Question about Panasonic PV-C2010 20 in. TV/VCR Combo
Is there a proper way of discharging the TV to make it safe to work on and remove the main board (not the tube board)? I can see exposed metal wires going across the tube, but the tube does not really have a metal surrounding frame that is that visible (covered with plastic case). What do I need and what is the procedure for discharging a tube, and when will I know if it's safe to remove the thick black wire going from the board to the rubber suction cup on the tube, so that I can remove the board and work on it? Thanks
First off there is no capacitor that holds the High voltage on the tube. Its the tube itself that stores the charge and if you dont discharge a tube properly it will bite you!!You can disconnect the 2nd anode of the tube(thats what the cup is called)that puppy can hold a charge for months as I've picked up used tubes that other service men may have striped out of a junk sets and still got zapped weeks later and it can burn a hole right in you if it bites you the right way. That metal strap is the ground for the crt(the picture tube) The proper way to saftly discharge a crt would be to take a screwdriver perferably a flat tip and connect a cliplead to the screw driver and clip the other end to the ground strap. Carefully slide the screwdriver up UNDER the cup on the crt till you reach the middle of the tube as you will feel it as it wont go any farther. In the meantime you might hear a pop sound and that would be the dischargeing of the tube.. Keep that screwdriver in place a min. of 30 to 40 secs. then remove . Then pinch the cup the oppisite direction on both sides that the wire is running as the cup is held in place by a small hooks on both sides Be carefull not to rip off the cup or bend the small hole suround that the cup is attached. And never ever poke a hole in the cup as I've seen peeps do and when you turn back on a set you will have fireworks as the high voltage will arch out all over the place and if your hand or face is close to it it will get you too!! Now take the clip lead and attach to the grounding strap and clip the other end to where you just took off the cup and your all set.Good Luck with your repair
Posted on Apr 11, 2006
Hi! First of all, If you don't have any technical training, I advise you to take it to a shop for repair, but the old way to discharge the tube is to take a long screwdriver, connect an aligator clip from the steel shaft to ground on the chassis, then making sure you hold the plastic handle of the screwdriver only, slide the end of the screwdriver under the suction cup on the tube, you will feel it hit a metal clip, and if it is still charged, there will be a loud "snap" as the tube discharges to ground. Again, I must stress this can be very dangerous, and I don't recommend you do it, but if your going to work inside the set regarless.... then this procedure should make it safer for you.
Posted on Apr 10, 2006
People should not be commenting on jobs like this unless they do this for a living.
The only time you need to discharge the high voltage left in the high voltage anode on the CRT is if you need to remove the high voltage flyback lead from the CRT. If you do, don't use a screwdriver and a clip as most places tell you. I have seen the voltage jump over the handle of a screw driver. If you are an amateur, then put a nail in a piece of wood (at least two feet long). Connect an alligator clip to the nail and the ground ******** the back of the CRT. Slide the nail under the anode cap. Move it around to discharge as much as you can. Make sure you only hold on to the wood. As someone mentioned, the one-hand-rule tells you to hold one hand behind your back while you do this just to be safe.
If you are starting to do this for a living, use your high voltage meter to discharge most of the voltage. Then you can use the screwdriver and alligator clip to remove whatever is left.
You are lucky that your TV was unplugged for so long and most of the voltage dissipated.
It's also a good idea to discharge the main filter capacitor in the power supply if you need to work in the primary section. Use a 10K resistor connected to an alligator clip which is clipped to the ground side of the capacitor. Handle the resistor with a good pair of insolated pliers. Do not use the chassis ground since it is for the secondary circuit, not for the primary (assuming you have a switching powersupply in your TV).
Congrats on repairing the fault in your TV. Well done. The ringing you are getting may be the flyback, but is most likely caused by one of the coils. You can tell which one it is by running the TV and using a wooden ruler to touch each coil. When you find the right one the pitch will change as you move the coil slightly. This MAY be solved by replacing the coil, glueing the coil to the chassis, replacing any capacitors connected to the coil, or in the worst case scenerio removing the coil, soldering wires to the coil leads, mounting the coil to whatever is handy using plastic ties and then soldering the wires into the holes the coil went in. Make sure you insulate the coil leads well with electrical tape or heat shrink tubing. This may sound extreme but it is a solution provided by a manufacturer to our shop to solve a similar problem.
Make sure you observe the polarity of the coil as you did with the capacitors. Most coils don't have a polarity, but some (such as linearity coils) will have a stripe down one side and a mark on the main board. If you get this wrong, you may notice the horizontal linearity is wrong while viewing a picture.
Posted on Nov 04, 2008
Hi.. what we usually did , here in Indonesia, we trying to discharged the high voltage to the ground on main PCB, and what we need is just using a cable with aligator (big enough to clip a screw driver) and flat head (-) screwdriver, but make sure to disconnect tv ac plug from wall and make sure you clip to Ground (on Main PCB)like tuner metal chasis and clip the other side of clip to screw driver metal (longer screw driver is best)and trying to touch the metal connector inside the suction cap on the tube, if its just turn off a few minutes and disconnect from ac wall unit, you'll be able to hear "crack" sound when you already touch the metal connector, and leave it for 3-4 second, and trying to touch it again 2-3 times to make sure the high voltage already discharged, and you are safe to plug out the rubber suction cup from the tube. Bonie
Posted on May 02, 2006
Leaving it unplugged for three days or even three months DEFINITELY WILL NOT DISCHARGE THE ELECTRICITY. You must discharge it to ground like the other people suggested. NEVER attempt repairs on CRTs without PROPERLY discharging the juice.
Posted on Mar 25, 2007
Waiting 3 days for the tube to discharge is not bad advice but I would'nt trust it...the pic tube can hold a charge for quite sometime. You don't need to disconnect the red high voltage lead to work on the chassis unless it's so short that you cannot remove the main board. Here's how to discharge the tube...carefully slip a flat screwdriver under the rubber cup until it touches the center connector. Now take a clip cord and fasten one end to the screwdriver and touch the other end to the outside black surface to the tube..if it's charged up you will get a spark..then wait a minute and touch it again. After you remove the board for repair place the tv's cover over the set to protect the tube. Don't leave it open because you might bump the neck of the tube and crack or break it.
Posted on Apr 30, 2006
I have a samsung projection tv model no.pcj522r
No video, getting getting tick sound...I was told that the board the capacitor sit on is bad, any idea how to discharge it being that this TV does not have the conventional picture tube
it has 3 seperate board
Posted on Mar 18, 2008
I am planning to work on my Magnavox TV (model 25TR12). All I have read about discharging of the high voltage is to connect one end of the alligator clip to the metal chassis. Since the modern TV have no metal chassis, what should be done?
Posted on Nov 05, 2007
Funny, nobody mentioned that while you discharge the tube like techman explained, you got to hold your free hand in a fist behind your back. IF you do get a shock, it won't go through your hart..
Posted on Jun 08, 2007
Yeah ive been trying those procedure and it is safe connecting to the cup and then to the ground chassis and you heard a spark on it indecating that the picture tube is discharging.
Posted on Feb 09, 2007
Sony - kv-28wf1u - tv switched off to go to bed wednesday night. switched on thursday night - went to standby flashing mode. Switched on & off several times before it would work. Friday night switched on & off - went to stand by flashing mode. Nothing worked.Power & signal ok.
Posted on Feb 20, 2010
I used uninsulated wirepliers but was smart and held them with wet newspaper.I now play cello in gods choir.
Posted on Nov 09, 2009
Hi the proper way to work on the TV IS AFTER 3 DAYS THAT YOU UNPLUGED IT FROM THE WALL the capacitor will discharge itself you can check it by measuring the voltage on the board or just connect the legs with a long screwdriver good luck windman
Posted on Mar 16, 2006
SOURCE: tv tube
The best,and safest way is to use HV Probe
specified at least 40KV This is a direct link to
give you an idea of what it is you can search
for a better price on the Internet
Posted on Nov 16, 2007
SOURCE: safely disassembling a tv
The tube is the most dangerous part. It contains a vacuum and also a very large charge. The easiest way to make it safe is to unplug the end by removing the pc board attached to the back. Once removed, you will notice a large round plastic "pin" that is keyed. With a pair of pliers, squeeze the end of that part. This will break the end of the tube and allow air to enter. Do this carefully and only break the very end of this glass part (indide the plastic). You will hear the air enter the tube. This will effectively remove the charge at the same time.
Posted on Apr 02, 2009
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