proscan PLDED3996A-C2 NO PICTURE POWERS ON

[mattstolte]

I turn this on and the led goes from red to blue as in powering on but no picture. Im thinking main board?

[budm]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

Can you completely remove the back of the TV and take straight shot pictures of the whole back side of the TV, the power supply/LED driver board (both sides of the board).
That power supply/LED driver board looks familiar.
I would say bad LEDs like this one:
https://www.badcaps.net/forum/showthread.php?t=45652

[mattstolte]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

I tested them red wires on the connector. They all read 20.7 volts. I think them wires are going to the leds? And shouldnt they read 24volts? Also i took picture of this diode. The board looks really brown burned up right under them 2 big diodes, the picture doesnt show it so good but it looks more burnt then shown in picture. But im thinking if them 20 volts is correct then i proly has bad led lights

[budm]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

Did you check both diodes yet? They are connected in parallel.
The 20.7VDC readings on the red wires are ref to the chassis GND, right?

[mattstolte]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

Yes bud the readings are done as you said, and also not sure what diodes connected in parallel mean but they both read 252 and checked them other way they say 1

[paulstef]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

not sure what diodes connected in parallel mean but they both read 252 and checked them other way they say 1

If they are in parallel they are supposed to share current equally between them. At least they don't look shorted . If you want to be absolutely sure, lift one terminal and measure again.

[R_J]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

I just repaired a proscan PLDED3273A-E, that has a different power board but the circuit may be similar. The voltage from the power supply for the led circuit was around 25-30 volts off the diodes, it then goes through the coil and is boosted to around 70 volts, I suspect that boost circuit is not working, if it is the coil should be getting quite warm. if its not getting warm check the boost circuit.
This video has a circuit diagram which may be usefull https://www.youtube.com/watch?v=GrfSmtzFjCc

[samcat69]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

: I have a PROSCAN PLDED3996A-C2 S/N A1305095130002210. I have sound and no picture. I can see the menu when I shine a flashlight on the screen. I cannot determine what part I need to replace, but its either the power board or LED controller board. I don't believe I have an inverter for the LED or its built into the main board. What part do I need? Model No TH390LK01-ACW1
Cell V390HJ1-P02
T201304032

[newtothis]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

It is more than likely bad LEDs

[samcat69]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

Ok so I bought a whole new power board/control board...Same problem. How do I find and replace the bad LED?

[mattstolte]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

you need to remove the screen and test the leds to find which is bad

[kjr2446]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

I'm having the same trouble same model # I removed the screen plugged n the main board/ power source, but none of the LEDS lit up

[Hitman]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

hey guys.
Newbie here. Same model and problem. Any updates?

[mattstolte]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

both of you are from Cincinnati? I am from canton area. I have led strips for this model available. what you need to do is test each led with your meter on diode mode. scrap the paint off on each side of the led and test each one they will light up if good just a little from the power on your meter. if they don't light up then its no good, if you need help message me

[spankyd]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

can someone send me pics on how to test the leds on this flat screen please, having same problem and want to be sure before buying parts,thanks

[TraciD]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

Just for data - I am taking one of these tv's to recycling today because of this same problem. The picture just vanished one day though the sound was good and everything else seemed to be working fine (channels would change/ we could turn it on and off). When I found it was possibly a "video inverter" and that this could be diagnosed by looking for the faintest hint of picture on the screen, I could in fact see a hint of movement when I looked at a severe angle. I took the thing apart after watching a YouTube tutorial that showed how simple it was to pop out an old video inverter and pop in a new one thinking that of course I could order a card and do THAT. Not so simple.

As I said, I'm dropping one of these off to the recycling place today. I wasn't ever even able to find out where the crummy "video inverter" was!

[SamyBoyz]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

Hi!

Mine turns on occasionally...red led is lit but doesn't turn on

Any suggestions? The power supply does not show any signs of burned components..

[budm]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

What Voltages did you check out so far?
We also need you to upload good clear pictures of the whole back side of the TV showing ALL the boards and then the pictures of the power supply board top and bottom side.

[SamyBoyz]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

It's been about 20 years i graduated from electronics school but unfortunately i never worked in the field, went straight to I.T.

I tested the 2 diodes which are in parallel and the 110v input from the connectors on the PCB..I wiggle the PCB back and forth while off and the tv works, i wiggle it back some more and it stops..would be indicator of bad solder, but i redid most of them..

I can post pictures of the power supply back and front but nothing seems darkened or unusual

[SamyBoyz]

Re: proscan PLDED3996A-C2 NO PICTURE POWERS ON

Hi,

Attached are the pictures you requested