Samsung BN44-00445A failed

[genius312]

Hi all,
I am having a problem with my Samsung plasma TV.
1 month ago I started it in the morning to let my child watch some TV on a rainy day. But after 5 minutes a big BAM was heard and the TV stopped working.
I then removed the power cable, and plug it back in. When I plug it in, a click sound is heard and 5 seconds after an other click.
Like if it was powering on and off after 5 seconds.

I started to read on the web for answers, found some different repair kit on ebay so I bought the one with the most different components.
Watched that video which is exactly my board: https://www.youtube.com/watch?v=dswtNRiZwN8
I contacted the company for help and they redirected me here !

I replaced all the component I received because the BAM sound was from a transistor and all its circuit was blown.
Well now it seams it circuit is working OK I get good reading out of the transistor, diodes and resistance.

But the 4 big capacitors that are suppose to give me 400V only give me 160V !

I have no idea where to look at now !
I cannot find the schematic so that I could read it and see where the issue is.

So I am stuck with a 1500$ TV opened in my garage and cannot fin which part to replace !
It probably is only 1 component to replace now, but have no idea which one !

Anyone here know this board and can help me ?
The TV is a Samsung PN59D550C1FXZC
Power supply is BN44-00445 version A

Here are some pictures I took of the board. I see a little black plastic coming out of a coil .. I do not know if it is normal. My multimeter is not good enought to get any reading out of it, I'll have to go see my neighbor !


Thank you very much for your help,
Martin L.

[Malachi]

Re: Samsung BN44-00445A failed

If needed there are places on eBay that will repair your board. The cheapest one was $52.

[genius312]

Re: Samsung BN44-00445A failed

I paid 70$ for the repair kit on ebay.
The problem is that i already worked on it, so i think no repair shop will want the work on it now !

[genius312]

Re: Samsung BN44-00445A failed

No one has ever worked on that power supply?

I am sure it is a smoke component to replace now but i have nowhere to look at without schematic.

[martino]

Re: Samsung BN44-00445A failed

http://www.shopjimmy.com/samsung-bn4...repair-kit.htm
Seen that one?
160volts on the main caps means psu is in standby,it's not being activated.First thing would be to see if you have standby voltage at CN801.
Also it would help if you have a list of the components you replaced. Their board numbers.

P.S: I will look tomorrow to make sure,but I think I have a psu like that. Interested in it if I do?

[genius312]

Re: Samsung BN44-00445A failed

Yes why not!
I would prefer to repair mine since I'll be good to repair it again if it fall a second time, but yeah see if you have one working in Stock.

I'll post the result of cn801 and what i have replaced at noon

[genius312]

Re: Samsung BN44-00445A failed

What do you mean by cn801 ? I cannot find a capacitor their (see picture attached)
What i replaced are:
QP802
QP804
DP804
DP807
QP806
QP806
QP807
QP808
ZDP801
ZDP802
ICP801
RP807
RP813
RP821
i think that is it.
What was blown (separated in 2 pieces) was the QP804

Please help
I must be only 1 component to replace now but without schematics it is really hard to figure!!

Thank you
Martin L.

[budm]

Re: Samsung BN44-00445A failed

Connector CN801 (12 pins), and also the 6-pin connector next to it.
Make sure to put pin name for each reading.

[genius312]

Re: Samsung BN44-00445A failed

Which pins should i check ?
I guess their will be no current at all if i do not plus this connector.
I need to plug it to get a reading on the big caps !

[budm]

Re: Samsung BN44-00445A failed

All the pins except the GND pin, there is a chart telling you what pin is what so make sure you put those pin names next to the Voltage readings. All the boards connected back in place when yo take the readings.
Black probe on the chassis since these Voltages are in the cold side.
We need to find out what is missing.

[genius312]

Re: Samsung BN44-00445A failed

I get 3.25v on ps_on (between 2 click from the tv)
5.30 on stby
And that's all i get..nothing else where !
My guess is that it needs 5v to power up but it only get 3.25v...
I have no clue

[genius312]

Re: Samsung BN44-00445A failed

Sorry i forgot the images

[budm]

Re: Samsung BN44-00445A failed

PS-ON signal for this power supply for Plasma TV is:
>3V = OFF
<1V = ON
BTW, if you leave the red probe on the PS-ON pin, do you see the Voltage changes state when you toggle the power switch on and off? If not then the main board is the problem.
So to force on this board you will need o hook up 100 Ohms resistor, 1/4 W should be fine, between and GND then you should see the vdc on the main filter cap goes up to 400VDC or so.

[budm]

Re: Samsung BN44-00445A failed

https://www.badcaps.net/forum/attach...4&d=1464313809
The solder works look really bad, I.E. QP804 (for PFC Voltage booster circuit) Drain pin does look like the solder even stick to the leg.

[genius312]

Re: Samsung BN44-00445A failed

As soon as i plug in the tv, it turns on immediately and turn off automatically in loop without touching the power button. ( i can hear the 'click' sound)
The voltage changes on ps-on after each 'click' from 3.25 to .2v
Thank you now we know the tv is switching on and off by itself. And the main board is ok!
If i leave the probes on the big caps, it is always 160v.
Not like ps-on which is always switching from .2 to 3.25 after each 'click'

[genius312]

Re: Samsung BN44-00445A failed

I am pretty sure the solder are ok, we have tested them

[budm]

Re: Samsung BN44-00445A failed

As soon as i plug in the tv, it turns on immediately and turn off automatically in loop without touching the power button. ( i can hear the 'click' sound)
The voltage changes on ps-on after each 'click' from 3.25 to .2v
Thank you now we know the tv is switching on and off by itself. And the main board is ok!
If i leave the probes on the big caps, it is always 160v.
Not like ps-on which is always switching from .2 to 3.25 after each 'click'

Well when that PS-ON goes low the PFC circuit is turned on which then the DCV on the cap will go up, but since it stays at 160V that means the PFC is not working, so you need to really recheck your woks.

[genius312]

Re: Samsung BN44-00445A failed

The problem seams to be my work ?

[budm]

Re: Samsung BN44-00445A failed

The parts that you installed. Too me that pin looks really bad, may be some one else can chime in.

[97Kouki]

Re: Samsung BN44-00445A failed

It looks as though the through-hole solder sleeve has pulled away from the trace on QP804. I would at least do a continuity test on the Pin in QP804 to the bottom left leg of DP802. If continuity exists then the connection would be OK on this side of the board even though it looks ugly. But just looking at it makes me think it's no longer connected to the trace.