Things you need:
- Soldering iron with a fine tip and fine solder (rosin core only, never acid core! I used .022 inch)
- Flux (if desired, I didn't use any)
- Desoldering materials (I used copper braid desoldering wick)
- Isopropyl alcohol (preferably 95% or better, for cleaning the board when done)
- Thermal grease (normally used for CPU heatsinks, I used Artic Silver)
- Masking tape (thin)
- Felt-tipped marker
- 2x STK392-120 IC's
- Hex-type screwdrivers or bits (I think they are called security bits)
- Multimeter for testing the nearby resistors
- Digital camera to record your work and help you put things back together
I recommend that you read this completely before starting, so that you know what's coming up and can gather anything else you think you might need that I've forgotten or neglected to list here. :)
Preparation:
- Buy two STK392-120s. Check my Links below for a dealer I had good luck with, or just search. Don't look at the 150s, 180s, or other newer models. Some people report success, but from the specs I've seen these parts are not perfectly compatible. When I'm tearing apart the back of a huge TV, I'm not taking any chances.
- Practive soldering and desoldering if you haven't done this before or in a long time. It had been almost 20 years since I'd used a soldering iron, so I did some practice in the days leading up to this with an old graphics card that I was willing to throw away. There are some great sites out there (see my Links below) that can show you how to solder, desolder, and fix soldering issues.
- Buy good ICs, don't buy generics. For just a few dollars more, you'll get a better part that will last longer. From what I've read, the Sanyo's and Panasonic's are good choices, but there are probably others.
Now let's get started!
- Remove the back cover from the TV (just the electronics cover, not the entire back of the TV!). Remove the black bracket that holds the RCA and other jacks as well as the black plastic bracket that holds the cables out of the way. There are different size screws used here, so keep them labeled or separated in a useful way.
- The only board you will care about for this repair is the one of the left side. There are a few connections between it and the center board to watch for, though. Slowly begin unhooking cables, labeling each cable and the corresponding plug-in spot on the board. Use the tape and marker. I started at “A” and worked my way up to “X” if I remember correctly, but you could use whatever pattern you like. There are 20+ cables (hence A – X), so take your time and get it right. Take pictures along the way. You will need to unscrew the vertical board at the top left to get further along, and you will eventually need to remove the large plastic “bridge” running above the center of the board. This one has screws at the base in front of and behind it, so it's a little tricky to get out.
- Pop all of the attachment boards off the mainboard. Press the three clips on the side of the board and pop it out. Carry it to your workbench of choice.
- Remove the clips that hold the ICs against the heatsink. Desolder the ICs and dispose of them. Since they were already dead, and I was fully committed at this point, I just clipped all of the IC pins with a small pair of diagonal pliers (dykes) and threw away the old ICs. Then I flipped the board over and desoldered each pin, pushing the remnant down through the hole so it dropped off the board to the bench. I had great luck with the desoldering wick, it sucked the solder right out of the joint and the pins pretty much fell out. Some took a little wiggling, but nothing was too difficult. After all the pins were out, I checked and cleaned the holes with the soldering iron (quickly).
- Flip the board back over and clean the heatsinks well. Line up the new ICs and make sure that the pins drop into the holes properly. Sometimes they get a little bent from shipping or your own handling, so line them up (gently). Apply a thin layer of thermal grease to the back of the new ICs. I spread mine with a razor blade, something that has worked well for me in the past doing CPU installs in computers. Drop each one into place, then use the clip to secure it against the heatsink. This will allow you to flip the board again and do your soldering without needing anything fancy holding things together.
- Slowly and carefully solder each pin. A good solder joint should look like a little “Hershey kiss.” Be sure not to run over onto adjacent pins and bridge the joints. I didn't have any trouble here, so I can't comment on how you would fix that.
- Once you're all done, clean the back of the mainboard with alcohol and a toothbrush to remove and flux or other gunk. Wipe it down and dry it thoroughly.
- While you're here, you might as well check the resistors. There are several large resistors around the ICs. Grab your multimeter and check their resistance. If you don't know how to read a resistor (it had been a while for me, too), check my Links below for some good charts.
- Now for the fun part-- put it all back together! Do everything you did to take it apart, but in reverse order. I put a laptop right next to me with my digital pictures on it to help, but you may not have that luxury. Take your time, make a checklist, and work through it. Refer to your pictures along the way to be sure. Try not to bump the CRT guns or the adjustment screws on them while you're working.
- Once you have it all back together, leave the back off and fire it up. Let it warm up for a bit and then check it out. Make sure you plug things in to the various inputs to see them work. I made the mistake of looking at the menus on screen, thinking all was well, and closing it all up. When I wheeled it back in place and hooked up all of my equipment, I discovered that only my HD input worked, nothing else! I had to open it back up and look around carefully until I found a small cable that wasn't seated properly. Once that was in, it all worked well.
- Don't be disturbed if the convergence is still off, it just needs to be adjusted (and it can be now). After a good long warm-up with plenty of bright colors, select the convergence menu. I reset mine back to factory defaults, then went through the multipoint convergence for both red and blue and lined things up again. You really should have the TV warmed up well, or the convergence will just drift off once it does get there.
Done! Now wasn't that easy (or at least easier than parting with $350+ for someone else to do it)? :)
Links: