Re: Problem Using a Commodore 1084s Monitor on a IIgs

[Polymorph <polymorph69@hotmail.com>]

On Jan 25, 9:43 am, Polymorph <polymorp...@hotmail.com> wrote:
> On Jan 25, 12:02 am, "Jeff Blakeney"
>
> <jeff.blake...@a2central.com.remove-sd5-this> wrote:
> > Sorry I haven't jumped in sooner but I fell behind on my newsgroup
> > reading this week.  If I remember correctly, I had added the 75 Ohm
> > resistor to try to match the termination expected by the1084S.  After
> > posting about my wiring someone else mentioned that they either didn't
> > need it for theirs or didn't think it was required and sure enough, my
> > current IIgs1084Smonitor cable no longer has a 75 Ohm resistor on it
> > and it works fine.

I've been really busy the last few weeks and had put this project on
hold, however, I finally got around to trying Jeff's suggestion from
1995 and have put a 75 Ohm resistor between composite synch and ground
and he was definately onto something. Instead of seeing a fast
scrolling mess, it was possible to fine tune the vertical hold to
produce the pictures below:

http://apple2.sytes.net/DSC00042.JPG
http://apple2.sytes.net/DSC00046.JPG

Now, as you can see from the above images, it doesn't appear to be
fully synched. All the characters are leaning to the right (like
everything is in italics), and you can see the black area on the RHS
of the screen which is wobbling around a bit.

I'm thinking that in my case, 75 Ohms is not quite right, but
something in the vacinity would be right. Does this sound plausible?
Do you recommend that I buy a variable resistor and try and find the
optimum value? Or should I being trying something else.

With the results I've achieved thus far, it would seem that this is
going to work with a bit more messing around.

What would you guys recommend as the next course of action? All
comments welcome.

Cheers,
Mike