Further 11/40 unibus questions...

[Warren Wolfe]

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