Tektronix 4014-1 troubleshooting advice
elson at pico-systems.com
Fri Mar 27 11:05:17 CDT 2015
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:
> 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?
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