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I wish to buy a JVC LT-42X788 Service Manual. he TV has only sound and the screen has only faint shades of blue vertical bands. Touching the screen shows that lighted ares thus the lamp seems to be OK. I need the Service manual to resolve this problem. TV was purchased November 2007. Thank you for a prompt reply. Willy

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  • whalpert May 21, 2009

    Thank you Bobby. We had checked the cables and digital card.
    Thank you again for showing me not just to check what seems obvious. 


    You get 5!


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This problem is related to a Board Failure on the TV. I garuntee is is not a Power Supply Problem since Sound and Backlight is OK. I have repaired a few of these and the most likely failed part is the board in the middle. I think they call it the analog board. This board has some regulator ICs at the top of it that power the Video Circuits. If these fail you will get the problem you see. Also check the cables between the middle board and the one on the right.

Posted on May 21, 2009

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I have sound no pic and t-con replaced. what do you suggest?

Fault with the main power supply regulator board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.

Nov 20, 2014 | JVC LT-42X788 42 in. LCD HDTV

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I see shadows on the top of the tv sometimes. This does not always happen. Is it a setting problem?

Set it to its factory settings and check. To do this, you have to enter its service mode option. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy. Surf the site with patience. Pull up older posts. Surf the site with patience.

Apr 08, 2014 | JVC LT-42X788 42 in. LCD HDTV

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Horizontal Band of Thin Red and Blue Lines on Screen

Sound like your Y-Sustain board has one foot in the grave. The Y upper buffer and Y lower buffer boards go when the Y Sus Goes too...

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JVC TV LT-42ds9bj Schematic required

If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy.

Mar 04, 2014 | JVC Televison & Video

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How to replace JVC lt-42x688 t-con board.

Assuming this is the same as my jvc 42x788 the small t-con board is near the top of the tv. It's behind the main panel that the other boards are mounted to. You don't have to take that main panel completely off, just take enough screws out to pull it out far enough to reach the t-con board. Also watch for any wires that need to be unplugged to get more room pulling the top of the panel out.

Apr 08, 2012 | JVC LT-42X688 42 in. LCD HDTV

1 Answer

I turn on my lcd jvc tv, there is sound but no picture

I have this same problem, any idea what the problem was?

Jun 30, 2009 | JVC LT-42X788 42 in. LCD HDTV

1 Answer

OT Bobby, I had asked you last week in regards to a JVC Television LT-42X788 with a with faint blue vertical bands screen, hearing sound and backlight working. You said that the problem would be the analog...

Soldering the Connectors will not fix this problem.
1. Remove the TV Rear cover.
2. Look at the wires on connected to the top of the middle board (Analog Board)
3. if they are White, this is 98% likely to be the cause of your problem. If the are a Tan/Khaki color these are OK.
4. If Tan/Khaki connectors on that middle board, I would replace the Video Process Board on the far right. Check Option 1 below for where to find boards.

I have a few options for repair of the white connector situation:

Buy the board on Ebay making sure you dont get one with the white connectors. You can use a board from the 42" and 47 inch versions of this TV. X688, X788, XM78 and I think they had a few others. Also, call JVC they may sell it to you. If not companies like Vance Baldwin or Aarons may sell it to you. This may be 40-140 depending on where you get it. The part number is on the sticker label printed on the board....not the generic label silkscreened onto the board.


Middle Board, Top Right connector. Remove the wires from the connector on the middle boards side and solder them directly to the board without the connector. This will not be as easy as it sounds. If done incorrectly, the problem will continue. If done correctly you will fix it. Also, take a look at the ICs at the top toward the connector and the similar ones along the board. Double check these to make sure they dont have any OBVIOUS damage. By Obvious I mean completly blown up or holes in them. Based on your symptom I am 98% sure it is the white connector thing but you never know.

I hope this helps and good luck. Also, unless you have a GREAT soldering Iron I don't necessarily recommend 2. These PWB have a large ground that transfers heat well. You can burn it if using the wrong IRON or TIP. 600Fahrenheit max for Lead free Solder no more :).

May 24, 2009 | Televison & Video

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Try calling the service center for technical help at these numbers
Check the status of a repair at any of the locations below.

bullet01.gif California Factory Service Center space.gif space.gif JVC Factory Service Center map_it_btn.gif space.gif 5665 Corporate Avenue
Cypress, CA 90630
(800) 252-5722

bullet01.gif Georgia Factory Service Center space.gif space.gif JVC Factory Service Center map_it_btn.gif space.gif 1500 Lakes Parkway
Lawrenceville, GA 30043
(800) 252-5722

This was all the website had to offer for customer service on the website. Hope this helps you with your problem.

May 17, 2009 | JVC LT-42X788 42 in. LCD HDTV

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