|
One other thing to be aware of if you need to separate the CRT and chassis or work on the HV is that most sets of the time used 9-25KV of HV with very low current. It should not cause injury unless you have a heart condition, but is on par with the meanest static electricity jolt you've ever taken. Glass CRTs have an integral capacitor that can hold HV charge for days (metal cone CRTs typically have a doorknob cap that does the same in the HV cage)...If the HV works and you need to service the set within a week of running it you may need to discharge the HV...To do so (with the set off) take an HV meter with it's negative connected to chassis and measure and measure the HV or connect one end of a 1M ohm resistor to chassis and the other to the metal shaft of a well insulated screwdriver and slip the tip under the HV connection suction cup on the side of the CRT and he it there for a count of 10.
You could dispense with the resistor and short HV to chassis but that tends to cause dielectric bounce back where the cap recovers a portion of it's charge a moment after discharge... that can be almost as bad a jolt as not discharging (says someone who has experienced both).
If you ever get a set that used a 60Hz transformer to supply HV (only a few 1940s sets were made like this) those have very lethal HV supply systems and great caution should be observed.
|