samsung LN-T5271F

[ilikesteel]

can someone tell me if the PS board 351135A has pull up resistors for the PS_ON and the BL_ON?

thanks

[ilikesteel]

samsung LN-T5271F Power Supply Question

is this power supply equipped with pull up resistors for ps_on and BL_on?
thanks

[budm]

Re: samsung LN-T5271F

That P/N does not look correct, it should be something like BNXX-XXXXX.
http://www.shopjimmy.com/catalogsear...sung+LN-T5271F

[ilikesteel]

Re: samsung LN-T5271F

Budm,

thanks for the reply. I went to shopjimmy and with the link you provided. this is what they showed.

Samsung BN44-00184A (IP-351135A) Power Supply for LNT5271FX/XAA

I cannot find the BN44-00184a number on the circuit board, but the
IP= 351135a is clearly marked on the circuit board. here are a couple of pics.

I have an intermittent problem. sometimes the set powers on perfectly, and sometimes it will come on with sound and no picture.. I can see from the back of the tv that there is some light visible, but nothing on the screen when it does not display a picture. no obvious connection problems.

I'm trying to identify where I can start the process of elimination as to the cause of the no picture with sound when it occurs. I thought if the PS has pull up resistors, I could try disconnecting the main board cable to see if the PS allows the backlights to come on every time.

the PS connection plug is very small and almost impossible to get voltage readings from the back of the pins. I have not tried to remove the board and take measurements from the back if that is possible.

I appreciate yours and anyone elses input on this crazy problem.

thanks, frank

[ilikesteel]

Re: samsung LN-T5271F "bump"

"bump"

[jmarsello]

Re: samsung LN-T5271F

Hopefully someone will get back to you on this issue. I have been looking over issues on this site and the guys are spot on when they are working with an issue. I have been having the same issue with a samsung. I just havent posted yet. I am curious to see the results of this issue. Best of luck.

[budm]

Re: samsung LN-T5271F

You can use small sewing needle to stick into the connector, check the POWER ON/OFF pin when TV is ON and when TV is OFF.
http://www.shopjimmy.com/media/catal...bn4400184a.jpg

I cannot find the diagram for this power supply yet.

[ilikesteel]

Re: samsung LN-T5271F

Budm,
thanks for the response. I will try to take the voltage readings today. do you mean the PS_ON signal pin. I will check that with power on and power off.

ilikesteel

[truep]

Re: samsung LN-T5271F

When you say sound but no picture, Do the backlites come on?
If not, you probably a 24V power problem. if they do, TCON or main.

[ilikesteel]

Re: samsung LN-T5271F

thanks Budm and treup,

budm, the link you gave me is indeed the power board. here are some voltages plus the one you requested.

CN801 on PWR board

set powered off, pin 1= .04V
set powered on= 2.74V
also on the same connector with power applied to TV. backlight visable, but no display or black and white confetti.

pin 3 should be 2V, it was 5.14V

pins 4-6 gnd

pins 7-8 should be 12V, it was 12.02V

pins 9-12 gnd

pins 13-16 should be 5.4V, it was 5.59V

pins 17, 18 gnd

pin 19 should be 13V, it was 13.50V

pin 20 gnd

pins 21-22 should be 13V, they were 13.50V

also, there is a 5 pin connector just above CN801. it's name is CN1805.

pin 1 is inverter on/off, it was 5.42

pin2 is DIM, it was 3.49V

pin 3 is PWM, it was 4.96V

pin 4 is gnd

pin 5 is DET_5V, it was 5.60

now all of that is with the power on.

truep, there is a backlight on, I can see it from the screen, and from the back of the TV. I don't have it hooked to a TV, however, when the set comes on normally without any input source, you can see black and white confetti on the screen. hooked to a cable source, the TV would come on as normal with sound and picture when it works properly.

I don't get a menu screen. I do have a DVD hooked to the TV, but cannot select the input source for the DVD because of no display capability.

thanks guys, hope this helps isolate problem.

ilikesteel

[budm]

Re: samsung LN-T5271F

OK, we need to check the DC voltage on both ends of the SMD fuse on the T-CON board next.

[ilikesteel]

Re: samsung LN-T5271F

budm,

I'm having a problem removing the metal cover from the t-con board. I removed the 4 screw holding the board and cover to the chassis. the metal cover will not separate from the board. I looked at the 4 connections to the panel. I tried to remove one of the cables from the board to the panel, but was unable to get it loose. I'm afraid to man handle the cable and connector for fear of destroying what I'm trying to fix. any ideas?

[budm]

Re: samsung LN-T5271F

Sometime there is notch in the frame that the metal shield slide into which some time you will have to lift up the whole LCD frame assembly to remove the bracket to get the shield off.
Post good clear pictures so we can see how it is put in place.

[ilikesteel]

Re: samsung LN-T5271F

budm,

attached are the pics, hope it helps. do the cable connections from the t-conn to the panel slide straight upwards? there seems to be a white tab on each. is this where the cable should be pulled from to lift the connector off the t-conn board?

[budm]

Re: samsung LN-T5271F

You have to flip up the brown locking tab to release the cable.

[ilikesteel]

Re: samsung LN-T5271F

Budm, Thanks for the info. I was able to release the cables with the lock tabs as you suggested and removed the T-conn board. the board was stuck between the metal cover by two gray cushion pads attached to the cover. it came apart easily once removed from the set.

I did take the voltage reading as you suggested. with the TV powered on, there was 0V across the pins for Fuse F1. I also checked from GND to each of the pins on the fuse. it read 13.1V from GND to each side of the fuse.

I assume you've already established that some parts of the set are working properly. what is your thought process based on the info and voltage readings I provide? thanks for the help!!!

ilikesteel

[budm]

Re: samsung LN-T5271F

OK, so the T-CON is getting the voltage from the main board OK, but it is not working.
Can we see the pictures of the top side of the board so we can give you some voltage test points to test on this T-CON?
You can mount the board back in place, just leave the shield off for now.

[ilikesteel]

Re: samsung LN-T5271F

Budm,
attached are the pics of the T-Conn board. hope they are detailed enough. do you think the T-Conn is causing the backlight from coming on, or is the backlight on, but nothing is being transmitted to the screen?

thanks for a great experience.
ilikesteel

[budm]

Re: samsung LN-T5271F

If yo do have backlights then the problem is either the main board is not sending the signals to the T-CON or the T-CON is not working at all.
BTW, I see two LVDS cables to the T-CON, this TV is 120Hz/240Hz? It may have another board that gets the signals from the main and process the signals and send them to the T-CON.

Can we see the whole back side of the TV to see how all the boards are connected together?

[ilikesteel]

Re: samsung LN-T5271F

Budm,

attached are the pics you requested. I also took a few shots in the dark from the back of the set and the front side while the set was powered on. the start up twinkle sound that the samsung's produce is there at power on and power off.

does the light we see indicate the backlight is working?

thanks,

ilikesteel