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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Toshiba Rear Projection Convergence board problem
Hey,
I had a post about a problem with a rear projection 24KHz RGB monitor from a Waverunner arcade game (old topic was "50" Mitsubishi Rear Projection Help"). Anyway, after looking at it, I noticed that it's actually a Toshiba, but I'm unsure of the model (it's missing the back panel where the model number should be). I'm starting a new topic as the original problem appears to be solved, and this is more of a specific problem now. I had problems with the monitor not staying on, and it ended up being a problem with the convergence board. I found an opened resistor at the -15V line on the convergence board, which is a 2 ohm (appears to be a 1W) resistor. I don't have an exact replacement, but I have lots of other low value resistors, which I hooked up to get within the 5% allowed of the original resistor. Anyway, now it comes up, but the convergence is WAY off. This model has no manual pot adjustments, so I guess I have to adjust it all through the menu. I do have the remote, but it doesn't seem to be allowing me to change any of the convergence manually. It'll let me change size and position, but when I follow the instructions for adjusting convergence that I found online, it just sits there doing nothing. You can see a pic of how bad it is he http://dogp.home.comcast.net/waverunner/DSCF0741.JPG and a picture of the convergence board he http://dogp.home.comcast.net/waverunner/DSCF0745.JPG and a picture of the chassis he http://dogp.home.comcast.net/waverunner/DSCF0671.JPG and: http://dogp.home.comcast.net/waverunner/DSCF0672.JPG I also pulled the convergence adjustment pages out of the manual and they can be found he http://dogp.home.comcast.net/waverunner/convergence.pdf , in case any of you guys recognize the adjustment procedure from other Toshibas, and have seen a similar problem. Does anyone know why when I hit the adjust buttons, nothing happens? Would it be something with the new resistor I put in, or would something else be blown, or is there some sort of protect switch or something? Searching the internet for Toshiba convergence problems seems to pull up a lot about the output transistors on the convergence board, would that make it unadjustable and way out of adjustment, and would it seem possible that all three colors are not adjustable? So far, I've tested all large transistors on the convergence board, and none are shorted, and I've tested the outputs of the remote, and they're good. Any other ideas of what to check? Thanks, Pat |
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