Riddled TV Repair Forum

jbero · Joined: 26 Aug 2011 Posts: 1 Location: okc ok

I have a RCA L32HD31, with after 3 years of reliable service, went completely dead one morning without warning. The only thing that comes on when the remote "on" button is pressed is the small pilot lamp located on the bottom front. It has been some time since I have worked on a project such as this, however, I consider myself a skilled troubleshooter and proceeded to open up the unit for a look see. Working without a schematic, I have tested what appears to be a power supply and with the aid of some of the postings here have determined that the board is dead except for the presence of a 5-volt output ( 4.9-volt actual ). There is no obvious sign of part failure on the board---Cap leakage or swelling, burned spots, the fuse is fine, however, without the schematic, I cannot know if there is some small surface mounted fuse on the under side of the board. I do not recognize such after searching with a magnifying glass.

Operating on assumptions at this time I can only surmise that the five volts is for the CPU on the main board. If this is true, then:

1.) The main board might be designed to send a signal back to some sort of electronic switch or relay on the power board to turn on the other power circuits.

2.) Or, all circuits on the power board should be on at all times; which would focus my attention to primarily the power board.

3.) In the absence of a schematic, the questions are: If number one is true, is there a signal wire from the CPU to the PB, and if so, where is the electronic switch/relay located on the board and how does one go about testing this?

4.) There is a component on the PB near the AC input marked as VR1; does this stand for Variable Resistor and if so, should I focus on this?

5.) The signal from the CPU may be missing, in which case the main board likely needs replaced; can one test for the presence of such a signal w/out a scope?

6.) Maybe 4.9-volts is not sufficient to operate the CPU correctly.

Google

twentytwoac · Joined: 04 Dec 2011 Posts: 1

My RCA L32HD31 set had the same problem as you described. By chance I came across a similar set that had a busted screen. I exchanged the power supply circuit board and that procedure restored power to my tv. Now it works like new. I did not have time to troubleshoot the bad board. I did like you and went over it with a magnifying glass but saw nothing abnormal. I did not use a multimeter, but I believe that if you trace the ac voltage to where it becomes dc then you will be able to find the faulty component.

mb · Joined: 24 Dec 2011 Posts: 1 Location: FL

I had same L32HD31 with yellow indicator in front (not turn into green)
Pic sound is there in 1"top visible light at the top of screen.

I doubt Main Board or T con .T con Vcc shows +12V which is not as per mark+5V at J20 Socket connect T Con with Main Board.

If any boady Help to solve is most welcome .
Question

Need Boards to confirm problem.

Power supply board, Backlight Invertor, are working perfect.
Thaks
MB