Samsung 24" power supply BN44-00195A first stage voltage?

[budm]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Can we see that picture of that shunt/jumper? Also good pictures of both sides of the board.

[andy2]

Pictures

All right everyone, thanks for your patience, I uploaded the pictures as required. -)

But I should also admit to making few innocent mistakes. I should have a pole in front of my desk with a road sign saying parts numbers on your board don't match the schematic. -)

Anyway - I was to remove the DB803 right? Well, I did remove a DB803 as it was printed on the board - but guess what? I actually should have removed DB804, because that's how those parts are messed up. -)

The damage is clear - it is that jumper I mentioned - before (immediately after removing the PS from the monitor) there was no smoke and that glue wasn't burned. It got burned like that because I connected the power with fuses shorted up and it kept sparking for like 2 seconds.

Now I got the correct diode out, the other one in and I have beautiful 5.2V.
Steady. 166V on the main cap - the PFC is dead. It will be dead even with the diode in because I took that broken QP801S out. Luckily it's the same part number as on the board. -)

I think I am gonna put that jumper back in and reconnect the diode.
Should I check anything else prior to doing that?

[budm]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

First thing I would do for sure is to remove those brown/yellow glue from the board, they are conductive when it gets old. I see the blacken section on one part already. It will also eat away copper traces and component leads.
I see that burnt mark where the jumper is, and that is due to conductive glue in that hugh voltage and high switching frequency area.

[andy2]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

I'll remove the glue. But right now I am inspecting the QB802. I think it is burned. It should not pass the 16V with the collector of PC801S disconnected.
Right?

This optocoupler has a different part number than the print. Board says PC802S and it is the first one from the edge of the board. I took out the jumper J810, so I expected the M_Vcc to be 0V, but it is going through.

I also see a small chip in the TDA4863G - it looks like that part is gone too.

[Duncanbest]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Remind you : remove all of glue on pcb and take the schematic as reference only.

It's not fully the same as PCB board.

Like ICM852 MC33167 in schematic is not the same as ICM801 MC33067 at PCB .


Hope to hear good news from you soon !!!

[andy2]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

thanks - yeah, I am removing the glue right now. -)
I started with the cap CM808 and now I am in process of removing it from the QB802. My first switcher repair and I am removing glue. Interesting. -)

Actually - could you please say what the difference is between the two chips?
It looks like the sparking is what killed the whole device - and it seems the voltage came from the area of that IC. It had to - since sparking is gone with power disconnected from the 2 MOSFETs driving the final transformer to 24V section. It is going to be difficult to diagnose because I can't power up that section knowing what it does. I have to hold on and wait until the weekend though.

[selldoor]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Actually - could you please say what the difference is between the two chips?
.

You need to read the data sheets - just google the part numbers and download the pdf



MC33067 are high performance zero voltage switch resonant mode controllers designed for off–line and dc–to–dc ...

MC33167 series are high performance fixed frequency power Buck Boost Inverting Switching Regulators that contain the primary functions ...

[kusarigama]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Hello everybody!

I have the same problems with my BN44-00195A. It's from my 2493HM. He stopped working with an explosion. Looking at der power supply i found a blown resistor RM801 and QM802. Both became new.

After switching on the power supply there was an explosion too. The RM801 was blown again - also the fuses at the psu and the fuse of the room.

I have no idea what else i can do. Can anybody help me?



I hope my english is not too bad.

[tibimakai]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Did you remove all the glue from all the components? That glue becomes conductive after some time.
That's how I fixed my monitor. Did not have to replace any components.
I had sparks around the big transformer. There are some jumpers and some round little blue caps that were shorting out through this glue.

[Toasty]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Also remove all the black residue/carbon tracks as that is also conductive.
A toothbrush with some alcohol works well and dries fast.

If the fuses and the resistor failed, you probably killed the switcher transistor(s) also (again).

Also, check the main cap for value if possible. An open mains cap will blow the switchers immediately.

>> Be sure the PSU is unplugged and then discharge the mains cap before doing the following test. <<

A quick test utilizing an analog ohmmeter on high range will at the least jump to low then slowly rise as the cap charges. Test both ways by reversing the leads.

T

[budm]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

RM801 is the fusible resistor for the QM801, QM802 MOSFETs which may have shorted out.

[kusarigama]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

I have removed the glue completely - also from the blue caps. The RM801 was blown and the QM802 shorted. I replaced these parts - after power on RM801 blown again. I have no idea what else i can do. :-(

I read something about a shorted transformer on TM801. Might this be an option?

[tibimakai]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

use a bulb tester and try again after you hsave removed the glue.

[kusarigama]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

@Toasty: Thanks for the tip. I thought the main cap will never die - i will test it. :-)

Bulb test too...after washing with alcohol...

[budm]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

When that MOSFEtS goes out, it will also damage the SMP IC output drive circuit inside the IC also, so if the output stuck high (steady high B+ at the output) insstaed of swithcing on/off at 80,000 ~100,000 times a second, it will take out you new MOSFETs.
Tibimakai can atest to that when I was helping him troubleshootin the power supply. You can find out if it has the output pin shorted to the B+ pin of the IC or shorted out to the ground pin by using Ohm meter to verify that. I would recommend repalcing the IC and the MOSFETs at the same time, not worth blowing out new MOSFET, some people will replace the IC without checking the MOSFETs first, then it will blow out the new IC again, Tibimakai can also atest to that. So you neeed to check ALL the Gate drive components to make sure they are OK.
Not usre if -00192 diagram is close enough to -00195 diagram or not.

[tibimakai]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Bud is right. It happened to me too. By the way Bud, soon I will go back to that LG and Sharp.

[kusarigama]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

I checked the ICP801S and it really might be shorted. I think it would be better to replace the parts of the PFC:

ICP801S - FAN7530 ? (bad to read)
QP801S - FCPF11N60
DP802S - F10UP60S
QM802 - FQPF9N50C
QM803 - FQPF9N50C

Is it right?

I really hope that the psu will work after replacing these parts.

Otherwise - sh.. and thrown on the scrap heap.

[kusarigama]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

It was impossible to get these parts in Germany so I ordered them in Asia. Today arrived last parts. After changing all parts the TFT works as well as before.

Thanks all for your help!!!

[budm]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

Thanks for the repair feedback, good job getting it running again.

[kusarigama]

Re: Samsung 24" power supply BN44-00195A first stage voltage?

I was also really glad - especially the exchange of the small FAN7530 (SOP-8) was difficult. Only possible with hot air from my soldering station - first time usage.