My TV doesn't turn on. How to repair it?

cowboybob said:

Ok. Thanks for the clarification.

I can see now that the brown (blackish) wire appears to go to the Horizontal board (with the fly back transformer). I can envision that board being the problem. that circuit is by far the most power (current) hungry and with the highest voltages floating around. Not unusual for a component to be overloaded and fail to a shorted condition. AND take out other components in the process.

A portion on the PS schematic:

The three red arrows on the right feed the Horizontal Board, HV (24.5kV), Focus and Screen grid elements of the CRT and represent a significant load on the PS. Of course, the problem may also lie in the feeder circuit(s) of the PS.

In all honesty, it is going to be difficult (at best) to trace, let alone troubleshoot, where the problem is.

I should note that the manufacturer assumed that field repairs would be handled by Board Level replacement.

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J_Nichols said:

Thank you very much for the time and information you are bringing.
It will be difficult, as you say, to repair it.
But one question... I have seen in one youtube video that the problem could be caused by the PTC, and replacing it with a new one could solve the problem. I ask you that because I have seen that the brown black cable is very near of the PTC. What do you think?

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cowboybob said:

A PTC ( Positive Temperature Coefficient fuse), ordinarily, reacts to an over-current event with an exponential increase in resistance (due to an increase in temperature), effectively removing a path for the current (a "sort of" open). When power is removed, the PTC cools and a low resistance path is restored: a self healing fuse.

In your case, there is a "hard" short somewhere in the circuit(s) that is blowing the mains fuse. It could be more than one.

Can you read schematics?

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J_Nichols said:

So you mean the problem can be in more than one place at the same time as you wrote in the last post.

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cowboybob said:

I'm afraid that's a distinct possibility. Might end up chasing the problem(s) all over the place.

I might encourage you, though, to continue your pursuit of an electronics learning curve. Start with something a little less complex and come back to ETO for any help you might need.

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cowboybob said:

You're welcome.

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