Ridding TV Monitor of Static Electricity

Stonefield wrote on 7/18/2005, 9:02 PM
Hey all,

It was a hot day up here in Vancouver BC and unforturnately the heat in my little apartment can get up there sometimes during the day.

I want to transfer some DV onto VHS for a friend of mine and found my tv monitor is having some kind of visual "hiccups." It's almost a vertical roll but not quite. Hard to explain the problem but I'm pretty sure the cause is an awful lot of static electricity built up over the past day.

The TV was working fine last night but tonight It seems to have the static electricity "hiccups."

Anyone know how to get rid of the static electricity that's attached itself to my tv ?

Comments

epirb wrote on 7/19/2005, 2:51 AM
Deguassing eh ? Depending on how big the set is, if its small try this .. with the tv off turn it upside down, then turn it on for a minute, the picture will look funny maybe even green. shut it off and turn right side up.

Beleive it or not it works sometimes. but a little hard if its a 55" widescreen. : )
farss wrote on 7/19/2005, 4:24 AM
Most likely the humidity is very high. What happens is dust builds up between the EHT connection to the tube and the ultor, that's a metalic coating on the inside and outside of the tube that forms a high voltage capacitor to provide filtering to the EHT supply.
In times of high humidity the dust becomes conductive and you get a flash over. The currents turns the dust to carbon and that becomes even more conductive so more zaps which also overloads some of the deflection supplies.

Anyway to fix this. First of all be VERY CAREFUL, the EHT supply is well over 20,000 volts, perhaps not enough current to kill you but more than enough to require change of underwear and probably if you get zapped you'll drop the tube and it'll explode and then you'll really dirty your duds. Worse still, that capacitor can hold the charge for a long time. So even after you turn the power off and unplugged the thing, leave it for at least an hour for the charge to decay.

Open the unit and carefully clean around where the high voltage supply connects to the tube, you can't miss this connection, fat red wire going into the side of the CRT with a large rubber washer around where it goes in. Clean the lead, the washer/insulator thing and the surrounding class. Methylated spirits is good for this.

If you don't feel confident doing this, use a vacuum cleaner to blow the dust out and then maybe a hair dryer to dry any remaining dust out.

Like I said, show a lot of respect for these very high voltages, they can jump quite a distance, CRTs can implode causing serious injury and unless the unit is unplugged from the wall outlet even when switched of there are lethal voltage inside.

If I've scared you right off having a go yourself, at least you know it's most likely nothing expensive to fix so take it to a qualified person and don't let the hoodwink you.
Bob.

JJKizak wrote on 7/19/2005, 5:30 AM
It's not static electricity you are talking about but high voltage arcing due to excessive dust buildup. That high voltage connection has to be perfectly cleaned as now you have minute carbon tracks. Make that tube shine.


JJK
GlennChan wrote on 7/19/2005, 8:47 PM
Maybe it's a ground loop?
To see what that looks like:
Take the yellow RCA connector, and take it out. Shove it in so the outer ring part doesn't touch, but the inner male thingamabobber touches the inside of the connector. (Sorry if that sounds dirty.)
You should now see a wonderful rolling bar.

If the signal is coming from the VHS tape, maybe it's have tracking issues? You'll see this jitter in the picture.



From what I've read on repair FAQ:
A- The voltage in the TV *can* kill you.
B- The capacitor in there will hold the charge for weeks.


Apparently it's also quite difficult to make the picture vaccuum tube implode, although it can be done. The glass shards will mostly get sucked in... but you can probably still get hurt.
Blues_Jam wrote on 7/19/2005, 10:21 PM
I am an FCC licensed electronics technician and have to agree with glennchan on this. You will find voltages of 10K to 20K volts in black and white television sets but in color sets the number is UPWARDS of 50,000 and even 80,000 volts. It doesn't take much current to put a heart into Ventricular Fibrillation (cardiac arrest) which IS FATAL if not corrected in time and may leave you brain damaged if not corrected within 12 minutes of onset.

One hour disconnected from AC power is definately nowhere near enough to discharge the capcitive charge in a color television set. A number of DAYS are needed for a full discharge and even then the correct discharging procedure should be performed to ensure a complete discharge before sticking ones hands inside.

I can't emphasize this enough: Only a trained technician should perform this procedure! DO NOT ATTEMPT this on your own as it has the potential to cost you your life!

I again agree with glennchan that the problem sounds more like a VCR tracking issue. At any rate, a static charge build-up on your TV will only help it to attract dust but will not affect it's operation.

Blues
Stonefield wrote on 7/20/2005, 12:24 AM
Ok this is weird...

I put an image up onto the screen and when I turn the contrast all the way down, the flickering stops. When I turn the contrast up...the flickering resumes, the higher the contrast, the faster the flickering.

The flickering is the screen distorting slightly ( warping inwards ) then a flicker, then a brief clear pic, distortion, then flicker. Reallly hard to explain, really frustrating.

Side note :....the VHS copies I made were fine. The signal flow from the DV Camera to VCR was fine. So it's not the DV Cam or VCR.

Also don't worry, I won't be goin into the TV and mess around, not worth the new hair do and early grave.

I'm also not ruling out that the TV might be dying but I'd hate to think so.
farss wrote on 7/20/2005, 3:03 AM
From what you're are describing almost certainly EHT flash over, sometimes you can actually hear the 'splat' as well.
If you're not feeling brave and I sure don't blame you, just try blowing air through the vents, you might get lucky. vacuum cleaner switched to blow would do.
Problem you face is every zap turns more dust to carbon so the problem gets worse by itself. If all else fails take it to a techo, they really shouldn't charge much money for 15 minutes work.
Bob.
Stonefield wrote on 7/20/2005, 7:04 PM
Yes, I CAN hear the "splat" as well. Gonna try to clean it this weekend.