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Need a bit of help resurrecting my PDP-11/73

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    #16
    The slot allocation looks OK. So the machine never had an MS device actually installed?

    Yes, take the cards out and give them all a bit of care and attention. Use sensible antistatic precautions if you don’t have an antistatic mat and strap.

    Make sure the cards go back in the same place.

    Blow the dust (and dead bugs) off the cards. Do you have any edge connector cleaner?

    Off on a business trip now for a few days. Good luck...

    Dave

    Comment


      #17
      That's an RD53. They are notorious for not coming up properly due to stuck heads. Not to the platter, but to the head stop in the drive. I've found that whacking it on the side with a rubber hammer while powering up will sometimes free the head, other times you have to take the top off and move the head assembly.

      Note that while the historical wisdom was that taking off the top is instant doom, these drives did have filters in them to filter out any particles anyway so they should probably be ok for the short term. Still, I would back up the data as soon as possible.

      Note2: If you get an RD54 you do have to change jumpers on the RQDX3.

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        #18
        Just ordered an anti static mat/wrist strap kit and some Deoxit. Thanks for the assistance!

        Comment


          #19
          Originally posted by czunit View Post
          That's an RD53. They are notorious for not coming up properly due to stuck heads. Not to the platter, but to the head stop in the drive. I've found that whacking it on the side with a rubber hammer while powering up will sometimes free the head, other times you have to take the top off and move the head assembly.

          Note that while the historical wisdom was that taking off the top is instant doom, these drives did have filters in them to filter out any particles anyway so they should probably be ok for the short term. Still, I would back up the data as soon as possible.

          Note2: If you get an RD54 you do have to change jumpers on the RQDX3.
          How hard do you whack them... tap, gentle hit, or really smack it? I can give it a go.

          Is the controller able to detect that it's not working and that's why it's reporting Not ready?

          Update: I tried the whack, no luck. Took the cover off the drive. I see what you meant by the air filter. Anyhow, I could not get the head arm to move at all, using careful gentle persuasion. Should I have been able to?

          I really wish there was a way to get some indication that the RD53 is even getting signals. I reseated all the cables on the front plane, no difference.

          I may see if I can boot off of an XXDP tape cartridge.
          Last edited by GreyHairedDECfan; December 7, 2021, 10:50 AM.

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            #20
            Can't boot off of the MU: drive. When I try, it reports Non-existent drive. Also the TK50 has something stuck, it won't let me eject a tape. Had to remove the drive and flip up the solenoid-driven latch to allow the cartridge to be removed. Fortunately there wasn't tape all over the place.

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              #21
              Wednesday's update. I found a tutorial on unsticking the RD53 drives. Was able to free up the heads after going through that. Still, DU0 reports as Not ready.

              I really wish there was some visual indication that it's getting any signals from the controller. Unfortunately on the RQDX3 controller there are no lights, nor are there any on the drive itself. So I can't see (and I can't hear) that it's attempting to do anything. The only thing I know is that the controller seems to see the drive, since if I unplug it it reports Non-existent drive. I just can't get it to read from the drive (or so it seems).

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                #22
                I seem to remember (back when I was trying to create a bootable drive for my 11/84) that "Disk not Ready" could indicate it's not finding anything bootable on the drive. Can you hook the drive up to a power supply and listen to it spin up? You should be able to hear that and the heads mounting.
                PDP-8 and PDP-11 enthusiast. But enjoy most older PC stuff too.

                Comment


                  #23
                  Originally posted by tradde View Post
                  I seem to remember (back when I was trying to create a bootable drive for my 11/84) that "Disk not Ready" could indicate it's not finding anything bootable on the drive. Can you hook the drive up to a power supply and listen to it spin up? You should be able to hear that and the heads mounting.
                  I don't have a separate power supply to use. I slid the drive out a bit, and removed the TK50 (to cut down on the noise). Listened and didn't hear much. However, two things have changed:
                  1. The rear end of the drive is now getting warm, so it seems to be doing something
                  2. On one startup attempt, I got this far... after it entered dialog mode,I got this:

                  Testing

                  Boot in progress - Please wait - Type CTRL C to exit

                  But it just sat there. I will reseat the cables on the drive end again in case something is loose.

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                    #24
                    Ok, that seems to indicate the drive does have something bootable on it. Maybe it's gotten corrupted though and still can't boot. Yes, having a separate power supply is a good thing at times. I have several older SCSI drives I am trying to determine whether are useable. First test is the "do they spin up test". Could the TK50 somehow be interfering with the hard drive? I don't know how that would be but you never know. Just kinda weird that once you removed it the drive went further on booting. Keep at it and you'll get it sorted out.
                    PDP-8 and PDP-11 enthusiast. But enjoy most older PC stuff too.

                    Comment


                      #25
                      Well, it only got to that point once. After reseating the cables again on the frontplane, it's back to where it was before.

                      I have some Deoxit coming Friday and will take the cards out one by one (documenting where each one goes for sure) and cleaning the edge connectors. There's a lot of dust in the sockets on the entire machine that I'll use a gentle brush to remove and then vacuum.

                      I wish I knew what the LEDs indicate on the back of the CPU. Generally I have (from the top down) 2 small red LEDs lit, then a large green lit, then another small red lit. This is after it fails to boot. I did some searching online but can't seem to find what those LEDs indicate.

                      Also wish I knew what the Continuous Self Test (in Dialog mode) is actually testing. I have let it run several times for say 10-20 minutes, then Ctrl-Z out. Every time it reports some number of Passes and Errors. Errors are always zero.

                      Comment


                        #26
                        Well, reading from my 11/84 manuals and the 11/84 is a M8190 board. There should be 6 red LEDs. 3 before the green and 3 after. The green indicates DC Ok. The 6 red leds should be the same as the octal number on the front panel. They are read from the back of the unit forward looking from the back side of the CPU card.
                        PDP-8 and PDP-11 enthusiast. But enjoy most older PC stuff too.

                        Comment


                          #27
                          Well, my guess is your drive is toast. I have one of the Dave Gesswin MFM readers and spent a lot of time this fall hooking up old drives including some RD53's. If you really want to you can send it to me and I'll see what (if anything) is on it. I have a couple of RD53's but I keep them around for my Pro/380's to consume.

                          What do you want to do with this thing? Play games? Hack?

                          Comment


                            #28
                            There are some DEC people in that area. If I still lived there I'd offer my machine to help you out. It is likely your HD is toast though being an RD53.
                            PDP-8 and PDP-11 enthusiast. But enjoy most older PC stuff too.

                            Comment


                              #29
                              Originally posted by czunit View Post

                              What do you want to do with this thing? Play games? Hack?
                              Just hack a bit, I suppose. The allure of running something that I set up 30+ years ago.

                              There's nothing on it that's critical, of course, just old files and my company's old programming to reminisce on.

                              I've been mulling around the idea of stripping the guts out and mounting a Raspberry pi running simh in it. Could be fun to do a little custom wiring to get some of the original lights and power switch to function with the new "engine" inside. Also rework the rear distribution panel to accommodate USB and other modern-day ports.

                              This weekend I'm going to pull all the cards out and clean everything well and see if that makes any difference. I'll give it a few more tries before calling it a day.

                              Comment


                                #30
                                Running with a Pi in there just isn't as much fun as the real thing.
                                PDP-8 and PDP-11 enthusiast. But enjoy most older PC stuff too.

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