The tv is a 21inch lg flatron tv and the fault was that when you switch it on,you will be hearing the sound but there is no trace of any picture on the screen,in short the tube is not working at all.
OBSERVATION
The filament light at the tube base is coming up but the screen grid voltage is 0.I detach the video board from the tube base of the crt,powered the tv and the sreen voltage was now 230v,so definitely the crt is shorted.How do I know these?I connect the video board to the tube base again , took another voltage reading and it gives a 0volt and it is only when there is a short that such fault occur.
HOW I CLEAR THE CRT SHORT
I took a 47uf 250v capacitor,soldered a meter probe to the positive terminal of the capacitor.I soldered the negative terminal to GND on the video board.What I want to do is to charge up the capacitor.The green,red and blue cathode on the video board had their normal voltages.I placed the probe on the red cathode terminal on board for about 3secs and immediately removed it to place it on the G2 terminal on video board.It made a spark and instantly the shorts clear away and the picture came out fine.It really works like magic.
CONCLUSION
When the crt was still shorted the ohms reading between G1 and G2 was around 5k but after clearing the short the reading was at infinity.You can repeat the process if it fails the first time.Please comment in the box for any question on this fault or if you know of any other method to clear a crt short.
OBSERVATION
The filament light at the tube base is coming up but the screen grid voltage is 0.I detach the video board from the tube base of the crt,powered the tv and the sreen voltage was now 230v,so definitely the crt is shorted.How do I know these?I connect the video board to the tube base again , took another voltage reading and it gives a 0volt and it is only when there is a short that such fault occur.
HOW I CLEAR THE CRT SHORT
I took a 47uf 250v capacitor,soldered a meter probe to the positive terminal of the capacitor.I soldered the negative terminal to GND on the video board.What I want to do is to charge up the capacitor.The green,red and blue cathode on the video board had their normal voltages.I placed the probe on the red cathode terminal on board for about 3secs and immediately removed it to place it on the G2 terminal on video board.It made a spark and instantly the shorts clear away and the picture came out fine.It really works like magic.
CONCLUSION
When the crt was still shorted the ohms reading between G1 and G2 was around 5k but after clearing the short the reading was at infinity.You can repeat the process if it fails the first time.Please comment in the box for any question on this fault or if you know of any other method to clear a crt short.
How to clear crt short in LG Flatron tv
neyod
