Based on the maintenance experience, put integrated circuit IC101 AN5138 weld is very easy to appear the fault, observe the IC does exist in weld and welding test machine fault still. From the video terminal input VCD signal, observe the screen is still interference, indicating that the fault and the IC has nothing to do. Because the machine has no drawings, to the maintenance inconvenience, after checking the Panasonic TC-2185 type color TV drawings and similar, so the machine drawings for maintenance. First check the video and the brightness of the channel, check the brightness delay LC301 normal, IC601 (AN5601K) brightness control {18} pin voltage for 2.8V does not change with the fault, indicating failure and brightness adjustment circuit. Will be the comparison of the potentiometer assembly welding cleaning, installed after the failure of the machine, the replacement of the maintenance switch S601 is invalid, suspected of decoding block IC601. Unintentional measurement service switch 4 pin voltage, found the unsteady, the foot is by controlling the fault opening scanning circuit for CRT white balance, triode O602 beside the maintenance switch measured the B voltage change between the 4V~ 8V with fault, the triode tube different from ordinary three electrode tube, bandstop transistor H4111, weld have been measured leakage, confirmed its position according to the is maintenance through the switch to control the field scanning circuit of work and not to adjust white balance and normal watch can not, because hand without the tube, so temporarily installed test machine, fault exclusion.