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Television problem

davelectronic

Dec 13, 2010
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Hi all.
I have a problem, ok my TV a Sony flat screen trinitron, bit dated but works, thats when its on, i dont do much TV stuff, but when its turned of and power removed it plays up and takes several or more attempts to fire up, before this started i noticed what i would call a high tension twang type noise on powering up, i had a feeling it might escalate and it has.

Its on now, but turn of and its a git to get it back on, i understand tv theory and am comfortable working on high tension circuits, i think it might be a relay maybe latching thats at fault, as when its on its fine, and when it does fire up now after multiple attempts there is no twang noise, does or can any one give me any ideas, in addition to what ive put above, ideas appreciated, it was second user when i got it, so it about 4 years or a bit more old, there is no picture, or other peripheral problem, thanks for looking in. Dave. :)
 

Resqueline

Jul 31, 2009
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The twang noise when turning on from a cold state is the CRT degaussing circuit kicking in. It (a PTC) needs a minute or two w/o power to cool down and reset itself.
The hard start from cold is probably due to a small electrolytic capacitor (10-100uF, 16-35V) having gone dry in the primary side of the PSU.
 

davelectronic

Dec 13, 2010
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TV problem

Thanks for looking in Resqueline. I will open it up and have a look, if it looks like a massive task i will just get another second user tele, but its a nice picture, so worth a look, my kits limited so can only carry out normal basic tests, but its worth a look before resigned to replacement. Dave.
 
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Resqueline

Jul 31, 2009
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I seem to remember the Sony's get a bit wobbly when you remove the back cover, and that it's almost impossible to work/measure on the PCB without removing it..
 

davelectronic

Dec 13, 2010
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TV problem

Yes ive worked on stubborn boards, the dreaded component you cant reach, or a specialized tool is needed, today manufacturers only expect you to get so long out of a consumer electrical product, in that we will all go out and buy the next model or piece of tech.

On one of my better days i will open it up, have a look, i wont expect it to last forever, as iam not to tight with money to replace it, but if i can get it to tied me over a little longer then thats a bonus. Dave. :)
 
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