samsung 32 ln32b360c5d no power no indicator

[ben7]

Re: samsung 32 ln32b360c5d no power no indicator

Im thinking this is the 5/13vsb transformer.

Try tracing it out, and see what components it connects to. I would check the mosfet that drives it, and the secondary rectifiers too. If some zeners blew, that could have made the mosfet blow too.

[tom66]

Re: samsung 32 ln32b360c5d no power no indicator

That's probably the gate drive transformer for the CCFL FETs, but I could be mistaken.

[Beowulf]

Re: samsung 32 ln32b360c5d no power no indicator

Greetings everyone.

I have this same problem on the same TV using the same board number BN44-00289B.The TV looks dead and unresponsive. The fuses, to my knowledge, didn't blow.

In my case, the diodes ZM804, DM852, ZD804, ZD803, as indicated by other people with the same problem to have been the cause of their problems, are in good condition.
I'm getting the right voltage (177v) at main filter cap, but no voltages at all at any of the outputs (not even stby voltage).
The resistance I'm getting is 3.5 M ohm on TM 801s' primary without the fuse FM802s.

Checking IC UM801s this is what I'm getting:

Pin
1-Varies from 0v to 0.9v.
2-0.36
3-0
4-178v
5-178v
6-NC
7-Varies from 11v to 17v
8-GND

To my understanding the behavior of the IC UM801s is that it's resetting itself due to problems in the circuits before it.

I'll appreciate any ideas on where to look next.

I'll continue looking around and update if I find anything.

Regards,

[Beowulf]

Re: samsung 32 ln32b360c5d no power no indicator

Update:
I just found a shorted diode (ZM801) that's part of the feed back circuit.

[budm]

Re: samsung 32 ln32b360c5d no power no indicator

Also check Zener ZD803, 804 for cracked body and short. Also see the bulletin.

[Beowulf]

Re: samsung 32 ln32b360c5d no power no indicator

Always appreciate your help @budm. Thanks for the service bulletin. Luckily that diode it references is ok, let's see once I get the tv to turn on.

As per the zd803 and zd804, as I mentioned before, they're ok.

So for now I've only found that shorted diode and I'll order it to see what happens.

Regards,

[budm]

Re: samsung 32 ln32b360c5d no power no indicator

The reason I mention the two zener Diode is that we just found the circuit that uses the same setup as your board but not the same IC to have one bad 12V ZENER.
https://www.badcaps.net/forum/showth...869#post335869

It looks like we have to keep an eye on that shorted Zener you found on my list of what to look for in this power supply setup.

[Beowulf]

Re: samsung 32 ln32b360c5d no power no indicator

Right! I saw that and other threads where the board version was the BN44-00262A instead of the ***289B on my set. I'll order those other suspect diodes too, just in case.

[tibimakai]

Re: samsung 32 ln32b360c5d no power no indicator

I have picked one of these up myself with the BN44-00260A PS board and I have found the MUR360 shorted.
Thanks Bud for that bulletin.

[Beowulf]

Re: samsung 32 ln32b360c5d no power no indicator

After replacing the diode I got the primary section to somewhat work cause I started to get some output voltages.

Situation at the moment:

No power, flashing stby led.

Readings from CN802 (main output power connector)

Pin
1-gnd
2-sync 0v
3-Det-5v varies from below 0v to 3v then down and up to 4v
4-E-PWM varies from below 0v to 3v then down and up to 4v
5-Inverter on/off varies from around 2v to 3v
6-13v(m) around 6v on and off
7-13v(m) around 6v on and off
8-gnd
9-5.3v varies from around 2v up to 5v
10-5.3v varies from around 2v up to 5v
11-gnd
12-gnd
13-13v(s) varies around 6v
14-gnd
15-stby 5.3v varies from around 2v up to 5v
16-Pwr on/off varies around 0.7v

Checked all six electrolytic caps on the secondary side and they're all good for esr and capacitance.

[budm]

Re: samsung 32 ln32b360c5d no power no indicator

OK, so the standby power supply 5.3V and 13V are not stable after replacing the shorted out Zener diode ZM801 at the FB pin2 of IC UM801.
It looks like it is starting up and shutting cycle, one can be the startup caps CM804 47/50V, CM808 22/50V. Check or try replacing them
I would like to to lift one leg of the 12V Zener diode ZN803 or ZN804. They are the two diode that failed in the other board, but it uses the same setup us your board.

[Beowulf]

Re: samsung 32 ln32b360c5d no power no indicator

Alright the caps checked out ok. The diodes I have tested before and were fine. Tomorrow I'll check them out again and try replacing what I can even if they check out good, just for the heck of it.

thx

[Beowulf]

Re: samsung 32 ln32b360c5d no power no indicator

Ok, I found my problem. It was the PC802S opto isolator ic needing to sit better. In the beginning while fooling around I removed all three of them to check them out then this one had one of the legs rather lifted (good thing I have microscopes) and was not making good contact with the pad.

So to resume, in my case the only problem was the shorted diode ZM801.

Thx

[tom66]

Re: samsung 32 ln32b360c5d no power no indicator

Nice!

[budm]

Re: samsung 32 ln32b360c5d no power no indicator

Great news.

[tibimakai]

Re: samsung 32 ln32b360c5d no power no indicator

I have replaced the MUR360 diode and it's working!
Thanks Bud.

[tom66]

Re: samsung 32 ln32b360c5d no power no indicator

Yours had power but no backlight though?

[1frankwright1]

Re: samsung 32 ln32b360c5d no power no indicator

I have replaced the MUR360 diode and it's working!
Thanks Bud.

What diode did you replace?
DP804?
thanks

[eastcoastcarwiring]

Re: samsung 32 ln32b360c5d no power no indicator

no there is no voltage at any of the pins

Hi there got no voltage on any of the pins where shood i check next?

[rlega]

Re: samsung 32 ln32b360c5d no power no indicator

I found replacement diodes for the TV, because I could not find the MUR360AX. I ordered them, and walla, the TV is working. The problem was sound, but the backlight was not working.

I found them on eBay (Seller: maziz3)

Thanks