Multiple Power supply failures

I have a Sony RB 38G computer that has had 3 power supply failures in
the last four months. The first one was 2 months after warranty
expired. When I had it replaced, the guy said that a connector on the
motherboard was a little burnt. He said he cleaned it up and that
there should not be a problem. He replaced it with a 450 watt Okia.
Three weeks later it went bad. He replaced it under the 30 day
warranty. Two months later it has failed again. Should I replace the
power supply with a better one than Okia, or should I replace the
motherboard and power supply? If I replace the motherboard, are there
any suggestions as to specific motherboards for this computer?

crownroyale@comcast.net wrote:

> I have a Sony RB 38G computer that has had 3 power supply failures in
> the last four months. The first one was 2 months after warranty
> expired. When I had it replaced, the guy said that a connector on the
> motherboard was a little burnt. He said he cleaned it up and that
> there should not be a problem. He replaced it with a 450 watt Okia.
> Three weeks later it went bad. He replaced it under the 30 day
> warranty. Two months later it has failed again. Should I replace the
> power supply with a better one than Okia,

Yes.

> or should I replace the motherboard and power supply?

Nope. That wont be the problem.

> If I replace the motherboard, are there any suggestions
> as to specific motherboards for this computer?

crownroyale@comcast.net wrote:
> I have a Sony RB 38G computer that has had 3 power supply failures in
> the last four months. The first one was 2 months after warranty
> expired. When I had it replaced, the guy said that a connector on the
> motherboard was a little burnt. He said he cleaned it up and that
> there should not be a problem. He replaced it with a 450 watt Okia.
> Three weeks later it went bad. He replaced it under the 30 day
> warranty. Two months later it has failed again. Should I replace the
> power supply with a better one than Okia, or should I replace the
> motherboard and power supply? If I replace the motherboard, are there
> any suggestions as to specific motherboards for this computer?

As this is your fourth one, it's time to to a *thorough* inspection of
the motherboard for shorts (top and bottom). Something may be killing
PSUs. The burnt connector is a Danger Will Robinson kind of thing. Also
inspect the rest of the system for shorts.

In other words, it's like having the same fuse blow three times in a
row: stop replacing fuses and hunt down the problem.

In article <1155875315.403174.124470@h48g2000cwc.googlegroups .com>,
"paulmd@efn.org" <paulmd@efn.org> wrote:

> crownroyale@comcast.net wrote:
> > I have a Sony RB 38G computer that has had 3 power supply failures in
> > the last four months. The first one was 2 months after warranty
> > expired. When I had it replaced, the guy said that a connector on the
> > motherboard was a little burnt. He said he cleaned it up and that
> > there should not be a problem. He replaced it with a 450 watt Okia.
> > Three weeks later it went bad. He replaced it under the 30 day
> > warranty. Two months later it has failed again. Should I replace the
> > power supply with a better one than Okia, or should I replace the
> > motherboard and power supply? If I replace the motherboard, are there
> > any suggestions as to specific motherboards for this computer?
>
> As this is your fourth one, it's time to to a *thorough* inspection of
> the motherboard for shorts (top and bottom). Something may be killing
> PSUs. The burnt connector is a Danger Will Robinson kind of thing. Also
> inspect the rest of the system for shorts.
>
> In other words, it's like having the same fuse blow three times in a
> row: stop replacing fuses and hunt down the problem.

The service person should be using his clamp-on DC ammeter
to measure the current, especially on the pin that burned.
The maximum current allowed per pin is 6 amps.
The motherboard is overloading the connector and causing
too much current to flow. The service person should have
realised this the first time, when seeing the burnt connector.
Half a repair, is no repair at all. (First the repair guy
removes and replaces the connector, and then uses the
ammeter once the connector is repaired, to see if too much
current is present on any pin. It only takes 5 minutes to
check with a clamp-on DC ammeter, and it will take more time
to solder a replacement connector on there, than to do the
measurement.)

Yes, you could replace the motherboard, but it would really help to
track down the problem, so that when the replacement motherboard
is installed, you can be sure that the replacement will fix the
problem once and for all. Checking the current flow with a
clamp-on ammeter, with the new motherboard in place, would
be a good thing to try.

If you know which pin is burned, that is useful information.
Here are some connector pinouts. Your motherboard either has
a 20 pin or a 24 pin connector. You should be able to orient
yourself by using the stated wire colors below. The 24 pin type
is the two columns on the left, and is a more modern connector
than the 20 pin type on the right. Which pin is burned ?

<----- ATX 2.0+ main connector -----> <--- ATX previous versions --->

Pin Signal Color Pin Signal Color Pin Signal Color Pin Signal Color
1 +3.3VDC Orange 13 +3.3VDC Orange 1 +3.3VDC Orange 11 +3.3VDC Orange
2 +3.3VDC Orange 14 -12VDC Blue 2 +3.3VDC Orange 12 -12VDC Blue
3 COM Black 15 COM Black 3 COM Black 13 COM Black
4 +5VDC Red 16 PS_ON# Green 4 +5VDC Red 14 PS_ON# Green
5 COM Black 17 COM Black 5 COM Black 15 COM Black
6 +5VDC Red 18 COM Black 6 +5VDC Red 16 COM Black
7 COM Black 19 COM Black 7 COM Black 17 COM Black
8 PWR_OK Gray 20 Reserved N/C 8 PWR_OK Gray 18 N/C or -5V
9 +5VSB Purple 21 +5VDC Red 9 +5VSB Purple 19 +5VDC Red
10 +12V1DC Yellow 22 +5VDC Red 10 +12VDC Yellow 20 +5VDC Red
11 +12V1DC Yellow 23 +5VDC Red
12 +3.3 VDC Orange 24 COM Black

Paul

Paul <nospam@needed.com> wrote:
> In article <1155875315.403174.124470@h48g2000cwc.googlegroups .com>,
> "paulmd@efn.org" <paulmd@efn.org> wrote:
>
>> crownroyale@comcast.net wrote:
>>> I have a Sony RB 38G computer that has had 3 power supply failures
>>> in the last four months. The first one was 2 months after warranty
>>> expired. When I had it replaced, the guy said that a connector on
>>> the motherboard was a little burnt. He said he cleaned it up and
>>> that there should not be a problem. He replaced it with a 450 watt
>>> Okia. Three weeks later it went bad. He replaced it under the 30
>>> day warranty. Two months later it has failed again. Should I
>>> replace the power supply with a better one than Okia, or should I
>>> replace the motherboard and power supply? If I replace the
>>> motherboard, are there any suggestions as to specific motherboards
>>> for this computer?
>>
>> As this is your fourth one, it's time to to a *thorough* inspection
>> of the motherboard for shorts (top and bottom). Something may be
>> killing PSUs. The burnt connector is a Danger Will Robinson kind of
>> thing. Also inspect the rest of the system for shorts.
>>
>> In other words, it's like having the same fuse blow three times in a
>> row: stop replacing fuses and hunt down the problem.

> The service person should be using his clamp-on DC ammeter
> to measure the current, especially on the pin that burned.

That wont necessarily be there now. More likely that
was due to a mains spike which is long gone now.

> The maximum current allowed per pin is 6 amps.
> The motherboard is overloading the connector
> and causing too much current to flow.

That wont kill a properly designed power supply.

> The service person should have realised this
> the first time, when seeing the burnt connector.
> Half a repair, is no repair at all. (First the repair guy
> removes and replaces the connector, and then uses
> the ammeter once the connector is repaired, to see
> if too much current is present on any pin. It only takes
> 5 minutes to check with a clamp-on DC ammeter, and
> it will take more time to solder a replacement connector
> on there, than to do the measurement.)

Unlikely to be there all the time if the system works fine for a while.

> Yes, you could replace the motherboard, but it would really help to
> track down the problem, so that when the replacement motherboard
> is installed, you can be sure that the replacement will fix the
> problem once and for all. Checking the current flow with a
> clamp-on ammeter, with the new motherboard in place, would
> be a good thing to try.

I doubt it would show anything given that the system works fine for weeks.

> If you know which pin is burned, that is useful information.

I doubt it.

> Here are some connector pinouts. Your motherboard either has
> a 20 pin or a 24 pin connector. You should be able to orient
> yourself by using the stated wire colors below. The 24 pin type
> is the two columns on the left, and is a more modern connector
> than the 20 pin type on the right. Which pin is burned ?
>
> <----- ATX 2.0+ main connector -----> <--- ATX previous versions
> --->
>
> Pin Signal Color Pin Signal Color Pin Signal Color Pin
> Signal Color 1 +3.3VDC Orange 13 +3.3VDC Orange 1 +3.3VDC Orange
> 11 +3.3VDC Orange 2 +3.3VDC Orange 14 -12VDC Blue 2 +3.3VDC
> Orange 12 -12VDC Blue 3 COM Black 15 COM Black 3 COM
> Black 13 COM Black 4 +5VDC Red 16 PS_ON# Green 4
> +5VDC Red 14 PS_ON# Green 5 COM Black 17 COM Black
> 5 COM Black 15 COM Black 6 +5VDC Red 18 COM Black
> 6 +5VDC Red 16 COM Black 7 COM Black 19 COM Black
> 7 COM Black 17 COM Black 8 PWR_OK Gray 20 Reserved N/C
> 8 PWR_OK Gray 18 N/C or -5V 9 +5VSB Purple 21 +5VDC Red
> 9 +5VSB Purple 19 +5VDC Red 10 +12V1DC Yellow 22 +5VDC Red
> 10 +12VDC Yellow 20 +5VDC Red 11 +12V1DC Yellow 23 +5VDC Red
> 12 +3.3 VDC Orange 24 COM Black
>
> Paul

crownroyale@comcast.net wrote:
> I have a Sony RB 38G computer that has had 3 power supply failures in
> the last four months. The first one was 2 months after warranty
> expired. When I had it replaced, the guy said that a connector on the
> motherboard was a little burnt. He said he cleaned it up and that
> there should not be a problem. He replaced it with a 450 watt Okia.
> Three weeks later it went bad. He replaced it under the 30 day
> warranty. Two months later it has failed again. Should I replace the
> power supply with a better one than Okia, or should I replace the
> motherboard and power supply? If I replace the motherboard, are there
> any suggestions as to specific motherboards for this computer?

Why did the contacts overheat and burn? Because unless they were
loose, there had to be an overload from the mobo, either because of a
short to the case or the CPU voltage regulator straining because its
capacitors have gone bad.

Okia is really bad, and I can't believe that any legitimate technician
would install one. A 500W Okia is shown at the bottom of this page, to
the right of a 600W Enermax. Click on the photos to enlarge:

www.bigbruin.com/reviews05/enermaxeg701ax/

Notice how much less crowded the Okia is than the Enermax and how much
smaller its components are, especially the heatsinks, transformer (big
thing between the heatsinks), and output filter coils (donut coils at
the left). It doesn't even have an EMI line filter to reduce radio &
TV interference (see missing parts in upper right). This quality 300W
PSU looks a lot beefier (the EMI filter is near the bottom -- see the
two donut coils):

http://static.flickr.com/38/75117436_1de7a3142d.jpg

crownroyale@comcast.net wrote:

> I have a Sony RB 38G computer that has had 3 power supply failures in
> the last four months. The first one was 2 months after warranty
> expired. When I had it replaced, the guy said that a connector on the
> motherboard was a little burnt. He said he cleaned it up and that
> there should not be a problem. He replaced it with a 450 watt Okia.
> Three weeks later it went bad. He replaced it under the 30 day
> warranty. Two months later it has failed again. Should I replace the
> power supply with a better one than Okia, or should I replace the
> motherboard and power supply? If I replace the motherboard, are there
> any suggestions as to specific motherboards for this computer?

I'm not sure the specs on that board, but I'm guessing that it only has a
20-pin main connector from the PS. It probably also is a real early P4.
Probably either your 3.3v line or 12v line has over-currented. those
molexes can't support much, which is why they had to introduce extra
connectors, first 3.3v extra headers, then 12v extras, then the 24-pin
supplies.

Get a new board, and any power supply with compatible connectors.

poly-p man

If you had ISA cards, that might also lead to the problem. If you do, I bet
that every single PS was missing the white wire.