A dead TV set was brought to my shop for repair. There was no stand by light. Usually that is an indication of a problem either in the fly back and the horizontal transistor in that section or the power section of the TV.
Upon opening and checking the voltages at the high tension area, I found out that there was no voltages reaching the horizontal transistor. I unplugged the TV set and checked the horizontal transistor while on board with a multi meter set to diode setting. The meter gave me a continuous beeps on the three legs. That gave me the indication that the horizontal transistor was shorted. I soldered it out and checked it again. it was D 1555 and was a shorted transistor.
I used the light blub trick which is connecting one wire of the light blub to the collector on board and the other wire to ground and turned the TV on. The light bulb came on and I got a reading of 115 volts at the horizontal transistor. I replaced it with a new one and turned on the TV. It worked for while but I started seeing blue sparks in the TV screen. At first I thought it was a problem with the fly back transformer and I started doing some checking in the high tension area but all the parts there checked Ok.
There was one thing left to do and that is to replace the fly back transformer itself. I looked and searched for one in my electronic junk bile and found a good working one. I installed it and turned the TV on and the same problem happened, blue sparks inside the screen. Conclusion: that was not a fly back problem.
I searched the net for this kind of problem, I could not find anything about this kind of problem. I started calling my repair friends and asked them about this problem. Nobody new about his kind of problem except one guy. He is an old man, and with this age comes a lot of experience in electronics repair.
He said that this problem is due to a bad crystals in the oscillation section. He asked me to look for two crystals there that has the following numbers on them: CSB 503 ES and B500. Usually one has to do with picture and the other one has to do with sound but he told me to replace both of them any ways. The trick to this is, it has to be taken from the original board of a JVC TV board other wise it will blow the horizontal transistor.
He also gave me the two original crystals the he took out of another working JVC TV set. The moment I installed them, the TV worked normally and there was no sparks in the screen anymore.
I was happy to see that but most of all very happy to know this new repair tip. So I am sharing it with you guys out there. I hope you will find this new information helpful.