Anybody have a Vivitar Zoom Thyristor 3500 flash with DM/C module?

I was given one of these today, but can't find a manual anywhere.
This doesn't look promising for off-camera flash because in Manual
mode there is no power adjustment. But as an automatic thyristor
flash, it might actually work on-camera as a poor man's TTL.

First things: I measured the voltage between the center contact
and the shoe shell contact, and it's 9.5V on my R/S meter, which
reads a bit high. So probably 9V. Does that sound safe for a Canon
XT?

I assume the "DM/C" module means it fit FD, or whatever the Canon
film camera flash standard was in the early '80s. It has two
contacts in addition to the center contact. So I assume the XT
would treat it like a manual flash.

The flash has three manual zoom settings - W, N, and T. But there
are two other settings. One sets the ASA (25 to 800), and the
other selects between M(anual) and one of three colored dots -
orange, green and red. I believe the dots are related to the
thyristor function, but I don't know in what way.

Also there's a green LED that lights up for a second when I trigger
the flash in any of the dot settings, but not in M mode. I'm not
sure what the LED indicates.

Well, if anyone has any explanations, or a link to the manual, or
warnings, please post a response. Thanks very much.

By chance I was looking up the 3500!

I am getting rid of items for a relative who has gone abroad. Amongst
them is
a Vivitar Zoom Thrystor 3500 flash with a small integral unit at the
base that pulls away. I doubt seeing that the manual was printed in June
1982, I doubt the unit has any value. Perhaps someone can confirm.

If that assumption is correct may be I can get the manual to you
physically or scanning the English pages to a pdf