Samsung LNT3253HX/XAA No picutre and stuck on standby.

[Guest]

Hi guys, my 6 year old Samsung LNT3253HX/XAA died a week ago. First symptoms is the TV won't turn back on after watching TV for long period of time and power led indicator stays solid red with the blue light blinking under TV with a clicking sound. So I open the back to check power board and seen 4 bulged capacitor so I replaced 6 capacitor that I ordered online. But problem still persist , the same clicking sound from the relay, no backlight and on the connector going to main board reads the voltage bouncing like the TV is trying to get out standby mode.

I'm trying to rule out which board is the culprit so I could can buy a replacement. To do this I need to jump the power supply board by shorting 2 pins to get out of standby to check voltage under load with multimeter. From watching youtube.com/watch?v=n54IurMvr6o, you need to short the pin on/off and standby on the small connector for the inverter and the same with the long connector going to main board. My powerboard is little different from the video so I am not sure which pins on the small inverter connector to short, the pins reads 1.on/off, 2. A/D 3. P/D 4.GND 5. 24v DET. Do i need short pin 1. and 5.? sorry if I'm newbie to this, I'm just afraid of frying the powerboard.

[budm]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

https://www.badcaps.net/forum/showthread.php?t=39740

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

Hi Budm, here's the image and the first image is the connector I'm talking about. thanks.

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

Bump

[budm]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

OK, lets find out if the standby power supply is putting out steady voltage or not first, no need to turn the TV on at this point, just have it plugged into the outlet.
Check the DC Voltage between the exposed leg of Diode DB851 and chassis ground, that is the standby power supply output.
BTW, which caps on the board that you replaced? Did yo use proper caps with LOW ESR type?

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

Budm, the standby voltage is a steady 5.1 from the long connector and I get the same reading on the Diode DB851. The capacitor is the Nippon Chemi-Con kZE and are low ESR from what the seller told me. Also use the same uF and voltage as the original capacitors.

[budm]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

OK, the standby power supply is OK , but I am having problem figuring out the pin out of that connector to goes to the main board, it is double-row but the label does not tell us which pin those labels belong to. The power supply board is BN44-00156A which I cannot fine the diagram for it yet so it will not be easy to figure out which pin is what.

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

the wires are blocking the pinout label from my imagines. Here's the pinout

[budm]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

OK, take the readings of all the pins with the name of the pin next to the reading.

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

Tested all pins with my multimeter, but most of pin voltage fluctuate except for ST-BY. So i recorded the lowest to highest voltage for each pin.

[budm]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

OK, according to shopjimy, the BN44-00156A can be replaced by
BN44-00191A
BN44-00191B
BN44-00192A
BN44-00192B
So the connetors are the same, I look up the diagram for BN44-00191A

Pin 1 is the POWER ON/OFF (PS_ON, or ON/OFF as show on you board), according to your reading, the Voltage is going up and down between 1~4V.

pin 3 is the Standby 5.2V which your board is putting out steady voltage to feed the main board.

The variation on the pin 1 ON/OFF (PS_ON) is causing the other voltage outputs of the power supply to go up and down because they are being turning on and due to not getting solid ON/OFF voltage from the main board.
Try disconnecting the cable between the T-CON and the main board to see what happen, at this point you have bad main board.
I attached the BN44-00191A so you can see the pinout of the connectors.
You cab try forcing on the power supply to see if the output voltages will be on steady by using 3V power source from batteries feeding the POWER ON/OFF pin through 100~500 Ohms resistor, but you must disconnect this POWER ON/OFF signal line back to the main board first.

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

I've tested the pins again with the T-CON disconnected from the main board and the same reading with the voltage fluctuating. About forcing on the power supply, instead can i just connect pins on/off and standby while the 2 connectors disconnected from the main board like the youtube video i link in the first post?

[budm]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

"can i just connect pins on/off and standby while the 2 connectors disconnected from the main board"
Yes, you can do that also.

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

Ok, I jumped pin on/off and standby with a straight wire and notice 12v and 13v pins tend to fluctuate a lot and reads low. Does this tell you the Power board is the problem? What part of the power board that be causing this?

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

Ops, there's one typo with one of the reading, pin 13v second from the top should be 8-11.30v not 8-10.30v.

[budm]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

OK, something does not make sense on the readings:
All the 5.3V pins are all tied together which should give all the same readings which you do have.
All the 12V pins are also tied together, same for the 13Vpins, so all the readings of the 12V pins should be all the same, same for the 13V pins.
All those voltages: 5.3V, 12V, 13V, and 24V are generated by the same transformer so it does not not make sense to have 5.3V steady but not the 12V, 13V, and the 24V.

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

For pins with 12v& 13v the reading moved to fast and it was hard to get a good reading and round off on some of the reading, but I never seen it hit 12v or went under 8v.

I've tested it again this afternoon with pins on/off and standby connected. Reading was somewhat steady, but voltage read much lower for pins 12v&13v and stay between 7.0- 7.5v.

[Guest]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

budm, do you think there's a problem with the power board?

[budm]

Re: Samsung LNT3253HX/XAA No picutre and stuck on standby.

At this point, yes, the way those voltages are showing.