RCA 1861, NTSC and a DEC VR-201

From: Ethan Dicks <ethan_dicks_at_yahoo.com>
Date: Fri Sep 24 01:02:00 1999

What do those things have in common? Apparently not much. I was attempting
to lighten my load for the VCF and I ran across a small problem. I have this
cable I made to use a VR201 with an Amiga. It works. I even tested it tonight
to eliminate sources of failure. When I try to hook a COSMAC VIP up to it, I
get nothing. The numbers (from the RCA 1861 spec sheets) look like this:

            NTSC 1861 _at_ 1.76064 Mhz 1861 @ 1.764000 Mhz 1861 @ 3.579545/2
        -------- ------------------ ------------------- -----------------
Line 15750 Hz 15720 Hz 15750 Hz 15980 Hz
Field 60 Hz 60 Hz 60.11 Hz 60.99 Hz

The xtal in the VIP is 3.521280 Mhz (2 x 1.76064 Mhz). It seems that the
VR201 is sensitive to a 30 Hz difference in the horizontal freq. Barring
the chance that I can locate a 3.528 Mhz xtal before the VCF, am I hosed
here? I had hoped on using either my VR201 or one brought to the show by
a kind soul. As it stands now, I'll have to hope for a kind soul to help
me with a standard NTSC monitor (I've just tested the VIP with a more
ordinary Commodore 1084S).

Can any video guru's shed any light on my dilemma? Is the VR201 that
sensitive? Is there a way to get around this?

Thanks,

-ethan




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Received on Fri Sep 24 1999 - 01:02:00 BST

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