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Hitachi CTP-1838 TV the boot after a period of time the screen showing horizontal stripe, shutdown and rest for a while and then boot repeated fault repair method of the phenomenon

Time£º2014-07-24 08:50:26  Source£ºNetwork  Author£ºUnknown  Clicks£º1238
  

This is the line scan out-of-step phenomenon. On normal, out-of-step components poor thermal stability. The cause of this failure; HtLservice manual download site
 HtLservice manual download site
(1) line oscillator attune slants, slightly after the temperature drift is beyond the scope to keep. HtLservice manual download site
(2) the line oscillator stability, temperature rise after the frequency drift is too large. HtLservice manual download site
(3) an AFC Lei detectors, bad filter characteristic and keep synchronization range reduced. HtLservice manual download site
(repair method) HtLservice manual download site
(1) adjust line frequency potentiometer R703 after boot, check whether its in the best position, it is normal. Has a very wide range of synchronous keep around, that is not horizontal frequency partial tone, nor is it an AFC keep the scope small. HtLservice manual download site
(2) after being out of step adjustable R703 again, still image synchronization, there is still a good synchronous adjusting range. But restart after shutdown cooling, horizontal frequency and need to readjust to sync. Specify is horizontal frequency drift after temperature rise is too large, need to check the line oscillator oscillation and timing components. HtLservice manual download site
(3) check the absorber swings IC701 C70I peripheral components, C70Z, R703, R704, found R703 carbon film or the center tap end and poor contact between the pins, sliding contact slide to endpoints will still be around 2 k Ω resistance, and sometimes this resistance is zero. To replace the new 5 k Ω potentiometer, don't appear this fault. Explain R703 can contact when the phone is switched on. But after the temperature rise of poor contact, causing the line frequency change, the image out of step. HtLservice manual download site
(4) if and attending IC701 (1), (2), (3) the feet peripheral elements are normal, should consider to replace IC701.HtLservice manual download site