JVC AV-65WP74 Problem - Vertical Lines

I would be looking for a bad connection between boards or something similar.

The television has never been moved in 3 years, more that 12 inches to attach cables. JVCA emailed and suggested disconnecting all sources and reconnecting the cable tv connection, then running the automated convergence test, and the lines are still an issue. Could it be the IC's or STK chips?

It does not appear to have a convergence problem. Looks like something from the internal test pattern generator getting into the video somehow. This is not likely a DIY project.

I would still be looking for a bad connection, bad ground, wire dress problem or something similar.

We had this happen on or new LCD Viewsonic under warranty and it ended up being a problem with the power supply board. They replaced the entire board.

Power supplies with problems in the filtering can contribute all kinds of symptoms like this in any type of set, so that is a possibility. Best to check the obvious first, then to be sure you would need to look at the supply lines with a scope.

**** UPDATE ****
I found a local technician, who addressed what they thought was a convergence and/or power supply issue, but they claim the real problem was what they called a micro or computer board. $395 later, they replaced the convergence chips, power supply and the micro board, the tv is working normally with no vertical red & green lines now, BUT.....

I warned the technician NOT to power on the TV with back off or the DVI would be disabled, and once the tv was returned - NO DVI !!

I have found a few posts stating the DVI can be re-enabled through the Service Menu, is this true and if so does anyone have the steps to reset the DVI?

I found a post where 2 pins could be shorted with a pc type jumper and powered on and off then the jumpers removed to reset the dvi - any ideas?

Not sure. I was under the impression that shorting the pins was the procedure to do to be able to operate the set with the back open, not to restore it. I have never had to restore a lost digital function, but what I have heard is that you have to jump through hoops with JVC to get the parts.

I remember I read somewhere else that there's an EPROM for this DVI. There's a round optical hole on top of the EPROM. When TV is on and light goes through the hole to EPROM, the EPROM will be ERASED. There used to be a lot of these kind of EPROMs for MCU. JVC will be your last resort to get it programmed or get a pre-programmed part.

What someone really should do is to take off the back cover while TV is powered off, and use something like black electrical tape to cover that hole up before powering up the TV again.

The technician is supposed to come back tonight to look at the issue, I have 10 pages of posts of what can happen if the back is removed while powered on, do you think covering the hole with tape, replacing the back and powering up the tv will reset the dvi?

No that won't do it. EPROM erase is like deleting permanently the files in a harddrive.

Ok - I guess the company that performed and didnt read the CAUTIONS in the service manual will have to send the EEPROM to JVC to be reprogrammed or if they have a good EEPROM from another same model, would a dvi module swap work ?

I think it should work but not 100% sure. I'm just a DIYer with EE background, You need to confirm it with professional.

When I was at university there was programmer for EPROM and also eraser which emits ultra-violet light to erase EPROM

Good luck

czipster said:

The technician is supposed to come back tonight to look at the issue, I have 10 pages of posts of what can happen if the back is removed while powered on, do you think covering the hole with tape, replacing the back and powering up the tv will reset the dvi?

Click to expand...

Ten pages of posts are not relevant. He, or you, need to talk to JVC and get the real information on the matter. If he is not a JVC ASC that may be difficult, but they should at least be able to refer you to someone who can answer your question definitively.

I was able to find a service bulletin on the DVI problem. While I do not generally do research on individual problems nor post service bulletins, this affects lots of people and the so called "booby trap" on the JVC sets is so irresponsible, IMO, that I think it is appropriate to post the info publicly.

The service bulletin is in a sticky here:

http://www.hometheatershack.com/forums/jvc/17982-no-dvi-video.html

ljryjj said:

I remember I read somewhere else that there's an EPROM for this DVI. There's a round optical hole on top of the EPROM. When TV is on and light goes through the hole to EPROM, the EPROM will be ERASED. There used to be a lot of these kind of EPROMs for MCU. JVC will be your last resort to get it programmed or get a pre-programmed part.

What someone really should do is to take off the back cover while TV is powered off, and use something like black electrical tape to cover that hole up before powering up the TV again.

Click to expand...

IIRC there is simply a photodiode that changes a setting in the EEPROM in these (if activated while the set is plugged in), not an old style UV erasable EPROM. Note the difference in the acronym. There is no schematic data on the digital input board, however, so it is hard to be sure exactly what they are doing, but most techs routinely cover it or just don't fire the set up with the back cover open.

I found this same fix yesterday, I'm a MCSE so I had a jumper in my desk to an old IDE hard drive, I tried it last night and the DVI is now functional, thank you to everyone who contributed to the resoltuion of my issue!

sorry czipster and lcaillo, my memory didn't serve me right. raying:

But I'm happy to learn something new again. Solute to master lcaillo!

BTW I don't understand why JVC design the DVI this way. I don't see this thing with my Hitachi 51SWX20B and Sony 46WT510. They both have DVI inputs.