So I have this Tek 464 which was my first Tek and I know already for quite sometime that its CRT is on its way out to ceramic pottery heaven.
Throughout one year that I spent restoring it, cleaning, attempting to rejuvenate its CRT, recapping and calibrating, I've been in almost each of its departments and had been able to fix or calibrate it accordingly.
The only exception to the above is its storage subsystem.
For twice I tried already to follow its calibration procedure and I can't get it right, as the screen don't seem to ever look similar to the screenshots on the calibration procedure.
For instance, at page 5-46, steps 2.a. 2.b and 2.c, to adjust R1933 (the front mesh operating level), it calls for adjusting R1933 so that the screen "barely darkens" after pressing the ERASE button, and it gives as example the screenshots figures 5-G-1, A thru C. where the ideal picture shows a soft darkening evenly distributed near the edges, left right, top and bottom, slightly darker near the corners.
Well, on my 464, when it start to "barely darkens", it happens only to the right side of the screen... If I keep turning R1933 enough, then, at the point that the left side starts to darken, the right side has gone already completely dark, and the screen will have only the left side still flooded, definitely different from the screenshots.
To summarize, after trying several iterations, there seems to be a distinct difference between the left side and the right side, and the left side show visibly more capability to store any trace.
The disparity between left and right sides is less noticeable in variable persistence mode, but in fast mode, the faster signals seem only to store up to 2/3rds of the screen, and If I crank up the storage control, eventually I get something stored on the rightest 1/3rd of the screen, but at the expense that the leftiest 2/3rds get over exposed and completely blooms or fades up.
My questions to the group are:
1. Do any of you have particular experience with the 464's storage calibration, or else, have seen this kind of LEFT/RIGHT disparity in storage modes before?
2. I can only associate this kind of behavior to one of the flood guns be worn-out differently, but then, I wonder... how that could possibly be? If both are connected together and biased together?
3. Do you think that any malfunction on the storage timers and/or amplifiers, or else, any of the storage CRT elements' biasing can explain a LEFT / RIGHT behavior?
Thanks for your thoughts,