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Path: utzoo!utgpu!water!watmath!clyde!rutgers!cbmvax!grr
From: grr@cbmvax.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: I'm trying to make a cable for a Maganavox 8CM515 monitor
Message-ID: <1944@cbmvax.cbmvax.cbm.UUCP>
Date: Thu, 28-May-87 17:09:14 EDT
Article-I.D.: cbmvax.1944
Posted: Thu May 28 17:09:14 1987
Date-Received: Sat, 30-May-87 05:36:56 EDT
References: <880@sdcc13.ucsd.EDU>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Distribution: world
Organization: Commodore Technology, West Chester, PA
Lines: 25
Keywords: Weird problems

In article <880@sdcc13.ucsd.EDU> mu106sbn@sdcc13.ucsd.edu.UUCP (Stephen Hartford) writes:
> I'm trying to get a Maganavox 8CM515 Analog RGB monitor to work with
> an Amiga 1000. It appears to work fine, asking for Kickstart. But
> after Kickstart loads, the screen goes black. The weird thing is
> that if I boot all the way up using composite, it works fine. If
> then, while in AmigaDOS, I plug the RGB cable in, presto! A perfect
> RGB picutre. Can anybody help? I'm sure its soldered correctly...

The horizontal and vertical sync signals are not buffered (being used for
both input and output) and may be a little wimpy when driving an arbitrary
monitor/cable combination.  If the monitor loading is too great, the system
will either not work at all, or enter "genlock" mode and enable the (non-
existant) external clock...phuttt.

The solution is generally to buffer then sync signals with a couple of
transistors in the connector shell, however some people have reported
good results by simply putting 100 Ohm resistors in series with the sync
lines.  This is obviously a bit simpler than the transistor solution.
You might try values in the range from 47 to 220 Ohms, as much depends on
the monitor's input circuitry.

-- 
George Robbins - now working for,	uucp: {ihnp4|seismo|rutgers}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@seismo.css.GOV
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)