Scored a JVC widescreen projection

[devoid]

Just in time for turkey day football. The model is av-48wp34. It's got obvious convergence issues which I'll start on before the mashed potatoes.

In a little research I found that the DVI moudle on this set has a light sensor built into it. If the set is even just plugged in the wall and sees light it erases itself. Then supposedly has to go back to Japan for reprograming. Black tape fix. Any other seedy features I should watch out for on this one?

Other than that I'm feeling like a pig in shit with this thing.

[JCFitz]

No need to remove the back for convergence trouble on this one. Just remove the front bottom. The screws are in the back sides. In the front you will see the convergence board with 2 STK392-110 convegence output ics. Replace both and check for any overheated low ohm resistors. The value of those resistors is very critical.If any are off by even a few tenths of an ohm you won't be able to obtain good convergence. With a new set of STKs and no changed value resistors it should only require minor adjustment which is available in the customer menus.On removing the back as long as the set is unplugged you're ok.The set can be run with the back off with the digital module unplugged but you won't need to remove the back for your problem.Just be careful with the convergence board.It is very flimsy.

P.S. Make sure you buy Sanyo original STKs. Do not buy them from MAT or any of the discount electronic houses. The generics are knockoffs made in China that don't have the power handling characteristics of originals and will cause you much grief.I've seen generics send all 6 low ohm resistors up in flames in a Samsung widescreen the instant the set was turned on.Tritronics carries Sanyo original ics. You don't have to buy them from JVC. Sanyo makes them for all the original manufacturers.I change several sets every week on a wide variety of brands of projection tvs. They are high failure items much more so than in older projection tvs. 2-3 years for modern ones verses 8 years or longer they lasted on older projection tvs.My mom's 1987 Mitsubishi projo still has the original STK4273s in it. Unbelievable that that tv works as good as it does with the amount of hours it gets on it.Still a good sharp picture.

[devoid]

2.2 ohm resistor and we're back in buisness. Watching Jaws right now on AMC. Did I mention it was a curb freebee? Gonna put some fresh heatsink compound on the convergence outputs

[matt314159]

Sorry to bump a thread from the stoneage, but I wanted to see if Devoid is still using this tv and how the repair worked out long term. I just scored a JVC 48WP30 CRT RP HDTV, it wasn't a curbside pickup, but I paid $100 for it. Same problem as you had, it looks like.

I have removed the convergence board, and taken out the two convergence IC's.

I bought the parts from a store called servicemanuals.vstore.ca...i'm wondering if they are a good source for the original sanyo IC's or if they're going to be knock off's. I paid $70 for a kit that contained both IC's, about 12 resistors, along with pretty good looking instructions (which was why I paid higher than retail...I know the parts seperately would have cost much less)...but I'm concerned that the IC's that come in the kit they sell might not be the original high quality originals. If you have any information that could help, I would appreciate it. I've also got several discussions going on over at fixya but I thought maybe if you had any thoughts, maybe you could help me out and post them here too. The parts haven't gotten here yet so i'm not committed. If I need to buy new convergence IC's I still can.


Thanks, and sorry for bringing this thread back from the dead.

[rcaman]

original sanyo,s do not have any writing on the back of the ic,s. if you put generics in there and they short out you stand a good chance of corrupting the convergence dcu module. not a good thing. never use generic stk,s i would put stk392-180 in place of the stk392-110. steve

[rcaman]

if the ic,s have green numbers on the back send them back or throw them in the garbage. steve

[Carmine]

I found that the DVI moudle on this set has a light sensor built into it. If the set is even just plugged in the wall and sees light it erases itself. Then supposedly has to go back to Japan for reprograming. Black tape fix.

Explian this for me also, yes?

[matt314159]

Thanks for the replies, I appreciate the tips on what to look for on the IC's.
I had read about potentially replacing them with 150's, 180's or even the newer generation 120's, but other people also said that can sometimes tax other components on the board by drawing different amounts of power, or other things I didn't understand, so I decided to replace like for like.

When the IC's get here today I'll take a look at them. I emailed the guy and asked him, and he said they are OEM ICs bought in bulk, so we will see...

[matt314159]

Originally Posted by rcaman

if the ic,s have green numbers on the back send them back or throw them in the garbage. steve

Very interesting. I just checked the back of the STK's I pulled off the convergence board, and, IN DARK GREEN WRITING, it says 392110BK39....

I had noticed that there were only four dots of thermal grease on the back of the chips, but it didn't look like it had been soldered before other than the original time...did JVC use cheap STK's to start, or has mine been repaired before with cheap parts?

[devoid]

Why am I always beconed when I'm eating chicken legs... Anyway I sold the set to a friend and after a while it craped out. We put in new chips sourced from MCM and a wall wart powered fan to keep them cool. It's been fine ever since. And do wrap that module in back tape. The sensor's there to screw you out of the digital input.

[matt314159]

Well the new IC's got here, and had black writing on the back. I decided what the hell, and installed them anyway. I'm giving my eyes a break before I replace all the resistors, and then we'll pop her in and see if it works.

One thing I'm curious about, I guess maybe our tv sets aren't identical after all, mine is the 48WP30 model, but anyway I didn't have to open the back at all to get to the convergence board, all I had to do was take off the speaker grille and a wood panel, and it was right there in front.

I'm not a technician by any means, in all reality I probably shouldn't even be working on this, but I got the service manual and some good instructions, and i've been hitting up all the forums from here to timbuktu getting all the info I can on it.

The scariest part so far was reaching into the set to disconnect one of the cables from the riser card coming up out of the middle of the mainboard. I just tried not to touch anything. I'm aware that there are several places in the set that hold voltage enough to knock me on my keester even after the set has been unplugged for days or weeks, which is rather intimidating...

Anyway, on to go replace the resistors, and then install it and see what happens. I really should have practice soldering more before trying those IC's but I think I made out okay. got the hang of it after a few pins. nothings bridged and everything looks alright. Used plenty of thermal grease on the IC's as well...considering the last time they only used four dots on each corner of the chip.

Thanks for getting back to me. I really want a plasma or LCD tv, so I think I may just get this back to working condition and offload it onto craigslist for whatever the market will bear, and then put that toward a flat-panel.

[andy]

000

[matt314159]

Okay, well I replaced the STk's and all 12 resistors on the Convergence PCB....
Now comes the time to hook it up and see if my tv blows up.

I have checked, and double checked, and then triple checked everything, in fact I used my digital camera on macro mode to take close up pictures and then blow them up on the computer screen.

Here goes nothing. I'm nervous.

[matt314159]

Well crap, now I'm pissed.

Original problem with the blue convergence is fixed, but now the red convergence is F'd up.

Here was the original problem:


The blue convergence had both vertical and lateral movement, but had that slope down at the top and couldnt' get itself far enough up to align itself.

After replacing the two STK392-110's and the 12 resisters on the convergence board, the Blue is now perfect, and aligns to the green just fine. But now the red has lost all lateral motion. It can move up and down vertically but has no side-to-side adjustibility.
Here's my new dilemma:


That's as good as I can get it to converge.

All that effort for nothing.

Any ideas? like I said befoe, I am 1200% sure of all my solder joints, I looked it over in painstaking detail. Words cannot express how disappointed and disgusted I am right now

[andy]

000