27 Mar
2015
27 Mar
'15
9:05 a.m.
On 03/27/2015 12:03 AM, Josh Dersch wrote:
Hi all --
Picked up a Tektronix 4014-1 terminal. It's in pretty
good shape, nice and clean and it's in nearly-working
condition except that the storage behavior isn't quite right.
On power-up, write-through doesn't. (That is, characters
don't get stored to the tube.) Clearing the display via
the RESET/PAGE key clears a roughly elliptical region in
the center of the display but leaves the outer edges a
mess. The cleared region stores characters properly. You
can see the overall effect here:
http://yahozna.dyndns.org/scratch/tek4014/clear.jpg
After a 2-3 minutes of warming up the area cleared by
RESET/PAGE increases. I haven't run the terminal long
enough to see if it eventually completely erases the
screen (while the power supply appears to be within
tolerances, I still need to rebuild/reform it so I'm not
going to run it too long yet).
Let it fully warm up. My guess is the cathodes in the flood
guns are getting weak. Allowing them to fully warm up will
probably help some. Also, as others have suggested, there
may be some voltage adjustments that need to be set.
But, the final adjustment is to set some of the voltages on
the guns for optimum performance. there is a VERY critical
adjustment of the flood guns (I think that's the right term)
to get the storage to be stable as long as possible. Too
much or too little flood beam causes the stored image to
either bloom or fade. Then, the erase is performed by
changing some voltage on the storage grid and pulsing the
flood guns, and secondary emission (I think) erases the
charge on the storage grid. It has been 30 years since I
had to mess with a 4010/4014 series, but I THINK I still
kind of remember how they work.
Have you checked bitsavers for a manual?
Jon
