Rasterlist Archives: RE: Getting a stable picture on the Amiga 1

From: David Shoemaker <davids_at_oz.net>
Date: Fri Apr 19 2013 - 00:36:11 EDT

I use a 1084 (non D) on my bench. It has the DB9 input.

It syncs to most everything I throw at it without any real issue. Only down
side is it can't do mid res games (for that I have a Nec Multisync 3D)

Maybe you need to cap kit it? With the warm up time that is the first thing
I would look at.

David

-----Original Message-----
From: owner-rasterlist@vectorlist.org
[mailto:owner-rasterlist@vectorlist.org] On Behalf Of Matthew Rossiter
Sent: Thursday, April 18, 2013 11:23 AM
To: rasterlist@vectorlist.org
Subject: RASTER: Getting a stable picture on the Amiga 1084D monitor

I use an Amiga 1084D monitor for testing. I also use an RGB converter
hooked up to a flat panel computer monitor, which works great but if there's
a problem with the video signal that I'm trying to troubleshoot it much
easier to see the problem on an old school monitor.

The problem with the Amiga is that it's hard to get a steady picture on many
games. Atari boards are usually rock solid. After about 30 minutes of warm
up time the picture will finally hold.

Does anyone have a solution to resolve this problem already?

I'm not an expert by any stretch of the imagination but here's what I
thought.

I'm testing a Warp-Warp board (for example) and it's sending out a sync
signal about 15.5 kHz, which might be slightly higher than what the monitor
expects. I'm thinking of making a simple astable circuit using a 555 timer
with a 90% duty cycle, negative sync pulse, and with a potentiometer to
adjust the frequency slightly and just use that as the RGB sync. Then maybe
add an inverter for games that use a positive sync pulse?

I have some other ideas, but just thought I'd throw this out there.

Matt

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RE: Getting a stable picture on the Amiga 1084D monitor