Announcement

Collapse

Forum 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.


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.


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.



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.


"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.

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

Still have two issues with Kaypro 4/83

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

    #16
    Alan,
    I've done lots of Alignments over the years with my Dysan Alignment disk, but over they years that has slowly leaked
    from my old memory cells. Here is a site that TEZ has that explains it pretty well and TEZ doesn't have an Alignment
    Floppy. https://www.classic-computers.org.nz...andon-m100.htm

    He has lots of other good articles on his site.
    https://www.classic-computers.org.nz...ive-repair.htm
    https://www.classic-computers.org.nz...ealignment.htm

    My other suggestion would be to not use any type Grease on the Drive Guide rods. Either a Graphite or Silicone lube, but
    Dri-Slide is the best. It works for years and doesn't attract dirt, or make the head(s) carriage sluggish as the years go by.

    Larry
    Last edited by ldkraemer; May 8, 2021, 01:46 AM.

    Comment


      #17
      A couple of other things to check for:

      I had the B drive head assembly stuck hard to the rails. When it tried moving the head, it actually caused the metal band connecting the stepper motor to the head assembly to tear a little where the attachment screw went through the metal band. It was slight but would never get consistent track positions.

      The replacement drive developed a squeal and again poor read/write performance. The drive spindle needed some lubrication and restored the read/writes.

      Comment


        #18
        Thanks everyone; I *finally* think I am getting somewhere with this drive.

        Here is the roadmap of what I've done to get here.

        Thankfully the good drive has been good and I've not had to mess with it.

        This morning I decided to start fresh and see what I could do with the alignment. I set out to make my own "one track on each side" alignment disk. I used a radio shack bulk eraser to erase a disk in the usual pull it away in a circular pattern while enabled technique I've seen people use on TV's. Sure enough I put the blanked disk into the good drive with the scope hooked up to TP1 and there is no signal when I tried to read a track. This is where I learned the bios will try reading, then do a home or something on the drive to return to track 0 and then repeat the read. It does this 3 times before returning a failure to read.

        Then I used the Kaypro copy utility to write a single track to the blanked disk. Well two tracks. I wrote track 40 (which is one sides track 20) and I write track 41 (which is the other sides track 20). Now I have a disk with one formatted track on each side and all other tracks unwritten. The copy utility only gives the option to format a single track on drive B:, so I had to change the drive jumper while the system was up and running with the copy utility. Now I have my alignment disk (at least one that is aligned to my good drive).

        I then put in place the bad drive which was somewhat aligned, but not perfect. It was good enough to boot CP/M and load my disktool which I will attach. My disktool doesn't have a lot of options, but one of them is a read track function where you specify the drive, the track, and the number of retries. The command for this is X04099 which is disk 0, track 40, retry 99 times. Now with the scope hooked up to TP1, I can see the amplitude of my single track on the scope. I loosened all 3 bolts and started adjusting. What I learned is that when I tighten the bottom two, it will change it slightly so you need to account for that. My technique was, turn it completely clockwise. Then approach the signal and learn where its maximum amplitude is. Then go back clockwise again and reapproach that position. My scope was set to 200mV per div and if you approach it by don't get to the optimum signal by maybe 1/5 or 2/5 graduations, that will be ideal because as you begin to tighten the bottom two bolts back and forth nice and even, they will pull it into its maximum signal that you originally found. Finally tighten the top bolt carefully as well.

        My test for alignment is this. Use Kaypro copy command again. O-X formats A:, and O-F formats B:. Put a disk in each drive and format them both. Then do an O-V to verify the disks are the same. It should pass with no errors. Then swap the disks. DO another O-V. If it passes that then each drive is reading the one that the other formatted. Do this multiple times. I've run an O-V again and again swapping the disks again and again and it is always passing now!

        In the end I think this drive was so tough to fix because it had multiple issues going on.

        #1 - It has bad tantalum capacitors. The most meaningful one to change was C1 which is used for an opamp that probably amplifies the signal coming from the head. This was the cause of the signal strength changing on a whim and why it would sometimes seem to work and other times fail.

        #2 - It has a problem with the 5V trace from the connector to the first parts it connects to. It would get weak and introduce 25+ ohms of resistance choking off the drive for power. I tried resoldering it, but I don't think it was the connector, but the trace itself somehow. I finally got sick of messing with it and ran a stranded wired jumper from the topside of the connector to the capacitor it first connects to. Finally a sub 1-ohm reading of continuity.

        #3 - bad alignment. It may not have started with this issue, but it could have been introduced by me trying to previously fix the drive not knowing about issues #1 and #2. My technique above is how I fixed that.

        The last remaining thing is that sometimes it seems to start out not knowing what track it is on and then seems to do a home to figure that out. I suspect that perhaps a track 0 sensor adjustment can be done to improve this. After reading the manual I learned that this sensor does not just identify track 0, but actually when the carriage is close to track 0 getting activated somewhere between 0 and 3. Then it relies on the phase of the stepper being at 0 to know it is on track 0. Ideally I would think then you would want the track 0 sensor to activate on the edge tracks 2 and tracks 1. I still need to check that on both drives and see how it performs.

        Comment


          #19
          Here it my Kaypro CP/M disktool.

          rD - reads disk (makes sure all sectors can be read without error)
          tD - tests disk (that was written with wD command, each sector contains counting pattern plus track/sector number)
          wD - writes disk (writes a disk with each sector containing a counting pattern plus track/sector number)
          xDTTNN - track testing - repeat track reading TT is track NN is retries
          @D - writes 0xAA disk - writes all sectors to 0xAA

          D is drive

          error <E#,#> is an error. First # is track, second # is sector
          error <B#.#> is the same, but not a disk read/write error, but a compare error. It comes up if you use tD to test a disk and the sector is read, but contains the wrong data.
          Attached Files

          Comment


            #20
            Thanks everyone for the help in this thread! Both problems are fixed and my kaypro 4/83 is running tip top now!

            One other note - when checking the track 0 sensor - remember that the tracks are doubled because there are no heads. track0/1=0, 2/3=1, 4/5=2 and so on when doing the test. The sensor should turn ON when you go to track 2 and off when you go to track 4 when using my disktool to test it.

            Comment

            Working...
            X