Darn need help guys samsung ln-t4042h 24v backlight problems

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

ok lets try it .....brb

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

cn1803 inverter on/off... its at 0.02v always add 5v? would turn on backlight no?

I think the Inverter On Signal comes from the inverter to tell the Main board that the inverter is on and all is well, so do not put 5v on that pin.

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

Don't confuse the two CN's and signals we are talking about.

Lets first confirm which CN - Connector and which Pin we are discussing.

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

With TV switched on but in standby check the voltages at all the Connectors and list the results.
Then do the same with the TV on, or at least attempting to come on.

This may be time consuming but worth the effort.

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

guess what we have backlight but nothing on the screen it just lite

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

with 5v to cn1803 pin 1

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

How did you get the back light to come on?

CN803Pin 1 Power on / off

Picture 7 in Post 13 Top left corner of solder side of PS board.

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

OK, so PS 24v supply is good.

Check voltages as mentioned before in stby and trying to come on.

It is looking though the fault lies with the Main A/V board.

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

thinks so.... ok ill order one
thanks beer and pizza for you guys...but the pizza mybe cold coming form this far....lol

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

Are you turning on the Tv with a remote or the side panel buttons?

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

thinks so.... ok ill order one
thanks beer and pizza for you guys...but the pizza mybe cold coming form this far....lol

Further checks need to be made before ordering anything.

Not yet concluded that the fault lies with the Main A/V board.

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

front on button on tv..... should i use the remote

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

ok its a 24 pin connector..ill get the volts with tv stand by and on ...brb in about 15 min

[budm]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

PS_ON (Power supply ON to turn on the 12v and 24v POWER SUPPLY), BL_ON (INV_ON) is the signal for turning on the PWM circuits of the Inverter board (the inverter needs 24v to run), Dim (or PWM) is for lamp brightness control. All those signals are generated by the Main board, the signals are routed through the power supply board (for clean wiring lay out).
So you need to find out for sure if you do have all those 3 signals from the Main board.

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

front on button on tv..... should i use the remote

Might be worth chcking it also works from the remote and check to see if the other function buttons on side/front panel and remote work, though of course with no picture you will be limited as to which functions you can confirm work. The IR LED flashing doesn't really confirm that the function is actually working.

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

got this ....relay clicks backlight on.. got all listed volts per pins on cn801 5v 12v 13v
ok relay off backlight off v drops to 0v on 12v 13v but stb 5v stays at 5v guess all is good on ps no?

[budm]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

So right now the backlights are on when you turn on the TV and it stays like that with Glowing screen but no picture?

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

i would have to unplug it for 30 mins to get it in stand by mode...but when i plug it in now 1 clicks backlight on...in 10 sec the relay clicks backlight goes off for 3 sec... relay clicks backlight on again for 10 sec ....follows this cycle over and over till unplugged

[davewilson61]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

when backlight if off no 12v 13v...but has stb 5v
backlight on have 12v 13v
but no 5v on pin 1 of cn1803 just my jumper

[notallbad]

Re: Darn need help guys samsung ln-t4042h 24v backlight problems

got this ....relay clicks backlight on.. got all listed volts per pins on cn801 5v 12v 13v
ok relay off backlight off v drops to 0v on 12v 13v but stb 5v stays at 5v guess all is good on ps no?

Did you power off the tv or did it switch itself off?

Ok ignore that.

With your 5v jumper you are forcing the bl on, remove your 5v jumper and put it back as it should be.
Is there no 5v on pin 1?
Testing needs to be made on the main a/v board.