Hi all: I'm a new registrant here and I'm hoping to get some help in this very excellent forum.
I have a 7 year old Mits. model WS 65908. It has operated perfectly and without incident since it was new, up until about 5-6 months ago when it began exhibiting the symptoms of the apparently common convergence and image distortion problems described in this forum variously as the "rainbow", "3-D movie", "bow-tie" and "hour glass" effects. Comments in this forum pointed to the two convergence chips, either failure of the chips themselves and/or of one or more of their solder joints. I was able to confirm this on my set by tapping the chips gently with the tip of a wooden dowel rod, which would cause the picture to snap back to normal. It also seems to be the case usually that the problem occurs, sometimes intermittently and sometimes constant, for the first hour-or-so after the set is turned on, and then the picture will snap back to normal on its own and remain normal thereafter until the set is turned off.
It seemed possible, based on the behavior described above, that the problem was caused by deteriorating solder joints, and I therefore decided that I'd address that issue first and hope to get lucky. So I foolishly jumped in where angels fear to tread, and undertook to make the indicated repairs. Removal of the pcb from the chasis was a snap, thanks to the many helpful comments found here, and I then proceeded to take the board to the workbench and re-solder the pins of the two convergence chips.
I then re-installed the board and the heat sink to which the chips are bound, and re-connected all the wiring. But when I turn the set on now there is no picture at all, not for 2 minutes, 2 seconds, or even 2 miliseconds. The set DOES come on, the green status light DOES come on and stay on steadily, the sound DOES work and the tuner DOES change the channels. But the screen is totally dark. The 3 CRTs are also totally dark, and there is no visible indication of any sort to suggest that any power is being supplied to the lamps. And when the set is queried for a trouble code (ie., by depressing the front panel device+menu buttons) it returns code number 12 (1 + 2), which I understand means "no faults found, check power supply".
So either something went wrong on the pcb while I had it out, or, less likely, I made a mistake or committed some oversight in the re-installation and/or re-connection process. I can't justify an expensive service call for a rear-projection set that has already been operated for 10,000 hours but I thought I'd try once more before giving up, and perhaps this time replace the convergence chips and pico fuses.
I would appreciate any suggestions and recommendations for troubleshooting and fixing the picture black-out problem described above. I don't solder for a living, but I'm reasonably competent, and while I don't know a great deal about electronics beyond the basics, I have built and made various elementary repairs to a number of computers. Thanks very much for your responses!!