AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

[Per Hansson]

Hi, this has been a difficult PSU to fix.
Came in with bloating Ltec caps and user said PC turned off and then did not power back up. (I did ask if it smelled or smoked but he said no).

I replaced the secondaries with Panasonic FR caps, PSU did not turn on.
I tried desoldering the primary Elite 420v 120uF cap and one leg came off, it had corroded off!
Bought 2x Nichicon PT 100uF 450v caps on eBay, because the Swedish stores wanted just silly money.
I actually think I scored originals at only $2 plus $4 in shipping, very nice! (Price including shipping for only one in Sweden would have been four times that!)

Tried powering up again but nothing, realized the fuse was blown so I replaced that.
Tried powering up again and then the fuse in my main breaker shut off!
So now I've desoldered and tested the bridge rectifier, that checks out good.
But there is a short when I measure with my multimeter on the primary side where the bridge rectifier was taken out of the circuit, not good!
So I desoldered the primary side heatsinks and MOSFET, I have one Toshiba K2698 that is completely shorted (Removing that from the circuit made the primary side then read open).
Next to it is a Toshiba K2749 that might be bad, I am not sure.
When I charge it with my multimeter in diode test mode from source to gate I do get a reading when moving the positive over to the drain.
But it disappears after only 2 seconds, is that normal? (Tried Fluke 113 & CHY 17 multimeters)

What can I replace these with?
Can I just scavenge a MOSFET from some trashed computer at work and hope for the best?

[everell]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Your power supply has APFC, a circuit called Active Power Factor Correction. My experience with APFC fuseblowers has been:

Comes with fuse blown and one of FET transistors shorted. Changed fuse and FET then powered up. Blows fuse and FET transistor again. Problem....intermittently shorting booster coil. Replaced booster coil, FET transistor, and fuse. Power supply works again.

These power supplies are made as cheaply as possible. So the quality of the booster coil is not the best in the world. Some of them get very hot while in operation (don't touch it while power is on or you will get shocked). If it looks like coil winding is burnt, especially at the bottom of the coil where it solders into the pc board, then there is a good chance you are getting an intermittent short.

[Per Hansson]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Thanks for your input, I'm thinking it could be a better move to buy the same used known working PSU on eBay and then simply move my new capacitors over to it...
(Rather than spend more money on components and hoping they don't blow up).


The PSU looks very good though, no burnt coils or components, even the PCB looks very nice for being manufactured in 2007.06.22 and subsequently in use since then...
I scavenged a PSU at work today that I thought the components looked the same in but they where actually 2SC2625, me thinks that is not a drop in replacement

[LDSisHere]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Here are datasheets I found in case you do not have them already.

[Per Hansson]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Thanks LDS, I must have found the wrong PDF before, the 2SC2625 does not look like such a bad fit afterall, anyone else disagree?
I think I'm gonna try it when I get home today and see if it goes

[Per Hansson]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Well it took a few days more because I did not find another pigtail fuse.
But I decided to ghetto mod a normal glass fuse with legs today, it worked fine but it was a real PITA to do!

To my surprise the PSU did not become a smoke generator or trip my main breaker when I connected it to mains, and even the green LED lit up!

It even powers on when I short the green ATX pin to ground!
Bad news is that voltages are out of whack, is it due to the replacement MOSFETS I used maybe?
(Original K2698 & K2749 where replaced with 2x 2SC2625)

5vsb = 5.0v
3.3v = 3.33v
5v = 4v
12v =10v

[LDSisHere]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Could you post some better pictures of the top and bottom of this supply? I do not know if I can help but I would like to try.

Although I think the 2SC2625 are fine for testing I am not sure that I would want to run with them if it was me. They have a lower voltage rating and higher switching times. I am not saying this is the source of your voltage problems, just pointing it out.

How well did you check for damaged components downstream from the shorted FET? Is it possible there is a leaky diode or transistor somewhere that could be causing this problem?

[Per Hansson]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Sure LDS, I'll snap some photos when I get home today...
My troubleshooting was only to confirm that the FET was shorted, when I measured on the bridge rectifier there was a short between positive and negative...

After desoldering the FET there was no longer a short...
And when putting in the FET I scavenged from another PSU there was also no short any more...

Excuse my ignorance but how do the FET's work? Is one for 5vsb and the other for all other rails or do they work in tandem?

[LDSisHere]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Unless there is a PWM chip for the 5vsb it should have its' own FET which may be the purpose of the K2749 that you removed. It is rated at 7 amps while the shorted K2698 was rated at 15A. Power supplies do sometimes have FETs that work in tandem but they should be identical and would still be separate from the 5vsb.

[Per Hansson]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

There is also a much smaller FET on the board, I never desoldered it and did not check it's numbers, but it's probably for the 5vsb...

[LDSisHere]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

There is also a much smaller FET on the board, I never desoldered it and did not check it's numbers, but it's probably for the 5vsb...

I think you are correct about this smaller FET being for the 5vsb after looking at the PCB. A 7A FET seemed like over kill for a 5vsb.

I would start by checking the following:

R2 - This is on top of the PCB in heat shrink tubing. I would think it should be less than 2 ohms but do not hold me to this.

R3
R91
D17
D11

These are on the bottom and it may be hard to get accurate readings while they are on the board but you may can at least get an idea if they are OK. I could not make out the numbers on the resistors so you will have to see if you can get their values.

The other thing you may could try is adjusting VR1 to see what effect it has on the output. The problem with this is that it will probably change the 3.3V rail as well and that one is good.

Hopefully Everell will have time to take a look at this as I am sure he would have a much better idea where the problem could be.

It may also be helpful if you could get some shots of the daughter board and the numbers off of the IC's on the supply (top and bottom).

[everell]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

The 5vsb is regulated by a 431 chip. This seems to be working OK.
The 3.3 volts is regulated by a 431 chip. This seems to be working OK.
The 5 volts and 12 volts are regulated by a third 431 chip. Not working OK.

The 431 chip that regulates the 5 volts and 12 volts may be bad. There may be a potentiometer that is not adjusted properly on the voltage divider of the 431 chip, but usually it will not go that low in voltage. You could have a bad resistor in the voltage divider. As LDSishere said, check the resistors for obvious defects. The 431 chips often give troublesome flakey problems, so I would change it for starters.

I just recently fixed a Bestec TFX series which is also one of these small power supplies. Although the problems were different, one thing I noticed was that it had NO load resistors on the 3.3V, 5V, and 12V rails. What are you using to load this power supply while testing it? That could be a part of your problem.

Look at the toroid coil which is used for group regulation in the 5V and 12V rails. Does it look burnt or overheated? This coil can also cause some flakey problems.

[Behemot]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

I think you are correct about this smaller FET being for the 5vsb after looking at the PCB. A 7A FET seemed like over kill for a 5vsb.

That's quite OK. I bet it is forward design with the small transistor as driver and the big one as the power switcher.

[Toasty]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Umm, err.....

Why are you using 2 NPN transistors where 2 MOSFETs belong? You can't draw -any- conclusions other than "nothing else is shorted" using those. You need to switch them to the correct devices. The delay/switching is waaaay too long and is why you see the low voltages.

Look at the tf (fall time) times in the datasheets.
K2698 & K2749 run 50-65ns (0.05µs)
C2625 runs 1µs (1000ns) = 20 times longer!

Please don't run it that way. You'll fry the transformer if you start loading it.

Think of it as trying to run a coil meant for radio waves from your 50 or 60 Hz wall outlet.

K2698 runs the boost
K2749 runs the PSU

T

[Per Hansson]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Thank you very much Toasty, I really did not check the specs before testing other than confirm that it was a FET
I was primarily interested in seeing if it would just blow up from my hack or not
I did check on eBay for new MOSFET's and when I did the search the only one in a sensible price range was not gonna be shipped until Feb 20 due to the Chinese new year...
Of course I searched for the same part numbers, because I'm not sure what a "safe" replacement is... (And also wanted a seller selling both items so I could combine shipping)
Looking at the Swedish site Elfa all I'm finding are MOSFETS costing as much as a whole PSU on eBay!

I just recently fixed a Bestec TFX series which is also one of these small power supplies. Although the problems were different, one thing I noticed was that it had NO load resistors on the 3.3V, 5V, and 12V rails. What are you using to load this power supply while testing it? That could be a part of your problem.

I'm using a dead hard drive (click of death)
It does not even spin at these voltages.
I can't connect much else because the PSU only has two SATA power connectors and a "mini" ATX connector
The PSU's own fan does spin though

Look at the toroid coil which is used for group regulation in the 5V and 12V rails. Does it look burnt or overheated? This coil can also cause some flakey problems.

No coils or other parts look burnt, actually the whole PSU looks quite unused for being made in 2007...

LDS; I guess I should replace the FET's with something more suitable and see how that goes, otherwise maybe I'll just be chasing ghosts

[Behemot]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Thank you very much Toasty, I really did not check the specs before testing other than confirm that it was a FET

You obviously failed here, Toasty clearly said those are NPN. Clasical bipolar transistors, no FETs!!

TBH, they've been somewhat familiar to me, but I've been lazy to check

[Per Hansson]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Edit: Quick (maybe really stupid) question: Could I replace the K2749 with a K2698?
That way it gets much easier to find a seller on eBay, if I only need two identical MOSFET's....

You obviously failed here, Toasty clearly said those are NPN. Clasical bipolar transistors, no FETs!!

And on that bombshell I think I need some coffee! Well I gotta blame something don't I?

[Toasty]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Check with Big "Joe" Pope. After the new Year, he might get you some nice prices.

T

[Per Hansson]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

I would prefer to buy within Europe to speed up shipping, what do you think about using 2x K2698 MOSFET's in the place of the K2698 & K2749?

http://www.ebay.co.uk/itm/2x-Power-T...item35b31b4760

[Behemot]

Re: AcBel PC6013 HP 5188-7521 160w Shorted Blowing Fuse

Joe is not responding to my messages for several months now, for that reason I have also started (and succeded) in finding capacitors directly from manufacturer.

You don't have to necessarily use the same transistors. Just use anything with close enough specs. We have tens of types of FETs in every local shop here, I doubt you won't find anything suitable…