Search Posts:

PDP 11/40 M7234 TIMING CPU Card Fail

SHARE

Return to Threads
  PDP 11/40 M7234 TIMING CPU Card Fail by Bill Degnan - 09/25/2019 09:37
PDP 11/40 TIMING module DEC 5380 SN20628N 2-input NOR removed
Closeup of a PDP 11/40 TIMING controller card, M7234 where a Dual NOR DEC 5380 SN20628N 2-input NOR chip has been removed. It caught fire. A replacement chip was pulled from donor M7234 and the card appears to be working correctly again. Click image for larger view.


Full disclosure - I accidentally plugged the M7234 into the wrong UNIBUS CPU backplane slot, ug. Too much juice to the chip fried it.

Using three sets of 11/40 CPU controller cards I had been swapping cards around in the effort to get an EIS CPU card (M7238) running. The EIS is necessary to boot UNIX but I have been unsuccessful in finding a working set of CPU boards that like the EIS installed.

If you're familiar with the 11/40 CPU card set you may have been through the complicated jumper combinations necessary so that they all work correctly together. I need to recheck everything to compile a working base CPU configuration. Once I get back to a base CPU set I can run more complex diagnostics.

Reply

Resources:

  • Home
  • Manufacturer photos, software, docs
  • Disk Images
  • Computer History Articles Scans and Files
  • YouTube.com Videos
  • Sale/Trade/Wanted/Miscellaneous
  • Photo Gallery
  • The Ultimate Vinage Computing Links List
  • Switch to DOS Prompt view

    • Buy a Commodore Computer Poster

    Popular Topics and FAQs


  • TM990/101 M
  • Altair 8800bt notes
  • TRS 80 Model 4 Engineering Sample
  • Altos 5-5AD
  • Morrow Wunderbuss Motherboard - Fried!
  • Epson PX-8
  • C64 emulator to run on PC
  • Mac 128K with SAD MAC error 041800
  • IMSAI 8080 With Processor Tech. Cutter
  • Secrecy is the keystone of all tyranny
  • Cromemco System Three
  • Commodore "Coherent"
  • Exatron Stringy Floppy Update
  • TM 990/189 or PP189
  • Lanier Word Processor Model 103
  • Univac 1219 rescue
  • IMSAI 1.4 BASIC vs. MITS 8K BASIC
  • Atari 520ST
  • DEC Information Request Reply Card
  • Amiga 2500 Restoration
  • IBM XT sn 4359455
  • Amiga 2000 with Dual Drives and HD
  • A New 68000 CPU S-100 Board
  • Edmund Scientific Co Ad 1973
  • Micropolis 10xx Drive Inventory
  • Texas Instruments 99/4a with PHP1200
  • MITS Altair 8800b T with Dual Drives
  • Burroughs L5000 Controller Card Photos
  • Digital PDP 11/44
  • TRS 80 Model III Exatron Stringy Floppy
  • Digital PDP-9 The Serious Computer
  • Live long and prosper, Spock
  • PDP 11/40 M7656 Serial Comms
  • 1993 Compaq Deskpro 5/60M
  • 1974/5 TCC-3700 i8080 Computer
  • Processor Tech 3P + S ASR 33 Jumpers
  • Tektronix 4015-1 Graphics Terminal
  • Lear Siegler ADM-3A GraFix Board
  • UNIVAC 1219 USS Midway CV-41
  • Commodore VIC-21
  • Prevent VMS MULTINET SMTP Relay Hijacks
  • NExT Cube Restoration
  • 1976 P.C.C. Features the MAI JOLT 6502
  • 1961 Beckman DEXTIR Computer
  • UNIVAC 1 and UNIVAC File Computer 1
  • Computer Music Using the IBM 7094
  • 1985 PCs Limited Turbo PC
  • Digital Equipment Corporation PDP-8
  • IMSAI 8080 Chase the Lights Variations
  • XYBASIC on the IMSAI 8080
  • Cromemco Dazzler
  • Cramer Intel 8080A Microcomputer
  • Original ACHTUNG Computer Lab Humor
  • Leading Edge Computers

    • Past Issues:

    Before we switched over to a blog format, past page archives here:
  • Vintage Computer Festival East 3.0 June 2006
  • Commodore B Series Prototypes July 2006
  • VOLSCAN - The first desktop computer with a GUI? Oct 2006
  • ROBOTS! - Will Robots Take Over? Nov 2006
  • Magnavox Mystery - a Computer, or? Jan 2007
  • The 1973 Williams Paddle Ball Arcade Computer Game Feb 2007
  • The Sperry UNIVAC 1219 Military Computer May 2007
  • VCF East 2007 - PET 30th Anniversary June/July 2007
  • The Electronic Brain August 2007
  • Community Memory and The People's Computer Company October 2007
  • Charles Babbage's Calculating Machine December 2007
  • Vintage Computing - A 1983 Perspective February 2008
  • Laptops and Portables May 2008
  • From Giant Brains to Hobby Computers - 1957 to 1977 August 2008
  • Historic Computer Magazines November 2008
  • World's Smallest Electronic Brain - Simon (1950) December 2008 - Feb 2009
  • Free Program Listings Spring 2009
  • Computer Music Summer 2009
  • Popular Electronics Jan/Feb 1975 - Altair 8800 Fall 2009
  • Early Microcomputer Mass Storage Summer 2010

    • HIDIC 100 cover

    This image was selected at random from the archive. Click image for more photos and files from this set.