Aug 112014
 

I got this board always from Ebay sold as faulty:

Superman_PCB

When I first powered up it I got a solid black screen.Probing the CPU I noticed some strange activity on 68000 address/data lines and watchdog was indeed active.So I piggybacked the two 62256 work RAMs @U1 and U4 and  I got this:

work_RAM_error

Despite the message error,this was a good sign of life so I desoldered the two RAMs and I found them really bad:

62256_testing

Replaced them but still black screen and watchdog active.So, I noticed there were other two RAMs connected to 68000 CPU but not directly but through two 74LS245 and enable pin of these were stuck high.I traced back it to an output of a 74HC4075 so I started to test it with logic probe and while I was probing it suddendly the PCB succesfully booted to title screen:

Superman_title

I can’t really explain this but now the PCB is now working perfectly every time I power it on and this is the most important thing.See you next repair!

 

 Posted by at 6:38 pm

  One Response to “Superman repair log #1”

  1. One of my favourite games, great to see it brought back to life 🙂

    – Ben