my dual p3 pc is dying

[Th3_uN1Qu3]

Re: my dual p3 pc is dying

What switching transistors does it use? Is it on mosfets or bipolars? If it's on bipolar transistors, the snubbers have either gone bad or have been poorly designed in the first place. Unfortunately you're going to need a decent scope, an isolation transformer and some patience to calculate new ones if needed.

[shovenose]

Re: my dual p3 pc is dying

no i cleaned it...like a week ago. while chekcing for bad caps and other problems...

[c_hegge]

Re: my dual p3 pc is dying

Could also be running hot from dust. How old is the PSU? I've known some PSUs to blow out hot exhaust air when they get dusty

[shovenose]

Re: my dual p3 pc is dying

well it has more power on all the rails

[PCBONEZ]

Re: my dual p3 pc is dying

I dunno.
Enermax made lots of different PSUs.

Why don't you compare amps/rails to the old 1U FSP?

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[shovenose]

Re: my dual p3 pc is dying

ok so its not like its gonna overheat due to crossload of having heavy minor rail load and low load on 12v?

[PCBONEZ]

Re: my dual p3 pc is dying

Probably just a low efficiency PSU. - Lots of heat losses.
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[shovenose]

Re: my dual p3 pc is dying

oh, also: why does this enermax psu get REALLY hot air exhaust? it has extremely high-airflow dual fans, which are super noisy, and blow lots of air, but the air is very hot. and the hot air is from the psu itself, the air coming out of the case fans of the pc is barely warm. but the psu runs hot? is that bad? (no bad caps in psu i looked)

[shovenose]

Re: my dual p3 pc is dying

ok well i am glad i dug up that 300w psu (i didnt realize i had it). cuz now everything is working again. but i am going to post internal pictures of the liteon (uses ost caps) in the build quality pictorial later today...so was it the crappyness of the psu or the missing -5v that was the problem.
and the mobo (a TYAN THUNDER LE-T) has mostly rubycons. so im not worried about that...

[everell]

Re: my dual p3 pc is dying

1. Different case means different cooling ability. New case may be building up heat pockets which cause computer/power supply failure after a certain time period. Running dual cores, you might want to unsolder the power supply fan from its temperture controller, and solder the leads.....red to 12 volt rail and black to ground. Fan would stay on full blast all the time and make more noise, but you would have better cooling. Likewise, you may want to connect case fan directly to +12 and ground rather than plugging it into the mother board which has temperature controller and reduces fan speed.

2. LiteOn power supplies from that era use Chinese crap glue. Should look white, but after a few years turns yellow, then brown, then black. Also turns from gummy to brittle. Dark brown and black is resistive or conductive. Brittle sometimes has black holes inside the glue (you can see it if you poke at it with a small screwdriver and it crumbles). This indicates arcing. Glue which is shorting/resistive/arcing is stealing power from the power supply.

3. Bad caps which don't look bad - not failing totally but stealing power from your power supply. That power supply is old enough that a total recap with GOOD capacitors will improve performance.

4. Small pc board soldered to main pc board with supervisor chip. The small pc board has two potentiometers on it. The one on the left adjusts the voltage level for the +5 and +12 rails. The one on the right adjusts the +12 volt rail max current amount. Some of these older power supplies are running a little low on voltage, so they can be adjusted upward. Adjusting the one on the left, I try to set the +5 rail for 5.1 volts under a small load (one hard drive and one cd rom)

[PCBONEZ]

Re: my dual p3 pc is dying

The 1U FSP probably doesn't fit the ATX case real well.
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[Toasty]

Re: my dual p3 pc is dying


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[kc8adu]

Re: my dual p3 pc is dying

so put back the fsp already.the clue here is that it ran fine till you messed with it.

[PCBONEZ]

Re: my dual p3 pc is dying

so what do i do?
the liteon model is: ps-5251-08

ok so: even if the 3.3 and 5v rails are being overloaded, it still has more amperage than the fsp 200w. im sorry i just dont get it. would a different psu:
enermax eg301p-v(e) its a 300w:
+3.3v: 28a
+5v: 30a
+12v: 15a
-5v: 1a
-12v: 1a
+5vsb: 2.2a
ill try this and let you know how it goes.
but t\what i think is wierd is that the pc worked just fine yesyetrday running prime95 for several hours...

Some newer spec PSUs need a minimum load on +12v and that P-III may not have enough, so yes, try a different one.

You can fake the extra load by adding 2 or 3 hard drives [don't need to connect data, just need them to spin up] to see if the PSU will kick-on that way.

Also if an existing drive ate it that can keep the whole system down.

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[PCBONEZ]

Re: my dual p3 pc is dying

Does this board have OST or KZG caps?
Sudden death with no bloaters kind'a sounds like them.

[shovenose]

Re: my dual p3 pc is dying

so what do i do?
the liteon model is: ps-5251-08

ok so: even if the 3.3 and 5v rails are being overloaded, it still has more amperage than the fsp 200w. im sorry i just dont get it. would a different psu:
enermax eg301p-v(e) its a 300w:
+3.3v: 28a
+5v: 30a
+12v: 15a
-5v: 1a
-12v: 1a
+5vsb: 2.2a
ill try this and let you know how it goes.
but t\what i think is wierd is that the pc worked just fine yesyetrday running prime95 for several hours...

[PCBONEZ]

Re: my dual p3 pc is dying

Even if a P-III boad doesn't have an ISA slot it may have the ISA BUS to support 16-bit based Chips.
That situation was common for sound, LAN, PS/2, Floppy, and even some IDE controllers.
MSI actually continued using 16-bit chips w/ISA BUS [no slot, just the BUS] right into their early socket 478 boards. [Some.]
That was kind'a sleazy. Was basically an easy way get away with using cheaper IC chips.
Not sure if anyone else did it into 478.

The -5v isn't used for power as such, it's a biasing voltage. [-12v is too.]
That's why there isn't squat for amps on that rail.

Not all 16-bit chips need -5v but if some chip does and the chip isn't doing anything the board may work fine right up until that chip is called upon to do something.
Then it will likely throw errors, BSOD, reboot, lock-up or just shut off.

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[everell]

Re: my dual p3 pc is dying

What is the model number of that 250 watt LiteOn power supply?

Also, how many volts did you measure on +5 and +12 rails? On each of the two power supplies?

[Th3_uN1Qu3]

Re: my dual p3 pc is dying

Yes at both questions. I have an ISA soundcard. Well, at least, used to... My latest dual-PIII board does not have an ISA slot anymore.

[PCBONEZ]

Re: my dual p3 pc is dying

Have an ISA slot?
Have any 16-bit IC chips on an ISA BUS?

Either of those requires -5v.