Hi Guys,
An update . . . I just returned from my brother-inlaws. As I posted earlier, he picked one of these up for free off of Craigs List.
We ran down this weekend so I could take a look at it. The set was in perfect condition - not a mark on it, screen was crystal clear with no scratches, etc.! The previous owners had taken excellent care of it! It was even pretty clean inside, hardly any dust at all!
We rolled up our sleeves and took it apart. My brother inlaw is a DIYer but has zero electrical experience -> He pitched right in though!
This TV is the easiest one to put convergence chips in I've ran across so far!!! The chips are on a thin rectangular board at the front of the tv set. You take the front panel off and there's a cut out in the cabinet that allows access to it. There are only six cables running to the board. The first one runs perpendicular and is on the middle, left side of the board. The other five run horizontal across the back of the board. The second cable is at the top left of the board (as looking from the front of the tv set) and unplugs. The third cable though we could not get to come loose - it's apparently not a socket/plug assembly but rather some sort of permanently attached header assembly. That cable breaks into three separate plugs on the other end. Two went back to the a/v input panel and plugged into a silver box on it (sorry, I didn't unhook it, my brother inlaw did and I forgot to look at what it was later). The third plug went to the circuit on the left CRT tube and was easy to unhook from the front as the CRTs are right there. The fourth, fifth, and sixth cables are the red/green/blue outputs that go to the CRTs and they unplugged easily. Once all the cables were unhooked the circuit board can be removed. It was easy too - it's got three plastic tabs at the front edge of the board, I just lifted up on the heat sinks for the STK chips and pried the first tab back, kept upward pressure and pried the other two back and the board came right up, then just pull forward a tad and it'll come right out.
The board it's self was easy to solder on - like the other convergence boards I've worked on, it's not overly dense in components so it's not bad to solder on. The STK chips are screwed to the heat sinks which I think I like better than clips as I know they are being held down firmly to the heat sinks. I had to gently pry the STKs loose from the heat sinks. When I did I was utterly surprised to find that one had heat sink grease on only about 2/3 of the chip! The other was worse! It was just a round blob in the middle of the chip and I"ll bet it only covered 1/3 of the chip surface! I'm amazed this unit ran 7 years that way!
The chips were easy to remove using the Radio Shack $12 desoldering iron/bulb unit. I also replaced all of the resistors listed in my earlier post. Most of the resistors were off white with the values stamped on them rather than the more traditional appearing ones with color bands to denote their values. All visually looked OK except for R843. Both ends of it were dark brown. I don't normally test the convergence resistors as to do it right you need to pull one leg up and if I'm going to half unsolder it it's not that much more to just fully unsolder it and put in new ones. I did test the R843 that looked bad though and it was infinite resistance so it was definitely bad.
I replaced the STK392-110 chips with STK392-150s from Acme in Orlando. I considered the 394-160s as Leonard has done several of these sets successfully with them but he did mention others had reported having problems with this sub and it's a couple hour trip and both families have busy schedules so I didn't want to risk them not working and having to make another trip down as it would probably be hard to get that lined up in the near future and I hate setting projects aside and having to pick them back up weeks later. The 150s were just the safer bet for "works the first time".
I installed the 150s with Arctic Silver heat sink paste. Probably over kill, but I work on PCs all the time so I always have some on hand. I replaced all the resistors too without incident. All the resistors are lined up just in front of the STKs on the board, no hunting - they are all easy to find.
We reinstalled the board - that was simple, there are two horizaontal holders the back edge of the pcb goes into, just start the edge of the pcb into those holders and then press down and the board will snap down past the from connectors and slide right into place. We then replaced the front and rear cover panels as there is a sort of trap in these units that will disable the digital input if you fire it up with the back panel off (see earlier post above about this). Finally we fired it up - it fired up with no problems but the convergence was off. We went into the menus and pulled up the auto convergence. It took a minute or so and when it was done a gorgeous picture popped on for us!
We let it run for an hour or so and did the auto convergence again, then I also did a manual convergence. The auto got it close so I just had to touch up the corners a tad with the manual convergence.
The picture it made was GORGEOUS! The thing is HEAVY too! My son's 51" Magnavox is more akward than heavy, but this JVC is definitely a chunk! I'm thinking that speaks to build quality - the Magnavox has some lower end particle board for the cabinet, a plastic mirror, etc.. This unit seems to have a little better particle board in the cabinet, and I noticed the mirror was glass.
All in all my brother inlaw was ecstatic! And I hope I'm not jinxing anything, but I found this tv almost FUN to work on! It's really easy compared to the Toshiba and Magnavox units I started this hobby with! I would like a big screen for our family room and I think I'm putting JVC on the short list of brands to look for!
I hope the above helps someone else - if you have one of these units and are wondering if you can really do this yourself or not the answer is
yes, you can! I imagine that's the answer for most of these rear projections, but some are harder than others and I'd say from my very limited experience that there probably aren't many easier than this model (for convergence chips anyway, I have no idea on anything else)!
Take Care,
Steve