Noname 350w dead

**everell** · 12-18-2010, 04:31 PM

Re: Noname 350w dead

First step, let's see if the 5vsb is working correctly. you will need to plug the power supply in to ac wall outlet. You don't need to short green and black wire to turn on power supply. Just measure between the violet wire and one of the black wires. You should get 5 volts.

When working with a power supply out of the case, be very careful. Best to wear safety glasses as sometimes parts explode.

**bluebear** · 12-18-2010, 04:38 PM

Re: Noname 350w dead

First step, let's see if the 5vsb is working correctly. you will need to plug the power supply in to ac wall outlet. You don't need to short green and black wire to turn on power supply. Just measure between the violet wire and one of the black wires. You should get 5 volts.

Sry, missed to write that down. I had already measured +5vsb and it was
5.04v so its ok.

Best to wear safety glasses as sometimes parts explode.

Hehe, thanks for the hint. I´m going commando at the moment

I might also say that the reason I don´t know the brand or wattage is because the sticker is missing (torn away). On the pcb it is written "atxl-350p 2008".

**goodpsusearch** · 12-18-2010, 05:37 PM

Re: Noname 350w dead

Omg! That power supply looks identical to that Konig that I have:
https://www.badcaps.net/forum/showthread.php?t=10076

It has Nicon caps, DM311 for 5vsb and the same WT751002 monitoring ic.

My power supply had the same problem with yours. 5vsb was ok but the psu acted like shorted when green wire was shorted with ground.

I checked every cap, schottky and mosfet and found nothing bad.

Finally, I replaced the big toroid coil that had some burnt glue on it with another one that I found from a dead power supply:
https://www.badcaps.net/forum/attach...2&d=1280409453

Then the psu worked! I fully recapped it, fan-modded it to run cooler and added some parts to make the input filter complete and there it is:

https://www.badcaps.net/forum/showpo...7&postcount=24

**bluebear** · 12-18-2010, 06:38 PM

Re: Noname 350w dead

Agree!
It looks very much the same. I´m switching the coil tomorrow.
Thanks for the hint goodpsusearch!

**bluebear** · 12-19-2010, 12:05 PM

Re: Noname 350w dead

Switched with a coil that looked like the one I have.
No change, still dead with a fan twitch. I will most likely switch back to the original coil.

**goodpsusearch** · 12-19-2010, 01:59 PM

Re: Noname 350w dead

I'm sorry that didn't work for you...

You say you have already tried to power it with load connected to it..

I would check the solder side and every output rail for possible shorts.

**PCBONEZ** · 12-19-2010, 02:45 PM

Re: Noname 350w dead

power it with load connected to it
........ with load connected to it

**bluebear** · 12-20-2010, 05:57 PM

Re: Noname 350w dead

Originally posted by PCBONEZ

power it with load connected to it
........ with load connected to it

I have always tried with a cdrom and a hdd connected. Made a test with moterboard hooked up today, still no dice.

**Agent24** · 12-27-2010, 01:55 PM

Re: Noname 350w dead

Originally posted by bluebear

One coil on the output side seems to have been slightly overheated since some glue on top of it has turned black.

Perhaps the glue has gone conductive and shorted something out. Have you tried removing the glue?

**everell** · 12-28-2010, 08:14 AM

Re: Noname 350w dead

I have built a handy tester for troubleshooting power supplies. See this thread:

https://www.badcaps.net/forum/showth...hlight=everell

When using this tester, you will notice that when the fan twitches, the LEDs also blink. In my experience, when you have problems on the primary side (switching transistors, mains capacitors, bad transformer) the LEDs don't blink, and fan doesn't twitch. When LEDs do blink, problems are usually on the output side.

Sometimes, one of the LEDs doesn't blink, but the others do. The nonblinking one points to which rail is giving the problem. I have fixed several psu which had 3.3 volt rail not blinking, and the regulating transistor in the 3.3 volt circuit was the culprit.

**bluebear** · 07-05-2011, 01:01 PM

Re: Noname 350w dead

Originally posted by everell

I have built a handy tester for troubleshooting power supplies. See this thread:

https://www.badcaps.net/forum/showth...hlight=everell

When using this tester, you will notice that when the fan twitches, the LEDs also blink. In my experience, when you have problems on the primary side (switching transistors, mains capacitors, bad transformer) the LEDs don't blink, and fan doesn't twitch. When LEDs do blink, problems are usually on the output side.

Sometimes, one of the LEDs doesn't blink, but the others do. The nonblinking one points to which rail is giving the problem. I have fixed several psu which had 3.3 volt rail not blinking, and the regulating transistor in the 3.3 volt circuit was the culprit.

I know this is very late, but things came between. I checked and both 12v and 5v comes up, but 3.3v doesn´t. I will check the regulating transistor. Any idea where it could be?

**Th3_uN1Qu3** · 07-05-2011, 02:29 PM

Re: Noname 350w dead

Originally posted by bluebear

I will check the regulating transistor. Any idea where it could be?

It's on the secondary heatsink next to the 12v and 5v schottkys.

**bluebear** · 07-05-2011, 03:14 PM

Re: Noname 350w dead

Originally posted by Th3_uN1Qu3

It's on the secondary heatsink next to the 12v and 5v schottkys.

2x SB20100CT Dual Schottky barrier rectifier 20A (12v)
2x STPS 2045CT Schottky diode 10A (5v)
1x MOSPEC S30D45C Dual Schottky barrier rectifier 30A (3.3v)

No voltage regulator, is the S30D45C acting as one?

**Agent24** · 07-05-2011, 05:13 PM

Re: Noname 350w dead

I don't think switchmode PSUs typically have any regulators on the output. Just the rectifiers and then some filtering capacitors etc.

The voltage control is done by the main controller IC that takes feedback from some or all of the rails.

I would check that S30D45C for being open-circuit.

**bluebear** · 07-05-2011, 05:30 PM

Re: Noname 350w dead

Originally posted by Agent24

I don't think switchmode PSUs typically have any regulators on the output. Just the rectifiers and then some filtering capacitors etc.

The voltage control is done by the main controller IC that takes feedback from some or all of the rails.

I would check that S30D45C for being open-circuit.

Yes, you are right! Can´t belive how i could have missed this.
Its short on all legs. Have to find a replacment then. Not that easy.

Edit: Could this be the right stuff?
http://cgi.ebay.com/ws/eBayISAPI.dll...ht_1728wt_1306

**Agent24** · 07-05-2011, 05:45 PM

Re: Noname 350w dead

Looking at the datasheets it should be OK.

If anything the Vishay looks slightly better on paper than the Mospec.

Maybe a bit expensive for just one PSU but then you are getting 10 of them so not a bad deal.

I think though these rectifiers are fairly generic so anything with the same or better specifications should work...

**c_hegge** · 07-05-2011, 10:59 PM

Re: Noname 350w dead

I think that it will be fine. The only thing to bear in mind it that it could be physically bigger than the original, so you may have to bend the two outer legs inward slightly, but it will still work. I did that when I re-built my 400W Rexpower PSU with both the 5v and 3.3v rectifiers and the primary switching transistors.

**PCBONEZ** · 07-05-2011, 11:51 PM

Re: Noname 350w dead

When you have to bend leads for a different spacing make sure they fit smoothly into the holes so the leads are not being pulled to the side in the cap's bung once it's mounted.
Want no side pressure on the rubber.
Can cause leaks over time.
.

**Th3_uN1Qu3** · 07-06-2011, 12:18 AM

Re: Noname 350w dead

Originally posted by Agent24

I don't think switchmode PSUs typically have any regulators on the output. Just the rectifiers and then some filtering capacitors etc.

Some do, some don't. The ones with the second coil for the 3.3v rail have one, but it's still a switching regulator. It's called a "magamp regulator" and it uses the coil as both energy storage AND the control element. There is a second coil in that PSU - you typically find a 40A MOSFET for the 3.3v rail.

Noname 350w dead

Noname 350w dead

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