Polaroid FLM-2601 - Power Supply keeps blowing fuse

[drpj23]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Well replaced the diode, and same results as before.

Do have standby light and 5v STBY but no main output (.25v).

Tries to cut on but reverts back to standby

[budm]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

So what resistance reading do you get between Source and Gate now, it was really low last time with the shorted Diode, it should be around 4.7K.

[drpj23]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Yep, 4.69kohm

[budm]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Well, I think the SMPS IC will be the next thing to try.

[drpj23]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Could you perhaps guide me on doing that?

[budm]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

You will need to get that SMPS IC NCP1207 as I post the spec sheet on post 46.

[drpj23]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Alright, I'll let you know when it's in.

[drpj23]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Ok so parts came in....as I began to de-solder....I noticed I never soldered back down pin 5 ......so I feel very special right now.

Anyways, life is back in the TV except for one problem, the backlights are flickering on and off. The 24v rail is there but is jumping around 21-23v

[budm]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Great, I was so worry that the new IC will not fix the problem.
Is the DC voltage on the large DC filter cap (250~450vdc) also fluctuating?
I worked on Insignia last month after replacing the secondary power supply caps, turn it on and the backligts were flickering, I jump the main DC filter cap with another cap, the flickering stops. The ESR of the bad cap was 3 Ohms, but enough to cuase problem.
http://s807.photobucket.com/albums/y...cpZZ1QQtppZZ20

[drpj23]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Yes it is also fluctuating between 380 and 400.

The main cap had .3ohm. But to rule that out, I put another chemicon cap in with no change.

I have replaced all the caps (except one I missed (47uf 25v) since it was in heat shrink.) but I put one with .1ohm to replace it (I had sitting around). There was also a resistor beside the main cap that read half of what it should have been and replaced that as well but there is still no change.

I should also mention that the p/s is squealing too.

[drpj23]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Without a load, it tests steady on the cap and output and there is slight hum from the transformer.

Well for kicks (I had replaced the 11N80s with new 11N60s) I put back the 80s and put it back in the TV and well the fuse blew.

So took those back out (tested fine) and put the 60s back in. Put back in the TV and we have same symptoms as before post fuse.
The diode is still ok and resistance is still there, plugged back up without a load and it tests OK; steady 23.55V and 380 on cap.
Resistor I replaced is actually OK, was just coming up weird due to bad connection.
This is where I am at.

[ben7]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

Without a load, it tests steady on the cap and output and there is slight hum from the transformer.

Well for kicks (I had replaced the 11N80s with new 11N60s) I put back the 80s and put it back in the TV and well the fuse blew.

So took those back out (tested fine) and put the 60s back in. Put back in the TV and we have same symptoms as before post fuse.
The diode is still ok and resistance is still there, plugged back up without a load and it tests OK; steady 23.55V and 380 on cap.
Resistor I replaced is actually OK, was just coming up weird due to bad connection.
This is where I am at.

Were the 11N80s short circuited?

Have you checked the secondary rectifiers?

I see that you took the heatsinks off the PSU. When you test it, be sure to put them back on (if you haven't), and be SURE the correct MOSFETs and diodes are insulated from the heatsinks!

Have you checked the snubber diode yet?

-Ben

[drpj23]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

On the diode setting, the sec rectifiers come up .31 in one direction for each diode.
And I have not checked the snubber yet partly because I have no idea where that would be. But I have checked all the diodes on the board and all on the meter seem to be OK.

[Mega]

Re: Polaroid FLM-2601 - Power Supply keeps blowing fuse

I'm working on one of these power supplies. I'm searching for parts and the MC33260D is listed as obsolete at mouser. I can't find the chip anywhere. Is there a place to get parts that are out of production? I've used the cross ref at mouser and onsemi.com. But they only cross to other obsolete chips.