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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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LA7838 Vertical IC and Mitsubishi CS-3535R
"T o d d P a t t i s t" bravely wrote to "All" (11 Oct 05 11:34:16)
--- on the heady topic of "LA7838 Vertical IC and Mitsubishi CS-3535R" That kink might be due to ripple in the vertical IC's supply voltage. Follow the vertical IC's supply lines until you get to the filter electro and rectifiers from the flyback derived +24 volts, change these too. A*s*i*m*o*v Todd From: T o d d P a t t i s t Todd Xref: core-easynews sci.electronics.repair:344895 Todd I'm at the end of a long repair of this Mitsubishi CS-3535R. Todd I've replaced the switching regulator and related caps to Todd get the primary side working, the 30 volt regulator Todd transistor and related zener with bias resistors that burned Todd up, a burned zener and bad cap near the "black level Todd corrector IC," a couple of fuses and finally the vertical Todd output IC - a Sanyo LA-7838 and all the caps in the vertical Todd section. Todd The initial failure involved smoke and the repair was a Todd pain, as I smoked several components on the main board and Todd saw smoke once in the vicinity of the CRT neck. The last Todd bit of repair was the replacement of the LA-7838, which I Todd replaced with an NTE sub. Todd The picture currently has a slightly brighter horizontal bar Todd about 20% down from the top. The scan lines are slightly Todd closer together there, and I suspect that it is the closer Todd scan lines that make it appear brighter there, but it may Todd actually be brighter. The picture is slightly compressed at Todd the line, but looks OK above and below. The caps were all Todd replaced in the vertical section hoping to get rid of the Todd vertical problem (which was not there prior to the power Todd supply problems.) Todd I've gotten advice from some here whose advice I really Todd respect, and the consensus is that it's probably not the Todd vertical IC, despite the fact that I used a sub. However, Todd having replaced all the electrolytic caps in the vertical Todd section, I'm not sure where to go now. [,,,] .... 'Keep the smoke inside.' -- 1st Rule of Electronics. |
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