A friend of mine brought this TV to my shop not for repair but to give it to me to use for parts or sell it. He just bought an LCD 32” TV and wanted me to have his old CRT TV. It was a big 29” TV, Korean made and it was really heavy.
I plugged it in and I could hear only audio coming out of the speakers and only a horizontal line across the screen. This is a deflection problem and it cost only about 10 dollars to fix. So I decided to fix that and see if I can sell it cheap.
I opened the cover of the TV and started measuring voltages on the pins of the IC. I could see 40 volts on pin 9. This testing is very important. Before changing the vertical deflection IC, you need to make sure there are voltages reaching the IC. Usually these 25-40 volts come from the fly back transformer. One of the pins of the fly back transformer will give out usually 25-40 volts then it goes through a diode to change it from AC to DC, then it goes through a resister fuse, usually 1-3 ohms 1-3 watts. Sometimes, the fuse resister will be open causing this problem to appear on CRT TV.
The vertical deflection IC TDA3654 is very easy to find on board. It has a heat sink and usually it is very close to the Yoke sockets. I could not find TDA3654 in the electronic shops around me but instead, I put a TDA3653.
I replaced the bad IC with the new one but did not turn on the TV yet. It is very important to check the capacitors around this IC. Sometimes bad capacitors cause the vertical IC to go bad again. Check the capacitors before turning the TV on. I found two bad capacitors that had a high ESR reading. It was a 1000uf/25 volts and 100uf/25 volts.
I turned the TV on after connection a picture/Audio source. The sound was great and the picture was great. After five minutes, I could see horizontal lines on the top of the screen and the picture started shaking. Usually this is a capacitors problem and based on that, I started checking the capacitors in the power section area and the vertical deflection area as well. Found some bad capacitors there but it did not solve the problem. I touched the IC with my finger and realized that the IC was getting hot causing this problem to show on the screen. I used the hair dryer to make the IC hot so it will speed up the repair time. The problem got worse as I was applying hot air to the IC. I applied cold air to the IC and the problem disappeared. There was something wrong with the IC.
I started studying the specification of the IC I replaced. The bad IC TDA3654 is the original one and it can handle temperature 90-110 C but the TDA3654 can handle only 90 C degrees. It does make sense, once it got hotter; the IC was acting up showing this problem on the screen.
I looked for the original TDA3654 and found it, used one actually. I replaced it and I tested the TV for more than three hours and it worked nicely. It was a long repair time but was not wasted in vain. I have learned a few things, but most important, I know now that TDA3653 is not a replacement for TDA3654.