Hi to all,
Hi Devicemodder,
i watched your short video, operation looks OK. As you don't show the picture expansion & fade, it's hard to diagnose anything.
Questions:
does just the Windows computer content display disappear & screen stays lit or does the CRT brightness die?
In traditional TV, image expansion & decrease in brightness usually points to a dying EHT rectifier.
In the schematic you posted, EHT rectification seems to be included in the Flyback transformer (modern "split-diode" transformer technology).
To assess if the transformer is at fault (or not) additional data is needed:
- the schematic showing the CRT, its type & hopefully electrode voltage.
Something might be drifting & driving the CRT to cutoff, blanking the display.
How is the Tektronix VDU powered; own power supply, bench PSU,...?
Have test gear: multimeter, HV probe,...?
If possible, a new video showing the "expand & fade" fault,
For anyone interested, the TekTronix TDS-510A digital Scope service manual* (284 pages/4Mb) is on TekWiki:
https://w140.com/tekwiki/images/5/52/070-9704-02.pdf
*didn't see schematics.
TekTronix TDS-510A wiki main page:
https://w140.com/tekwiki/wiki/TDS510A
Best Regards
jhalphen
Paris/France