the replacement(s) stand up off the board. If the problem is fixed, then I sink them down and snip them, and of course replace the rest.

The one you replaced was obviously by itself. The others are probably a bank of five and they are probably off the output of a switching regulator. They might be running at like 2 volts and anywhere from 2 to 20 amps depending on processor load. The math says 0.2 ohms is way too high. Say it's 3 volts at 10 amps. That's like a 0.33 ohm load approzimately. That could make the ripple voltage almost half of the supply concievably. Coming off a high speed switching regulator, that is quite noisy and the data will be FUBAR. Temperature will also affct it.

If you find those five caps are just all in parallel, the ESR should be practically imeasurable.

If it doesn't work, that's why you didn't cut the leads on the replacements..

wrote in message
...
Replace some of the ones that read 0.2. They are probably a bank of caps.
The common thing is to use a bunch of them in parallel. You can confirm this
by meter. Of course all the negatives will read continuity, but in a bank
of caps, both leads will read continuity.

If you have a bank of five caps, 0.2 ohms ESR is too high and that's one of
the reasons they used so many. Another is ripple current.

When you have this, you can just replace a couple in a bank to see if it
cures the problem. In fact when it gets to that point I don't even clip the
leads off, I just let the replacement(s) stand up off the board. If the
problem is fixed, then I sink them down and snip them, and of course replace
the rest.

The one you replaced was obviously by itself. The others are probably a bank
of five and they are probably off the output of a switching regulator. They
might be running at like 2 volts and anywhere from 2 to 20 amps depending on
processor load. The math says 0.2 ohms is way too high. Say it's 3 volts at
10 amps. That's like a 0.33 ohm load approzimately. That could make the
ripple voltage almost half of the supply concievably. Coming off a high
speed switching regulator, that is quite noisy and the data will be FUBAR.
Temperature will also affct it.

If you find those five caps are just all in parallel, the ESR should be
practically imeasurable.

If it doesn't work, that's why you didn't cut the leads on the replacements.

Hi,

I'll have another look at how the caps are wired. Some are located close to
each other but at first glance you wouldn't think they would be in parallel.
I'll report back my findings.

Thanks for your reply.
--
David Farber
Los Osos, CA

www.badcaps.com

David Farber wrote:

I'm trying to repair an old model Gateway GT5056 Windows XP system.

Hmmmm. I saw about a half dozen 1,000uF 6.3V capacitors that
were bulging.

I repaired a roomfull of Dell computers at work that all had the capacitor
plague. There are some caps in a switching supply right at the CPU
chip that suffer very high AC ripple that cooks them. I replaced all
the caps in that bank (identified by the bulges or leaks) and they
all worked fine. I did another system where a graphics board
had the same problem.

Jon

The real problem is when the ripple and noise causes data errors. It can FUBAR a harddrive or the BIOS. If it access the wrong address it can be as bad as a power outage during a BIOS flash. I have a Dell I think board like tha there that is destined for the trash actually.

In some motherboard manuals I remember they called it "system will hang permanently" which is about the equivalent of bricked.

Motherboard caps (switch mode converters) and the power supply caps have to be as close to perfect as possible. You want the highest ripple current with the longest life. Price is secondary and 'good enough' never is. I don't even bother with ESR measurements. Just replace them. A problem is the new boards have polymer caps rather than 'lytics so the large variety of 'lytics are no longer carried my Mouser. DigiKey was not as complete as Mouser but is OK. On the good side we won't need to be replacing nearly as many caps in the future.

The latest motherboard I did was an IBM that had a solid plane (no thermal reliefs) on the top AND bottom of the board. My Metcal had enough heat but the little wire through the board couldn't conduct the heat fast enough. I ended up with the soldering iron in one hand and a hot air gun in the other.. The holes ended up very clean and it runs like new again.

G²

wrote:


The latest motherboard I did was an IBM that had a solid plane (no thermal
reliefs) on the top AND bottom of the board. My Metcal had enough heat but
the little wire through the board couldn't conduct the heat fast enough. I
ended up with the soldering iron in one hand and a hot air gun in the
other. The holes ended up very clean and it runs like new again.
Yes, this is a problem. I used a Weller WMP which is a 65 W mini-pencil
iron, and with the most massive tip available for it. First,
dilute the no-lead solder with SnPb solder to lower the melting
point of the solder. Then I heated each
capacitor lead for 10 seconds or so and then levered the cap which
pulled the pin back through the board a bit. Then go to the other pin
and do the same. After one cycle of that, the cap is far enough off the
board you can pull one lead fully out of the board, then the other.
Then, I used the 65 W iron on one side and a Pace desildering tool
on the other side at the same time, and it pulled the solder out of
the hole. Resoldering the new caps was a breeze compared to the
extraction part.

Jon

"David Farber" wrote in message
...

wrote in message
...
Replace some of the ones that read 0.2. They are probably a bank of caps.
The common thing is to use a bunch of them in parallel. You can confirm
this by meter. Of course all the negatives will read continuity, but in a
bank of caps, both leads will read continuity.

If you have a bank of five caps, 0.2 ohms ESR is too high and that's one
of the reasons they used so many. Another is ripple current.

When you have this, you can just replace a couple in a bank to see if it
cures the problem. In fact when it gets to that point I don't even clip
the leads off, I just let the replacement(s) stand up off the board. If
the problem is fixed, then I sink them down and snip them, and of course
replace the rest.

The one you replaced was obviously by itself. The others are probably a
bank of five and they are probably off the output of a switching
regulator. They might be running at like 2 volts and anywhere from 2 to 20
amps depending on processor load. The math says 0.2 ohms is way too high.
Say it's 3 volts at 10 amps. That's like a 0.33 ohm load approzimately.
That could make the ripple voltage almost half of the supply concievably.
Coming off a high speed switching regulator, that is quite noisy and the
data will be FUBAR. Temperature will also affct it.

If you find those five caps are just all in parallel, the ESR should be
practically imeasurable.

If it doesn't work, that's why you didn't cut the leads on the
replacements.

Hi,

I'll have another look at how the caps are wired. Some are located close
to each other but at first glance you wouldn't think they would be in
parallel. I'll report back my findings.

Thanks for your reply.
--
David Farber
Los Osos, CA


I had to use my Weller 100/140 watt gun to generate enough heat to get the
capacitors out. Even with flux and SnPb solder it was a chore. The results
were, one was 1.3 ohms and the remaining four measured from 4.7 to 5.0 ohms.
I will order the replacements and report back.

Thanks for your reply.
--
David Farber
Los Osos, CA

David Farber wrote:




I had to use my Weller 100/140 watt gun to generate enough heat to get the
capacitors out. Even with flux and SnPb solder it was a chore. The results
were, one was 1.3 ohms and the remaining four measured from 4.7 to 5.0
ohms. I will order the replacements and report back.
Yup, highly likely replacing them will fix the computer.
Be sure to get high-temp, low ESR caps for the replacement.
A lot of pwople are selling totally pedestrian caps as
low-ESR on eBay and such, but they are actually junk,
and not suitable. If the machine works with them, it won't
last long. The proper units are available from Digi-Key
for under $2 each. You just have to scan for the low ESR
rating.

Jon

En el artículo , David Farber
escribió:

Just to make sure the hardware was ok, I ran a RAM test which passed. I
cleaned out the CPU fan and heat sink. Then I visually inspected the
motherboard. Hmmmm. I saw about a half dozen 1,000uF 6.3V capacitors that
were bulging. In fact every capacitor of that particular value was bulging.
I checked ESR and only one was out of tolerance. It measured 6 ohms while
the others were less than 0.2 ohms. I replaced the one that was out of
tolerance thinking I'd go back and do the rest of them

Go back and do the rest. Make sure you use top quality 105 degC
replacements. Panasonic are good.

--
(\_/)
(='.'=)
(")_(")

On Saturday, April 19, 2014 9:18:06 PM UTC-7, Mike Tomlinson wrote:
snip
Go back and do the rest. Make sure you use top quality 105 degC

replacements. Panasonic are good.

snip

Panasonic has caps that are good but also has ones that are useless for motherboards. We bought a used VTR that had all the caps replaced. The tech used Panasonic NHG. These are rated for 105C but the ripple current is less than 1/3 of the FM/FR series.

The thing that really got me was the Digikey price. The lousy caps were $80/1000 while the excellent caps were only $85/1000. Why would anybody buy the junk for repairs? Someone asked me about prices of the caps and is it important. I told them that on a good day I might use $20 in caps which is a small fraction of what I'm paid. If I'm worth it so are the caps.

G²

On 4/17/2014 10:58 AM, Jim Haynes wrote:
www.badcaps.com


I bought caps from the above a couple years ago.
Very happy customer.
Mikek

"Jon Elson" wrote in message
...
David Farber wrote:




I had to use my Weller 100/140 watt gun to generate enough heat to get
the
capacitors out. Even with flux and SnPb solder it was a chore. The
results
were, one was 1.3 ohms and the remaining four measured from 4.7 to 5.0
ohms. I will order the replacements and report back.
Yup, highly likely replacing them will fix the computer.
Be sure to get high-temp, low ESR caps for the replacement.
A lot of pwople are selling totally pedestrian caps as
low-ESR on eBay and such, but they are actually junk,
and not suitable. If the machine works with them, it won't
last long. The proper units are available from Digi-Key
for under $2 each. You just have to scan for the low ESR
rating.

Jon

Hi Jon,

I ordered from Digi-Key. Their part number is, 493-1467-ND.

The caps are rated at 6,000 hours, @ 105 degrees. Ripple current is 840 mA.
The impedance is 87 mOhm.

There were other choices with lower impedances but they were rated at
shorter lifetimes.

Thanks for your reply.
--
David Farber
Los Osos, CA

amdx wrote:
On 4/17/2014 10:58 AM, Jim Haynes wrote:
www.badcaps.com


I bought caps from the above a couple years ago.
Very happy customer.
Mikek

How do they compare to Digikey on price and shipping?

"David Farber" wrote in message
...
"Jon Elson" wrote in message
...
David Farber wrote:




I had to use my Weller 100/140 watt gun to generate enough heat to get
the
capacitors out. Even with flux and SnPb solder it was a chore. The
results
were, one was 1.3 ohms and the remaining four measured from 4.7 to 5.0
ohms. I will order the replacements and report back.
Yup, highly likely replacing them will fix the computer.
Be sure to get high-temp, low ESR caps for the replacement.
A lot of pwople are selling totally pedestrian caps as
low-ESR on eBay and such, but they are actually junk,
and not suitable. If the machine works with them, it won't
last long. The proper units are available from Digi-Key
for under $2 each. You just have to scan for the low ESR
rating.

Jon

Hi Jon,

I ordered from Digi-Key. Their part number is, 493-1467-ND.

The caps are rated at 6,000 hours, @ 105 degrees. Ripple current is 840
mA. The impedance is 87 mOhm.

There were other choices with lower impedances but they were rated at
shorter lifetimes.

Thanks for your reply.
--
David Farber
Los Osos, CA


It was a good thing I ordered ten of these caps because after I replaced the
first half-dozen, I found another four that were slightly bulging. The ESR's
of these caps varied from 1.5 to 4.5 ohms. When I put the new ones in, the
in-circuit ESR's were nearly undetectable.

The results of all this were that the freezing up and blue screens never
reoccurred.

Thanks for all your great replies.
--
David Farber
Los Osos, CA

amdx wrote:

On 4/17/2014 10:58 AM, Jim Haynes wrote:
www.badcaps.com


I bought caps from the above a couple years ago.
Very happy customer.
Mikek


I've bought from he

http://www.thecapking.com/whatwestock.html


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com