audioguru said:
Nigel Goodwin said:
The 25,000V in a TV is limited to only about 1mA, far too low to be fatal.
My 32" Sony colour TV seems to light-up my whole large room with about 100W of light, so the current must be at least 4mA.
Just checked the spec for a KV32HX15U (32 inch Sony TV), it's
total power consumption is only 75W according to both the specification and the service manual (the 28 inch version is 72W).
So EHT is presumably limited to around 1mA?, as it's always been since the early days of colour TV.
BTW, a 32 inch TV will have higher EHT than 25KV, but the manual doesn't specify what it is.
I have heard that the HV in a large colour TV is "stiff" and fairly regulated so when it shocks you its current instantly increases. When souping-up my old TV I never got shocked because I stayed away from its HV.
No, EHT isn't highly regulated, just the opposite, it's current limited. The current drawn by the line output stage is monitored (it's called beam current limiting), if the beam current exceeds 1mA then the contrast is reduced. If this doesn't drop the beam current enough then the set will be shut down.
There's also over voltage protection on the tube as well, if the EHT rises excessively then the set will shut down, in Japanese sets this is called "X-ray protection" - because excessive EHT can cause a CRT to emit X-rays, which is basically how they are generated in X-ray machines.