RCA LCD Main board compatibility question


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RCA LCD Main board compatibility question

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dicepackage
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Mar 22, 2010, 4:30 AM

Post #1 of 15 (7412 views)
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RCA LCD Main board compatibility question	Can't Post

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 and it shares the same part number. The board looks almost identical but has one less coil piece. My question is will this be compatible? I am mostly concerned that a board for a 37" TV will incorrectly scale for a 32 inch but since they both run at the same resolution would that really matter?

jts1957
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Mar 22, 2010, 10:16 AM

Post #2 of 15 (7404 views)
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Re: [dicepackage] RCA LCD Main board compatibility question [In reply to]	Can't Post

Shine a flashlight at the screen at an angle and look for very dim moving picture or use a known test pattern and look for that.
If there...

See if the inverter board has B-Plus (usually 24VDC - can be alltime or switched); And an enable voltage (usually 3.3 to 5 VDC) that comes on and stays until you cycle the unit's "power" button (usually will also have a backlight brightness voltage which varies as the unit's brightness {or back light brightness} is adjusted.
If both are present = most likely NOT the motherboard.

-------------------------
Location: Far, Far Away

dicepackage
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Mar 22, 2010, 11:31 PM

Post #3 of 15 (7389 views)
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Re: [jts1957] RCA LCD Main board compatibility question [In reply to]	Can't Post

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 the voltages aren't labeled but I do get markings for what they are:
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

jts1957
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Mar 22, 2010, 11:43 PM

Post #4 of 15 (7386 views)
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Re: [dicepackage] RCA LCD Main board compatibility question [In reply to]	Can't Post

"0V" (or low) with set "off"
"3.28V" with set "on" (and "stays" all the time the set is on)?
If it does, Main board causing is UNLIKELY. I'd start suspecting the inverter board, bad fuse, lytic, open transformer winding, etc. (or bad CCFL bulb(s) is also a possibility). Cool

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

-------------------------
Location: Far, Far Away

dicepackage
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Mar 23, 2010, 12:32 AM

Post #5 of 15 (7383 views)
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Re: [jts1957] RCA LCD Main board compatibility question [In reply to]	Can't Post

10 E_PWR: 3.28 volts with set off
12 BLON: 0 with set off

board repair
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Mar 23, 2010, 1:43 AM

Post #6 of 15 (7381 views)
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Re: [dicepackage] RCA LCD Main board compatibility question [In reply to]	Can't Post

There is a slim possibility the two boards would be interchangeable . Right above the model # you see will the same model # with 2 letters and 1 number . There are 7 different versions of the 32" and 6 different 37" . What are the 2 letters and 1 number and i check for a motherboard or inverter board part # . I've repaired these sets in warranty and the motherboard was changed when the set would not turn on or the picture was not stable . Although i did have an L32HD33D RCA that had no picture but the sound was ok and it was the motherboard ( Digital Main ) . As JTS1957 stated i could not with bright light see any picture image on the screen . The motherboard ( Digital Main ) has been a problem for RCA LCD's , sometimes a digital VOM just isn't enough to check them out . Let me know if you need part #'s , James

dicepackage
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Mar 23, 2010, 4:38 AM

Post #7 of 15 (7378 views)
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Re: [board repair] RCA LCD Main board compatibility question [In reply to]	Can't Post

I'm not exactly sure what number you wanted from where so I decided to give you everything I could. I'm also now more uncertain about what is wrong with the TV since it appears to be getting the BLON voltage but still no backlight. Could this still mean the main board is bad?

On the back of the main board it is listed as 2147499B and above it the board says PCB SCALER IFC 130/230 (EU). Shop Jimmy calls the 2147499B number the part number for this board. I believe it lists the serial number as SCALER76A A followed by 96561624351296.

And in case it helps on back of the inverter board I found the following: <br>VIT70002.61 0620T 44328 <br>27-D002544 l320B1-24-V04-L2B0 REV:2B
In this instance the VIT70002.61 is the part number.

I see that there is also a TV model L32WD12YX1 but mine is just L32WD12 and I have looked all over the TV for anything more.
So to summarize:
Main board part number: 2147499B
Inverter board part number: VIT70002.61
TV Model: L32WD12

(This post was edited by dicepackage on Mar 23, 2010, 4:53 AM)

board repair
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Mar 23, 2010, 4:57 PM

Post #8 of 15 (7368 views)
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Re: [dicepackage] RCA LCD Main board compatibility question [In reply to]	Can't Post

Ok there are 4 different versions that end with YX1 - YX5 - YX7 - YX9 . Sometimes they are on the the back side of the dispaly panel if it is not on the back on the set . YX1 & YX7 call for a 271711 . YX5 calls for a 271707 . YX9 calls for a 274594 . The number you found on shopjimmy 2147499B is a drawing number and is not a part # used by RCA for ordering parts . Now if the drawing number on your board matches the drawing # that shopjimmy has it will work . The power boards on these sets are all different that is why the scaler has to be the same . Now as to the inverter board there is a problem . Your going to have to find one that is ( used ) because RCA only makes it availible with the panel which would cost more than a new TV . Hope this can help you get the right part . James

dicepackage
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Mar 23, 2010, 8:32 PM

Post #9 of 15 (7366 views)
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Re: [board repair] RCA LCD Main board compatibility question [In reply to]	Can't Post

Here are two pictures of the board. Perhaps this will help to find the missing number. I have looked all over and can't find it.

Mainboard front view

Mainboard rear view

board repair
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Mar 23, 2010, 9:19 PM

Post #10 of 15 (7364 views)
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Re: [dicepackage] RCA LCD Main board compatibility question [In reply to]	Can't Post

I was only able to see the drawing # as RCA ( i don't know why ) doesn't put there part # on there boards . I did check the shopjimmy website and it does look the same and should work ok . I also noticed they had two different prices for the two boards they had . The one board for $89.95 was made by RCA & the for $129.95 was made by LG . If you look at the two shopjimmy ones ( LG ) the bottom right of the $129.95 has the same two plugs yours has . Do you use both of them ? So your best bet would be go for the $129.95 or if you want to try the $89.95 you can as long as you don't need those plugs . Looks like you can send it back but you have to pay to send it back and lose the shipping cost to you . It is starting to sound like LG made the TV for RCA and that is why i can't find the model # without those letters and number at the end of it on RCA's website . Just ran into an Hitachi 26" LCD under warranty and went to Hitachi's website to order the part and couldn't because it was made by Orion so i had to order from them . Sometimes it hard to figure out who made what . James

dicepackage
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Mar 23, 2010, 11:20 PM

Post #11 of 15 (7361 views)
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Re: [board repair] RCA LCD Main board compatibility question [In reply to]	Can't Post

There are two tuners on this TV. Would each coil be for an individual tuner? If so I have no problem going with only one.

dicepackage
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Mar 24, 2010, 1:12 AM

Post #12 of 15 (7359 views)
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Re: [dicepackage] RCA LCD Main board compatibility question [In reply to]	Can't Post

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. <br>

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.

(This post was edited by dicepackage on Mar 24, 2010, 1:13 AM)

board repair
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Mar 24, 2010, 4:05 PM

Post #13 of 15 (7350 views)
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Re: [dicepackage] RCA LCD Main board compatibility question [In reply to]	Can't Post

Yes , but did you check the fuses on the inverter board ? Some of the RCA's use 1 - 2 or 3 fuses . Or does any of the transformers look like they've been getting hot ? The board will be darker around that transformer . Also look for the capacitors being bad , maybe even bulging at the top of them . There is also a chance of the CCFL background lamps maybe your problem too . Suspect the inverter board though . They do make an inverter tester but it is not cheap @ 100.00 , but worth it if you are working on LCD sets . If you suspect the inverter if bad your only going to get it used as RCA made it availible with the panel only . The number you listed VIT70002.61 is what you have to find . Google it and start checking prices .

dicepackage
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Mar 25, 2010, 2:49 AM

Post #14 of 15 (7345 views)
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Re: [board repair] RCA LCD Main board compatibility question [In reply to]	Can't Post

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
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Apr 3, 2010, 9:31 PM

Post #15 of 15 (7313 views)
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Re: [dicepackage] RCA LCD Main board compatibility question [In reply to]	Can't Post

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

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