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Recent content by djg

  1. djg

    LA8-P M8365 Printer Interface Schematics

    The link was to DEC's original distribution of the driver. I have attached my modified copy. Renamed to supported extension for attaching. It does have proper CR/LF line end termination.
  2. djg

    LA8-P M8365 Printer Interface Schematics

    Its in the LPTSV handler. SNA CLA TAD LPT214 /OUTPUT FORM FEED IF BLOCK 0 I changed first line to CLA and commented out second in my copy of driver to stop wasting paper. Driver here. https://www.ibiblio.org/pub/academic/computer-science/history/pdp-8/os78/v2/lpsv.pa
  3. djg

    VME systems

    Company I worked with started with Multibus then decided to pass on Multibus II and went with VME. Systems started with mix of commercial boards and custom boards. Need for custom boards declined with time and then use of VME itself. We stopped using it around time VME was switching to various...
  4. djg

    LA8-P M8365 Printer Interface Schematics

    https://www.pdp8online.com/pdp8cgi/query_docs/view.pl?id=2068
  5. djg

    PDP-8/s restoration in OZ

    Agreed. Have not seen anything like that in the supplies I have replaced the cap in. Always quick disconnect to cap and no resistor.
  6. djg

    St 506 emulator card

    https://www.pdp8online.com/mfm/
  7. djg

    Seagate ST-225 Hard Drive Showing Questionable Signs of Life?

    For common issue of heads out of alignment causing read errors its possible but may not be worth the effort unless you really want the data. https://www.pdp8online.com/mfm/microstep/index.shtml
  8. djg

    PDP-8/s restoration in OZ

    Where was the 15ohm resistor in series with the cap physically? I had only seen the one the schematic shows as load on +10V which I assume is the one we see in the second picture.
  9. djg

    PDP-12 #435 at the University of Minnesota Duluth

    I would check the diodes forward voltage drop if you haven't. Those look like D664's that are highest failure rate component in R series logic. Then whichever is easier for you testing out of circuit or putting it on extender and seeing what is going wrong with signal.
  10. djg

    PDP-8/s restoration in OZ

    I haven't seen enough theory to know. I did take some measurements on effect of capacitor value. Don't have equipment to change frequency. https://forum.vcfed.org/index.php?threads/capacitor-value-effect-on-ferroresonant-power-supply.1250770/
  11. djg

    PDP-8/s restoration in OZ

    When I've wanted to fit a holder and modern are wrong size I have bought old caps online as long as I can see they say non PCB and protected and hopefully date to see if not too old. Mouser has one. Didn't check size. I would have to dig through old emails to see where I have bought what...
  12. djg

    PDP-8/s restoration in OZ

    Look in the metal shield DEC 1016 in the second picture. I've seen them in there. Its oil filled with PCB and not protected so will spray boiling PCB oil when it fails. I've had multiple failures so replace them before trying to operate with modern AC capacitor. Hope it goes well. Would be...
  13. djg

    Cleaning of dirty wire-wrap backplane

    On worry about stuff in water/if its really needed I think that's just one of the things that people will disagree about. Way to hard to do a test to verify. The machine was sitting in a barn for 50 years. Barn was deteriorating at the end. Mouse nest was on the power transformer. The steel...
  14. djg

    Cleaning of dirty wire-wrap backplane

    I did similar for a barn straight 8. Washed with hose and soap and soft brush, rinsed, blew off most of the water with compressed air then let dry in the sun. May have hauled out a fan for more air. Compressed air can vibrate the wires so I kept some distance to reduce force on wire side. The 24...
  15. djg

    RS-232 Then and Now (Notes and Discussion)

    https://www.mouser.com/c/?q=max232 $7 to $12. 75188/75189 around $1 so still a good price premium.
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