Picture shaped like a bowtie, (shrinking)
This is your classic convergence Amplifier IC problem. Here is a way to deal with it.
These are generic instrustions:
1) Get the schematic/service manual for this TV (You will need it because it contains the part numbers and component values you will need for replacement)
2) On the schematic/service manual locate the convergence amplifiers (STK392-110, 120, 150) and the biasing resistors (Write the resistor values down from the schematic)
3) Unplug the TV and remove the rear cover to expose the electronic circuitry.
4) Using the schematic/service manual find the physical location of the two convergence amplifiers (Usually attached to a big metal silver in color heat sink) (Basically it will look like two big black six sided flat modules with a lot of pins on the bottom (18-22 to be exact)).
5) After finding the heat sink and amplifiers remove the screws or the tension bar holding the amplifiers in place.
6) Using a soldering iron and a de-soldering device (either a de-soldering pump or de-soldering wick) remove the solder from the pins of the amplifiers and biasing resistors that protrude from the solder side of the circuit board. (Take into mind that you may have to remove the board in order to do this, use the instructions in the schematic/service manual to do this, and make sure you mark everything you remove to make sure you have a guide as to how to put it back)
7) After removing the solder from the pins off the amplifiers and the biasing resistors, remove the resistors making a list of the value, part number, and location on the board (all of this should be in the schematic/service manual). Then remove the two convergence amplifier modules taking care so as not to damage the circuit board. NOTE: The heat sink compound (the white goopy stuff) may have hardened and caused the module to stick to the heat sink, you will have to gently pry the module away from the heat sink, I have used a light application of isopropyl alcohol to dissolve the heat sink paste.
8) Once the modules are loose from the heat sink, you can gradually remove them from the circuit board.
9) Clean the heat sink off by using the alcohol and a heavy paper towel (remove all of the heat sink paste, and yes this is messy)
At this point you have removed the two convergence amplifier modules and the biasing resistors and cleaned the heat sink.
Now you will have to use your schematic/service manual to find the part locations, values and numbers you will need to replace the old parts I suggest replacing the biasing resistors first.
1) Sort out the resistors you will need and as stated in the schematic/service manual and replace them according to the schematic/service manual locations and part numbers.
2) Solder the components (resistors) in place making sure not to short out anything in the process.
3) Apply heat sink paste to the metal side of the modules one at a time and the put the modules into the circuit board lining up the screw holes of the modules with the screw holes in the heat sink, use the removed screws or tension bar to hold the modules down once in place in the circuit board and on the heat sink.
4) Solder the pins of both amplifier modules to the circuit board, taking care not to short out anything.
5) Reinstall the board to the TV, reconnect all cables removed (DOUBLE CHECK EVERYTHING)
If all went well the convergence amps should be working, and you will need to realign the convergence of your TV, I suggest using the AUTO Convergence feature of your TV (Use the instructions in the schematic/service manual).
All should be good now.
Now these instructions are generic in nature but can be use for a number of Models of Projection TVs.
In addition to this also make sure your Yoke transformers on your CRTs are functioning as they should, check the voltages applied to them.
I hope this helps,
Jun 10, 2009 |
JVC AV-56WP30 56" Rear Projection...