I have a shorted pic tube in a Toshiba 32" 32afx61 flat screen Thompson tube. Before I trash it how can I try to clear short? Shops want $100 bucks to try 'with no promisses' of course. Id rather put taht money towards a new tv. I know trying this is a last ditch effort. The tube is shot anyway. So I know I cant hurt it. Its only about 3 1/2 years old. I already tried to isolate heater. The short is not to the heater. The red gun is shorted I dont know the label of the other pins that are shorted. It is NOT ...blue, green, heater, or G1. The 2 other pins that are shorted to the red are connected to ground on the neck board. Looking at the tube from the back they are from about 7 oclock to 2 oclock. The RK is in the middle and the other 2 are are at each end. I tried tapping on neck. didnt help. I would like to try to burn it clear if that is the next thing to try. How can I do that? Thanks Roy
For starters, how about telling us the code/type of CRT. 32afx61 is not the tube type. Then, how do you know it is shorted, which pins are shorted to which pins,etc.
I've had some interesting results with a stun gun. Not enough energy to melt a hard short, but can smoke a bit of debris. mike
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You will need the CRT rejuvenator unit, and to know how to use it.
Since you were quoted a high price in your opinion to try to rejuvenate the CRT, you should call around your area to find a service shop that would do it for a lower rate.
I've had some success charging up a capacitor to a couple hundred volts and discharging it into the shorted pins. Start with something small, maybe 10uF and go from there. In a pinch you can charge it from rectified AC line.
numbers on tube The tube is Phillips tube not a thompson. Sorry bout that. A80ERF031X13 D-9223
Im doing this from memory I could have missed a pin BUT I know the shorted pins are the pins on the ends and the red K. pins are numbered from 5 to 12 clockwise (not including the pin in the 'key') none are labeled but I know what some are.
I rechecked the tube and Pins are correct as labeled. Pin 7 has 270+ volts on it. There are 2 pins in the 'key' that have wires running back to the flyback. I dont know G1 from G2 with them being labeled for me. This flyback has 3 adjustments though...screen,and what appears to be 2 focuses (focii?)
I was able to clear the short to pin 8 ,the red, (charged a 150 uf cap to
200 vdc) 5 and 12 remain connected. dont know if they should be. The pics still looks pretty bad, alot of red and blue. I suppose cutoff is controlled in the service menu huh. No pots on board. This is the newest tv ive ever worked on! I'll push on slowly. Thanks for the replys, Roy
I have never in my life seen such a high G1 voltage. It is most certainly G2. In that case the voltage is a bit low, which is either caused by the load of the voltmeter, or somehow related to your problem.
Wrong again, probably. These are the 2 focus connections.
picture went red again after about 5 minutes of running. I zapped it again. It shows clear when checked with an ohmmeter but goes red with retrace a few seconds after I turn it on. It must short as it heats up. pin 8 has about
100 volts on so its not a dead short. I put 3.7 volts on heater pins to simulate running and checked red cathode resistance, but no shorts. also noticed inside the neck of tube is not glowing very bright when I applied power to heaters compared to how bright it is when set is turned on. Does heat come from the guns themselves or from a short I have in tube? Also when I ground blue cathode...screen is solid blue. when I ground red cathode.... no change since screen is already red. when I ground green cathode... NO CHANGE screen still red. Is this tube screwed completely? I get no continuity between any pins except the heaters. Still messing with it. Roy
RaR> picture went red again after about 5 minutes of running. I zapped it RaR> again. It shows clear when checked with an ohmmeter but goes red with RaR> retrace a few seconds after I turn it on. It must short as it heats RaR> up. pin 8 has about 100 volts on so its not a dead short. I put 3.7 RaR> volts on heater pins to simulate running and checked red cathode RaR> resistance, but no shorts. also noticed inside the neck of tube is not RaR> glowing very bright when I applied power to heaters compared to how RaR> bright it is when set is turned on. Does heat come from the guns RaR> themselves or from a short I have in tube? Also when I ground blue RaR> cathode...screen is solid blue. when I ground red cathode.... no RaR> change since screen is already red. when I ground green cathode... NO RaR> CHANGE screen still red. Is this tube screwed completely? I get no RaR> continuity between any pins except the heaters. RaR> Still messing with it. RaR> Roy
RaR> (pin 7 is screen)
What happens is that a loose flake of chrome from an electrode lifts off due to the electrostatic charge of the potential difference. It may not then jump the distance across the 2 affected electrodes until the metal has a chance to expand from the filament heat warming it up. This is why there is typically a time delay for the short to act up from when the crt is cold and then warms up. Some may take 5 minutes, some 20 but eventually it is permanent. Zapping with very high voltage is good because the static force lifts out the loose flake somewhat and is then more likely to burn off completely.
A*s*i*m*o*v
... Electrical Engineers do it with more frequency and less resistance.
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