Kapanadze Cousin - DALLY FREE ENERGY

[AlienGrey]

  Hoppy, Itsu:
  I have been trying to repair my fairly new feed back power supply, which has blown.
  Although I had ordered a 110-220v to 24v PS, I got only the 110v to 24v one. And this one has a fan, which really I did not want.
  Anyway, so I over voltaged it, and burnt up the bigger filter caps, which blew their oil all over. I have since replaced the two big 240v, 470uf caps, and pulled out and tested the switching transistor (mosfet) which seams to be ok. But, only 7v is getting to that mosfet (single fet), and it won't switch. Any ideas as to what to do about it would be great.

Nick Hi !
I use to get loads of this stuff in for repair and (3 phase controllers (much easier to earn money on ) Anyway your text says 'universal' any way looking at your bare board I see a switch by the large caps!  what you need to do first is check the voltage going to the chip !
if it's a spray on blob, your working a 'bit' in the dark but no bother.

Now how good at electronics are you ? each time you power the thing up you need to discharge the caps or other contraption of choice, connect a bulb across it!!!

because I can step you through some repair tricks if your interested but i don't want you
to bad mouth me if you kill your self because you need to make a list of what you do as if we fix it you have to put it back.
I have to say that, but your a big boy now you can do it and learn a new trick in your arsenal about how PW-P works first hand.

Any way first of all find what the chip supply voltage should be with your meter and then trace back to see what the switch does
withe the capacitors.

Or find the main dropper resistor (disconnect any mains input first)  and power the chip with your variable power supply
monitor the Fets Gate or IGBT's Base input see if control goes active (but it might have other lock outs other than under voltage)
what your trying to do is see if the device still alive.

[NickZ]

Nick,

For starters what DC voltage do you read across the caps and how did you test the mosfet?

  The problem seams to be in the input filters and full bridge rectifier at the very input of the PS. I replaced the yellow 0.1uf cap, already, but it still won't fire up. There is also a small brown cap next to the NTC, which has a number on it, of 392, which might be bad. Only about 4v DC come out of the bridge rectifier. So, the same is on the big filter caps.

  I tested the power mosfet by pulling it out and tested it with a multi meter, same as I do the IRFP260N fets that I use on the induction circuit of my device. It is not shorted out, and seams ok.
   The voltage at the 240v caps is very low, about 4v. Same as on the mosfet gate.
   The switch on the side is for changing from 12v to 24v output. Not for changing the input voltage.
   It looks like there is not enough voltage going into the device through the input filters, and rectifier. Although it is getting 120v from the mains. Voltage at the full bridge rectifier DC side is very low, 4v,  and can mean that that rectifier may be bad.
   I'm not very good at trouble shooting and repairing bad electronics. But, hopefully I'll get this PS working again.

   AG: what "chip" are you talking about?

[Hoppy]

Nick,

Sounds like you have a blown FWBR. If you decide to replace this, then do not power up by plugging in directly to the mains. Get hold of a mains lamp holder and connect this in series with the live conductor. With say a 60W bulb in series, you will see if there is a short circuit, as the bulb will fully light and you will save futher damage to the PSU. If all is OK, the lamp will flash on connection and go very dim or out, assuming there is no load on the output. There could still be damage but an overvoltage at the input often just takes out the caps and FWBR. You should measure around 170V across the caps assuming they are connected in parallel. If in series, then half that across each. Be very careful as these caps will hurt you if connections are accidentally touched!

The PWM chip is seated on the rectangular green strip, bottom RHS of PCB and can look like a black blob.

[NickZ]

   Yes, I hope that it all it needs. I've already replaced the two big 470uf caps, and the 0.1uf input filter cap.
   My older PS is 110v to 220v, so the rectifier is different, and can't be used to replace the one on the new PS.
   I'll look for another 110v rectifier in my junk pile, first, one that fits the PCB on the new PS. And report back.
   The small green rectangular board has a chip on it, but no black blob.

[AlienGrey]

Nick,

Sounds like you have a blown FWBR. If you decide to replace this, then do not power up by plugging in directly to the mains. Get hold of a mains lamp holder and connect this in series with the live conductor. With say a 60W bulb in series, you will see if there is a short circuit, as the bulb will fully light and you will save futher damage to the PSU. If all is OK, the lamp will flash on connection and go very dim or out, assuming there is no load on the output. There could still be damage but an overvoltage at the input often just takes out the caps and FWBR. You should measure around 170V across the caps assuming they are connected in parallel. If in series, then half that across each. Be very careful as these caps will hurt you if connections are accidentally touched!

The PWM chip is seated on the rectangular green strip, bottom RHS of PCB and can look like a black blob.

Yes that's what I think and yes the blob on the green board does the housekeeping can you put a 15w night light bulb across the caps if you have that switch on 110v and you put 240v on it did you see any arching ? you could have had nearly 900v you need to test everything on the board
I bet the PW TX didn't like that but if your lick you might get away with it, but test everything else for damage .

You can test fets if you put voltage across gate and sauce with a meter or a cap meter should be about 2nf and make sure it turns on  and off,
or we will be sending Hoppy out 

PS be sure to check out those blue tings!