The contrast voltage appears to be too low if memory serves the voltage swing needs to be greater than 300mV, the manual indicates the swing should be around 4V (pg 38). It could be that VR1 needs cleaning or at least checking out or c106/c105 might have problems.
The display sounds like it is working just the contrast voltage is too low. If the display were dead the BASIC BEEP command would not work – the boot sequence checks the display and hangs if it does not read back correctly. From: M100 <m100-boun...@lists.bitchin100.com<mailto:m100-boun...@lists.bitchin100.com>> on behalf of George Hines <mrthreepla...@gmail.com<mailto:mrthreepla...@gmail.com>> Reply-To: <m...@bitchin100.com<mailto:m...@bitchin100.com>> Date: Friday, July 5, 2019 at 10:15 AM To: <m100@lists.bitchin100.com<mailto:m100@lists.bitchin100.com>> Subject: [M100] Non working display on my m100 I checked v2 at the interface and it varies from 1.4 to 1.7 volts as I adjust the contrast.
