The third step: the integrated circuit with an oscilloscope to observe whether there is a pulse output. If there is no time oscilloscope , you can measure with a multimeter can measure the voltage of about 0.5-0.6V when the pulse . If not, the fault first -class signal processing circuit includes a line of small oscillation , the oscillation power line oscillation timing components or integrated circuit itself. Corresponding elements can be checked , wherein the timing element row oscillation clock oscillator prone to failure , power supply lines are also more prone to oscillations failure . Should be careful to check .
Step Four: If you access the dummy load , power supply 130V output is normal, weld line access under the dummy load resistor 130V power supply is not normal to prove that part of the fault line output , one is part of a direct line output short circuit , the measured line tube collector -to-ground resistance decreases , you should check the line pipe, flyback capacitor , S correction capacitors are breakdown. Which line pipe, flyback capacitor bad failure rate is higher.
Step Five : If the access line resistance 130V power is not normal, but the line -to-ground resistance tube collector is also normal, we can disconnect the line drive , and then measuring 130V is normal, if normal , the fault for the line output AC short circuit, there is a short circuit to make the down line pulse circumstances 130V voltage decreases. Determine the fault line output transformer line output transformer experiment should be replaced . Unplug CRT high voltage cap , then disconnect the outlet end of the tube , under the lead solder , and then each spot weld line output transformer is open , forced disconnect the line output transformer .
Now we look at the actual circuit , the circuit 130V normal , indicating normal switching power supply , measuring 130V added to line pipe collector , no serious rear line output short circuit , no high , medium and low voltage , indicating that the line did not work . We can use 10V AC line profile measurements promote secondary. No AC voltage , indicating that the line did not work to promote further test line drive tube collector 24V supply is normal , OK promote V431 itself is normal, there is no fault line drive forward measurement IC LA76810 (27) # no voltage output , the fault line oscillation further measurements ( 25 ) # no +5 V voltage regulator circuit power supply pre- check fails, replace the regulator , the regulator first unscrew the screws on the heat sink , then welded under the regulator, after replacing the circuit properly.

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