Fsp300-60btv

[golemmaster]

Ran across this FSP300-60BTV. Won't always power on when connected to a mainboard (D845EBT). Replaced it and computer works fine with another PS.
Opened the FSP and saw this (see pics). Looks like a big resistor with heat shrink on it. With age or heat or both, the tubing split and took the enamel with it. I don't know if this is the PSs problem or if it is just cosmetic. The resistor measures 7.5 Ohms. Since the enamel is gone I don't know what the value is supposed to be.

What do you think?

Caps look fine, BTW.

[momaka]

Re: Fsp300-60btv

See what it's connected to. Most likely it's a loading resistor for one of the rails.
The resistor next to the gray (PG) wire seems to have been running hot as well. Probably another load resistor again. Make sure it's not touching the case when it's closed as the enamel seems a bit chipped on that one too.

Perhaps if they really are load resistors, maybe they're providing some type of quick minimum load for the PSU to start. But again, see what they're connected to.
Also, have you checked the caps? Check the 5vsb voltage too.

[yanz]

Re: Fsp300-60btv

maybe that just a load resistor for +5V rail. on some 300-400W FSP, i just remove them. they can be destructive to the component nearside it.

like momaka said, recheck again. and be aware of minimum load issue if you remove it.

see my thread :
https://www.badcaps.net/forum/showthread.php?t=7202

[golemmaster]

Re: Fsp300-60btv

Just read through your thread.
Thanks bunches. Good info.

I'll poke around a bit more.

Since the power-on problem is intermittent, it's difficult to diagnose without more tools (and knowledge).

[golemmaster]

Re: Fsp300-60btv

Without the big resistor, voltages measure:
12@10.9-11.0, 5@5.25, 3.3@3.47
12 is very low, others a little high
without the smaller resistor, won't power on. even with a load on 3.3 or 5 externally.
WITH both resistors, power on fine, voltages better. 11.65, 5.01, 3.46
Both get darned hot. might need to relocate them away from other parts and wires, maybe onto a heatsink.
+5vsb runs at 3.46.
The dummy load I have only loads +5 and +12.

I think all my messing with it, desolder/resolder, may have taken care of the original problem. There was a questionable joint on the smaller resistor. Now I wonder about that 5vsb.

[370forlife]

Re: Fsp300-60btv

5vsb is probably whats causing the intermittent failures. May need to poke around there and see whats up.

[golemmaster]

Re: Fsp300-60btv

I also have a SPI FSP300-60GT whose 12v is at 11. Everything else is good. 5vsb is at 5. Caps look good.
I guess I need to take these things apart and check parts out of circuit.
I also need more spare time..... These are things I'm trying to learn... I value Your help.

[golemmaster]

Re: Fsp300-60btv

The 60GT also has a very low -12 @-10.3

[golemmaster]

Re: Fsp300-60btv

I don't get it..... I haven't done anything to the 60GT but run it and probe with my DMM. now 5 is @ 5.52 as well. Jeez!....

[PCBONEZ]

Re: Fsp300-60btv

Put more load on it when you check voltages.
If there is no load there is no current to regulate so it won't and the voltage will be off.
Try two hard drives on 4-pin drive connectors and maybe a fan.
With load 12v should go up and 5v down.

[golemmaster]

Re: Fsp300-60btv

The dummy load is an old antec load with PG switch. It's got a couple of big resistors on +5 and +12.
Here's a pic...

[370forlife]

Re: Fsp300-60btv

We use that same psu tester in my computer tech class. It only puts like a 10W load on each rail. Not enough.

[golemmaster]

Re: Fsp300-60btv

40 Ohm on +12, 10 Ohm on +5.
OK.
The answer is always... MORE POWER!

This thing has always been sufficient in the past.... why would it not be now?

[370forlife]

Re: Fsp300-60btv

Its really only designed to just be enough to get past any minimum load requirements on power supplies, which are typically 1A on each rail, and really only on cheaper, older psu's.

These older psu's are not designed to really work under anything less than about 50W.

[golemmaster]

Re: Fsp300-60btv

On the 60GT, I plugged up 4 HDs in addition to the dummy. Voltages are pretty normal. 11.9, 5.1, 3.4, -11.8, -5, 5.02vsb
Thanks.
I'm going to explore modifying that switch with more load and on other rails.

Now back to the 3.45vsb on the 60BTV. Hmmm.

[PCBONEZ]

Re: Fsp300-60btv

See!!

[golemmaster]

Re: Fsp300-60btv

Alrighty, then! I moved and mounted those resistors to a heatsink where the fan can cool them and are away from wires and things. (see pic)
I poked around some more... following the 5vsb traces... replaced a cap that looked fine but failed ESR. <YEC> 470uF 16v SH105C
5vsb is now at 5.12.
I'm a little concerned that 3.3 is at 3.51 but I don't have a load on that rail.

I don't need this PS. I was using it for experience. And now I have it too.
This may be trivial to you guys but it's another valuable lesson and gives me a needed feel-good-satisfaction in an otherwise frustrating work day.

Thanks for listening and for the advice.

[meicol]

Re: Fsp300-60btv

Hello .. was I reading everything and ultimately R3 which was his value? It was his purely aesthetic aspect or I replace it and for which.
I have the same problem this totally without his coverage like that that I do not see anything of what they were his values.
I need help !!!!
thank you