5 Jun
2009
5 Jun
'09
10:46 p.m.
Tony Duell wrote:
Sure. It is always best to look for the obvious things
first (says the
guy who once spent a long time fioguring out a low contrast fault on a
VT100 video board, only to find the CRT screen needed cleaning...). But
after a bit, it's best to attack the problem logically.
Long ago, I bought a Heathkit color television -- it was gorgeous.
Needed some work. Also, while I was contemplating buying it, the owner
offered to throw in a 'scope, too. It had never worked he said. The
screen was "grainy" and a new tube cost too much. I accepted. The
television was easy to fix (Heathkit, I said).
But, when I fired up the 'scope, I was shocked. He was right. The
scope image could be focused, but it never got clear. It looked like
the phosphor was painted on the tube with a roller. Then, I had to
laugh....
I took off the bezel, pulled off the graticule screen, and peeled the
tyvek sticky paper off the back of the plastic screen, and voila! A
nice clear trace.
Warren