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Hello and Welcome. My name is ***** ***** I'll assist you today. I'm sorry you're having trouble with it. I need additional info to troubleshoot the issue.
1- Could you please get me the complete model number written on back of TV?
2- What are the three boards you replaced in TV, please intimate name/ part number of those boards?
3- Is there any change in TV symptoms with new boards?
Thanks for the info, working on it and get back to you in 10 minutes, is this OK?
Please disconnect CNL802 connector of power supply board, this connector harness goes into screen for backlight, turn On the TV to see if it stays On now?
If not, disconnect CNL803 connector of power board that goes to main board, and check STBY (standby) volt with meter, are they stable/ constant?
Please reply back with the result.
Welcome, did you get my previous reply?
If not yet, let me repost it here....
Can you elaborate low ps?
can you find STBY pin of CNL803 and check 5V there?
While CNL803 disconnected, you will only get standby STBY volts on that connector.
Please check attached image of power board where connector pin configuration table is marked with red arrow.
This is odd, volts bouncing even both connectors are off of power board and only AC power cord is plugged in?
I agree, but standby section of this type of PS board does work even no load connected.
Do you have some kind of load to connect to 5V DC output (across pin-15 and GND pin) of power board to verify it?
I mean 6V bulb, small DC motor or 6V LED etc just to verify if it still bouncing?
Let me check if service manual contains schematics of PS section, hold on please.
I'm afraid, service manual doesn't have any schematics at all, do you need the copy?
Also try the load suggestion I mentioned in previous reply..
Do you have some kind of load to connect to 5V DC output (across pin-15 and GND pin) of power board to verify it?I mean 6V bulb, small DC motor or 6V LED etc just to verify if it still bouncing?
OK, now it is confirmed that power supply board is defective, standby volts must stay constant when plug power cord in as this volt supply boot up the main board that will turn On rest of voltage supplies. Please swap the power supply board to resolve the problem.
I trust my input will help you out. Please feel free to respond if you have any additional questions.A positive rating to answer would be greatly appreciated, please click on 5 star on this page then click submit/finish button so I can get credit on website for my work. If you don't see rating option then intimate here.Regards,Shahid.
Let me explain, we have isolated the Power Supply board now and standby volts is the only output that you can get it from which should be stable/ constant, is this correct and do you agree?
Have you checked pin-14 (A5V) output of power board?
Backlight supply would be approx 150V (it varies due to screen size, number of LEDs inside screen).
If power board is disconnected (say it is out of TV) and plug the AC power cord in it and hook it to wall outlet, PS board should provide standby 5V output that should be stable.
There are two 5V outputs on this PS board, one is B5V and other is A5V.
Have you checked both output volts?
Just to add more info, one of 5V output is switched, meaning it will turn On when power board get PS-ON command from main board.
If you look at connector, pin-14 is marked as A5V and pin-15 is for B5V, correct?Do you get a5V stable or bouncing?
OK, if pin-16 is high, jump it to Ground, if pin-16 is low then jump it to 5V, this will turn On the rest of voltage on power supply board.
pin-14 5V are stable that means standby section is working, this what I'm trying to explain.
OK, opting out.