Sony TV Hiss, weather?

[trennonix]

Hello,

I have a Sony TV that is working perfectly (picture and audio wise).
However, today it started making a hissing noise. The noise seems to come from somewhere near the HV cable.
The weather was very humid so I suppose this could be linked to the problem (i have 2 other sets that were not affected).

What should I do? Tried using a hair dryer but nothing

I attached a picture to give you an idea of the situation.

Thanks

 

[Sceadwian]

Electrical contact going bad? I'm not one for TV repair so I wouldn't trust my judgment but the only thing I can think of is to discharge all the HV portions disconnect the HV cable clean it up really nice and put it back on. There are some TV guys here though hopefully they'll chime in.

 

[trennonix]

I cleaned around the cable and the noise was reduced.
I didn't want to snatch the cable as I was afraid of breaking something.
Now I closed it up, maybe tomorrow, if the noise persists I'll do a proper clean-up.

 

[Nigel Goodwin]

Clean it up really, really well, using alcohol - let it dry off, hairdryer it, then smear silicon grease around it under the cap.

 

[unclejed613]

before you do ANYTHING with that anode cap.... with the unit unplugged from the wall, take a long skinny screwdriver, and clip an alligator clip wire to it near the handle. clip the other end of the wire to a chassis ground in the TV or to a metal braid that goes across the grey coating on the outside of the tube. slide the blade of the screwdriver up under the anode cap until it makes contact with the contact button on the tube. you may hear a pop. keep the screwdriver blade in contact with the anode button for a few seconds (count to 10). this discharges the capacitor formed by the outer coating and inner coating of the tube. you can now safely remove the anode cap. the anode cap connection is two metal fingers in the rubber cap. bend the rubber up so you can see them. push the cap to the side until one of the fingers releases from the recess in the tube and remove the cap. clean the rubber cap and the surface of the tube with 99% alcohol and let dey. coat the area around the button on the tube with silicone grease, and the matching surface of the rubber cap. bend the rubber cap backwards so you can manipulate the metal fingers back into the anode button. once they have a good grip inside the button let the rubber cap go and it should make a good airtight seal around the anode button.

 

[ericgibbs]

Jed,
That's good advice...

 

[Nigel Goodwin]

Jed,
That's good advice...

Nah! - it's taking all the fun out of it!

 

[trennonix]

You are one great uncle uncle jed!!
Thanks for such a detailed walkthrough.
Now the TV isn't making any noise so I might wait till it starts doing so again

 

[Sceadwian]

It'd probably be a good idea to nip it in the bud now if you can trennonix, if that's electrical arcing the noise you're hearing is gradual vaporization of the wire contact, not something you want to allow to occur, as long as you follow a few simple precaution that Jed mentioned it's quiet safe.

 

[unclejed613]

most likely it's humidity causing the arcing. clean and grease the cap anyway. after you clean it inspect it for any carbon tracks (looks like jagged black lines across the mating surface of the rubber cup, or rarely, straight black lines). if that's the case, the rubber cap is beginning to break down and, although you can clean the carbon out and restore the insulating properties of the cup, if it's beginning to break down it should be replaced. arcing, heat, and corona discharge cause the rubber to de-polymerize along the track, and although you may get all of the carbon out, the rubber in the immediate vicinity of the track has partially decomposed, and may be likely to form more carbon tracks in the future. silicone rubber in this condition will be crumbly, and may be brownish or a lighter grey than the rubber around it.. silicone rubber is a very good insulator with excellent high temperature stability, but it has it's limits...

 

[tvtech]

Now that is really sound advise unclejed

Good to see there are at least some of us humble TV techs that have the time to post good, detailed advise like yours.

I however am in a working environment/community/Town/Province where every Tom, Dick and Harry believes they can fix TV's.
And when they have screwed up/butchered the TV/s enough......they bring me the dregs to fix up the mess they have made of the chassis....

As a result, I never warn any local wannabe TV techs about the dangers of messing with EHT. Let them find out for themselves. The hard way.

Gotta stop them with some shocking, practical, hands on experience I thought....... Problem is, they are 100% from Africa and too thick to realize that it was the charged tube that bit them even though the TV was off.

Gotta be the hardest nation on earth to educate. Seriously.

The Soccer World Cup only showed the best here...not the rest. I deal daily with the rest.....

To give you an example: I work alongside an African "TV tech" who has been fixing TV's for as long as I have. To this day.....he doe's not have the interest or ability to fix a TV with a circuit diagram. He believes in swapping parts till the thing works.

That's his way. I have tried for two years to train him. Alongside him every day. Still as ******* stupid as ever. A waste of time and energy.

1. Power supply problem...he changes the PTC
2. Chopper transistor keeps blowing. He changes the Main Smoothing Cap. Repeatedly. Gotta be something wrong with the last lot....

It goes on and on and on.

I am over and out. Sorry for swearing.




Cheers

 

[unclejed613]

when i was a teenager, i started working in a TV shop as a summer job, that was in 1972. i had been interested in electronics since i was 5 and actually fixing stuff by the time i was 8.i devoured books on electronics (and continue to do so). i work with people who don't care to learn much about electronics. they continue to "shotgun" their repairs. they don't care to know what causes a particular failure as long as they can make a quick fix and move on. that's fine for the bean counters that see "X" number of repairs per day as a goal to be reached (i suspect at your shop like mine, you're probably paid by the hour). i prefer to troubleshoot to the component level on many repairs, even if the repair is a "board swap". i want to make sure i'm replacing the correct board. i'm a "sharpshooter" in my troubleshooting methods, and i hate wasting parts. if your fellow tech is still guessing in his repairs after being in the business for a long time, and refuses to learn, maybe it's time for him to take up a new line of work.. there was a tech where i worked recently, who didn't want to learn any more about electronics because he had dreams of working in management. he shotgunned repairs and "played the system" so his production numbers were astronomical. he is now gone, and the rest of us stuck with some of his backlog. i had an amplifier that he had ordered parts for (parts which, it turned out were unavailable through normal channels from the manufacturer). when we did finally get the board he tried to order, i got to finish the repair. the board he had ordered a replacement for wasn't working, because...... one of the connectors on it was unplugged

 

[tvtech]

I was born in 1963 and was only allowed to use a 12VDC soldering iron by my Mom in my pre - teen years. I used to use my Dad's company's car battery as a power source in the garage to solder with....he could never work out why the battery was always flat in the mornings.....Mom always covered for me!!!

I have loved Electronics from as far back as I can remember. Love of Electronics and why certain things happen to cause components to fail always keeps me interested in this amazing field.

Electronics is an inborn passion. It cannot be taught.

At least, that's the way I look at it.

Cheers.