Repeat the above phenomenon after the reboot by cutting off the electricity. gbyservice manual download site
 gbyservice manual download site
Look from the phenomenon after failure of some protection for the machines, then from the protection of electricity. Way of tracking fault origin. The whole protection of TC - 51 p300g by Q854 contact U plate, divided into field protection (O451), 140 v over-current protection (Q849), 35 v (D894) short circuit protection, over voltage or filament protection is performed by IC9601. Combined with the example, monitoring the 140 v voltage is always normal before shutdown, so basically can be ruled out after the two and will focus on two kinds of protection. gbyservice manual download site
 gbyservice manual download site
 gbyservice manual download site
 gbyservice manual download site
A. because of the EURO - 7 vp machine core aspects of the present failure occurs more, hence the key monitoring Q451 C voltage, found that even if the failure occurs, the voltage of 0 v, and rule out the possibility of a protection. gbyservice manual download site
 gbyservice manual download site
B. the failure for 140 v after flow that caused all the way to protect, observation before the shutdown screen grating is no exception, combined with the phenomenon, hence doubt is a kind of error protection, namely R885. R886 and Q849 itself from bad replacement after boot, 30 minutes after the fault remains. gbyservice manual download site
 gbyservice manual download site
C. since the autograph is not by mistake, the cause of action 140 v over-current protection circuit for the heavy load, the factors are: the line output transformer internal bad (T551) or high voltage distribution box, a projection tube arcing and medium voltage 220 v only short circuit, etc. Because of the limitation of parts on the impossible one by one all order replacement, do how? Hence again from the failure phenomenon analysis, found that since the problem is to cut off the power supply and can be immediately after the reboot, then component is poor performance of slight over-current protection, theoretically is completely can disconnect protection circuit to let machines continue to work in a short period of time, in order to observe hints from the screen.

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