Analysis and maintenance: the cause of the fault is complex, usually have the following situations:
1. line scanning circuits properly. Power light is on, indicating normal DC output. Should concentrate on examining the line scanning circuits. Check CRT filament-free highlights (pale red), line scanning circuits are not working (line scanning circuits in addition to picture tube required high voltage, but also provide filament power supply). Line scanning circuit does not work for two reasons: first, the oscillation circuit is normal; the second is horizontal output tube and its peripheral circuits are normal. Output pipe components which are easily damaged, mainly damping diode (when measuring resistance around 5~10 ω) and capacitance. Use a multimeter to check the fore oscillation circuit. +0.4V oscillator circuit and output voltage, measuring its drive transistor, Q401 R401 resistance is 0, indicating Q410 transistor has been penetrated. After the replacement, troubleshooting.


2. integrated IC410 is normal. Check the DC output voltage of the switching transformer T2 is normal. Multimeter test carefully, finds manifold IC401 pulse signal output; check IC401 the chip supply voltage is normal. A "presumed" method, assuming power supply power supply, integrated IC401 17th foot should have the sync signal input, but no output measured IC401 21st foot. Replacement, and troubleshooting.
3. high voltage circuit is normal. Manifold block IC401 output trigger pulse amplified by the transistor Q401, Q402, divided into two groups, respectively trigger line scanning circuits and voltage (voltage T501, Q502 and peripheral components). Power up the system, using two probes of oscilloscope in a charged state closer to the transistors Q502, to see if the pulse voltage. If there are line voltage pulse output, high voltage circuit is normal; if not, the high voltage circuit is faulty. The shutdown, the multimeter "Rx1K ω" test existence of the collector transistor Q502 overload protection. If not, whether Q502 fail. After the replacement, troubleshooting if after replacing, trouble still, you should check Q501 triode connected peripheral circuit, composed of Q510, Q511 is normal.
4. the power supply circuit is normal. Power supply circuit from Q505, L501, D508, ect. When the transistor when Q505, linear current flowing through the L501 rise; when Q505 deadline at the L501 current is increased to a certain extent, L501 pulse voltage produced on both ends, and then by D508 rectifying C516, filtered into a DC voltage to supply T501, Q502. Replacement failure still, you should check the drive tube Q504 and pulse-width modulation integrated IC501 is functioning properly.