ATX replacement PSU on aged NEC Direction PC unstable

My aged linux firewall/router box has recently started sounding like a rusty
coffee grinder - a problem quickly traced back to the PSU fan.

It's an NEC Direction Pentium-233 MMX (this heady amount of computing power
does just fine for it's allotted task) and appears to be a standard ATX form
factor.

Old power supply was rated at 235W, and a replacement noise-reduction power
supply that I fitted to it is rated at 350W, each one of the outputs on the
new PSU has a higher max current rating than the original.

The problem is that I've had to put the original back in it as the new one
has proved to be unstable.

Anyone know if NECs used non-standard ATX PSUs? The wiring colours are
different, but as far as I can see the pin positions for the various outputs
are the same.

When the new one was installed a couple of things happened. Firstly, the PC
is connected to a KVM & I got a "key stuck" bios error message appearing
after POST. Everything appeared to function normally after Esc was pressed,
and on the third boot (after the instability problems) this disappeared (so
it could have just been completely coincidental - a liberal bashing of the
keys might have resolved a genuine stuck key).

Everything booted just fine, and continued to do so for about five minutes,
after which it just powered itself off. A couple more boots showed that
this would happen fairly reliably - though on one occasion it didn't power
off but instead one of the NICs failed to operate properly, claiming a load
of collision retries. - I've never seen this problem on this system before.
It was after a couple of minutes of keyboard inactivity that it happened
each time.

I spent about 20 mins creating a couple of new scripts (just something I'd
been meaning to do- nothing related to trying to fix the problem) and the
system behaved just fine, completely reliable.

However, when I finished and left it to it's own devices for a couple of
minutes again with no keyboard activity then it powered down again.

Have I missed something - a schoolboy error here, or something as daft as a
BIOS setting? Are there likely to be fundamental incompatibilities with a
"P4 ready" ATX PSU circa 2006 compared with the c. 1998 vintage original?


Or is it potentially just a duff new PSU that needs to be exchanged with the
shop for a good one?

I was going to chuck it into the only other ATX system that I have to hand,
but this is a Dell Dimension desktop, and I've just read in another post
that Dell = non-standard ATX and not to even think about swapping it for a
std ATX supply.



--

Richard Sampson

mail me at
richard at olifant d-ot co do-t uk


.

Relevant Pages

  • Re: Single PSU to supply multiple (mini-ITX) motherboards
    ... I'm going to power 4 mini-ITX boards from a single ATX PSU and I intend ... The thing is, when one of the four motherboards activates PS_ON, ...
    (alt.comp.hardware.pc-homebuilt)
  • Re: ATX replacement PSU on aged NEC Direction PC unstable
    ... > coffee grinder - a problem quickly traced back to the PSU fan. ... > It's an NEC Direction Pentium-233 MMX (this heady amount of computing power ... > Anyone know if NECs used non-standard ATX PSUs? ...
    (comp.sys.ibm.pc.hardware.misc)
  • Re: How to turn on an AT-style power supply?
    ... > (I was trying to use an ATX supply before, but it seemed more complicated, ... > don't touch when I hit the power switch. ... AC wall socket, and then push the power button that comes with it, the fan ... If it does not, then the AT PSU ...
    (sci.electronics.components)
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  • Re: Iyonix power supply
    ... but in that case I'd suggest scrounging a PSU from another ... Iyonix is a standard ATX here - I don't know for sure). ... All of these are easier options than trying to order a replacement part, ... Bill GBP 5-10 for parts ...
    (comp.sys.acorn.hardware)