Just a thing to check.
I had a similar problem and it had me stuck for months. I finally located a bad 3 pin RAM selection jumper switch on the board. It had become slightly corroded. Once replaced with a nice new gold one (including jumper), things started working properly. My bad for not checking it earlier. Anyway it’s easy to rule it out and maybe worth checking.
Good Luck and Best Regards.
Lou
From: chromapolaris@yahoogroups.com [mailto:chromapolaris@yahoogroups.com]
Sent: July-22-19 11:01 AM
To: chromapolaris@yahoogroups.com
Subject: Re: [chromapolaris] ADC Range Adjustment
Thank you Bob,
I cannot read any pulse there neither, glad to know the 80186 looks easy to find and not expensive.