boosting CRT heater voltage

Tony Duell ard at p850ug1.demon.co.uk
Fri Nov 19 15:27:35 CST 2010


> > A couple of things can cause this, but yes, most common is a weak picture
> > tube.
> 
> The funny thing is, I've dealt with lots of CRTs and seen then die in various 
> ways, but this is the first one I've ever had with the poor brightness issue - 
> yet googling seems to suggest that it's pretty common. I must have been rather 
> lucky... :-)

I've had several monitors suffer from poor brightness, but the CRT wasn't 
the cause in any of them. The one I really remember is the Moniterm 19" 
mono monitor used on PERQ T2s and T4s. Low brightness on that is al;most 
always a problem with the HV power supply module.
> (One other observation is a simple eyeball test: the heaters *look* rather 
> dark, with a dull orange glow. Again though it's hard to be sure without a 
> direct comparison against something with an identical tube)

Wher dfid you measure the heater voltage? If not at the CRT pins, could 
it be a bad connection somehwere between the CRT base and the PSU? Heck 
could uit even be a bad connection between the CRT pins and the base 
connector?

-tony



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