Need suggestions repairing PSU

[SaiZo]

Just out of curiosity - what brand/make and model is your PSU? Can't find that information.

 

[grandpatzer]

this one: http://www.rwlabs.com/article.php?id=572

 

[grandpatzer]

so on another forum I was told it could be a NPN transistor, still not sure if its PNP or NPN.
however Elfa has 26 different NPN transistors and they are all rather cheap:
https://www.elfa.se/elfa3~se_sv/elfa/init.do?toc=19098&name=transistorer_med_integrerade_motstand

 

[de.das.dude]

:s going by the thread, i see that you lack experience in working with electronic components....

the first thing you should have done to "fix" the loosening of the green pcb is to take a small wattage needle pointed soldering iron and touch the point where the green pcb was mounted. that would have reflowed the solder and eliminated any cracks..

you have to be pretty clumsy while fitting it all back to not notice that the fan was too big and was hitting the pcb. nothig much can be done at this point, hope it works without that component.

i just read that you failed at soldering it and that you melted the component itself,.... so its impossible to even know what the component was....

if you knew what it was, its possible to fix it back with some delicate insulated copper wire and very intrinsic soldering. but that would require someone with a lot of practice and steady hands.


this doesnt pertain anyway to the topic, but i dont like those temp adjustable expensive ones. those are really for the uber elite class of people who solder day and night. the prob is they are high wattage usually and will maintain the tip at specified temp as constantly as possible. no problems when soldering continously/heavy stuff, but when it comes to delicate stuff like small LEDs, SMD components, thermally sensitive components etc, they are bad. For that type of applications a good 10 -15W iron does the job good for amateurs as it can only transfer a "fixed" amount of heat to the component before cooling down itself hence preventing melt down of delicates (pun intended)

 

[grandpatzer]

:s going by the thread, i see that you lack experience in working with electronic components....

the first thing you should have done to "fix" the loosening of the green pcb is to take a small wattage needle pointed soldering iron and touch the point where the green pcb was mounted. that would have reflowed the solder and eliminated any cracks..

you have to be pretty clumsy while fitting it all back to not notice that the fan was too big and was hitting the pcb. nothig much can be done at this point, hope it works without that component.

i just read that you failed at soldering it and that you melted the component itself,.... so its impossible to even know what the component was....

if you knew what it was, its possible to fix it back with some delicate insulated copper wire and very intrinsic soldering. but that would require someone with a lot of practice and steady hands.


this doesnt pertain anyway to the topic, but i dont like those temp adjustable expensive ones. those are really for the uber elite class of people who solder day and night. the prob is they are high wattage usually and will maintain the tip at specified temp as constantly as possible. no problems when soldering continously/heavy stuff, but when it comes to delicate stuff like small LEDs, SMD components, thermally sensitive components etc, they are bad. For that type of applications a good 10 -15W iron does the job good for amateurs as it can only transfer a "fixed" amount of heat to the component before cooling down itself hence preventing melt down of delicates (pun intended)

you clearly lack any reading comprehension but anyway thanks for trolling me

 

[SaiZo]

You could always try the last solution.. Not even sure it will work.. Take a picture of the PCB where the SMD was, and send it to rwlabs, and ask them the specs for the component.
If I knew what to look for, the chances of me having the same component would be 50/50 - but you would get it for free (could have sent it by mail).

I know those are tricky to solder, I have done it once or twice, last time was on an Opticon device. Not only do you need steady hands, but get something that can magnify when you are soldering the component.
For this reason, I have several soldering irons. Two of them are electrical, 175w & 30w and the third one uses butane. I bought extra tips for that one, just so I can make them as tiny and "sharp" as possible.

Usually I glue them on first so that something is holding it. Then I solder the "feet" to the PCB. Oh, and get one of them "helping hands" with a magnifier, might not look like much but they are great.

Good luck!

 

[grandpatzer]

On another forum a user thinks the LG is label for Toshiba, 2SC2712, according this manual the G stands for DC current gain hFE.
Toshiba datasheet

In that case I think a BC846 Transistor might be correct?
There is 3 transistors on Elfa, difference are 330mW, 250mW powerdissipation, and marking is Marking 1B, Marking 1B* , Marking 1Bs
Infineon sold on Elfa NXP sold on Elfa Diotec sold on Elfa

One problem is that it has 65v while the toshiba is 50v, not sure if that is problem?

 

[grandpatzer]

It would be helpful to see pictures of your psu. You should measure voltage I guess, or current, to see if it goes from one point to another, I mean to see if the current is "travelling" from point a to point b and everything is intact. But since you said the psu isn't powering on, something, somewhere must have broken.

You mean that the fan header (white one, picture two), was pushing down the PCB with force?
I guess you could add new solder to the parts that are "loose", but make sure that the PCB itself isn't damaged.
Had similar issue with the transformer on an HP screen a week ago, the power in socket was loose, but the PCB was too damaged to be repaired.

Try not to get a shock or start a fire, I know that the insurance companies here in Sweden are a pain in the @$$..

I don't know what exactly happens. You could simply lose one of the protections. Or your PSU could output wrong voltages and potentially damage your other hardware. You can't know without trying. You could even fry some other components of your PSU, further damaging it and reducing chances of successful repair.

You can try the PSU without the broken transistor, and it should actually output 5VSB (5 volt standby), even if the secondary doesn't work properly. Just don't try it on your hardware without checking if standby works (purple-black) and trying to jump-start it by shorting the green wire to one of the black ones, then measuring between yellow and a black (12V), red and black (5V) and orange and black (3,3V). If everything looks fine, you're one step from having a fully functioning PSU.

So on another forum a user suggested me a transistor which seems like he knew was the correct one.
Are these correct steps for me now?

Those are just different brands selling the same chip. The B version should work for you as well, the A doesn't have enough gain. Pick one and go.

I have ordered the transistor, I should have it nextweek for soldering

I want to be sure to have tested as good as I can before installing my PC components to the PSU, so besides these steps are there others to take?

1: Solder and assemble PSU
2: plug into wall PSU and with multimeter measure ATX 24pin Black + Purple, result should be between 4.75 and 5.25V
3: Measure Yellow and Black, should get 12v
4. Red and Black 5V
5. Orange and Black 3,3V
6. Install a fan and harddrive to PSU see if they start.
7. install PSU into PC?

 

[SKBARON]

If you have any old pc parts you don't mind losing, test the psu on those, if anything goes wrong at least you won't fry your system. But it should work alright after you solder that sucker back in place .

 

[grandpatzer]

If you have any old pc parts you don't mind losing, test the psu on those, if anything goes wrong at least you won't fry your system. But it should work alright after you solder that sucker back in place .

thanks that makes sense, Phaedrus suggested me the transistor, he was not 100% sure about it,
however
I know he knows about psu's so I'm hoping he's correct about the transistor.
I have ordered the transistor should have it next week.

post17 regarding the transistor:
http://www.jonnyguru.com/forums/showthread.php?t=11159&page=2

So I guess the multimeter measurements and attaching a harddrive to is a good start?

 

[SKBARON]

Yes, those test are a good start, just use a spare or old hdd , you seriously don't want any surprises.

 

[grandpatzer]

Yes, those test are a good start, just use a spare or old hdd , you seriously don't want any surprises.

I finally recieved the transistor and soldered it in, bad news seems when I measure with multimeter I'm not able to get correct readings... only Black purple gives me good readings:
Black Purple: 5.17v on level 20v on multimeter.

Black Red on level 2000m: 0019
Black Red on level 20v: -0.02

Orange black level 200m: 00.5

I also measured Green Black I believe that one was 4.79.

 

[xorbe]

I've been watching this thread with interest, and I'm generally all for DIY fixes, but in this instance, you might not really want to go repairing a power supply without proper knowledge, due to danger of fire.

 

[johnspack]

I hope there was not too much stress placed on the pcb when this happened, there could be breaks in traces in levels you can't see. Sorry, just glanced at this thread, normally I'd just chuck it out and start again. If you're sure it's just a top layer component, then go for it.

 

[grandpatzer]

I hope there was not too much stress placed on the pcb when this happened, there could be breaks in traces in levels you can't see. Sorry, just glanced at this thread, normally I'd just chuck it out and start again. If you're sure it's just a top layer component, then go for it.

My soldering tip is a bit too big for this job, it took me long time to solder it, I might remove the transistor and hopefuly it works without it there.

Also I think the transistor is not same as the old one because it's physicaly much smaller...