Grating, basic normal work of power supply, scanning circuit. Grating light, a round sweep line, electron beam current is too large, can be made of brightness channel, tube and power supply circuit fault cause. There are "squeak" sound that protection circuit. 5Kqservice manual download site
 5Kqservice manual download site
[maintenance method] 5Kqservice manual download site
(1) at the end of the boot test put board saw pipe collector voltage, are all 11 v, normal should be about 145 v, so the grating light. 5Kqservice manual download site
(2) check the decoding block IC501 15 feet luminance signal output voltage of 0 V, the normal is 6.8 V. This voltage make depending on the tube at the end of the current increases, the collector voltage is reduced. Sees itself at the end of the circuit is normal. 5Kqservice manual download site
(3) check IC501 22 feet dc supply voltage of 12 v, normal. Failure is not the power supply circuit. 5Kqservice manual download site
(4) the order check the brightness, chroma IC IC301 brightness channel each foot peripheral circuit. First off 15 feet external protecting tube ZD301, boot check, everything is back to normal. ZD301 pipe resistance, found a breakdown. 5Kqservice manual download site
ZD301 breakdown IC501 15 feet of a short circuit, so that the electron beam current is too large, the screen too bright. 15 feet after short circuit, blanking and not see at the end of the tube so flyback lines. 5Kqservice manual download site
After replacement of the 12 v voltage regulator tube ZD301 troubleshooting.5Kqservice manual download site