I am having an issue with my Mit VS-55601. It shows green "wavy" lines at the top of the screen, and then the green convergence is bad on the bottom 1/3 of the screen with the worst at the bottom (makes an upward arc like the St. Louis Arch with the middle being almost converged). So it appears it's only the Green, and only verticla (Red/Blue and all horizontal convergence seems fine, and I can adjust the Red/Blue in the adjustments). This did this really bad for 20 minutes one day. I turned it off for 20 minutes, turned back on and everything was fine for the rest of that day. Now for 3 days in a row it's had the problem return. I have tapped and reseat all the internal boards, and noticed no changes. I read a bunch of the posts, and most seem to suggest the convergence chips. My questions are: 1. Would the fact it broke, then worked, then broke again and that it is only the green gun, and only in the vertical direction, be consistant with the convergence chips goign bad? 2. Would removing the convergence board (any ID info would be great) and checking resistors feeding the chips and all solder joints help (or a waste of time)? 3. Say I replace the chips, would I need to do convergence adjustments after and if so how hard would that be? (if I have to start moving the yokes etc or sliding the magnets.. I'll call someone... :) ). 4. How much should this run for an at home repair? I can't get anyone to give me an estimate as they say it could be so many things, but not even ballpark on just the chips (which worries me). 5. Any other suggestions on what to check, where to buy a manual of schematics (readable and preferably original, vs downloaded). I saw several parts links to buy the chips in other posts. :) OH, and any suggestions for how to discharge the anode's on these tubes? I usually do the screwdriver under the suction cup method, but can't see where the leads enter the tube. Does the front just pop off to allow better access? Any help would be greatly appreciated. Thanks, Buzz
The old convergance on older sets worked basically of capasitance,thru resistors,diodes and caps.on these stk chips they have circutry also of these componets.sometimes you have to buy one or two of them to correct your problem.shelf life has something to with electronics also.part tolerance plays a part.these stk circuitry connect to each other on the convergence board by design.if you have one dominate color issue it is possible that maybe that color tube needs to be checked.retrace issues maybe what you have.or on your picture tube board circuit.
Before you call for help is a good idea if you check the solder conections to the convergence Ic's and resoldered them and while you are there check and resoldered any overheated areas.If the soldereing corrects the problem you will not have to worry about convergence adjustments,as long as the set is unplug you can carefully work in the chassis without having to touch the anodes of the picture tubes,stay away from them.Lets us know how it goes.
This is a convergence related issue, the converge Ic's should be mounted on a heat sink and they are marked STK.... on its face,Be careful when fliping the right board to look, while you do it some conectors might get disconected ,most of the wires are long so you can pull the chassis but others might have to be disconected and the reconected when done.
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You can see some more examples and find a fix using this link on Fixya http://www.fixya.com/support/r2861467-solution_video_looking_whiteish_dull
http://www.fixya.com/support/r2861467-solution_video_looking_whiteish_dull
You can see some more examples and find a fix using this link on Fixya http://www.fixya.com/support/r2861467-solution_video_looking_whiteish_dull
The problem is called green geometry.There is nothing wrong w/the green pix tube.It is critical to get the green geometry
accurate because the red and blue convergence overlays on
the green.If you have more than an alignment issue,that will need
repair before adjustments are attempted.
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Thanks jomaru! :) I will give it a try. To clarify, this does fit a convergence issue problem.(?) And also, the board I need to resolder is the big one on the right with the RF shielding over most of it and the large heat sink off the top, correct? :D
I just didn't want to start diving into resoldering if this was a non-convergence related issue.
Thanks again! I'll let you know how it goes.
Buzz :)
Update:
I removed the convergence board (disconnecting all connections) and found the following:
1. No resistors were burned, no overheat marks, and all the pins on the SK convergence chips looked ok.
2. I saw that one resistor and 2 pins on the VGR connector had flux near them (assuming this means someone had replaced these in the past). By tracing the solder traces these seem to be related to the center convergence chip and trace to the VGR connetor (assuming this is for the green convergence).
3. I removed (solder) and resoldered all the main resistors and flowed clean solder on them. I also reflowed the solder to all pins on the center convergence chip.
4. On powerup, I jiggled all connectors to the convergence card and the corresponding connectors on the yoke of the green tube (carefully!). I also adjusted the screen and focus for the green tube (worked fine).
None of the above changed the result. I still have convergence issues with the green tube and *only* in the vertical direction.
I spoke with a local tech friend who said something about each chip has vertical and horizontal convergence sections and there are separate sections per color (he said 2 chips: 1 vert 1 horizontal, then 3 colors per chip, but doesn't work on Mitsubishi's). From what I can tell this is 3 chips (1 per color) and guessing each chip has vert and horizontal sections.
Is the above correct? If so it would seem the chip could be bad for the vertical section.
The big question I have is this: If the chip went bad, why would the TV exhibit the problem, then have it go away for a day, then come back again? I would think once it goes bad it would stay bad?
I may order the chip and just replace it and see if anything changes, given I am dreading any manual convergence after replacement.
Is there a good source for these chips? Also, anyone know the SK number off hand? I will dissassemble tomorrow, but would like to order it tonight if anyone knows the number (I'll research the posts just in case).
Thanks for all the help! :)
Buzz
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