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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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Quasar Projection TV and AN5521 Vertical Problems
I have a Quasar Projection TV with a very unusal vertical problem.
This unit uses an AN5521 vertical IC. I have checked ALL of the electrolytic capacitors for value and ESR all check o kay. The vertical problem I have is that this unit will have full raster and no vertical foldover....after 20 minutes this unit will still have a picture or raster but with a faint line which is horizontal. Someone told me that this may be caused by oscillation of the vertical IC ( AN5521 ). I was also told that this could be fixed by putting a 560 PF capacitor on pins 2 & 5 of the vertical IC and if this did not work the try a 1, 000 PF capacitor. I am confused because this was to fix only vertical instability. And the chassis that were affected bu this problem a AMEDP 807, YAMEDP 807, AEDP 807, and YALEDP 807. Since Matsu****a made this chassis, the Panasonic models affected by this problem a PTP - 4586, PTP - 4588 , PTP - 5189. The measurements on the pins of the AN5521 read as follows: Pin # 1................ Ground Pin # 2............... Output 16.5 v DC and about 54 v Peak to Peak Vertical output Pin # 3.............. Boost about 29.8 v DC. Pin # 4.............. Input 0.7 v DC and about 0.8 v Peak to Peak input. Pin # 5.............. Feed Back Pin reads about (-) minus 0.2 volts Pin # 6.............. Amp pin .... 2.56 v DC Pin # 7............. Vcc about 28 volts DC This unit has no convergence problems noted with a cross hatch patteren. Could this be in the Jungle IC or Processor IC. Or else where? Any ideas will be greatly appriciated. Pat Green Cowboy's Appliances Beaumont, Texas |
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