Riddled TV Repair Forum

dicepackage · Joined: 14 Sep 2009 Posts: 40 Location: Detroit

TV Model: L32WD12
TV Description: RCA 32 Inch LCD 720p HDTV
Current Status: No picture, no backlight, working sound, responsive controls

My TV does not get any picture at all. When powered on there is no backlight at all. The sound does work fine and I am able to change channels, volume, and do anything else I just can't get a picture.

I aquired this TV from someone who said the "motherboard" was diagnosed as being broken. I believe this to mean the main board is broken and needs to be replaced.

I cannot find the main board from this model TV but I can find one from the 37 inch version of this TV with the same part number. The board looks almost identical but has one less coil piece. My question is will this be compatible? I basically want to know that if there would possibly be any issues with scaling since it is designed for a 37 inch.

Google

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

If you have sound, but no backlight, the main board is not likely. Examine the power supply for expanded electrolytics. Specifically, CS2, CS3 and CS43. Sorry, there is no board graphic to tell you location other than the schematic location. All are on the SMPS. You can also check CON3, Pins 5&6 for 24 VOLTS DC.

Hope this helps.

Jesse

dicepackage · Joined: 14 Sep 2009 Posts: 40 Location: Detroit

I opened up the power supply and didn't see any bulging caps. I specifically looked at the caps you mentioned and they all look good with no bulging.

There aren't any markings anywhere for voltages so I have no idea what anything is supposed to be but I will try to post some notable values I got.

On the power supply I get readings of:
Pin 1: 11.7 volts
Pins 2-4: GND
Pin 5: 3.13 volts
Pin 6: 24.2 volts
Pin 7: 24.2 volts

On the inverter board I get these voltages:
CN1
1-5 VBL: 24.3 volts
6-10 GND

CN2
1-4 VBL: 24.3
5 IL SEL: 0 volts
6-8 GND
9 SEL: 3.28 volts
10 E_PWR: .05 volts
11 I_PWR: .04 volts
12 BLON: 3.28 volts
When the TV is off 10 E_PWR registers 3.28 volts and 12 BLON gets 0 volts.

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

Do not know if this will work but it does on some models.
Disconnect the T-Con via the LVDS cable. If the backlight comes on you will be able to see if the panel is broken, yes, I said broken. The panel can be bad or broken and it is extremely hard to tell and it can be broken with a very small impact. (A two year old with a foos ball bat can break the panel) The only other way to see if the panel is broken or if the picture is there but without the backlight is to use a bright light and shine it thru the front at an angle and look for video movement. Sometimes you can also see the break with this method.

If there is video and the panel is not broken you may have a bad lamp or inverter. If the panel is broken your set is toast.

Hope this helps

Jesse

dicepackage · Joined: 14 Sep 2009 Posts: 40 Location: Detroit

The panel looks good but I know looks can be decieving. I disconnected the LVDS and still did not get any backlight.

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Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

With the LVDS cable hooked up you should be able to see video using a bright light if the panel is working.

Jesse

dicepackage · Joined: 14 Sep 2009 Posts: 40 Location: Detroit

No video, I've tried the flashlight trick but I get nothing.

dicepackage · Joined: 14 Sep 2009 Posts: 40 Location: Detroit

I have a correction. The tv is getting a picture. The flashlight method didn't work since I was doing it during the day and as a result couldn't see anything. I tried with the lights out and was able to make out a faint picture.

I am gonna guess that if the picture is displaying fine the main board is not likely to be the issue but could anyone confirm this.

dicepackage · Joined: 14 Sep 2009 Posts: 40 Location: Detroit

I actually was able to get part of the backlight work by using a backlight for a desktop computer. It was similar to this kit on newegg but not the exact same model http://www.newegg.com/Product/Product.aspx?Item=N82E16811994002. I wired it to one of the connections and I got a partial backlight. This was only 1/8 of the backlight but it showed me that the inverter board must be bad and not the backlight. I am therefore going to try replacing the board VIT70002.61.
I didn't notice any bad capacitors or any parts of it that were getting hot after being on for an extended time so it looks like I will have to replace the whole board.

dicepackage · Joined: 14 Sep 2009 Posts: 40 Location: Detroit

Just in case anyone comes upon this thread with the same problem I was able to fix it by replacing the inverter board.