Analysis and repair: the cause of the failure of a complex, often have the following several ways: pHQservice manual download site
1. The line scan circuit is normal. Power indicator light is lit, the dc output is normal. Should check the line scan circuit mainly. Examination revealed kinescope filament no window (dark red), line scan circuit does not work (in addition to providing needed for high pressure tube, line scan circuit provides filament). The scanning circuit does not work for two reasons: one is oscillating circuit is normal; Secondly, the line output pipe and its peripheral circuit is normal. Line output pipe components easily damaged parts mainly damper diode (online measuring resistance is about 5 ~ 10 Ω) and capacitance. Use a multimeter to check before level oscillation circuit. Oscillation circuit output voltage + 0.4 V, measuring its driving triode, found Q401 R401 resistance is zero, that triode Q410 has been breakdown. After replacement, troubleshooting. pHQservice manual download site
 pHQservice manual download site
 pHQservice manual download site
2. The integrated block IC410 is normal. Consult the T2 switch transformer secondary rectifier output voltage is normal. Multimeter is careful inspection, found that integrated block IC401 without the pulse signal output; Check the integrated block IC401 power supply voltage is normal. Method "adopt" the assumption that assumes that power supply is normal, the integrated block IC401 17 feet should be sync signal input, but no output measured IC401 21 feet. The replacement of the troubleshooting. pHQservice manual download site
3. High voltage circuit is normal. For integrated block IC401 trigger pulse output by the triode Q401, Q402 amplification is divided into two after the road, each trigger line scan circuit and high voltage circuit routing T501, Q502 and peripheral components (high voltage). Boot, in the condition of charged two oscilloscope probe near the triode Q502, observe whether there is a line of pulse voltage is generated. If you have any line of pulse voltage output, high pressure circuit is normal; If not, the high voltage circuit malfunction. Shutdown, the multimeter "R x 1 k Ω" file exists in the collector of a transistor Q502 overload protection. If no, judgment is due to Q502 fault. After replacement, troubleshooting; If after replacement, the fault is still, should check with the triode connected Q501, Q510, Q511 of peripheral circuit is normal.

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