How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dan Your Own Question
Dan
Dan, Master Tech and Repair Facility Trainer
Category: TV
Satisfied Customers: 7177
Experience:  USAF trained; A.A.S Electronics; A.A.S. Education; Currently teaching advanced troubleshooting and repair for the DoD.
42300671
Type Your TV Question Here...
Dan is online now
A new question is answered every 9 seconds

I have a LN40B530P7FXZA that had sound, but no picture. I

This answer was rated:

I have a LN40B530P7FXZA that had sound, but no picture. I had a tech come look at it and he replaced the panel, and it still didnt work. At that point he just kinda let me high and dry. After doing some research and looking on here, is there any way that i can tell if its the Power supply, Tcon board, or inverter that needs replaced. I pulled the back of the case off and looked over the Power supply and I don't see any bad caps on it. I do have some test equipment, and some basic experience with electronics and such.
Hello,

Thanks for the question. My name is Dan.

Before we test anything, let's try a couple things so we can narrow this down. Turn the lights off, and turn the TV on. Though the screen is black, can you see a faint glow coming from it, like the backlight is working? If you can detect the backlight, stop here and let me know. If you can't detect the backlight... with the TV still on, try holding a flashlight 1-2 inches from the screen. Can you see faint images or colors? Try bringing up the TV menu, so you’ll know what to look for.

Regards,
Dan
Customer: replied 6 years ago.
no i can't see a faint glow, and no faint images on the panel at all.

Ok, thanks. And you have a new panel, so we'll eliminate that.

 

We're left with a couple options here. Most likely is the power supply, or maybe the main board.

 

Did you pay for the panel?

Customer: replied 6 years ago.
yes I did, the thing that I found out afterwards is that the panel installed now is a V400H1-L07 Rev C1, but the tv actually shiped with a V400h1-L05. I'm not sure if thats a problem or not, but from what i can tell from the research i did online that it is an acceptable replacement part.

The L07 is a suitable sub for the L05, you're fine there. I hope you got it for around $200 after the core refund.

 

If you have the ability to troubleshoot with a multimeter, you can check the voltages coming from the power supply... they'll be labeled. Use the panel for ground. Make sure to do a good visual... burnt or open components, bulging/swollen or leaky capacitors. Else, replace the power supply. Well first, give me the part number from the board so I can look up pricing. Then we'll make a cost decision.

 

-Dan

Customer: replied 6 years ago.
I did a visual inspection of all boards, except the inverter (can't seem to find it), and non of them have any burnt spots, and all capacitors on the power supply have flat tops and look good to me. Going to get some readings off my multi meter here and will let you know.
Customer: replied 6 years ago.
model: H40F1_9D7 Code: BN44-00264b for the power supply. If you could pull a picture and let me know where you want me to take my readings, that would be great.
If you hold the board horizontally with the power plug on the lower right... the lower left corner should have a black table of nominal voltages. Can you confirm / deny?
Customer: replied 6 years ago.
ok i'm blind yes i see the table now.
Ok, good. Now run through them... use the panel/chassis for ground. Let me know what you find.

-Dan

Edited by Dan T. on 12/4/2010 at 2:51 AM EST
Customer: replied 6 years ago.
all pins show correct voltage except pin 27 which reads as DET 5v and its coming up with nothing
Ok, that's a standby voltage... it should be there anytime the TV is plugged in, even when it's powered off. So try that... be sure the TV if off but keep it plugged in. Then check 5V.

Let me know.
Customer: replied 6 years ago.
In order to test the pin i have to have the ribbon cable off, so i can't "turn on" the tv at all. unless there is another way to test it. I just tested it again and still nothing.
At the other end of the cable there should be a large connector on the main board... see if you can test it there.
Customer: replied 6 years ago.
ok was able to measure it from there and is coming out at 4.9 so close enough.
Ok, good.

I just reread our earlier posts... when you said you couldn't see a glow or images, did you hold a flashlight to the screen?
Customer: replied 6 years ago.
Ok was doing it in the day and didn't see anything now that i am doing it at night. I see a picture, which worries me that the new panels back light blew??
Nope, the backlight is fine. The backlight inverter is bad... the power supply for the backlight.

Funny thing, though... I can't find a part number for it.

Can you look around inside for something like this?
Customer: replied 6 years ago.
That is the one board i can't find, i've had this thing all but stripped down, was worried about pulling the LCD off the framing. any idea where it might be?
lol... in between the power supply and the panel. I don't have your manual handy. Might be a good idea at this point (here).
NOTE: It might be part of the LCD panel... which wouldn't be good. Again, let's check the manual.
Customer: replied 6 years ago.
Would they happen to connect to the T-con board or would it be directly from the Supply to the panel?
It'd be connected directly to the CCFL backlight... though I'm afraid it's integrated with the panel, this is a pretty common issue with Samsungs. I can double check in the AM... logging off for the night.

-Dan
Customer: replied 6 years ago.
CCFL i know is intergrated into the panel does that mean the inverter is too?
Not necessarily. I'll double check tomorrow. Sorry, have to head to bed.

-Dan
Customer: replied 6 years ago.
I think the Inverter is build into the power supply board
OK, I ran out this AM and got my service manual... it was bothering me last night that I didn't remember.

Give me a few to look through it and confirm.

-Dan
lol, geez... I'm a dummy. I must've been tired last night Undecided

Yes, your power board is an "IP" board... which means it's both, inverter and power.

New one - HERE

Rebuilt one - HERE
Dan and 3 other TV Specialists are ready to help you
Customer: replied 6 years ago.
I'm going to go ahead and order one you've been extremely helpful.
I'm glad I could help. Let me know if you need anything else... and thanks for the tip!