From: slavotinek@gmail.com   
      
   On 29.12.2022 22:24, Christian Holzapfel wrote:   
   > Once found in a dark dumpster, I have relentlessly tried to revive this   
   Ultimedia Video Adapter (7-5) for RS/6000   
      
   Since you have already tried all the basic troubleshooting steps, I'm   
   afraid you will have to do some probing to figure out what's wrong.   
      
   I agree that the issue most likely lies somewhere between the MCA edge   
   connector and the MIAMI interface chip (hopefully not inside the ASIC   
   itself). You don't need a 64-channel analyzer to check the buffers and   
   the other glue. You can probe them one by one and monitor only a subset   
   of the data pins together with the relevant control pins (-output   
   enable, direction, or what have ya).   
      
   Before you dive into that, it may be worth checking if the oscillators   
   are stable and outputting what they are supposed to.   
      
   Also, looking at the photo, the A1 pin on the edge connector looks   
   really suspicious. This is the -CD SETUP line, responsible for putting   
   the adapter into the setup mode. And that's when the adapter ID is   
   obtained, among other things. So, an unreliable connection could   
   definitely cause the described behavior.   
      
   You could also test the adapter in another machine (even a PS/2) and   
   check if the behavior changes in any way.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)