[Coco] Coco monitors 1084s-xx ?

[Gene Heskett]

On Sunday 30 March 2014 17:25:52 farna at amc-mag.com did opine:

> Date: Fri, 28 Mar 2014 23:45:50 -0400
> From: mike delyea <mdelyea at gmail.com>
> 
> None of them will work.  You need to wire in a 74ls02 to change the
> horiz/vert signal.  I have done this myself because nobody seemed to
> know how at the time.  I spent a lot of time tracking down pinouts for
> Amiga monitors and the signals on each wire.

A little known factoid might be fitting here.  The factory cable to run the 
1084 on an Amiga, and 10's of thousands of them were, actually had that 
74LS04 molded into the back molding of the DB23 plug.  I had one fail, and 
when I went to ring out the cable, comparing what one end was compared to 
the other, the synch line to the monitor was shorted to ground thru the 
failed chip, but it looked like I was trying to measure a integrated 
circuit input on the H&V sync lines from the amiga end.  I scratched my 
head on that for a few minutes and decided there must be an IC hidden in 
the plastic molding on the back of the db23 & started grinding away on the 
plastic with a dremel.  By being very careful I was able to preserve the 
chips marking, and teased it out and replaced it.  With a 74HC04.  Worked 
fine till the CRT in the 1084 was so burnt we couldn't use it for fine grx 
work anymore.

I don't know if that was supposed to be a secret, but it sure sold a lot of 
cables for commie when they didn't have anything else left to sell us.

> ==============================================
> 
> Mike, the later models apparently sense the polarity of the H/V sync or
> are made differently. I am aware that the 1080 needed the signals
> inverted, but the 1084S I had worked perfectly with just a simple cable
> matching signal pins. I posted a site with pin-out info earlier...
> 
> 
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Cheers, Gene
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