What is the caused of weak picture tube?
Answer:
Hi Fizzle, you must have been to same school as I ! Low emission is caused by gas and impurities leaching out of the electron guns over a few years, then the tube is said to be gassy ! As Fizzle says you can sometimes zap the tube with extra volts, in fact some TV techs carry a machine round on house calls called a CRT rejuvenater , it did similar to zapping !! Cheers Pete
Age, usually. The cathode (gun) back in the neck emits electrons that travel forward and strike the screen in order to make the phosphors glow. Over time there's a crust that builds up on the cathode's emitting surface or it erodes from the constant discharge. An old trick was to zap the gun with a higher than normal voltage in an attempt to blow off the crud and bring up a fresh surface on the cathode, and it did often work. I don't know if ayone actually does that anymore; it does sort of date me to know that. But if it could restore a fresh emitting surface, it would brighten the tube again.
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