DELL OEM H240AS-00 (HIPRO) ~ major blow up!

[ben7]

DELL H240AS-00
240W
Made by HIPRO

This is a decent PSU, with APFC. It's in some sort of small form factor case, not sure which type. But it's long and fairly skinny.

I recall someone saying to replace a ceramic cap, after I posted pics on the forums of the build quality.
Well, by then, I had already given the computer back to the owner!!! (It was de-virused)

It turns out, it finally blew! So far, it took out:
-STW12NK90Z (Main switching FET)
-680pF 1kV ceramic cap (This is the one that went bad)
-SPW16N50C3 (APFC FET)
-A 0.27 ohm resistor (2W rated I think)
-The control IC (more on this later)
-And various other parts (a few SMD resistors, a transistor, and a diode)
-Oh, and don't forget the fuse! It really took out the fuse in spectacular fashion!

The APFC current sense resistor, a 50milliohm resistor, measures as good. (Well, as far as I can tell. It measures pretty much 0 ohms on my meter, which can't do that low of a resistance)

The APFC diode, a BYV29X-600, surprisingly tests good, along with the thermistor.

The APFC IC is a UCC28019.
It doesn't look burnt, but I might replace it just in case, because the APFC fet was blown.

The bridge rectifier - a GBU606 - tests good as well.

Caps are Elite (APFC filter cap), Ltec and two Rubycon. None are bulging, but I might replace the crapcaps just for good measure ... if I fix this thing, that is!
The date codes on them appear to suggest that they were made in 2012.

The main PWM IC is ... I don't know!
I tried searching for it but couldn't find anything.
It looks like it might have been made by .. ON semiconductor? I dunno, the package marking is familiar though, I've seen multiple PSUs using a similar looking IC. It has a stripe on the end where pins 1 and 8 are.
The markings are:
CPx12A
PLWW
The "x" is where the IC burnt, I think it might either be a 6 or an 8. It's also possible that the 1 is actually an "L" or an "I".

It doesn't have a manufacturer's logo or name on it.
It looks almost like a UC3842 though, with a 10uF 50V cap across pins 5 (-) and 7 (+)!
The burnt pin - pin 6 - is the gate drive pin on a UC3842, which would explain why it is burnt ... because the main switching FET shorted out.

~~~ Now for the pics! ~~~

The badly burnt and blown fuse.
↓↓↓


Overall visible carnage.
↓↓↓


Cracked ceramic cap, and blown resistor.
↓↓↓


The ceramic cap came out in two halves!

(Note this cap was across the STW12NK90Z's D and S pins. No wonder it did so much damage when it shorted out.)
↓↓↓


D53 and R55 are blown.
D53 appears to have "D1" on it, which appears to be a 1N4148W
R55 looks to me like it was a 22 ohm resistor "22R0"
(Note the markings "Hi Volt FET" .. this is the STW12NK90Z for the main switching converter (a forward converter I think?))
↓↓↓


IC301 is the mystery IC, you can see that pin 6 has soot marks around it, and the plastic/resin is bubbled.
R304 is blown, it looks to me like it is a 2K2 resistor "2201"
Q301 tests quite a low resistance. It's marked "1P" which appears to be a 2222A NPN transistor.
IC302 - a TI UCC28019 - doesn't appear to be blown, but it might be.
↓↓↓


P.S. Sorry if the pics are too large, but I downsized them twice already XD
I know how some of us like to see the carnage though!..

P.S.2. The fan is a "Magic" fan by Protechnic.
Rated 170mA at 12V (it's a 60mm fan, 25mm thickness).
P/N MGA6012HS-A25

-Ben

[budm]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

Can we see the pictures of the whole board top and bottom side?
R55 (22 Ohms is about right)/D53 (1N4148 will be fine) is the RD Gate drive network, so the IC that drive the Gate of that MOSFET is more likely to be damaged, yes, I would change it for sure.
The burnt ceramic cap C52 is the snubber cap, the 0.27 Ohms resistor is for the Source of the MOSFET.

[ben7]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

R55 (22 Ohms is about right)/D53 (1N4148 will be fine) is the RD Gate drive network, so the IC that drive the Gate of that MOSFET is more likely to be damaged, yes, I would change it for sure.

The IC that drives that FET is IC301 ... the mystery IC.

-Ben

[stj]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

lol
notes for the sub-board.
r301 - 513 / 51k
r302 - 123 / 12k
r303 - 512 / 5k1
r304 - 2201 / 2k2
r305 - 100 / 10r
r306 - 0
r307 - not fitted
r308 - not fitted
r309 - 914 / 910k
r310 - 223 / 22k
r311 - 821 / 820r
r312 - 623 / 62k
r313 - 392 / 3k9
r314 - 18d / 150k
r315 - 2200 / 220r
r316 - 333 / 33k
r318 - not fitted
r327 - 221 / 220r
r328 - 471 / 470r
r329 - 432 / 4k3

d301 - 1n4148
d302 - 1n4148
d303 - 1n4148
dxxx - 1n4148
z301 - ?
z302 - ?

q301 - mmbt2222a
q304 - ksp2222a
q305 - mps751
ic301 - cp012a
ic302 - ucc28019a (ti)

[ben7]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

lol
notes for the sub-board.
r301 - 513 / 51k
r302 - 123 / 12k
r303 - 512 / 5k1
r304 - 2201 / 2k2
r305 - 100 / 10r
r306 - 0
r307 - not fitted
r308 - not fitted
r309 - 914 / 910k
r310 - 223 / 22k
r311 - 821 / 820r
r312 - 623 / 62k
r313 - 392 / 3k9
r314 - 18d / 150k
r315 - 2200 / 220r
r316 - 333 / 33k
r318 - not fitted
r327 - 221 / 220r
r328 - 471 / 470r
r329 - 432 / 4k3

d301 - 1n4148
d302 - 1n4148
d303 - 1n4148
dxxx - 1n4148
z301 - ?
z302 - ?

q301 - mmbt2222a
q304 - ksp2222a
q305 - mps751
ic301 - cp012a
ic302 - ucc28019a (ti)

Thanks for the info, but I think I'm screwed over on repairing this POS XD

1. The mystery IC is an unobtanium part ... after a LONG search, I found that it cross references to SCY99087 ... which is just sold by 3rd party, chinese vendors.

2. Looking online, it appears other people have had the same PSU fail, repeatedly (after being replaced). Even cases of arcing and smoking while continuing to work!

I think I'll probably end up getting a different PSU and modding the connectors to fit this computer.

I didn't even think of it to check, but I found this thread:
https://www.badcaps.net/forum/showthread.php?t=40726

STJ, you said in that thread to replace the cap with a 2 or 3kV cap ... but why? Why, if the FET is only rated for 900V? Do the higher voltage caps dissipate the heat better due to their bigger size?
Either way, I'd still need to get a replacement CP012A chip ...

-Ben

[momaka]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

... if I fix this thing, that is!

Fix it! (okay, only if you have nothing better to do or just as a challenge, that is)

I suggest to not bother with fixing the APFC circuit - not now, at least.
As for the mystery IC: see how it is connected on that daughterboard. Maybe you can successfully substitute a UC3842/3/5. Or perhaps do so with some modding. A simple UC3842 drive circuit isn't that complex, actually.

For the main FET, you can use whatever you got in your junk bin, as long as it has the same Vds voltage rating. This is for testing purposes, of course. Once the PSU is fixed, use same or equivalent parts to the originals.

And, of course, use the series incandescent bulb trick for all live testing. Unless you like to start New Year's fireworks show early .

[ben7]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

Fix it! (okay, only if you have nothing better to do or just as a challenge, that is)

I suggest to not bother with fixing the APFC circuit - not now, at least.
As for the mystery IC: see how it is connected on that daughterboard. Maybe you can successfully substitute a UC3842/3/5. Or perhaps do so with some modding. A simple UC3842 drive circuit isn't that complex, actually.

For the main FET, you can use whatever you got in your junk bin, as long as it has the same Vds voltage rating. This is for testing purposes, of course. Once the PSU is fixed, use same or equivalent parts to the originals.

And, of course, use the series incandescent bulb trick for all live testing. Unless you like to start New Year's fireworks show early .

Yeah, in fact I have a good STW12NK90Z FET in my transistor box! :P

I'm going to look in a few places to see if I have a CP012A chip ... I doubt it, but I might as well look...


Heh, in the end, I may end up going as far as reinventing the daughterboard using parts that can be bought everywhere (like a UC3842, etc...).
XD

-Ben

[stj]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

The mystery IC is an unobtanium part ... after a LONG search, I found that it cross references to SCY99087 ... which is just sold by 3rd party, chinese vendors.

they arent exactly unobtainium, i charged up the lithiums in my light-sabre, and went to the starwars bar AKA aliexpress and picked up a strip of 10 from some alien scum.

[ben7]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

they arent exactly unobtainium, i charged up the lithiums in my light-sabre, and went to the starwars bar AKA aliexpress and picked up a strip of 10 from some alien scum.

Yeah, I've seen those listings, but I have near zero trust for 3rd party vendors XD

[stj]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

http://www.datasheetdir.com/CP012A+PWM-Controllers

[ben7]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

http://www.datasheetdir.com/CP012A+PWM-Controllers

Yes I already saw that page, that is where I found the reference to the SCY99087, but it seems they still are hard to obtain (excluding 3rd party sellers, that is)

Interestingly, the page for that chip is blank. Well, it seems to connect to the server just fine, but there is no content on the page, just a white background...
http://www.datasheetdir.com/SCY99087+PWM-Controllers

-Ben

[stj]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

go to on-semi and put SCY99087 into the search box and the autocompletion system puts the rest of the code in - so it's theirs.
unfortunatly it then pretends they never heard of it!!

as for your cap question, the cap is hammered by reverse pulse every time the fet shuts off.
higher voltage caps are stronger in general and usually have a lower esr.

[ben7]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

go to on-semi and put SCY99087 into the search box and the autocompletion system puts the rest of the code in - so it's theirs.
unfortunatly it then pretends they never heard of it!!

Yeah, it's strange that they have covered it up. Mouser does the same thing! Search for the exact part, and you get it (they have no info and no stock on it of course!), but search for the 99087 itself, and you don't get it in the results!
It's as if they are hiding it!
EDIT: Perhaps they don't typically list it, because it isn't assigned a Mouser P/N.
Maybe HIPRO has some special deal with ON semi ... who knows!

as for your cap question, the cap is hammered by reverse pulse every time the fet shuts off.
higher voltage caps are stronger in general and usually have a lower esr.

This is a ceramic cap, so it shouldn't complain about reverse polarity, right?
Is the pulse just too high dV/dt?? (Too fast for the cap, because of ESR and/or inductance?)

-Ben

[stj]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

i think it's just a disipation issue.

[momaka]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

Heh, in the end, I may end up going as far as reinventing the daughterboard using parts that can be bought everywhere (like a UC3842, etc...).

I'm thinking that would actually be the easier route if you can't easily obtain a CP012A / SCY99087 PWM IC. Just grab any PSU with single-transistor forward and UC3842/3/5 PWM IC and copy the design of its primary side. And APFC - just forget about it altogether .

[stj]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

btw, have done another since.
i now know what the zeners are:
z301 - 18v 500mw zener
z302 - 5v1 500mw zener

[ben7]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

btw, have done another since.
i now know what the zeners are:
z301 - 18v 500mw zener
z302 - 5v1 500mw zener

Ahh, okay, thanks for the info!

I've since fixed the computer. Sorry for not giving an update until now...
I bought a replacement PSU. I actually opened that up (I know, tsk tsk tsk).
It is different inside. MUCH nicer build quality, it was amazing! Single 12V rail design, with DC-DC converters for the minor voltages.
I'm not sure who built it, as it wasn't obvious.
But it did use good capacitors as well. There were a few CapXons in there, but eh, I think they are fine now. They may be cheap and chinese, but they've obviously changed electrolytes now so they won't go bad as often ...
(A few of the CapXons were polymers, BTW)
(It also used a double sided PCB for the main board, something which I haven't seen very much in computer PSUs.)

I've since salvaged parts that were undamaged from the old PSU. Got a bunch of rectifiers, I think they were something like 3045CT or something similar .. idk, I can't remember XD
Oh and there was a FET on the secondary heatsink of the old PSU. I dunno what it was for, but maybe I can take a look at the PCB again and see if I can figure that out.

-Ben

[Wester547]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

Ahh, okay, thanks for the info!

I've since fixed the computer. Sorry for not giving an update until now...
I bought a replacement PSU. I actually opened that up (I know, tsk tsk tsk).
It is different inside. MUCH nicer build quality, it was amazing! Single 12V rail design, with DC-DC converters for the minor voltages.
I'm not sure who built it, as it wasn't obvious.
But it did use good capacitors as well. There were a few CapXons in there, but eh, I think they are fine now. They may be cheap and chinese, but they've obviously changed electrolytes now so they won't go bad as often ...
(A few of the CapXons were polymers, BTW)

How do you know that? The polymers may be fine. But CapXon will always be CrapXon, I wouldn't count on them to um, "rectify" anything about their manufacturing process. On the other hand, at least you have a PSU that doesn't harbor the same problem as the last.

EDIT: The "capacitor" plague has only gone away on motherboards. It still exists everywhere else. Extra cheap brands like CrapXon don't bother with proper (or any) QC testing or high purity and quality materials, so they will always be inconsistent and unreliable, unless they somehow come under new and better management (which I doubt).

[ben7]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

How do you know that? The polymers may be fine. But CapXon will always be CrapXon, I wouldn't count on them to um, "rectify" anything about their manufacturing process. On the other hand, at least you have a PSU that doesn't harbor the same problem as the last.

Well the more modern CapXon capacitors have been fine in devices like PSUs and such ... it was just those from the bad cap plague era that were a problem.

Then again, yes, I still don't fully trust cheap capacitors! :P

-Ben

[momaka]

Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

Well the more modern CapXon capacitors have been fine in devices like PSUs and such ... it was just those from the bad cap plague era that were a problem.

Not necessarily, IMO.
I have plenty of CapXon KM from the "bad cap" era, and they are all fine. Even used more than a few of them in temporary fixes while waiting for new caps, and they held in fine. I still (re)use them, too.

That's not to say CapXon is good. My junk/blown caps bin is dominated by failed CapXon, Sacon, Chemicon KZG, and Teapo (in order from worst to least worst). Even all of the PSUs I've found with Fuhjyyus have a better track record.