Does the relay respond to power sw press ?

Transistor Q752 not getting base current. I checked with the same GND you told me to use and I put the red probe on the base of that transistor and I got nothing. that base is going straight to the big IC. so it is not getting signal to on the transistor.

and when I on the power switch I am hearing click sound. so I feel relay going click and then nothing happens.
that means the relay is the culprit?

 

The voltage you took across the relay pins says that the relay is not getting switched. Then what clicking sound can you hear.
Connect the DMM across the relay pin, and switch on power.
If the voltage is ~10V across relay coil pin then the relay will click. If ~0V then the uC is not switching on the relay.

PS. If you short the CE of Q752 then the relay should click. And you should get more than 100VDC across the filter cap

 

The voltage you took across the relay pins says that the relay is not getting switched. Then what clicking sound can you hear.
Connect the DMM across the relay pin, and switch on power.
If the voltage is ~10V across relay coil pin then the relay will click. If ~0V then the uC is not switching on the relay.

PS. If you short the CE of Q752 then the relay should click. And you should get more than 100VDC across the filter cap

across the replay I am only getting 0v. also I did power switch on and off and I saw one big spark near the coil and it shock me little bit. I places black probe on one side of relay and red on other side of coil. and tried to on and off two times I did and I saw the spark. what could be the problem then. anything else that I can check.

 

Did you short the CE of transistor to switch on relay or you saw spark without turning on the relay.

Show a picture of the sparked area and point it out.

 

Did you short the CE of transistor to switch on relay or you saw spark without turning on the relay.

Show a picture of the sparked area and point it out.

no I did not do anything to the transistor. I just had probes on the relay coil on either side. then I was playing on and off continuous may be three times. and it spark from that area. I really cant say where exactly but it looked as though it came from this area. I have marked it.

 

Did I spoil something? I am worried.

 

Better to loose a bet than to loose your life.
It being an old CRT type, I would say let a professional handle it, or throw it away.
I think you've been lucky so far.

 

Better to loose a bet than to loose your life.
It being an old CRT type, I would say let a professional handle it, or throw it away.
I think you've been lucky so far.

I must thank R!f so much for his time he has spent to explain me. I am really grateful to him. he is such a nice teacher.

ok I will close it and give it to the professional. but it was really interesting troubleshooting and finding voltages. I really had fun. anyways I don't want to delay it. my aunt missing tv episodes.
but why instead of frightening some professionals wont help me solve it in a more safe manner. I mean professionals know what happens when you touch this and that. why they don't share the safety and troubleshooting ideas, so that curious electronic lovers like me will learn it and also be safe. just a thought.

 

That area is the yoke. The spark you saw could be through the yolk or the EHT or even may be inside the tube.
In all these 3 cases, the repair is out of the hands of a n00b.
A qualified tech can tackle these issues.

The uC might be in protection mode as due to the arcing but I believe if you saw a spark at that area or anywhere else for that matter, a beginner should not attend to fix it.

Still you did good.

 

That area is the yoke. The spark you saw could be through the yolk or the EHT or even may be inside the tube.
In all these 3 cases, the repair is out of the hands of a n00b.
A qualified tech can tackle these issues.

The uC might be in protection mode as due to the arcing but I believe if you saw a spark at that area or anywhere else for that matter, a beginner should not attend to fix it.

Still you did good.

Thank you so much Sir. ya i am going to close the TV and give it to professional man. but before i do. did i damage anything on yoke? and thank you so much for your time and help. i am going to deal with crt monitor now. i hope atleast that have easy solution.

 

I don't think you destroyed any thing that did not faulted before

 

How do I know? I am not getting ac voltage when I on the power button. So relay is not switching on. Can I give 9v DC and see if it is clicking?

You have to be careful about assuming what relays do.

In PC monitors it was very common to have a relay control the degauss posistor, it was actuated for a timed period then released - then the posistor cools down and is ready any time you press the degauss button.

Somewhat in a minority - but a few TVs had a similar arrangement.

With a set of that age, its more likely the standby control.