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Thread: New owner of a Kaypro 4 '83. Some questions.

  1. #1
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    Default New owner of a Kaypro 4 '83. Some questions.

    I restore 8088 machines on up, but this Kaypro 4 '83 model I just acquired is new to me and so is CPM.

    It mostly is in excellent working condition, but here is the rundown so far and I need some advice:

    1.) Drive A: works most of the time. Once in a great while it wont read a disc, but if I take the disc out and do a blow/shake and then reinsert it it will read it again most of the time.
    2.) Drive B: wont read any discs.
    3.) The screen works, but it has a bit of shaking in the image until it warms up and then stabilizes. It always is nice and bright though.

    Both drives seem like they need some lubricating as the motors sound rough at best. Kind of a grindy sound to them. Maybe that is normal with these Kaypro full height 5" drives? Probably want to check the guide rails as well. Any suggestions on what grease to use for those? I do have a new old stock floppy drive on the way just in case.

    As far as the screen goes what advice would you give as I am not a CRT tech and the thought of high voltage running through my nervous system does not excite me in the least bit, but do you think something like a shaky image when cold and normal when warmed up is a problem I should address now or just wait?

    Also, I have been researching imaging all the disks and of course that opens up a whole new can of worms. So I have one question. I have an old Pentium III socket 370 system with dual floppy support. Would a modern controller like that be able to handle one the Kaypro 4 drives directly? I was thinking about using something like WinImage with the drive hooked up directly to the Pentium III, but I have no idea if that would even work??? Imagedisk just seems like a pain, but if I must, I will use it. WinImage is just so elegant and simple to use with PC related disks.

    Thanks for any help. I have been using computers since the late 70s, but had zero exposure to CPM or the Kaypro line of systems.

    kaypro4_83.jpg
    Last edited by liqmat; December 7th, 2017 at 02:22 PM.

  2. #2
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    Very nice!

    Those look like Tandon floppy drives. They can be noisy, and that is fairly normal but may vary from drive to drive. Head stepping is usually quite loud compared to later drives. The exact sound can vary depending on the head stepping speed the the machine uses. The drive motors can be noisy too. I have two in my CDP1600 that make a good bit of noise when the disks spin. Keep in mind these are belt driven drives.

    Chances are the drives need to be removed an given a good cleaning and inspection. A common problem is dust collecting on the rails preventing the heads from moving. I usually use Lithum grease to lubricate rails. You can use a q-tip and alcohol to carefully clean the heads, although for routine cleaning a cleaning disk is less hassle.

    The wobbling in the picture until warm up sounds like there might be an electrolytic capacitor starting to go bad in the video circuitry. Not too hard to fix if you can find the guilty component. Although I am not sure how these units behaved normally. Small monochrome CRTs are not really dangerous, but as always be sure to follow the proper discharging steps.

  3. #3
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    Do the drive motors sound "grindy" without a disk inserted? My concern is that you're trying to use contaminated or deteriorated media with the result that the "grindy" sound is coming from the contact of the heads with the disk.

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    Quote Originally Posted by SomeGuy View Post
    Very nice!

    Those look like Tandon floppy drives. They can be noisy, and that is fairly normal but may vary from drive to drive. Head stepping is usually quite loud compared to later drives. The exact sound can vary depending on the head stepping speed the the machine uses. The drive motors can be noisy too. I have two in my CDP1600 that make a good bit of noise when the disks spin. Keep in mind these are belt driven drives.

    Chances are the drives need to be removed an given a good cleaning and inspection. A common problem is dust collecting on the rails preventing the heads from moving. I usually use Lithum grease to lubricate rails. You can use a q-tip and alcohol to carefully clean the heads, although for routine cleaning a cleaning disk is less hassle.

    The wobbling in the picture until warm up sounds like there might be an electrolytic capacitor starting to go bad in the video circuitry. Not too hard to fix if you can find the guilty component. Although I am not sure how these units behaved normally. Small monochrome CRTs are not really dangerous, but as always be sure to follow the proper discharging steps.
    Thanks for the reply. I am getting a new wrench set shipped to me as mine is shot. When that arrives I will be pulling both drives and giving them a thorough cleaning and lube if needed. These drives look like my ITT Xtra XP 80286 6MHz machine, built to last a long time. As far as the video circuitry I feel uncomfortable messing with that on my own because of the nasty voltages running through those parts and better to be safe than sorry. I did contact one TV repair guy and he just laughed me off and wont do the work on it. So I'll keep searching. I recap boards all the time, but never something like that where it can bite back even when unplugged.

    I'll ask again as I know it's a common question. Is Imagedisk the best approach to imaging these disks? I am a tad confused about the 250k > 300k or 300k > 250k and formatting to the exact sectors etc. so it will read the disks. I have a box of 100 new old stock KAO 5" MD2D double sided double density 48 TPI disks that I picked up cheap and I think those will be a perfect fit for this machine and I use them on my ITT Xtra 80286 as well.
    Last edited by liqmat; December 7th, 2017 at 01:47 PM.

  5. #5
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    Disks: First check that the media is not binding in the disk sleeve. Rotate the inner ring and look at the surface of the disk. Any scratches? Binding will slow the rotation enough to throw off a read, and may collect part of the jacket onto the media or from there onto the head. After that the cover has to come off so you can remove the drives from their cage. Pay attention or mark so you can differentiate A from B when you reinstall. A has no termination pack but B should have one. The '83 4 should have a fan at the back of the case; it draws air from the front and expels out the back. As a result the drives will probably be dusty. Clean with isopropyl alcohol. I wouldn't use any grease but some people like WD-40 on bearing surfaces.

    If Disk B's problem isn't obvious, e.g. loose cabling or wrong termination, there may be a capacitor at fault. There are test points on the disk's board but I don't think I have a Tandon service manual. Someone here will, though: maybe Chuck(G). Tandons sound like a coffee grinder when stepping so that in itself is not an indication of health or lack thereof. Cleaning won't alleviate that, anyway.

    Video wobble indicates a bad cap - probably electrolytic - and most likely in the display section behind the CRT. I don't think there are any electrolytics on the motherboard. But the good news is it stabilizes after warmup. If it were me I'd wait to see if it got worse or better as time goes by. Some caps that haven't been used in a long time can "reform" themselves with regular use.

    When you say you want to image the disks are you looking to make a backup copy of the software or an image of the disk itself that you can later transfer to new media? If you just want to read the files off the disk look for a program such as UNIFORM with which you can read CP/M format disks on a PC. There are numerous sites with already-imaged CP/M disks in archive. Check out WinWorld.com, for example.

    Two other things to look out for: With the cover off: there may be a clock backup battery on the motherboard. I would remove that for fear of leakage. In the keyboard: the keyswitch is a capacitive-switch that uses a foil pad on top of a foam pad. The foam pad may deteriorate, leading to dead keys.

    Hope this helps. The Kaypro was primitive and so was CP/M, compared to practically everything that came after it. Lord knows why we collect them. Masochism?

    -CH-

  6. #6
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    Quote Originally Posted by Chuck(G) View Post
    Do the drive motors sound "grindy" without a disk inserted? My concern is that you're trying to use contaminated or deteriorated media with the result that the "grindy" sound is coming from the contact of the heads with the disk.
    Yes. They have grindy sound with no disk and a slight squeal to them. Sounds like the belt might be sqealing a bit. I decided to take a new MD2D disk and stick it in the second drive and try and format it to see what happens. Bad sector errors constantly and its leaving physcial scars on the disk as you can see in my photo. This is not normal as the first drive does not display this behavior. Yikes. This drive needs some work if you ask me. Once my new wrench set comes in I'll get busy on it. I do not regret ordering another drive just in case. The first drive works most of the time. Once in a great while it will have trouble reading any disk so hopefully that is just a cleaning issue.

    diskmark.jpg

  7. #7
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    Quote Originally Posted by clh333 View Post
    Disks: First check that the media is not binding in the disk sleeve. Rotate the inner ring and look at the surface of the disk. Any scratches? Binding will slow the rotation enough to throw off a read, and may collect part of the jacket onto the media or from there onto the head. After that the cover has to come off so you can remove the drives from their cage. Pay attention or mark so you can differentiate A from B when you reinstall. A has no termination pack but B should have one. The '83 4 should have a fan at the back of the case; it draws air from the front and expels out the back. As a result the drives will probably be dusty. Clean with isopropyl alcohol. I wouldn't use any grease but some people like WD-40 on bearing surfaces.

    If Disk B's problem isn't obvious, e.g. loose cabling or wrong termination, there may be a capacitor at fault. There are test points on the disk's board but I don't think I have a Tandon service manual. Someone here will, though: maybe Chuck(G). Tandons sound like a coffee grinder when stepping so that in itself is not an indication of health or lack thereof. Cleaning won't alleviate that, anyway.

    Video wobble indicates a bad cap - probably electrolytic - and most likely in the display section behind the CRT. I don't think there are any electrolytics on the motherboard. But the good news is it stabilizes after warmup. If it were me I'd wait to see if it got worse or better as time goes by. Some caps that haven't been used in a long time can "reform" themselves with regular use.

    When you say you want to image the disks are you looking to make a backup copy of the software or an image of the disk itself that you can later transfer to new media? If you just want to read the files off the disk look for a program such as UNIFORM with which you can read CP/M format disks on a PC. There are numerous sites with already-imaged CP/M disks in archive. Check out WinWorld.com, for example.

    Two other things to look out for: With the cover off: there may be a clock backup battery on the motherboard. I would remove that for fear of leakage. In the keyboard: the keyswitch is a capacitive-switch that uses a foil pad on top of a foam pad. The foam pad may deteriorate, leading to dead keys.

    Hope this helps. The Kaypro was primitive and so was CP/M, compared to practically everything that came after it. Lord knows why we collect them. Masochism?

    -CH-
    Yes. Very familiar with floppy drive termination as many XT class machines are like this as well. I will check that once I get the drives out.

    I was not aware the 4 '83 had a case fan and mine does not nor do many of the units I see being worked on on Youtube. Are you sure they had fans in this model?

    I agree with you on the minor video issue. Wait and see. From what I can see the tubes are near impossible to find anymore so if it ever fails I might do a LCD mod, but that would be very involved I'm sure, maybe not. Has it been done yet?

    No clock battery and with any computer or console system I'm restoring it's the first thing I look for. Hell, I just ran across a Socket 370 board that had a leaking CR-2025 which was a first for me. Those usually don't leak. Luckily no damage. The plastic battery tray isolated the leakage from the traces.

    As far as this foam pad on the keyboard, that does not exist on the keyboard I have. Zero foam anywhere and it works perfectly. When you say foil and foam, are these materials internal to each key switch? I just don't see it. Attached some photos. The keyboard has no issues luckily and yes, it needs a deep cleaning.

    keys1.jpgkeys2.jpg
    Last edited by liqmat; December 8th, 2017 at 07:46 AM.

  8. #8
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    On the underside of the key switch is the pad and foil. You won't see it by removing the key cap but by disassembling the housing to reveal the matrix under the keys. The keyboard was made by KeyTronic and they won't even talk to you about this style of board any more. Here is a link with pictures showing the parts I reference: https://geekhack.org/index.php?topic=92067.0

    There is a fan in the Kaypro 10 case and in one of the 4 variants, but not sure it was this one. Ditto RTC and battery.

    -CH-

  9. #9

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    Quote Originally Posted by clh333 View Post
    On the underside of the key switch is the pad and foil. You won't see it by removing the key cap but by disassembling the housing to reveal the matrix under the keys. The keyboard was made by KeyTronic and they won't even talk to you about this style of board any more. Here is a link with pictures showing the parts I reference: https://geekhack.org/index.php?topic=92067.0

    There is a fan in the Kaypro 10 case and in one of the 4 variants, but not sure it was this one. Ditto RTC and battery.

    -CH-
    I read that thread. I didn't realize there were two different types of Kaypro keyboards. I need to check the ones I have to see.

  10. #10
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    Quote Originally Posted by clh333 View Post
    On the underside of the key switch is the pad and foil. You won't see it by removing the key cap but by disassembling the housing to reveal the matrix under the keys. The keyboard was made by KeyTronic and they won't even talk to you about this style of board any more. Here is a link with pictures showing the parts I reference: https://geekhack.org/index.php?topic=92067.0

    There is a fan in the Kaypro 10 case and in one of the 4 variants, but not sure it was this one. Ditto RTC and battery.

    -CH-
    Yeah, I don't see any evidence there was a fan in the case at any point. As far as the keyboard goes, what is the approach to removing the keys? Some keyboards are a straight pull up. Do not want to break this beauty so any advice on that would be appreciated. Thanks.

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