PSU no start on some PCs, ok on others

[sleepydog]

This is not the same PSU I mention in my other thread, it's from an old Shuttle Athlon XP, 200W Achme thingy. It appears:

1. half dead (motherboard LEDs come on, but nothing happens when pressing the power button) on these machines:
- Athlon XP 1.4GHz
- Athlon XP 1.8GHz
- Pentium 4 3.06GHz

2. perfectly alive on:
- Celeron 600MHz @900MHz (ancient overclocker, how I loved it!)

Considering that it starts only the weakest machine, I'd say that it just can't produce enough juice, whether on the main rails or the standby rail.

What do you guys reckon?

[kc8adu]

Re: PSU no start on some PCs, ok on others

bad caps.
acme+shuttle=bad fuhkkyu caps.
a friend has a cluster built out of 50 of the shuttle shoebox pc's
i have recapped all psu and mobo's...after only a year in service.

[kikkoman]

Re: PSU no start on some PCs, ok on others

you already said it.
it's simply too weak for those machines.
i strongly doubt that it's capable of 200W and probably it has bad caps, too. ----> toss it.

i managed to run an athlon TB 1.4 (~70W) system with a 120W PSU once, but that was a FSP unit. i guess it pumped out a bit more than 120W.

[gdement]

Re: PSU no start on some PCs, ok on others

If it was part of a complete package, then it may have been optimized for the load requirements of a particular motherboard. It may be fine on a certain Athlon board, but not provide any headroom to just work on any random motherboard you plug into it.

[sleepydog]

Re: PSU no start on some PCs, ok on others

If it was part of a complete package, then it may have been optimized for the load requirements of a particular motherboard. It may be fine on a certain Athlon board, but not provide any headroom to just work on any random motherboard you plug into it.

You'd think that, but actually the Athlon 1.8GHz is the Shuttle the PSU came with. Today I opened it up again, and this time I noticed a few bad capacitors (one leaky, 2-3 slightly bulged), so kc8adu, you got it there (and they are indeed Fuhkkyu, the bad ones are 1000uF, 10V, black - don't know color codes or anything).

Any suggestion on a reliable substitute?

[starfury1]

Re: PSU no start on some PCs, ok on others

well I don't know the psu off hand and others are far better to give a definitive answer on this.

although a colour code does exist for polyester type caps "green caps" another common name (or orange drops) is more commonly what you see
I don't think it has been used in years...could be wrong..well not real popular if it is still being used.(they are less then 1uF in value too non polarized...no +-)
(really the above is for clarity rather then saying they don't exist)

With "Electrolytic capacitors" its usually marked on the can.
The capacitance Value UF and the
Working Voltage also the
Series of caps and usually
who made them (this may take the form of a logo only)

The important thing is if they are "DC filtering Output caps"
they must be Low ESR types

This is possibly one of the few times you can actually go down in "voltage" with a capacitor...normally NEVER do this

the caps are "1000 uF 10V" you can use (provided they are on 3V3 5V rails) 6V3
12 Volt rail will probably have 16 volt caps

So 1000uf 6V3 Low ESR caps are what you need to buy
Such as Panasonic FC's there are a few that would do the job...example only

just a few guidelines on recapping

first question, is it actually worth recapping...some psu's are hazards to start with

normally the problem is space, a lot use thinner (8mm I think) caps
and getting these in a quality cap can be hard.

I think Samaxon make suitable caps in this size.

You can if you think they will fit use larger diameter caps
but this will depend on the actually supply layout
sometimes you can shoe horn them in even if they sit a little high

I'll leave it to those that know
if it worth recapping and what would be best suited
or try searching the posts, there's a fair chance this psu has been posted on before.

with MB and PSU use the right caps...what you get at hobby stores will not cut the muster with most caps that fail with these.

TC forum owner can supply suitable caps and he knows the issues so it worth a PM if you don't want to stuff around

but its up to you what you want to do

HTH cheers