Hi, I'm fixing (or trying to) a TV for a friend, and wondered if anyone had any wisdom relating to the following symptom.
This is a Sony BE-3D chassis, and exhibits an intermittent fault. When its doing it, the picture is still visible, but collapsed (jitteringly) upwards towards the top of the screen. It doesn't stay collapsed for particularly long. The sections of image which collapsed upwards also narrowed horizontally, leading to a tapered looking screen --------------- |\ /| | \ / | | \_______/ | | | --------------- (Although this diagram probably exaggerates it somewhat). None of the obvious supply caps tested for bad ESR on my meter (main PSU cap, the various secondary side PSU caps including B+, the flyback derived 200V supply etc.) Even when raster / scan has been lost completely, sound works fine. At one extreme I saw in person today, the vertical collapse left three horizontal lines (R,G,B) separated by an inch or so on the screen towards the top. No picture was visible (and I turned it off). I know this set has a common fault with flyback transformers failing due to internal arcing. I almost convinced myself this was probably the case, but now I'm not so sure. Could it cause the symptom? (It usually supposed to trip the sets overcurrent protect on the B+ line and shut down H drive, throwing the set into standby though - which it didn't seem to do for me today). Unfortunately its been several years since I last fixed a TV, and I don't have my handy box of bits for insulated prodding / light-bulb inserting / freezing / HV testing. I don't even have an oscilloscope here (although I could borrow one from the lab). I'm working with multimeter and ESR meter. I do have the schematics and service manual though, which is a big plus. Best wishes, -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user