no tv picture

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new guy
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no tv picture

Post by new guy » Wed Oct 13, 2010 8:27 am

My television picture went out. I can hear the tv and I can change channels. I can even hear a DVD playing or a VHS tape playing, but no picture just a black screen. Comcast says everything looks normal from their end. Does this sound like maybe it might be an easy fix or is it time for a new TV. This TV is an RCA about 8 years old. Not a flat screen. ps.( I've checked every connection and hooked it directly to the cable and followed the troubleshooting in the original owners manual??)

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haklesup
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Re: no tv picture

Post by haklesup » Wed Oct 13, 2010 10:35 am

You can try to fix it for educational purposes but YES, it is time to get a flat screen TV. Get the size you need, don't be lured into getting a giant TV for a small room.

If its a perfectly black screen as if the TV is not on then it sounds like the High voltage went out on your CRT Television. This is usually an easy to replace transistor or a hard to replace flyback transformer sometimes it's even an impossible to find IC chip.

If the screen lights up but is otherwise blank, it might be something wrong in the tuner section. Probably a cold solder joint or other open circuit preventing the video from getting out.

If you have a trace in the middle of the screen or light at the edges, it might be something else.

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dacflyer
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Re: no tv picture

Post by dacflyer » Thu Oct 14, 2010 4:39 am

would help to have more details on the problem you have..

haklesup >> why do you say a flyback is so hard to replace ?
i have replaced hundreds of them... you just need a good hot iron ( solidering gun ) and a good solider sucker. :D

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haklesup
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Re: no tv picture

Post by haklesup » Thu Oct 14, 2010 10:25 am

Compared to a transistor, they are harder to find exact replacements, more expensive, have more leads and often mechanical mountings and take more experience to diagnose definatively and often require more disassembly to access.

If someone handed me a broken TV, told me what was wrong and provided replacement parts and exploded view diagrams, it would be pretty easy.

I suppose a good approach for a novice would be to do an in circuit test without power on the most likely failed components. In circuit testing of continuity and diode measurements can be misleading in circuit though.

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Janitor Tzap
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Re: no tv picture

Post by Janitor Tzap » Thu Oct 14, 2010 8:32 pm

I will have to agree some what with haklesup,
In that some of the Flybacks can be hard to find.
But price wise they aren't that bad if they are available. {$15 - $30}

new guy,
Try this quick test.
Place a piece of paper in front of the screen of the television when it's turned on.
If the Flyback is working, it will charge the CRT with a negative charge.
This will cause the paper to stick to the CRT.
This would indicate a vertical problem, or that your loosing the video signal before it reaches the CRT.

Crack open the set.
First visually inspect the main board for burst or leaking capacitors.
Burned or charred resistors, or other components.
If you can't see anything damaged, move on to the next step.
If you can still read the markings on the damaged component/s.
Then get replacement component/s, and replace the damaged ones.

RCA TV's have been notorious for bad solder joints on the main boards.

Next, break out the magnifier, soldering iron and solder.
Start looking at the circuit traces through the Vertical Drive section first.
Where ever you see a bad solder joint.
Reheat the joint, and add some solder, fixing the joint.
Then look at the circuit traces in the Video Output Section next.
And do the same.

Once you feel satisfied that you touched up all the bad solder joints.

Try testing the set again, and see if you now have a picture.

Still no picture?

Well, if your just messing around with it as a learning experience.
Get an Isolation Transformer, Oscilloscope, DMM, and Schematic of the set.
And start checking voltages, and video signals, to determine what has failed.
Otherwise like Haklesup said.
but YES, it is time to get a flat screen TV.

Signed: Janitor Tzap

Ken1
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Re: no tv picture

Post by Ken1 » Sat Oct 16, 2010 6:58 pm

Hi, What make and model of tv? This is a very common trouble with the rca ctc203 chassis. If this is what you have, locate the B terminal of the horizontal output transistor and follow it back to a very small coil with wire about the thickness of a human hair. Resolder both leads of this coil regardless of how good the solder looks or the joints test. This will solve the problem in this chassis.

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