Missing Component In TV Repaired
This Singer CRT TV came in for repair with the complaint of Standby light On. For your information Standby light problem can be caused by improper output DC from the power supply, corrupted memory ICs, no high voltage, shorted components in the secondary side and etc. As usual, I had to remove the cover in order to access to the mainboard for troubleshooting. Upon visual inspection, I was surprised to see the vertical output IC had gone missing. See the photo below:
Next I proceeded to look at the back of the mainboard and found dry joints at the legs of the horizontal driver transformer.
I resoldered all the legs and also the surrounding area. See the two photos below:
I believe this could be the reason of the Standby problem because if there is no signal going to the horizontal output transistor due to dry joints then there will be no high voltage. If no high voltage means the TV would be in the Standby mode. After resoldering the horizontal driver transformer and power On, the TV still refused to work normally (still no high voltage).
I went ahead to check on the high voltage section area component and to my surprised again, I found that the Horizontal Output Transistor (HOT) was different from the original part number. I used to repair this model of TV thus I know very well the HOT part number. Instead of D2499, it was replaced by D1710 and it was leaky. See the two photos below:
I replaced the vertical output IC TDA9302H, HOT and cleaned the board completely and powered On. The TV picture came back to life again. See the two photos below:
Conclusion- This TV had been repaired by inexperienced repairer and even took out the TDA9302H vertical IC (missing component). The actual cause could only be dry joints at the Horizontal Driver Transformer and a bad HOT but somehow he was managed to locate the fault. If you want a proper way to troubleshoot and repair a CRT TV you can get Humphrey’s ebook in CRT TV Repair and he will provide you with technical support if you have difficulty in solving a TV problem.
This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.
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