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  • m_thompson's Avatar
    Yesterday, 03:53 AM
    Can you get a better image of the board side of the systems so we can see the part numbers on the handles, and a picture of the spare boards that...
    7 replies | 210 view(s)
  • m_thompson's Avatar
    March 20th, 2017, 03:38 AM
    m_thompson replied to a thread H724 woes, go figure! in DEC
    I always start by reforming the caps. The +15V output feeds the A1 regulator board, so a shorted C14, VR5, or Q10 could load the +15V. You...
    7 replies | 199 view(s)
  • m_thompson's Avatar
    March 19th, 2017, 01:31 PM
    m_thompson replied to a thread RK11-C / RK05 restore in DEC
    My bottom covers are not installed yet. There is a warn spot on the front cover under the spindle, so maybe yours is not a unique problem.
    28 replies | 1195 view(s)
  • m_thompson's Avatar
    March 19th, 2017, 08:03 AM
    m_thompson replied to a thread H724 woes, go figure! in DEC
    I had the +5 regulator on my 8/e die. The LM723 on the A1 board was the problem. I soldered lots of wires onto the A1 board so I could see the...
    7 replies | 199 view(s)
  • m_thompson's Avatar
    March 11th, 2017, 10:35 PM
    m_thompson replied to a thread RK11-C / RK05 restore in DEC
    I had a bad 723 regulator on my 8/e, so that might be a possibility on the -15 regulator. I believe that the +15 and -15 regulators are the same...
    28 replies | 1195 view(s)
  • m_thompson's Avatar
    March 6th, 2017, 09:04 PM
    My notes on that system are: Purchased in 1968/1969 time frame for use with EIA-680 Analog Computer for hybrid computation pair. The facility was...
    3 replies | 199 view(s)
  • MattisLind's Avatar
    March 6th, 2017, 08:49 AM
    Apparently the interface module is called M7452. It seems like the machine is somewhat intelligent in that it has both a 68000 and a 2901 bit slice...
    12 replies | 424 view(s)
  • MattisLind's Avatar
    March 6th, 2017, 07:59 AM
    This definitely sounds like interesting things. But I am in the wrong part of the world and should not get more stuff anyway. But I am a little bit...
    12 replies | 424 view(s)
  • m_thompson's Avatar
    March 5th, 2017, 06:28 AM
    m_thompson replied to a thread RK11-C / RK05 restore in DEC
    I would say no. If you put the toggle-switch on the servo-amp board in the down position it will disable the servo. If you put something soft between...
    28 replies | 1195 view(s)
  • m_thompson's Avatar
    March 4th, 2017, 05:30 AM
    m_thompson replied to a thread PDP-8/e Project in DEC
    On our 8/L all of the steering diodes had reasonable forward and reverse voltages, but we still had a section that did not work. We put 200mA through...
    70 replies | 3935 view(s)
  • m_thompson's Avatar
    March 4th, 2017, 04:14 AM
    m_thompson replied to a thread PDP-8/e Project in DEC
    I have seen lots of steering diodes fail in 8/I and 8/L core stacks. Maybe that is what is wrong with your stacks.
    70 replies | 3935 view(s)
  • m_thompson's Avatar
    March 4th, 2017, 04:13 AM
    m_thompson replied to a thread PDP-8/e Project in DEC
    There are some toggle-in serial tests that will check the skip, send, and receive logic.
    70 replies | 3935 view(s)
  • m_thompson's Avatar
    March 2nd, 2017, 03:43 AM
    m_thompson replied to a thread PiDP-8/I in DEC
    Lou, I have access to a running PDP-12, let me know if you need some help debugging VR12 behavior.
    125 replies | 13221 view(s)
  • m_thompson's Avatar
    March 1st, 2017, 08:27 AM
    m_thompson replied to a thread PDP-8/e Project in DEC
    Nope, just the earlier vanilla SN7474 parts. I haven't fixed anything new enough to have S or H parts yet.
    70 replies | 3935 view(s)
  • m_thompson's Avatar
    March 1st, 2017, 03:50 AM
    m_thompson replied to a thread PDP-8/e Project in DEC
    I have replaced an amazing amount of 7474 ICs in DEC equipment. I would replace it.
    70 replies | 3935 view(s)
  • m_thompson's Avatar
    February 27th, 2017, 08:15 AM
    Several months ago I cleaned and lubricated the brake bushings on my drive. Both drives on the PDP-12 and both drives on my PDP-8/e have the...
    219 replies | 22824 view(s)
  • m_thompson's Avatar
    February 27th, 2017, 03:48 AM
    m_thompson replied to a thread PDP-8/S on eBay in DEC
    The RICM has four PDP-8/S systems. We had the first one, a rack mount, running quite a while ago. It was amazingly slow compared to an 8/L or 8/I. ...
    3 replies | 261 view(s)
  • m_thompson's Avatar
    February 26th, 2017, 07:45 AM
    m_thompson started a thread PDP-8/S on eBay in DEC
    There is a PDP-8/S on eBay. Now is your opportunity to own the slowest PDP-8 ever built. It is also the lowest serial number 8/S that I know of. ...
    3 replies | 261 view(s)
  • m_thompson's Avatar
    February 26th, 2017, 07:40 AM
    The TC12 controller passed all diagnostics, but we didn't try the tape data test. During a tape format it writes the Timing and Mark tracks on the...
    219 replies | 22824 view(s)
  • m_thompson's Avatar
    February 26th, 2017, 07:15 AM
    DEC issued different versions of the documents. One of the front pages shows the date of printing. If your's are different than any on BitSavers, it...
    3 replies | 169 view(s)
  • m_thompson's Avatar
    February 26th, 2017, 05:20 AM
    Will you scan them and send them to Al?
    3 replies | 169 view(s)
  • m_thompson's Avatar
    February 23rd, 2017, 04:28 AM
    m_thompson replied to a thread RK11-C / RK05 restore in DEC
    Be careful with the elbow. Some get dried out and crumble. You have a later revision of drive if you have the elbow. I believe that the HEPA...
    28 replies | 1195 view(s)
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