"Michael A. Terrell" wrote:

Ian Field wrote:
?
? "Tilmann Reh" ? wrote in message
? ...
? ? Michael A. Terrell schrieb:
? ?
? ??? 80's vintage German printing equipment (offset press industry) uses a
? ??? video
? ??? plug-in card (made by the manufacturer of this equipment) to generate
? ??? parameter display for the operator. The display is a standard baseband
? ??? video
? ??? tube monitor. (It is possible, being German and sold in the USA market,
? ??? that
? ??? the video may be NTSC or PAL.)
? ?
? ? If it's monochrome, we don't need to talk about NTSC or PAL and their
? ? particular color carrier frequencies...

? In PAL ? NTSC; the colour carrier was a multiple of the line rate.


WHICH NTSC? There are two.





My first approach would be to see if anyone else still used the same
equipment and ask if they have the manuals, or would let you take some
photos for reference. Failing that:

https://docs.google.com/file/d/0B9rh9tVI0J5mOGFjYmM1ZTctMDNhOS00OTY5LTk4MTMtZDBlZ jZhNzFmMzVh/edit
uses a 22.68 MHz crystal, then a divide by two for 11.34 MHz. It also
has the code for the system. The problem is that there are too many
registers in that IC to give a pat answer. You would have to
disassemble the EPROMs to see how it was configured and calculate the
clock for yourself.

I would use a scope or frequency counter to see what the free running
H scan is on the monitor. (15,750 was NTSC Mono, and used on mono
computer monitors in the US.) Then I would disconnect the monitor and
try a crystal you think might be close enough to work, then measure the
horizontal drive frequency. A little math will get you in the ballpark.

The "CRT Controller Handbook" covered this CRTC, but I can't locate
my copy right now. There are several on Ebay for under $2 & shipping
right now. I believe that it covered the 8275 timing calculations, but
I haven't used the book in 20 years.

http://www.ebay.com/ctg/CRT-Controller-Handbook-Gerry-Kane-1985-Paperback-/4929442