It certainly used to be a real problem in the old days, when a PD500 shunt
regulator valve ( tube ) was used in the EHT supply. When working with the
deflection stage cage open, a lead glass shield had to be placed over this
device.

X Rays are easily created by accelerating a stream of electrons, and
slamming them into some kind of anode, and the 25 kV used in a CTV is plenty
enough to generate an electron beam with enough energy to do just this.

However, the electron beam should not actually ever touch the anode inside
the picture tube - otherwise no electrons would ever reach the faceplate to
light up the phosphor. The electrons do, however, dissipate large amounts of
their energy, when they collide with the slotmask inside the CRT. As far as
I know, this manifests as heat, but possibly, some soft x rays may be
generated. You are right that any generated to the rear or sides would
probably escape through the plastic cabinet, but the inside of this, or even
the plastic itself, may be treated to prevent EM radiation of all
wavelengths, as there is paranoia these days about such things.

I don't think that there is any significant danger from x rays any more from
CTVs. I would guess that as there is high voltage present, and high energy
electron beams present, the manufacturers err on the side of caution and
warn of the possibility of random x ray generation. As an addition, no x
rays would escape from the picture tube faceplate, as this is made from lead
doped glass to be sufficiently conductive to form the return path for the
spent electrons.

Geoff


"Darmok" wrote in message
...
When I was recently into the back of my Sony KV-27EXR15 set, I saw
some warnings about X-ray radiation exposure. Is there significant
exposure hazard while working on the set from the back? Since the
enclosure is entirely plastic, I would think that you'd be exposed to
x-rays no matter where you were located in relationship to the set,
not just when you opened the back to have a look.

Any comments?