How to stop the ANODE ARCING - CRT TVs
This
is the most dangerous and destructive fault with picture tube based
televisions as it may even make permanent damage to the final anode of
the picture tube.
- The complaint of this JVC CRT TV was the sparking sound when it was turned On. It was actually the arcing sound from the Flyback Transformer anode cap area to cold ground.
Users
will neglect this, as they will see the picture, even though this
arcing is there. This fault can be detected very easily, by its peculiar
smell of Ozone, emerges from the back topside of the TV.
The final anode of the picture tube [at the top side of its bell at back], have the final anode connection. It will look like a small hole, actually of any metal. The
hi-tension voltage [up to 15 to 28KV (15,000 to 28,000 VDC) is
connected which in turn accelerate the electron beam that falls on the
phosphor inside the front of the screen in turn gives light and shade to
produce a picture.
Anode arcing will be vigorous when humidity in atmosphere is high. You can even see it through the holes of the back of the TV cabin, if you look though it at darkness. There is a rubber bell at the end of the hi-tension wire, comes from the Line Output Transformer [LOT]. A
clip will be at the center of this rubber bell to connect it firmly to
this final anode hole. Before unlocking the final anode clip, you have
to discharge the picture tube. There will be a hi voltage charge there for a long time, ever after the set is switched OFF.
To discharge this voltage you can use the one probe of the multimeter. Just
lock one end of the probe to the aqudag earth braid wire, wrapped
around the bell of the picture tube, and just slide in the other pointed
end of the meter probe in between the rubber wedge of the anode
connection, deep into it, so that the pointed end of the probe to make
touch in the inside anode clip to discharge it. You
may hear a ‘Click” sound, as an electric discharge will occur there.
Keep the probe in touch with this anode pin, even after you have heard
the click sound. Discharge it well, otherwise you will get a hi voltage electric shock when you try to unplug the anode cap.
Just push in inner clip with the tip of a screwdriver or such instrument to make it release. Just look at the inner side of the rubber protection bell for any damage. Usually it will have some damage due to this arcing. It is best to replace this anode protection rubber bell. Look into the anode button for any residue of water. Residue will be there, and may some rust be. Clean it well. Just
clean all the water residue, with cotton swab, and the clean the anode
connection pit and the surroundings with medical quality turpentine. Do it well, as no rust or moisture should be there. If any residue is there, the arcing will occur again.
Replacing the anode cap is actually a skilled job. No sharp solder splash must be there. And all solder points should be rounded shape. As you know, high voltage electric charge will discharge very easily through a pointed edge. Keep this in mind when you replace the anode protection rubber bell of the LOT wire.
Before
replace the anode cap, be sure that there is no residue of water
content, or any other carbon particles around or inside the final anode
area.
Check
the set by switch it ON, as it is opened, and make sure that there is
no arcing occur. Make sure about it before closing the back cover.It is not tough to repair this kind of problem. I knew that many repairers already stopped repairing CRT TVs or Monitors and already shifted to repair LCD/LED TVs. But you need to know that many countries are still doing the CRT repair. As a repairer, if customers want me to repair their CRT TV/Monitors I will do my best to help them out. This can also help to save our environment.
