I wanted to write about this Macintosh Classic as it stumped me for a bit. We had replaced UH6 which is a LS174 that handles timing for the CAS circuit. When booted, the system just showed a sad Mac with the error code 0000000e.
This error means there has been a data bus error. The last four numbers of second row are the 32 bits representing the failed bits. In our case, it’s all of the bits.
This could be caused by a number of things but generally it is related to the LS174. We verified all of the address lines were present and working. We checked the output pins and they were looking about what we expected. On a whim I checked the ground pin…no beep. Fixing the missing connection got the board working again. I haven’t traced to see where the failure is yet but I plan to.