Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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  #1   Report Post  
jbr
 
Posts: n/a
Default Power supplies are burning out

I'm looking for ideas on what might be burning out power supplies in a
computer.

I have a computer that is on its 3rd ATX power supply in a short
period of time. In determining if the power supplies were bad I am
using a tester. Each time the tester has shown the power supply to be
bad so I replaced it and the system would work again. The latest
power supply lasted only a few days before failing.

The system is plugged into a surge protector along with other
equipment. No problems with the other equipment so I have doubts a
power surge is the culprit.

Thanks for any suggestions.

jbr
  #2   Report Post  
James Sweet
 
Posts: n/a
Default Power supplies are burning out


"jbr" wrote in message
m...
I'm looking for ideas on what might be burning out power supplies in a
computer.

I have a computer that is on its 3rd ATX power supply in a short
period of time. In determining if the power supplies were bad I am
using a tester. Each time the tester has shown the power supply to be
bad so I replaced it and the system would work again. The latest
power supply lasted only a few days before failing.

The system is plugged into a surge protector along with other
equipment. No problems with the other equipment so I have doubts a
power surge is the culprit.

Thanks for any suggestions.

jbr


What brand and model power supplies are you using? Some of them are just
garbage and not worth buying.


  #3   Report Post  
Jerry G.
 
Posts: n/a
Default Power supplies are burning out

Check to see the brand and model of supply. Some are not so good. Also
check to see if you are exceeding the rating. Maybe you need a 400 or 450
Watt supply???

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"jbr" wrote in message
m...
I'm looking for ideas on what might be burning out power supplies in a
computer.

I have a computer that is on its 3rd ATX power supply in a short
period of time. In determining if the power supplies were bad I am
using a tester. Each time the tester has shown the power supply to be
bad so I replaced it and the system would work again. The latest
power supply lasted only a few days before failing.

The system is plugged into a surge protector along with other
equipment. No problems with the other equipment so I have doubts a
power surge is the culprit.

Thanks for any suggestions.

jbr


  #5   Report Post  
JURB6006
 
Posts: n/a
Default Power supplies are burning out

That a P4 or Athlon XP ? If so get a good 400-450 watt PS, also the same if
you're a SCSI dude with more than two harddrives.

I assume you've made sure the thing gets adequate airflow

JURB


  #6   Report Post  
jbr
 
Posts: n/a
Default Power supplies are burning out

No 2 power supplies were the same. Here are the specifics of the ones
I used.

1st supply: L&C Technology Inc. LC-250ATX; believed to be original 2.5
years

2nd supply: No name wholesale (historically their parts are reliable)
- 350 Watt; lasted 6 days

3rd supply: QMAX LC-B300ATX; lasted 5 seconds but had been running for
2 weeks in a different machine.

FYI - The +5vsb light on my ATX power supply tester still lights when
hooked up to all three power supplies.

"Jerry G." wrote in message ...
Check to see the brand and model of supply. Some are not so good. Also
check to see if you are exceeding the rating. Maybe you need a 400 or 450
Watt supply???

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"jbr" wrote in message
m...
I'm looking for ideas on what might be burning out power supplies in a
computer.

I have a computer that is on its 3rd ATX power supply in a short
period of time. In determining if the power supplies were bad I am
using a tester. Each time the tester has shown the power supply to be
bad so I replaced it and the system would work again. The latest
power supply lasted only a few days before failing.

The system is plugged into a surge protector along with other
equipment. No problems with the other equipment so I have doubts a
power surge is the culprit.

Thanks for any suggestions.

jbr

  #7   Report Post  
James Sweet
 
Posts: n/a
Default Power supplies are burning out


"jbr" wrote in message
m...
No 2 power supplies were the same. Here are the specifics of the ones
I used.

1st supply: L&C Technology Inc. LC-250ATX; believed to be original 2.5
years

2nd supply: No name wholesale (historically their parts are reliable)
- 350 Watt; lasted 6 days

3rd supply: QMAX LC-B300ATX; lasted 5 seconds but had been running for
2 weeks in a different machine.

FYI - The +5vsb light on my ATX power supply tester still lights when
hooked up to all three power supplies.



That's really weird, I thought almost all supplies had thermal shutdown.


  #8   Report Post  
techforce
 
Posts: n/a
Default Power supplies are burning out

They have Overload Protection on the DC side to protect it against a Short
on a DC line.


Sounds like his AC power is Dirty on that outlet. Have seen alot of weird
stuff happen to PC Power Supplies when the Freq and voltage fluxuates on the
Input - say because of a Downed arcing power line somewhere. Smaller Cities
and remote villages dont have exorbidant Power Protection for their electric
power sources, basicly du to lack of funding....so this is becoming more
common since power Demand is greater then ever before - WORLDWIDE , because
of the Number of PC's and people using Electricity etc.

A Power Surge protector "MAY" help, but theres always the possibility
something may happen where it was not designed to see. A UPS wil definately
solve the problem, but the dirty power will probably take out the UPS sooner
or later....


"James Sweet" wrote in message
news:[email protected]_s54...

"jbr" wrote in message
m...
No 2 power supplies were the same. Here are the specifics of the ones
I used.

1st supply: L&C Technology Inc. LC-250ATX; believed to be original 2.5
years

2nd supply: No name wholesale (historically their parts are reliable)
- 350 Watt; lasted 6 days

3rd supply: QMAX LC-B300ATX; lasted 5 seconds but had been running for
2 weeks in a different machine.

FYI - The +5vsb light on my ATX power supply tester still lights when
hooked up to all three power supplies.



That's really weird, I thought almost all supplies had thermal shutdown.




  #9   Report Post  
John Keiser
 
Posts: n/a
Default Power supplies are burning out

I'm in Hawaii where power can be dirty. Lost a few power supplies until I
went to a UPS [make sure you get one that includes a "line conditioner" and
not just total outage]. No more problems.

--
Remove -NOSPAM- to contact me.


  #10   Report Post  
Steve(JazzHunter)
 
Posts: n/a
Default Power supplies are burning out

On Wed, 21 Jan 2004 04:23:30 GMT, "techforce"
wrote:


Didn't anyone read my post about the keyboard being enabled for power
on/off? I'm saying, - I had three systems that burned out more than
one power supply, and each time the cause was due to the constant draw
of power for the keyboard. The problem was solved by changing the
jumper on the MB to disable this function. A special power supply is
needed to avoid having problems if keyboard power is enabled.

The first supply was probably designed for the unit, subsequent
supplies probably had inadequate 12v standby current.

Make certain that keyboard switching is disabled in both the BIOS and
via jumper. If necessary consult the manual for the MB.

I've repaired and built hunderds of computers, and this has been the
only situation I've ever encountered which caused multiple power
supply failures. While dirty AC is a worry, it's more likely to cause
damage to the MB than to the power supply.

.Steve .

They have Overload Protection on the DC side to protect it against a Short
on a DC line.


Sounds like his AC power is Dirty on that outlet. Have seen alot of weird
stuff happen to PC Power Supplies when the Freq and voltage fluxuates on the
Input - say because of a Downed arcing power line somewhere. Smaller Cities
and remote villages dont have exorbidant Power Protection for their electric
power sources, basicly du to lack of funding....so this is becoming more
common since power Demand is greater then ever before - WORLDWIDE , because
of the Number of PC's and people using Electricity etc.

A Power Surge protector "MAY" help, but theres always the possibility
something may happen where it was not designed to see. A UPS wil definately
solve the problem, but the dirty power will probably take out the UPS sooner
or later....


"James Sweet" wrote in message
news:[email protected]_s54...

"jbr" wrote in message
m...
No 2 power supplies were the same. Here are the specifics of the ones
I used.

1st supply: L&C Technology Inc. LC-250ATX; believed to be original 2.5
years

2nd supply: No name wholesale (historically their parts are reliable)
- 350 Watt; lasted 6 days

3rd supply: QMAX LC-B300ATX; lasted 5 seconds but had been running for
2 weeks in a different machine.

FYI - The +5vsb light on my ATX power supply tester still lights when
hooked up to all three power supplies.



That's really weird, I thought almost all supplies had thermal shutdown.






  #11   Report Post  
LASERandDVDfan
 
Posts: n/a
Default Power supplies are burning out

I've repaired and built hunderds of computers, and this has been the
only situation I've ever encountered which caused multiple power
supply failures. While dirty AC is a worry, it's more likely to cause
damage to the MB than to the power supply.


Or, better yet, use better power supplies. Preferrably stuff from "PC Power
and Cooling," Enermax, or Antec. More expensive, but they're built to work and
built to last.

Another thing you can do is check out the weight of a power supply. This isn't
always an indicator of quality, but a heavier supply is bound to be more robust
than a supply of equal wattage but of significantly less weight. - Reinhart
  #12   Report Post  
techforce
 
Posts: n/a
Default Power supplies are burning out

Apparently, you have not been inside a PC Power Supply and worked on them,
else you would know this is quite the opposite unless the AC protection in
the design of the PS has been degraded or is non exsistent. Most Failures I
have worked on have the AC Protection still in Tact but other components
Fail.

Dirty AC actually causes Components inside the PS to 'degrade' more than
actually burn out, which in turn can disable partially or fully the overload
DC protection or alter the Regulation so that the Mobo is Getting less or
more than 12/5VDC with unregulated current. Its possible in some cases users
will not know somethings wrong, continue to use the Degraded PS, and damage
the MOBO.

Its also possible someone could detect the problem earlier because sometimes
the PC will have trouble shutting down or give other errors, and be led to
the PS as the cause.

I dont see how a constant Draw on that 12V Line for KB power - given a
**PURE CONSTANT SOLID AC** source , could be such a concern unless the PC
is on 24/7/365.....which may or may not be the case. Even then , if the DC
output were stressed by the MOBO the Shut down circuits would kill the D C
Power output, and the PS will Still have AC power Applied, and technicly be
partially in use. unless of course, Internal Components of the PS have
Degraded, as previously mentioned.

The KB power is really a Long Term effect on the Condition of a PS, side
its only effecting the DC side of the PS. All it could ever hope to do is
shorten the Expectancy of components in the DC circuitry. With only 5 or 12
Volts or less theres not a whole lot of damage that can be done if a problem
were there in a short time as opposed to on the AC side. Higher AC voltages
cause more damage in the Same time than Lower DC ones will.

Your experience by disabling the Jumper in effect took away power from the
PS DC side, which in effect reflects back to the AC side regardless of what
the Motherboard wants to do. Its unlikely 2 or 3 PS's would burn out in the
Same Way if there was a problem on the MOBO. They usually will shut down a
PS if the protection circuits are still working. But if those PS's were all
run on the Same DIRTY AC Power Source, then you have 3 Degraded PS's , and
are just looking at the symptom than the cause.


I've repaired and built hunderds of computers, and this has been the
only situation I've ever encountered which caused multiple power
supply failures. While dirty AC is a worry, it's more likely to cause
damage to the MB than to the power supply.



  #13   Report Post  
Steve(JazzHunter)
 
Posts: n/a
Default Power supplies are burning out

On Wed, 21 Jan 2004 17:41:00 GMT, "techforce"
wrote:

Apparently, you have not been inside a PC Power Supply and worked on them,
else you would know this is quite the opposite unless the AC protection in
the design of the PS has been degraded or is non exsistent. Most Failures I
have worked on have the AC Protection still in Tact but other components
Fail.


I would like to hear JBR say "Yes, I checked the keyboard power
jumper." It may not seem a logical cause for repeated power supply
failure, but that is what actually happens. Until I discovered this
one computer would lose its power supply within two weeks, in one case
the supply lasted about a minute. I finally read the manual,
discovered the jumper, and the system has lasted since 2000. In
another case a store-built clone was losing supplies, when the second
one failed he brought it to me, sure enough keyboard power was
enabled, changed the jumper, and no more failures. Yes using better
supplies would help, but only to provide enough standby current.
That's why I'm chipping in with this suggestion, it doesn't appear
that others in this thread have encountered this issue, or have, but
don't know it.

Step one, check for this jumper, if it exists even, and assuming it's
a PIII, THEN move on to incoming AC. Logical?

Also I don't find that the supplies "degrade" usually it's the zener
shorting, a resistor overheating, or some such.

. STeve ..

Dirty AC actually causes Components inside the PS to 'degrade' more than
actually burn out, which in turn can disable partially or fully the overload
DC protection or alter the Regulation so that the Mobo is Getting less or
more than 12/5VDC with unregulated current. Its possible in some cases users
will not know somethings wrong, continue to use the Degraded PS, and damage
the MOBO.

Its also possible someone could detect the problem earlier because sometimes
the PC will have trouble shutting down or give other errors, and be led to
the PS as the cause.

I dont see how a constant Draw on that 12V Line for KB power - given a
**PURE CONSTANT SOLID AC** source , could be such a concern unless the PC
is on 24/7/365.....which may or may not be the case. Even then , if the DC
output were stressed by the MOBO the Shut down circuits would kill the D C
Power output, and the PS will Still have AC power Applied, and technicly be
partially in use. unless of course, Internal Components of the PS have
Degraded, as previously mentioned.

The KB power is really a Long Term effect on the Condition of a PS, side
its only effecting the DC side of the PS. All it could ever hope to do is
shorten the Expectancy of components in the DC circuitry. With only 5 or 12
Volts or less theres not a whole lot of damage that can be done if a problem
were there in a short time as opposed to on the AC side. Higher AC voltages
cause more damage in the Same time than Lower DC ones will.

Your experience by disabling the Jumper in effect took away power from the
PS DC side, which in effect reflects back to the AC side regardless of what
the Motherboard wants to do. Its unlikely 2 or 3 PS's would burn out in the
Same Way if there was a problem on the MOBO. They usually will shut down a
PS if the protection circuits are still working. But if those PS's were all
run on the Same DIRTY AC Power Source, then you have 3 Degraded PS's , and
are just looking at the symptom than the cause.


I've repaired and built hunderds of computers, and this has been the
only situation I've ever encountered which caused multiple power
supply failures. While dirty AC is a worry, it's more likely to cause
damage to the MB than to the power supply.



  #14   Report Post  
w_tom
 
Posts: n/a
Default Power supplies are burning out

Assumed: a power supply can be damaged by too much load.
Not possible. In fact, Intel spec says how big a wire must be
to short together all power supply outputs - without damage.
That's right. All DC outputs from a power supply can be
shorted together and no damage may occur. So how does the
trivial load of that keyboard draw too much power?

Then a circuit limiting fuse on motherboard that provides
power to keyboard. Just another reason why keyboard could not
damage power supply.

Many 'bean counters' don't buy minimally acceptable power
supplies. Technical specs are simply irrelevant since price is
more important. Overseas manufacturers have discovered that
American computer assemblers are technically ignorant. So
they dump, at higher profits, supplies that can even be
damaged by load. If a keyboard is damaging a power supply,
then the problem is directly traceable to the North American
who buys that supply.

There is nothing new in these facts. Concepts are industry
standard for longer than PCs have even existed. Any
acceptable power supply is not damaged by too much load or a
short circuit of all outputs.

More myths - a plug-in UPS cleans power. Wrong. Power
connects directly to AC mains when UPS 'is not in' battery
backup mode. Where is the 'protection'? Furthermore a
plug-in UPS typically outputs its dirtiest power when 'is in'
battery backup mode. Power very dirty because any properly
selected power supply is not adversely affected by dirty AC
power. Electricity so dirty from this UPS that 120 VAC is two
200 volt square waves with up to a 270 volt spike between
those square waves. Electricity that could be destructive to
a small electric motor but is quite sufficient for a computer
power supply - because computer power supplies (properly
purchased) are so resilient.

The key phrase here is 'properly purchased'. Most power
supply problems are directly traceable to the human who got
the power supply they wanted. Price rather than value being
the reason for purchase.

Power supplies already have effective power conditioners -
internally. It is why that 200 volt square wave UPS output
does not affect computers. Increasing output wattage also
does not solve anything.

Every power supply listed by jbr sounds like classic 'dump
trash on Americans' power supplies - to increase
manufacturer's profits. If supply did not come with long list
of numerical specs, then, typically, it is a 'dumped' supply.
Such power supplies would be missing essential functions -
that means other computer parts would be damaged. Properly
purchased power supplies can not damage other computer
components. Just another function that those importers hope
North Americans don't know.

Why did those supplies fail? First, where are the long list
of specifications? No specs? Then supply probably performed
as manufacturer claimed. Then myth purveyors cite dirty
electricity, surge protectors, UPS solution, line
conditioners, and other nonsense. The supply was defective
when selected; a failure directly traceable to the human. No
long list of detailed numerical specs? Then assume the worst
- such as three failed supplies in one system.


"Steve(JazzHunter)" wrote:
I would like to hear JBR say "Yes, I checked the keyboard power
jumper." It may not seem a logical cause for repeated power supply
failure, but that is what actually happens. Until I discovered this
one computer would lose its power supply within two weeks, in one case
the supply lasted about a minute. I finally read the manual,
discovered the jumper, and the system has lasted since 2000. In
another case a store-built clone was losing supplies, when the second
one failed he brought it to me, sure enough keyboard power was
enabled, changed the jumper, and no more failures. Yes using better
supplies would help, but only to provide enough standby current.
That's why I'm chipping in with this suggestion, it doesn't appear
that others in this thread have encountered this issue, or have, but
don't know it.

Step one, check for this jumper, if it exists even, and assuming it's
a PIII, THEN move on to incoming AC. Logical?

Also I don't find that the supplies "degrade" usually it's the zener
shorting, a resistor overheating, or some such.

  #15   Report Post  
jbr
 
Posts: n/a
Default Power supplies are burning out

I appreciate the feedback from all.

Yes Steve I have checked the MB for this setting. The "Keyboard Power
On" setting is/was disabled.

By the way the motherboard is/was an ECS - K7AMA (1.5) with a AMD
Athlon Thunderbird 1.4GHz.

In pursuit of a remedy, needed ASAP, today I placed a new motherboard
in the system and brought it back online. I did not have another ECS
so I am using a Shuttle AK39N.

There is much discussion about the AC being "dirty" so as suggested I
may only be treating a symptom. The surge protector that the problem
computer plugs into is shared by a monitor and speakers. Would it be
unusual for only the PC to be effected by the dirty AC?

I will have to double check but I believe the circuit that feeds this
system is surge protected at the panel. Would that prevent the AC
from being dirty?

jbr

I would like to hear JBR say "Yes, I checked the keyboard power
jumper." It may not seem a logical cause for repeated power supply
failure, but that is what actually happens. Until I discovered this
one computer would lose its power supply within two weeks, in one case
the supply lasted about a minute. I finally read the manual,
discovered the jumper, and the system has lasted since 2000. In
another case a store-built clone was losing supplies, when the second
one failed he brought it to me, sure enough keyboard power was
enabled, changed the jumper, and no more failures. Yes using better
supplies would help, but only to provide enough standby current.
That's why I'm chipping in with this suggestion, it doesn't appear
that others in this thread have encountered this issue, or have, but
don't know it.

Step one, check for this jumper, if it exists even, and assuming it's
a PIII, THEN move on to incoming AC. Logical?

Also I don't find that the supplies "degrade" usually it's the zener
shorting, a resistor overheating, or some such.

. STeve ..



  #16   Report Post  
Steve(JazzHunter)
 
Posts: n/a
Default Power supplies are burning out

On 21 Jan 2004 18:00:48 -0800, (jbr) wrote:

I appreciate the feedback from all.

Yes Steve I have checked the MB for this setting. The "Keyboard Power
On" setting is/was disabled.


Ok, Thank you. There is a continuing discussion elsewhere in this
thread about how it is "not possible" that keyboard power can kill a
power supply, however that is precisely what has happened to me and is
the experience of a computer shop I'm associated with. Since it's not
primary power but rather a separate always-on circuit it might not be
subject to the same overcurrent protection as the main system, but is
still an essential part of the overall regulation.

Speaking of which, many motherboards were equipped with 1000 and 1500
mfd capacitors that used a defective electrolyte that overheated and
popped the can or let the cap short out. While a shorted capacitor
would generally not allow the supply to start, and a leaky one would
fail leaving a mess long before it would affect the supply, it is
worth making sure that there are no visibly damaged large-value
capacitors on the M/B.

Yes, use a UPS or filterchoke on the mains supply...

Finally, I had a PII (AT) that went through 4 power supplies in one
year. I never found a problem other than just plain bad luck. The
last supply I put in came from a 486, only rated at 175 watts, and
that has lasted for three years so far..

. Such is life..


. Steve ..

By the way the motherboard is/was an ECS - K7AMA (1.5) with a AMD
Athlon Thunderbird 1.4GHz.

In pursuit of a remedy, needed ASAP, today I placed a new motherboard
in the system and brought it back online. I did not have another ECS
so I am using a Shuttle AK39N.

There is much discussion about the AC being "dirty" so as suggested I
may only be treating a symptom. The surge protector that the problem
computer plugs into is shared by a monitor and speakers. Would it be
unusual for only the PC to be effected by the dirty AC?

I will have to double check but I believe the circuit that feeds this
system is surge protected at the panel. Would that prevent the AC
from being dirty?

jbr

I would like to hear JBR say "Yes, I checked the keyboard power
jumper." It may not seem a logical cause for repeated power supply
failure, but that is what actually happens. Until I discovered this
one computer would lose its power supply within two weeks, in one case
the supply lasted about a minute. I finally read the manual,
discovered the jumper, and the system has lasted since 2000. In
another case a store-built clone was losing supplies, when the second
one failed he brought it to me, sure enough keyboard power was
enabled, changed the jumper, and no more failures. Yes using better
supplies would help, but only to provide enough standby current.
That's why I'm chipping in with this suggestion, it doesn't appear
that others in this thread have encountered this issue, or have, but
don't know it.

Step one, check for this jumper, if it exists even, and assuming it's
a PIII, THEN move on to incoming AC. Logical?

Also I don't find that the supplies "degrade" usually it's the zener
shorting, a resistor overheating, or some such.

. STeve ..


  #17   Report Post  
Steve(JazzHunter)
 
Posts: n/a
Default Power supplies are burning out

On Wed, 21 Jan 2004 19:29:47 -0500, w_tom wrote:

Assumed: a power supply can be damaged by too much load.
Not possible. In fact, Intel spec says how big a wire must be
to short together all power supply outputs - without damage.
That's right. All DC outputs from a power supply can be
shorted together and no damage may occur. So how does the
trivial load of that keyboard draw too much power?

Then a circuit limiting fuse on motherboard that provides
power to keyboard. Just another reason why keyboard could not
damage power supply.


The keyboard power is separate from main power, it is always on, and I
don't want to hear any friggin' more about how keyboard power "can't"
damage a power supply, when it most definitely DOES, and repeatably,
and demonstratably. The keyboard can draw 500ma, ATX spec calls for
720ma on 5v standby, almost all AT and cheap ATX supplies are only
rated at 200 or 300 ma, that can fail, often within a minute,
sometimes after a week or more, but it DOES, and only because keyboard
power is enabled. Drop by sometime, and I'll blow some power supplies
for you.... g

. Steve ..

Many 'bean counters' don't buy minimally acceptable power
supplies. Technical specs are simply irrelevant since price is
more important. Overseas manufacturers have discovered that
American computer assemblers are technically ignorant. So
they dump, at higher profits, supplies that can even be
damaged by load. If a keyboard is damaging a power supply,
then the problem is directly traceable to the North American
who buys that supply.

There is nothing new in these facts. Concepts are industry
standard for longer than PCs have even existed. Any
acceptable power supply is not damaged by too much load or a
short circuit of all outputs.

More myths - a plug-in UPS cleans power. Wrong. Power
connects directly to AC mains when UPS 'is not in' battery
backup mode. Where is the 'protection'? Furthermore a
plug-in UPS typically outputs its dirtiest power when 'is in'
battery backup mode. Power very dirty because any properly
selected power supply is not adversely affected by dirty AC
power. Electricity so dirty from this UPS that 120 VAC is two
200 volt square waves with up to a 270 volt spike between
those square waves. Electricity that could be destructive to
a small electric motor but is quite sufficient for a computer
power supply - because computer power supplies (properly
purchased) are so resilient.

The key phrase here is 'properly purchased'. Most power
supply problems are directly traceable to the human who got
the power supply they wanted. Price rather than value being
the reason for purchase.

Power supplies already have effective power conditioners -
internally. It is why that 200 volt square wave UPS output
does not affect computers. Increasing output wattage also
does not solve anything.

Every power supply listed by jbr sounds like classic 'dump
trash on Americans' power supplies - to increase
manufacturer's profits. If supply did not come with long list
of numerical specs, then, typically, it is a 'dumped' supply.
Such power supplies would be missing essential functions -
that means other computer parts would be damaged. Properly
purchased power supplies can not damage other computer
components. Just another function that those importers hope
North Americans don't know.

Why did those supplies fail? First, where are the long list
of specifications? No specs? Then supply probably performed
as manufacturer claimed. Then myth purveyors cite dirty
electricity, surge protectors, UPS solution, line
conditioners, and other nonsense. The supply was defective
when selected; a failure directly traceable to the human. No
long list of detailed numerical specs? Then assume the worst
- such as three failed supplies in one system.


"Steve(JazzHunter)" wrote:
I would like to hear JBR say "Yes, I checked the keyboard power
jumper." It may not seem a logical cause for repeated power supply
failure, but that is what actually happens. Until I discovered this
one computer would lose its power supply within two weeks, in one case
the supply lasted about a minute. I finally read the manual,
discovered the jumper, and the system has lasted since 2000. In
another case a store-built clone was losing supplies, when the second
one failed he brought it to me, sure enough keyboard power was
enabled, changed the jumper, and no more failures. Yes using better
supplies would help, but only to provide enough standby current.
That's why I'm chipping in with this suggestion, it doesn't appear
that others in this thread have encountered this issue, or have, but
don't know it.

Step one, check for this jumper, if it exists even, and assuming it's
a PIII, THEN move on to incoming AC. Logical?

Also I don't find that the supplies "degrade" usually it's the zener
shorting, a resistor overheating, or some such.


  #18   Report Post  
w_tom
 
Posts: n/a
Default Power supplies are burning out

Even the separate "always on" power supply (keyboard power)
cannot be damaged by too much load. Standard design in every
power supply chip. Your experience, without supporting
fundamental knowledge, only demonstrates how junk science is
promoted. Power supply, properly designed, is not damaged by
too much load or by a short circuit.

If the keyboard is killing power supplies, then a human is
buying defective power supplies. Much too common with humans
who buy on price rather than value.

If power supply is damaged by keyboard, then power supply is
defective. If all power supplies are damaged same way / same
reason, then a human is the reason for continuous power supply
failure.

Overseas manufacturers have discovered a lucrative market.
Computer assemblers who buy only on price. Then when power
supply fails, they blame surges, peripherals, or anything else
they can 'speculate' without required fundamental knowledge
and real world data. It's called junk science.

Most likely reason for repeated power supply failures on the
line called +5VSB is a human. Notice this post comes with so
much real world knowledge that even the signal name for that
purple wire is provided. An obnoxious way of saying one
should first learn basic facts before making 'expert'
conclusions. If power supplies are repeatedly damage by that
keyboard (and it am not even convinced those power supplies
were damaged - another topic), then a human is reason for
failure. Load cannot damage the +5VSB on a properly designed
power supply - no matter how many "friggin"s are posted.

"Steve(JazzHunter)" wrote:

On Wed, 21 Jan 2004 19:29:47 -0500, w_tom wrote:

Assumed: a power supply can be damaged by too much load.
Not possible. In fact, Intel spec says how big a wire must be
to short together all power supply outputs - without damage.
That's right. All DC outputs from a power supply can be
shorted together and no damage may occur. So how does the
trivial load of that keyboard draw too much power?

Then a circuit limiting fuse on motherboard that provides
power to keyboard. Just another reason why keyboard could not
damage power supply.


The keyboard power is separate from main power, it is always on, and I
don't want to hear any friggin' more about how keyboard power "can't"
damage a power supply, when it most definitely DOES, and repeatably,
and demonstratably. The keyboard can draw 500ma, ATX spec calls for
720ma on 5v standby, almost all AT and cheap ATX supplies are only
rated at 200 or 300 ma, that can fail, often within a minute,
sometimes after a week or more, but it DOES, and only because keyboard
power is enabled. Drop by sometime, and I'll blow some power supplies
for you.... g

  #19   Report Post  
techforce
 
Posts: n/a
Default Power supplies are burning out



There is much discussion about the AC being "dirty" so as suggested I
may only be treating a symptom. The surge protector that the problem
computer plugs into is shared by a monitor and speakers. Would it be
unusual for only the PC to be effected by the dirty AC?


No Not unusual at all. Reason is because a PC Power Supply "generally" is
partially powered at all times if plugged into a HOT outlet.
"generally" Meaning depending on Design.

Ever See the Ones with the 1 / 0 Switch on the back? Those are most
Certainly (in my experience) almost always partially powered on even when
the PC is Shut Down by say initiating an OS Shutdown at the Software level.
Sometimes you will even be prompted that its now ok to shut down the PC, and
you go ahead and press the power button on the Front of the case - but the
1/0 button is still on , meaning the PS is Still running , but the DC side
is OFF...as well as the PC.

So any "dirty" AC power can enter the PS still on the AC side and 'degrade'
Components so that next time you turn it on, it will appear to be acting
strangely.

Now, I dont know how the KB Soft Start Cicruitry works myself, but I suspect
that perhaps a small amount of DC , probably in the Milliamps as described
by Steve, is pulsed into the MOBO as a 'keep alive' to detect press of a
key. Given what I just Explained, it DOES make some sense that one could
come to the conclusion that the Soft Start Jumper is "drawing too much
power" if you look at it like that.

The Design on those Supplies could differ than the ones W-O soft Start,
(which I think is that other Small Square Molded Connector?) Wheras the DC
side of thePS could be "Partly" energized at a very low level and even be
misinterpreted by the MOBO as AC , NOT DC.....which also will cause
Electrolytics to "****" excuse the term. There could also be poor
Electrolytics on the MOBO Of Course, but like I say , where theres Smoke (or
in this case Electrolyte) theres Fire or in this case Dirty power.


I will have to double check but I believe the circuit that feeds this
system is surge protected at the panel. Would that prevent the AC
from being dirty?


You may want to Either put the 1/0 switch to 0 after its Shut down, or Just
get one of those multi Power Centers where you can switch off each item so
its not always HOT.

The Protection on a typical cheapie Power Strip wont protect against the
Unusual, only the typical. Like I said Earlier, we are in Times in this
World where Electricity Demand is at an all time high. Dont think the East
coast USA blackout was just a glitch....if there was enough power to go
around , they wouldnt be borrowing it from each other.




  #20   Report Post  
Steve(JazzHunter)
 
Posts: n/a
Default Power supplies are burning out

On Wed, 21 Jan 2004 22:50:29 -0500, w_tom wrote:


I'd like to see you on the service bench repairing computers. You
wouldn't last a day. There is nothing "logical" about computers. You
spout theory, if theory doesn't work you blame the technicians, and
just can't face up to the fact that you're flogging the same thing and
haven't had actual experience in the matter.


Once, at a party, I met a well-known DJ. We got along famously until
he insisted there was no stereo before the Beatles. "Fantasia" was
not true stereo (maybe not), Audio Fidelity didn't have Stereo
records, they were Binaural (not true, Cook records were Binauaral);
The RCA and Sidney Frey "Wall of Sound" recordings were just fake
ambience; "The Robe" and other big-budget films of the 50's were never
stereo (which of course is how they are now presented on DVD.) Tthe
Pathe double-disc recordings of the 20's were just "loud. Of course
the first "Stereo" recordings of the Beatles have been released in
oriignal Mono.. The point is, he had made up his mind and explained
away anything that didn't agree with his mindset.

. Steve .

Even the separate "always on" power supply (keyboard power)
cannot be damaged by too much load. Standard design in every
power supply chip. Your experience, without supporting
fundamental knowledge, only demonstrates how junk science is
promoted. Power supply, properly designed, is not damaged by
too much load or by a short circuit.

If the keyboard is killing power supplies, then a human is
buying defective power supplies. Much too common with humans
who buy on price rather than value.

If power supply is damaged by keyboard, then power supply is
defective. If all power supplies are damaged same way / same
reason, then a human is the reason for continuous power supply
failure.

Overseas manufacturers have discovered a lucrative market.
Computer assemblers who buy only on price. Then when power
supply fails, they blame surges, peripherals, or anything else
they can 'speculate' without required fundamental knowledge
and real world data. It's called junk science.

Most likely reason for repeated power supply failures on the
line called +5VSB is a human. Notice this post comes with so
much real world knowledge that even the signal name for that
purple wire is provided. An obnoxious way of saying one
should first learn basic facts before making 'expert'
conclusions. If power supplies are repeatedly damage by that
keyboard (and it am not even convinced those power supplies
were damaged - another topic), then a human is reason for
failure. Load cannot damage the +5VSB on a properly designed
power supply - no matter how many "friggin"s are posted.

"Steve(JazzHunter)" wrote:

On Wed, 21 Jan 2004 19:29:47 -0500, w_tom wrote:

Assumed: a power supply can be damaged by too much load.
Not possible. In fact, Intel spec says how big a wire must be
to short together all power supply outputs - without damage.
That's right. All DC outputs from a power supply can be
shorted together and no damage may occur. So how does the
trivial load of that keyboard draw too much power?

Then a circuit limiting fuse on motherboard that provides
power to keyboard. Just another reason why keyboard could not
damage power supply.


The keyboard power is separate from main power, it is always on, and I
don't want to hear any friggin' more about how keyboard power "can't"
damage a power supply, when it most definitely DOES, and repeatably,
and demonstratably. The keyboard can draw 500ma, ATX spec calls for
720ma on 5v standby, almost all AT and cheap ATX supplies are only
rated at 200 or 300 ma, that can fail, often within a minute,
sometimes after a week or more, but it DOES, and only because keyboard
power is enabled. Drop by sometime, and I'll blow some power supplies
for you.... g


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