Samsung / Hansol BN44-00428b

[babudo]

Re: Samsung / Hansol BN44-00428b

Thanks 737mechanic for the fix and pics. just tried the same fix tonight and TV back online!

[JOSman]

Re: Samsung / Hansol BN44-00428b

Tried the solder today. Didn't work.


Thanks anyway.

[gutterbear]

Re: Samsung / Hansol BN44-00428b

Thanks 737mechanic!

Messed with this board for way to long to not notice that solder issue. TV has been working great all day after months of suffering with my backup TV.

[shaheedamirkhan]

Re: Samsung / Hansol BN44-00428b

JOSman
Did you find the problem ?

[shaheedamirkhan]

Re: Samsung / Hansol BN44-00428b

I changed my power supply and i have the same .. on of problem , my screen is flashing on and of but the tv does not start up

[kartwood]

Re: Samsung / Hansol BN44-00428b

I am working on one of these at the moment. It's out of a UN55D6900.
The back light flashes on for less than a second every three or four seconds. Same symptom with the main board disconnected. Without the LEDs, the relay still clicks on and off.
Referring to the schematic, Vdrv gets just over 100V then the relay opens. If I disconnect the LED drive circuit (remove DM851,852), the low voltages are all good and stable.
I can't make any sense out of the protect circuitry. It seems to involve PCS820S.
Samsung doesn't have these in stock in Canada.

Was hoping to find a bad solder joint but no luck. Any thoughts?

[Nedco]

Re: Samsung / Hansol BN44-00428b

Cycling of Samsung Power Supply/Inverter for Model#: UN55D6900WF LED TV



I had a similar problem of the Power Supply on this Samsung LED TV recycling on and off where you can hear the main relay clicking on and off

After extensive tracing and diagnosing (and lots of luck----I did not have a schematic to work with) I found that if you ground the collector tab of D9052 to COLD Ground, the cycling will cease and a normal operation is restored.

Apparently, on this Model TV set, if the Light Inverter circuit senses an anomaly to the current and voltage fed to the LED light banks, it will throw off and error signal to the input pins of D9052 which will turn the collector of D9052 (tab---the center outward pin) to 3v instead of virtual zero volts. This 3 volts will trigger the cycling of the power supply.

[ampicoe]

Re: Samsung / Hansol BN44-00428b

Hi all, this is the first time I have ever contributed to any forum before today, I was given a TV which has this problem. I tried the fix in the last posting, the clicking on / off of the relay has stopped, No relay on click and no LEDs when connector removed from the PS board. I'll keep looking and check the voltages with my DVM. There must be many issues that cause the same problem. I would be very happy if someone has another suggestion. Thanks for the helpful leads. Happy Christmas to all.

[tcimperman]

Re: Samsung / Hansol BN44-00428b

I had the same problem with a Samsung UN55D6900WF powering on and off. First it started to do it fairly randomly and I could hear the audible 'clicks' as it would turn on /off. It would last a minute or two, and then the TV would work. It gradually got worse and worse over the course of 3-4 months, and then the TV was pretty much useless as it cycle for 10 minutes and then wouldn't even turn on. I checked the capacitors on the PCB's and all looked to be in fine shape. I then found this forum, and saw the post from 737mechanic about seeing a small arc at a connection point for TM801S. My television had a cold solder joint in the exact same location. I too could see it intermittently arcing a tiny arc when it would cycle on / off. It literally took about 5 minutes to fix and that includes disconnecting and re-connecting the board so I could solder it from both sides! Total out of pocket cost to fix was $0.00. Thanks for the great troubleshooting 737mechanic!

[au.vi]

Re: Samsung / Hansol BN44-00428b

I'm investigating a UE55D7000 with a BN44-00428B PSU. Cycles On-Off so I checked the joints on the transformers first. All OK.

Then measured the output voltages of the 4 LED drives, which pulse high just upon switching on, but one of them gets much higher than the other three. The one at D9451 reaches way over 200 Volts, and the other three just over 170 V.

So I'm assuming that one of the backlight strings has an open circuit / bad LED.

Giving up. Or is it feasible to replace the broken LED string ?

[Curt1915]

Re: Samsung / Hansol BN44-00428b

I have a Samsung UN55D6900 that is having the same issues. I opened it up and all the Caps looked good on the PSB. After finding this thread I'm going to check for cold solder joints as well. Hoping that fixes the problem. I was trying to find what Nedco was talking about but could not find D9052. Any idea where that is located? Maybe I need to look harder!

[Robell824]

Re: Samsung / Hansol BN44-00428b

Kudos 737mechanic!

I only checked physically for capacitor issues did not find any, so I jumped on to checking bad solder joints and as the picture showed the main transformer has cracked solder joints.a

[Louis82]

Re: Samsung / Hansol BN44-00428b

Hey guys,
I have a samsung tv that uses same power supply BN44-00428b. TV turns on and after 33 sec it cuts off and comes back on by itself. May any of you tell me if the readings on the LED connectors look good. I think there are some pins measuring incorrectly and that my problem could be an LED string. Before i take this tv apart I wanted to know your opinion. Thanks

Voltages measured during the 33 sec that the tv shows picture.
CNL801A
Pin 1: 102v
Pin 2: 102v
3:0
4:0
5:0
6:0
7: 41v
8: 41v
9: 0
10: 0
11: 102v
12: 102v
13:0
14:0
15:0
16:0
17: 41v
18: 41v
19:0
20:0
21:3v
22:3v

CNL801B
Pin1: 164v
2: 164v
3: 0v
4: 0v
5: 0v
6: 0v
7: 102v
8: 102v
9: 0v
10: 0v
11: 164v
12: 164v
13:0v
14:0v
15:0v
16:0v
17: 102v
18: 102v

[budm]

Re: Samsung / Hansol BN44-00428b

Hard to tell what those Voltages readings are for since there are no pin names to tell us what they are.

[vinceroger69]

Re: Samsung / Hansol BN44-00428b

shematic if needed

[Louis82]

Re: Samsung / Hansol BN44-00428b

Thanks for replying. Here are pin names:
(Pic is attached)

CNL801A
Pin 1 L2+: 102v
Pin 2 L6+: 102v
3 L2-: 0
4 L6-: 0
5 L1+: 0
6 L5+: 0
7 L1-: 41v
8 L5-: 41v
9 : 0
10: 0
11 L8+: 102v
12 L4+: 102v
13 L8-: 0
14 L4-: 0
15 L7+: 0
16 L3+: 0
17 L7-: 41v
18 L3-: 41v
19 : 0
20 : 0
21 IF1:3v
22 IF2:3v

CNL801B
1 R7+: 164v
2 R3+: 164v
3 R7-: 0v
4 R3-: 0v
5 R8+: 0v
6 R4+: 0v
7 R8-: 102v
8 R4-: 102v
9 : 0v
10 : 0v
11 R1+: 164v
12 R5+: 164v
13 R1-: 0v
14 R5-: 0v
15 R2+: 0v
16 R6+: 0v
17 R2-: 102v
18 R6-: 102v

[Louis82]

Re: Samsung / Hansol BN44-00428b

Bump. Anyone?

[Louis82]

Re: Samsung / Hansol BN44-00428b

Anyone who can check these voltage readings and tell me if the reading of 164v Im getting on connector CNL801B is too high and indicates the failure of a led string. Thank you.

@Vince: Thanks for schematics. I have tried to understand it and see if I can find the answer to my question but I can't.

[budm]

Re: Samsung / Hansol BN44-00428b

According to the Voltage chart, the LED Voltage is supposed to be 188V (Loaded).
The board has 4 boost converter circuits as you can see.
Per diagram, CNL801A pin 1 and pin 2 are not used but they are being used on your board, so the diagram for the CNL801A, B (pin 17 and 18 are not used per diagram) does not look to match the board actual connection.
I will have to trace out the board to see how the LED strings get the Voltages.
BTW, this board is know for having bad solder joints on the transformer pins, you should try resoldering them.

[Louis82]

Re: Samsung / Hansol BN44-00428b

Thank you. Yes, I'm aware of the bad joints on this board. I have spent hours resoldering it and still.

Any suggestions? Main Board? I have applied frozen air to every single IC on main board to see if it last longer but no luck.