I bit the bullet and broke out the SOL schematic. After a short time I found that the BLINK cursor signal was not getting through the NAND gate at U60. The problem was pin 3 was always high causing the output at pin 1 to always be low...hence no cursor. I chased the input at pin 3 back through the 74175 at U42 pin 11. The input for pin 11 was pin 12 (CURSOR BIT), which leads back to the 9102 (or 2102) RAM at U21. Replacing this RAM fixed the problem.

This is the second time I've fixed the video RAM. Previously I had an issue with two cursors on the screen!!! Take a look here.

I was in the process of fixing two S-100 EPROM boards when I noticed the cursor on my SOL-20 had disappeared.

I first thought it would be easiest to simply, one at a time, replace the all the IC's in the cursor section of the board, as there is only about 5 and I have all but one of the IC's in my parts bin. 20 mins later I had changed out everything I had, and the cursor problem persisted.

neoncluster.com

Screen showing no cursor