help please - antec trouble!(not caps)

[stj]

hello.
i'v been reading here for months, but just registered by need!

i'v got a couple of psu's i'm repairing that are trouble.

1: Antec smartpower sp-500p
PFC fet shorted and desroyed the pfc choke!!!
anybody know the current and henry rating?
or have a spare?

also the soldering is the worst i'v seen in years!
so bad that a resistor is missing!
on the low-voltage side in one corner are 4 chip components in a line.
1 cap & 3 resistors.
the endmost resistor is prefixed "R63a" and *missing*
anybody know the value of it?

these smartpower crap use sleeve-bearing fan's btw!

the other psu is a Thermaltake pure-power 480APD

there is a small upside-down board over one side that has carbonised a resistor, a diode and a chunk of the board.

i'll need to foto this, does anybody have any experience with this psu model?

merry x-mas btw.

[Toasty]

Re: help please - antec trouble!(not caps)

re: SP-500P -
Does R63A have a red dot of glue? Flat or pointy? Very odd for one to -fall- off.

Best bet is to get a dead one and swap parts. The shorted FET may be the result of a failed mains filter cap or other component. Odd the fuse didn't catch this.

Pics please.

[stj]

Re: help please - antec trouble!(not caps)

it took the fuse to hell with it.

R63a was there, the glue is missing and took a patch of the green laquer with it - also i can clearly see the rectangle imprints in the solder.

maybe the guy i got it from caught it on a screw-post taking it apart for a look.

getting a dead one - i did - this is it.
no chance of seeing another - nobody i know buy's antec anymore thanks to a combination of this forum and the price.

Btw, how good are superflower? i know a few people with them who have run them fine for several years.

[Toasty]

Re: help please - antec trouble!(not caps)

I meant a dead one from Craig's list or Ebay or a swap meet.

Put it up in the -wanted- thread. Maybe a member has one sitting in the junk shelf.

What are the numbers on R62 & R63? I have a SP-450 here that matches your layout. Understand that these are factory applied variable values that are used to set voltage or current. 2 resistors in parallel to "trim" a particular setting. Cheaper than trimpots.

Pics

[stj]

Re: help please - antec trouble!(not caps)

i'l open it again - maybe a nice cermet-trimmer would be a worthwhile upgrade.

i de-wound the inductor now - 73turns of 1mm copper.
and sanded the burned paint & laq off of the ferrite ring - so i'll re-wind it.
that just leaves this damned resistor.

[Toasty]

Re: help please - antec trouble!(not caps)

Adventurous soul, aren't we?

If that core is indeed ferrite (how do you know), and it has been substantially overheated, the magnetic permeability (Mµ) will have been affected. That means no matter what you do in rewinding, the end result will not be correct. If it was a minor overheat and just crisped the wiring, you may be okay. If it's a powdered iron core, you're okay as they are not generally affected by overheating.

Trimmer does no good as it's not an adjustment that needs to be made. It is factory set and should be left alone.

>>that just leaves this damned resistor.<<
...and the MOSFET, and input cap, and relubing the fan, and......

All this for a $35 PSU.............?

Toast

[stj]

Re: help please - antec trouble!(not caps)

not $35 in Europe i can tell you - more like €50+

the inductor had got so hot that the laq had turned black and fused to the core instead of the wire.
i can easily get another core from some junk.

the resistors are:
r64 = 2k
r63 = 12k

[stj]

Re: help please - antec trouble!(not caps)

oh yea, i already binned the filter caps - they were branded "fukyu"

[Toasty]

Re: help please - antec trouble!(not caps)

R63A = 10kΩ

The 3 resistors and the cap are in parallel across the base lead of the H945 transistor (right next R63A) to ground. Their measured value on my 450 is 1.44kΩ. The -calculated- value is 1.463kΩ.

The transistor emitter feeds the 3.3v OV/UV signal through the zener diode ZD2 to pin 5 of the TPS3510 supervisor IC.

You are sure the coil is the PFC coil, correct?

Check the diodes around that coil and FET(s) too. One (I think) is mounted on the heatsink.

Toast

[Toasty]

Re: help please - antec trouble!(not caps)

Pics of the area:

[stj]

Re: help please - antec trouble!(not caps)

that's exactly what i needed! thanks.
and an easy value to scavenge too!

yes, the pfc coil and the pfc fet on the end of the heatsink IRFC460A
i'v already pulled them and all the electrolytics off.

i'm making a list to recap an sp, a tp2 and a couple of fps's at the same time.
then i'm going to look at my ac-bel i pulled from a powermac-G3 & converted to atx.

that's running my athlon used to post this msg till i sort the fsp's, it runs fine but it's had a hard life so i dont want to push my luck with it.

[stj]

Re: help please - antec trouble!(not caps)

already checked the pfc diodes btw, they look fine when cold.
i'm more concerned about the i.c. that drives the fet - the fet was shorted pin2pin.