Q-Bus Memory Diagnostics and Repair

[Jerry Weiss]

I have two bad memory boards and could use some advise on how to
repair them. 

The first is an MSV11-PL 512KB-Q-Bus 22bit. 
Dead to both CSR and Memory address access in ODT.  
Was working until a short time ago. Checked all the jumpers and 
no evidence any magic smoke has been released. I have a copy of 
MP01239_MSV11-P Field Maintenance Print, but before start poking 
around with my scope I wonder if someone has seen this before 
and/or can recommend a particular methodology to finding the fault.

The second board is a CMV1000 that probably has a bad Memory Chip.  
The results of CVMJAB0 point to “Bank 35”.   I don’t have either 
prints or a manual for this board.  Partial report follows: 

   512K OF Q-BUS PARITY MEMORY
   512K WORDS OF MEMORY TOTAL

                        MEMORY CONFIGURATION MAP
                             16K WORD BANKS
                1       2       3       4       5       6       7
        012345670123456701234567012345670123456701234567012345670123
ERRORS                               X
MEMTYPE PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP
CSR     00000000000000000000000000000000

  PC    BANK  VADD     PADD     GOOD     BAD     XOR  CSR  MTYP INT PAT
025770   35  157752  03577752  000377  03577752  03577752  0     P       17
025770   35  157712  03577712  000377  03577712  03577712  0     P       17
025770   35  157652  03577652  000377  03577652  03577652  0     P       17
025770   35  157612  03577612  000377  03577612  03577612  0     P       17
025770   35  157552  03577552  000377  03577552  03577552  0     P       17

024564   35  141612  03561612  061612  03561612  03561612  0     P       01
024564   35  141652  03561652  061652  03561652  03561652  0     P       01
024564   35  142712  03562712  062712  03562712  03562712  0     P       01
024564   35  143712  03563712  063712  03563712  03563712  0     P       01
024564   35  143752  03563752  063752  063752  000000  0     P       01
024564   35  145552  03565552  065552  03565552  03565552  0     P       01
024564   35  145652  03565652  065652  065652  000000  0     P       01

024622   35  141412  03561412  116365  03561412  03561412  0     P       02
024622   35  141452  03561452  116325  03561452  03561452  0     P       02
024622   35  141512  03561512  116265  03561512  03561512  0     P       02
024622   35  141552  03561552  116225  03561552  03561552  0     P       02

I was expecting bad and xor to be 16bit  values, but they appear to be
mostly 22bit addresses. But then again this isn’t a DEC board.

The board itself is labeled with bits 0-7 P0 P1 8-15 across the top and
8 rows of chips (MT4264-15).  Any suggestions as to which chip might be
suspect?

Jerry