Interesting hardware problem

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Man-wai Chang

Motherboard: Asus CUBX
CPU: P3-700MHz

The board's PS/2 ports have died.

If I overclocked the CPU to 933MHz, BIOS reported 384M RAM.
If I didn't overclock, BIOS reported 512M RAM.

WHY?

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Man-wai Chang said:
Motherboard: Asus CUBX
CPU: P3-700MHz

The board's PS/2 ports have died.

If I overclocked the CPU to 933MHz, BIOS reported 384M RAM.
If I didn't overclock, BIOS reported 512M RAM.

WHY?
Click to expand...

When you overclock, the RAM runs at a faster speed on
many mobo's, and this can be faster than the memory
is designed to run, so it looks like you have one or more
sticks of RAM that run OK when overclocked and one
128MB stick that fails.
HTH
 
Man-wai Chang said:
Motherboard: Asus CUBX
CPU: P3-700MHz

The board's PS/2 ports have died.

If I overclocked the CPU to 933MHz, BIOS reported 384M RAM.
If I didn't overclock, BIOS reported 512M RAM.
Click to expand...

The possibilities:

RAM not fast enough
CPU not fast enough
CPU too hot
Power supply marginal
Voltage regulator for CPU marginal (worn electrolytic capacitors)
Voltage regulator for RAM marginal (worn electrolytic capacitors

Measure all voltages with a meter, including CPU voltage. The latter
may be difficult since the power transistors and diodes for its
regulator are right next to the CPU socket and possibly blocked by the
heatsink. If any electrolytic capacitors around the regulators are
bulging or leaking, replace all of them (not just the visibly defective
ones) in both of those circuits with a Japanese, American, or European
type made especially for high frequency switching applications (low
ESR). The 440BX is one of the best motherboard chipsets ever made,
and a board containing it is worth repairing if all you have to spend
is the cost of new capacitors and soldering and desoldering supplies.
 
Rob said:
When you overclock, the RAM runs at a faster speed on
many mobo's, and this can be faster than the memory
is designed to run, so it looks like you have one or more
sticks of RAM that run OK when overclocked and one
128MB stick that fails.
Click to expand...

Tell ya what: the *real* memory is 384M: 256+128 :)

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ESR). The 440BX is one of the best motherboard chipsets ever made,
and a board containing it is worth repairing if all you have to spend
is the cost of new capacitors and soldering and desoldering supplies.
Click to expand...

I sent my old Abit BP6 motherboard to a repair shop a week ago. It had
one or maybe more bulging capacitor. This morning, I phoned the shop.
The engineers said they could not repair it. I wonder if there could be
better engineers in Hong Kong. :)

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Man-wai Chang said:
I sent my old Abit BP6 motherboard to a repair shop a week ago. It had
one or maybe more bulging capacitor. This morning, I phoned the shop.
The engineers said they could not repair it. I wonder if there could be
better engineers in Hong Kong. :)

--
.~. Might, Courage, Vision, SINCERITY. http://www.linux-sxs.org
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
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^ ^ 21:48:01 up 6:12 0 users 1.10 1.12
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Click to expand...

First,stop posting in html.Second those caps can be replaced by just about
anyone with a steady hand and some guts.
 
First,stop posting in html.

No.. not me. :)
Second those caps can be replaced by just about
anyone with a steady hand and some guts.
Click to expand...

Removing the old capacitors may be difficult!


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/ v \ Simplicity is Beauty! May the Force and Farce be with you!
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Man-wai Chang said:
I sent my old Abit BP6 motherboard to a repair shop a week ago. It had
one or maybe more bulging capacitor. This morning, I phoned the shop.
The engineers said they could not repair it. I wonder if there could be
better engineers in Hong Kong. :)
Click to expand...

If it was working before you sent it to them, even working erratically,
then most likely they broke it because the most common defects are
capacitors and the transistors and diodes that drive them (when the
capacitors get very bad, those components have to work much harder).
 
Man-wai Chang wrote:
Removing the old capacitors may be difficult!
Click to expand...

You'll need a soldering iron with plenty of power since an underpowered
iron requires more time to melt the solder and is more likely to damage
the board. 50W is not unreasonable for a multilayer board. If you
don't have a desoldering iron (solder is sucked up through a hole in
the tip) with an _electric_ vacuum pump, the safest method of removal
is with a 45-50W iron and some narrow (2mm) copper desoldering braid.
The braid has to be cut off immediately after it absorbs solder, and
the leads have to be wiggled side-to-side to crack any remaining traces
of solder before the component is pulled out. An even safer way to
remove a capacitor is by cutting it off from the top so that each of
its leads can be removed individually. This allows safe removal even
without desoldering braid, if you're careful. Always first practice on
a junked circuit board having at least 4 layers of copper since boards
with just 1 or 2 layers aren't realistic practice.

I don't know how good computer techs are in your area, but in the U.S.
they rarely know how to do real repairs and instead just replace entire
circuit boards.
 
I don't know how good computer techs are in your area, but in the U.S.
they rarely know how to do real repairs and instead just replace entire
circuit boards.
Click to expand...

I have gotten the BP6 back. Maybe I would keep it till someone good in
EE crossed my path... and resurrect it. :)

--
.~. Might, Courage, Vision, SINCERITY. http://www.linux-sxs.org
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
/( _ )\ (Ubuntu 5.10) Linux 2.6.16.14
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No, you are confused. Computer techs aren't ALLOWED to do real repairs in
the U.S. There's a huge difference there. Let's face it, nobody's going to
pay you big bucks to repair a circuit card that's worth less than you earn
in a half hour. For the U.S. employer, it is a sound financial decision to
insist that your tech find the defective card and REPLACE it.

Now I've met many computer techs in the U.S. who weren't even qualified to
swap cards. But to paint them all with a broad brush and state that they
are incapable of doing real repairs is not quite accurate. Many computer
techs in the U.S. are capable of doing real repairs, but aren't allowed to
do so, by their employers.

I can imagine the situation would be quite different in countries where
computer techs are paid very low wages. If you are earning less in (for
example) 3-4 hours than what a particular 'card' costs, then the employer
would come out ahead by having the tech spend an hour repairing that
ard. -Dave
 
No, you are confused. Computer techs aren't ALLOWED to do real repairs in
the U.S. There's a huge difference there. Let's face it, nobody's going to
pay you big bucks to repair a circuit card that's worth less than you earn
in a half hour. For the U.S. employer, it is a sound financial decision to
insist that your tech find the defective card and REPLACE it.
Click to expand...

I'm basing my opinion not only on what computer shops have told me but
also on experiences with job applicants who claimed to be computer
techs. Among the latter, almost all had poor hardware troubleshooting
and repair skills on PCs and non-PC systems (the vast majority of our
non-office equipment).
 
Man-wai Chang wrote:


You'll need a soldering iron with plenty of power since an underpowered
iron requires more time to melt the solder and is more likely to damage
the board. 50W is not unreasonable for a multilayer board. If you
don't have a desoldering iron (solder is sucked up through a hole in
the tip) with an _electric_ vacuum pump, the safest method of removal
is with a 45-50W iron and some narrow (2mm) copper desoldering braid.
The braid has to be cut off immediately after it absorbs solder, and
the leads have to be wiggled side-to-side to crack any remaining traces
of solder before the component is pulled out. An even safer way to
remove a capacitor is by cutting it off from the top so that each of
its leads can be removed individually.
Click to expand...

don't remove the leads solder the new leads to the stubs left
over....shoddy? yep but the odds of anybody, outside of a lab, getting the
job done on all layers....is not in their favor...better to try grabbing the
old, already finished lead.

This allows safe removal even
 
I'm basing my opinion not only on what computer shops have told me but
also on experiences with job applicants who claimed to be computer
techs. Among the latter, almost all had poor hardware troubleshooting
and repair skills on PCs and non-PC systems (the vast majority of our
non-office equipment).
Click to expand...

Well I know in our company, the computer techs we hire...
- have some kind of formal education in electronics (not trade school)
- have at least a couple of years of professional electronics repair
experience (not necessarily related to the IT field)
- have documentable computer skills, related to hardware, common
operating systems, common business applications and basic networking.
Sometimes we'll let them slide (with good references!) if they are
certs-only, as there is a probation period after hiring (If they are paper
tigers, they CAN NOT survive the probation period. Our computer techs work
in the field, alone, with limited to NO support. In that kind of sink or
swim scenario, paper tigers SINK.)
- It's also a huge plus if they have field service experience. But again,
we can bend on this for someone with good references.

If your resume' doesn't reflect all of that above, I won't interview you.

I have seen many job applicants (just like you) from people who claim to be
computer techs and couldn't troubleshoot even the most basic of computer
hardware problems. But now when I'm hiring I take a different approach to
it. In hiring computer techs, I ask for resume's from electronics
technicians (I don't advertise it as a computer tech opening). A good
percentage of resume's I get reflect skills that would qualify them to work
for us as computer techs (including documentable computer skills).

So it's in the way you approach it. Ask for computer techs, get high school
graduates who barely know how to hit the reset button. As for electronics
technicians, and get relatively skilled computer techs. :) Almost without
exception, all applicants have been pleasantly surprised to learn the real
nature of the job (those who qualify to be interviewed obviously need to
know what they are interviewing FOR), so I don't see it as too terribly
deceptive . . . or if so, not harmfully so.

The ironic thing is, the job REQUIRES electronics technicians, people who
can do "real repairs" as someone else wrote. But the vast majority of the
time, you end up just swapping cards, as you don't have time to be screwing
around with a soldering iron out in the field. And if you did, the card you
are repairing isn't worth the money I'm paying you to repair it. :) (so
just replace the damn thing and be done with it already) -Dave
 
Mike T. said:
Well I know in our company, the computer techs we hire...
- have some kind of formal education in electronics (not trade school)
- have at least a couple of years of professional electronics repair
experience (not necessarily related to the IT field)
- have documentable computer skills, related to hardware, common
operating systems, common business applications and basic networking.
Sometimes we'll let them slide (with good references!) if they are
certs-only, as there is a probation period after hiring (If they are paper
tigers, they CAN NOT survive the probation period. Our computer techs work
in the field, alone, with limited to NO support. In that kind of sink or
swim scenario, paper tigers SINK.)
- It's also a huge plus if they have field service experience. But again,
we can bend on this for someone with good references.

If your resume' doesn't reflect all of that above, I won't interview you.

I have seen many job applicants (just like you) from people who claim to be
computer techs and couldn't troubleshoot even the most basic of computer
hardware problems. But now when I'm hiring I take a different approach to
it. In hiring computer techs, I ask for resume's from electronics
technicians (I don't advertise it as a computer tech opening). A good
percentage of resume's I get reflect skills that would qualify them to work
for us as computer techs (including documentable computer skills).

So it's in the way you approach it. Ask for computer techs, get high school
graduates who barely know how to hit the reset button. As for electronics
technicians, and get relatively skilled computer techs. :) Almost without
exception, all applicants have been pleasantly surprised to learn the real
nature of the job (those who qualify to be interviewed obviously need to
know what they are interviewing FOR), so I don't see it as too terribly
deceptive . . . or if so, not harmfully so.

The ironic thing is, the job REQUIRES electronics technicians, people who
can do "real repairs" as someone else wrote. But the vast majority of the
time, you end up just swapping cards, as you don't have time to be screwing
around with a soldering iron out in the field. And if you did, the card you
are repairing isn't worth the money I'm paying you to repair it. :) (so
just replace the damn thing and be done with it already) -Dave
Click to expand...

exactly..... 90% of the time its a warranty issue on a fairly new part that
the techs are going to be dealing with. This requires you to do nothing but
pull the card and send it back. I'm retired now but at the time, without a
single piece of sheepskin that referred to electronics, but a degree in
computer science, I ran circles around the certified whatevers. In fours
years I was running the IT dept. at AB DICK in the Chicago area.(yeah yeah I
heard them all). Most of the problems back then were 'cabling ' related, or
network interface problems. Rarely were we tearing down copiers or printers
or servers at the PCB level.. UNLESS !!! it was a MacGyver moment and
someone wanted to play hero, cause the secretarial pool just hired a babe.
(NOTE the historical references). I think its even easier now and IT techs
should just do it for free as a hobby. ;^)
 
exactly..... 90% of the time its a warranty issue on a fairly new part
that
the techs are going to be dealing with. This requires you to do nothing
but
pull the card and send it back. I'm retired now but at the time, without a
single piece of sheepskin that referred to electronics, but a degree in
computer science, I ran circles around the certified whatevers.
Click to expand...

That doesn't surprise me. In my experience, there are people who are
certified in something or other, and there are people who are actually
proficient in that same something or other. Rarely do you find a single
person who is both certified and proficient. They DO exist, but they are
kind of an oddity. :)

I think it boils down to, the people who want to do something get the
certifications to try to prove that they can do it. (but in actuality, it
just makes THEMSELVES feel better) Meanwhile, the people who are actually
doing it (WELL!) don't need the certifications to prove that they are
proficient. (everybody they work with already KNOWS, and they can use the
references to get the next job, if necessary)
In fours
years I was running the IT dept. at AB DICK in the Chicago area.(yeah yeah
I
heard them all). Most of the problems back then were 'cabling ' related,
or
network interface problems. Rarely were we tearing down copiers or
printers
or servers at the PCB level.. UNLESS !!! it was a MacGyver moment and
someone wanted to play hero, cause the secretarial pool just hired a babe.
(NOTE the historical references). I think its even easier now and IT techs
should just do it for free as a hobby. ;^)
Click to expand...

Yeah, IT techs sure do have an easy job, if they know what they are doing.
I try not to do any IT type work OUTSIDE of work. Unfortunately, it's like
a doctor . . . everyone you meet has a computer problem that they want your
opinion on. That is so fricking annoying. I love computers, I service them
for a living. It's not my LIFE, though. In my free time, I often don't
want to even think about them. -Dave
 
No, you are confused. Computer techs aren't ALLOWED to do real repairs
in the U.S. There's a huge difference there. Let's face it, nobody's going
to pay you big bucks to repair a circuit card that's worth less than you
earn in a half hour. For the U.S. employer, it is a sound financial decision
to insist that your tech find the defective card and REPLACE it.
Click to expand...
Well I know in our company, the computer techs we hire...
- have some kind of formal education in electronics (not trade school)
- have at least a couple of years of professional electronics repair
experience (not necessarily related to the IT field)
- have documentable computer skills, related to hardware, common
operating systems, common business applications and basic networking.
Sometimes we'll let them slide (with good references!) if they are
certs-only, as there is a probation period after hiring (If they are paper
tigers, they CAN NOT survive the probation period. Our computer techs work
in the field, alone, with limited to NO support. In that kind of sink or
swim scenario, paper tigers SINK.)
- It's also a huge plus if they have field service experience. But again,
we can bend on this for someone with good references.

If your resume' doesn't reflect all of that above, I won't interview you.
Click to expand...

Your company seems better than at least 90% of those in the business.

Most of our equipment is non-PC, often located far away or in tight
nooks or crannies, some of it is almost one of a kind, and their boards
often can't be swapped since they're too expensive or unavailable
(replacements may even contain the same design bugs). So we tend to
hire people who are more electronics than computer oriented, and we've
had the best luck with those from the military, industrial companies,
and telco.
I have seen many job applicants (just like you) from people who claim to be
computer techs
Click to expand...

Er, I've never claimed to be a computer tech.
 
The ironic thing is, the job REQUIRES electronics technicians, people who
can do "real repairs" as someone else wrote. But the vast majority of the
time, you end up just swapping cards, as you don't have time to be screwing
around with a soldering iron out in the field. And if you did, the card you
are repairing isn't worth the money I'm paying you to repair it. :) (so
just replace the damn thing and be done with it already) -Dave
Click to expand...

I don't have a electronic engineering qualification, but I learnt
soldering simple things in my summer jobs. With that, I soldered a
serial printer cable to connect an old Prime hi-speed printer to a
Netware 3.x server. It's a simple task actually, esp for EE.

While it's true most companies couldn't afford their employees to
troubleshoot PCBs, there should be companies specified in this task. I
don't know why everyone just dumped circuit boards without giving them a
chance to get repaired... It could have been a lot less to the
environment. Most boards and equipemnts are environmental hazards.


--
.~. Might, Courage, Vision, SINCERITY. http://www.linux-sxs.org
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
/( _ )\ (Ubuntu 5.10) Linux 2.6.16.16
^ ^ 14:47:01 up 23:14 0 users load average: 1.00 1.19 1.19
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And if they are to dump those damaged PCBs, why not throw them into the
magma in those active volcanoes? That should save a lot of fuel and
artificial incenerators... :)

--
.~. Might, Courage, Vision, SINCERITY. http://www.linux-sxs.org
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
/( _ )\ (Ubuntu 5.10) Linux 2.6.16.16
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