Announcement

Collapse

Forum Rules and Etiquette

Our mission ...

This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.


Rule 1: Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.


Rule 2: Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.



Rule 3: Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • Use the Private Message system for posts that are targeted at a specific person.


Rule 4: "PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.


Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Rule 5: Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.


Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.


New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.


Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

8 CDC Floppy Drive Repair

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    8 CDC Floppy Drive Repair

    Hey,
    Just today, I got my hands on this cool 8 drive that I plan to use with my Zenith Data Systems Z-110 to transfer data between 5.25 and 8 inch disks.
    image.jpg
    image.jpg
    image.jpg
    When I bought it, I already knew that it was very dirty, and that it was also missing two capacitors for the power circuitry, which I have already bought and am replacing tomorrow, but there are a few more issues that I had not anticipated that I could use some advice to try and fix.
    First, the belt on the back of the drive had become brittle and snapped. Im not sure where I can get a new belt or what kind I need. Also, the power switch on the front of the enclosure doesnt click back and forth like it should, and instead loosely moves between the on and off positions, as if its not catching the physical switch mechanism. Id love to know what kind of switch I could use to replace it, and if there is a way that I could short past the switch until I get a replacement. I have photos of the belt and switch attached below. Just ask if you need any more info or photos!
    Thanks!
    Belt (w/ 8 disk for scale):
    image.jpg

    Front of switch:
    image.jpg

    Back of switch:
    image.jpg

    #2
    The switch looks like an ordinary illuminated rocker switch Like this However, you'll need to measure the hole size to get an exact fit.

    As far as the rest of the drive goes, it would be helpful if you could post the model on the nameplate. CDC made endless varieties of these things.
    Reach me: vcfblackhole _at_ protonmail dot com.

    Comment


      #3
      Originally posted by Chuck(G) View Post
      The switch looks like an ordinary illuminated rocker switch Like this However, you'll need to measure the hole size to get an exact fit.

      As far as the rest of the drive goes, it would be helpful if you could post the model on the nameplate. CDC made endless varieties of these things.
      The switch looks good, thanks. I’ll be sure to measure it.
      Here’s a photo of the information on the drive, made by Magnetic Peripherals, Inc, which was a subsidiary of CDC. I drew over the image to make the stamped-in numbers more readable:
      37B31C4B-06EE-482F-B94E-99A758FA0563.jpg

      Comment


        #4
        This is the basic maintenance manual for several variations of CDC 8" floppy drives Yours is included: see page iv.
        Reach me: vcfblackhole _at_ protonmail dot com.

        Comment


          #5
          Originally posted by Chuck(G) View Post
          Thanks for the manual. I can’t seem to find much information on the belt. Do you know where I could find a potential replacement?

          Comment


            #6
            It's not going to be easy. If I recall correctly, these are rubber-reinforced fabric belts. At this point, they're probably strictly a custom item. There is a forum member, MicrocomputerSolutions, who specializes/specialized in repair of 8" drives. If he's still around, you might drop him a PM.
            Reach me: vcfblackhole _at_ protonmail dot com.

            Comment


              #7
              Originally posted by Chuck(G) View Post
              It's not going to be easy. If I recall correctly, these are rubber-reinforced fabric belts. At this point, they're probably strictly a custom item. There is a forum member, MicrocomputerSolutions, who specializes/specialized in repair of 8" drives. If he's still around, you might drop him a PM.
              Thanks, I did that. Apparently he hasn’t been online in months. Any other potential solutions in case he doesn’t reply?

              Comment


                #8
                Well, there's this old discussion from Lorne on Herb Johnson's retrotechnology site.

                The guy referenced by Lorne is isellprojectorbelts and is still doing business. He won't know from beans about CDC drives, but if you provide him the exact dimensions of your belt, he might be able to find a replacement.
                Reach me: vcfblackhole _at_ protonmail dot com.

                Comment


                  #9
                  Thanks for all the info! I was able to find a part number for the belt and contact a company that reports 11 in stock, so I’ll have to wait for a reply. I also contacted isellprojectorbelts.

                  Comment


                    #10
                    Good luck! It sounds as if you've got a handle on things.
                    Reach me: vcfblackhole _at_ protonmail dot com.

                    Comment


                      #11
                      Here I am again. I’ve completely repaired the drive, new belt, capacitors and everything. I also crimped my own IDC cable to connect to my Zenith Data Systems Z-100. The drive powers up and the spindle rotates, and if connected to the computer and a disk is installed, the head “clamps down”. However, the computer doesn’t recognize the drive in Z-DOS at all. I’m not exactly sure what to do, and there is a 4 switch block (red block in the 3rd picture) on the drive PCB. The head motor seems to want to move, as it rotates just a fraction, but doesn’t move any further. I can move it with my fingers, but it definitely has some resistance. Any ideas on what I can do?
                      Photo spam:
                      image.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpg

                      Comment


                        #12
                        See here, page 31 (PWA diagram). Note that you have 4 DIP switches instead 4 shunts. One of these needs to be closed to access the drive. On PCs, this is normally the second drive select, but I'm familiar neither with your cable nor with the Z100, so your mileage may vary.
                        Reach me: vcfblackhole _at_ protonmail dot com.

                        Comment


                          #13
                          Thanks, that’s helpful. I must have missed that when I read the manual earlier. I have, however, closed one of them and didn’t get much progress. I’ll try again with each one tomorrow, but I’m not sure which address I’d need. The cable is just a 50 pin Shugart card edge connector to a 50 pin IDC connector that I put together myself. I’m not exactly sure if software could be an issue, either. The computer runs Z-DOS, which is Zenith’s version of MS-DOS, but I also happen to have an IBM compatible MS-DOS that runs on my Zenith. I’ll try that with the drive also.

                          Comment


                            #14
                            You'll have to figure out which drive select the Z100 expects--that's something I've never fooled with. If you get nowhere, there are some things we can try.
                            Reach me: vcfblackhole _at_ protonmail dot com.

                            Comment


                              #15
                              If it's the only drive on the cable, why not close all 4 drive select switches for now.

                              Touching a grounded wire to the STEP pin (36) of the interface should move the head; if not, try it with the DIRECTION pin (34) grounded.

                              Congratulations on getting this far; how did you ever manage to find that belt?

                              Comment

                              Working...
                              X