I have a Tektronix 650HR monitor here which recently developed an odd fault..
there is no lumininance on the display, just chroma!

Should be easy to figure out, until I discovered that the manual that I have
is for the Tek 650 and does not cover the 650HR. The only difference between
the two is the chroma detector circuits, which of course are what has gone
wrong on this unit.

Does anyone have a 650HR manual, or docs on the aperture card for the 650HR?
I believe the problem is on the aperture card, as when I disconnect the
aperture card outputs, there is a white flash on the screen rather than just
a color streak. There's a weird coaxial relay on there too which I'd try
bypassing for test purposes if I had a pinout.

Anybody with any suggestions? I know the beast is old, but it has served
well for a long time.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."