SOURCE: Green Convergence problem
O.K. This is a CRT Projection TV see http://www.tacp.toshiba.com/televisions/product.asp?model=50H82 The Manual is available from http://www.tacp.toshiba.com/tacpassets-images/models/50H82/docs/50H82_om_e.pdf , and this describes the Manual Convergence process, I doubt this will help, but it's step #1. The problem you are describing sound to me like a deflection problem. The electron beam in the green projection 'tube' (a super bright CRT) is probably not being controlled correctly. This can be caused by several things, from least likely to most :) I do not recommend that someone untrained in electronics attempt to service a CRT based television due to the potential for extreme shock or electrocution. That caveat said, here are the possibilities. #1 Physical Trauma: The TV has been shifted moved or bumped hard, and one or more of the fixed permanent magnets used to help convergence has come loose, or the CRT projection tube was damaged. I don't think these TVs use convergence magnets anymore, but it's possible. The green CRT tube failing would be more likely if all four corners were affected, but I've seen a failing CRT affect a single corner/edge before. I believe that this model has projection tubes that are separate from the colored filters, so swapping the tubes around may be possible. I do not have a service manual for this set, and this may be a hazardous operation due to high voltages. #2 Stray magnetic field: Someone dropped a magnet into the TV, and it landed close enough to the green tube to effect it only, or perhaps some other piece of equipment is effecting JUST the Green CRT (clock radio, speaker, badly designed wall wart, etc.). Removing the offending magnetic field may cure the problem. Perhaps the offending magnetic field has been removed, but it's presence is still felt. Try using the degauss function built into the TV set (I can't find one in the manual, but it may be present). You may want to try using a degaussing coil, and see if that helps the problem. Just be careful not to get the coil too close to the base of the projector tubes. #3 Deflection drive electronics: A CRT works by using an electron beam to excite fluorescent compounds on the face of the CRT. To move the electron beam about, a process called deflection is employed. Magnetic coils (the choke) are used to steer the electron beam up, down, left or right. These coils are driven by transistors, and as one fails, you will get an image that starts collapsing in the affected section. On a standard CRT TV, that would mean the entire image is affected, but a CRT projection display uses separate red, green, and blue CRT projection tubes to build the image, so you have three times the deflection, three times the possible transistor failures, and in your case, the odd result of just the green part of the image displaying incorrectly. This problem will probably require a service call, and a electronic board swap, but the problem could be the choke (the magnetic coils) on the green CRT projection tube. Swapping the green tube for another tube could prove if it's the tube or if the deflection electronics that are going out. Again, my feeling is that this is a deflection issue requiring a board swap (I doubt anyone actually does component level repair anymore) Sorry, I don't have a better answer, peace. Paul.
SOURCE: color convergence
Usually, what happens in those sets is that one of the STK output IC's shorts out. Each IC has 3 separate channels, and one of the channels shorts out, which sends B+ or B- to the convergence coil. This burns out the low-value resistor associated with that channel. If the bad IC is replaced but the resistor is not, that channel will continue to not work. Look for 3 large resistors right next to each IC. These resistors are 1 or 2 watt resistors, have a value of about 1.8 ohms and sometimes are under the heat sink fins that the IC is bolted to. Measure all 6 resistors with an ohm meter and you will probably find one of them is open. Replace that resistor and your colors should return to their normal positions.
SOURCE: Red color convergence on Toshiba 57H81
Often convergence issues do not require the entire board to be replaced. You can resolve it by replacing the convergence ICs. The part in question is STK392-110. You will need two of them and they cost around 10$ each. But replacing them is a pretty complicated procedure and I would not suggest it to someone without prior experience. A service manual should get you started in the right direction if you are planning to do this yourself.
https://www.completeservicemanuals.com/toshiba/crt-projection-television/57h81-service-manual/prod_1128.html
PS: Disconnect from the power supply before you start the repair. Also read the legend, the hv circuits are denoted by a special symbol, so you will know what you shouldn't touch.
You may also need to replace the nearby resistors that may have popped the IC in the first place. Read the service manual for further details.
Good luck,
Sai.
SOURCE: colors out of focus- like a really bad 3-d movie
the convergence issue can be usually repaired by replaceing both of the STK392-110 Convergence amps and the six 1.2 ohm 2 watt resistors. You can get replacement parts at the following link with instructions on how to replace the ICs.
http://servicemanuals.vstore.ca/
SOURCE: the convergence is off. When I try to use touch
Ok, we go to solution of your problem===The pico fuses are green and on the main power board--have you removed the back and looked inside--most of these sets have the two STK-392-110 on the main board to the right-they are usually on the left edge of this board on two very large metal heat sinks--chips are about 2 1/2 inch wide X 1 1/2 inch tall--is this how your set looks inside? they will have the number printed on the black face of each chip in white--The fluke meter will allow you to check all the grey protect resistors--most are 1.8 ohm and the pico fuses will be near the edge of the board to the left----All I expect from you for help is a vote here--if you remove the back do you see the chips?
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