Kaypro II drive problem

[tezza]

Hi,

I've recently acquired a Kapryo II with drive issues as posted about in the collections thread.

Today I pulled the machine apart to inspect the drives. They are Tandon TM 100-1A models. There is little about them on the web.

Anyway, I disassembled them and lubed the rails of both, reconnected and tried to boot. Same result...the disk could not be read.

I decided to swap the drives over. Knowing that there is both a terminator block and drive number selector to change somewhere, I looked for these. I found them (see below) and exchanged them. Interestingly, what I'm assuming is the terminator (disguised as a blue IC) was on drive B not drive A? Even though drive A was last in the chain. Is this usual?

Anyway...

So I booted with the swapped drive (was B now A) and volia! The drive spun for a second and up came CP/M 2.2. Typing DIR revealed the below..

What a beautiful sight!

So, drive A seemed to have issues and Drive B was ok (actually maybe not but more on that later).

I looked more closely at Drive A. Ah ha...a broken wire on a plug!

I figured this was the problem but after re-attaching the wire, and reconfigring it as Drive A again, it STILL refused to boot a disk. It can't read a directory as B either. Obviously there is a non-visible fault with this one. I figured I might have broken that wire myself when I removed the plug to unscrew the circuit board when I cleaned it. It is strange though, as it was almost as if that wire was NEVER attached? The flex was kind of flat (not pointed) and there were no remenants of wire in the pin itself?

Ok, anyway, I have a least one working drive right?

Well...I'm not sure. Typing a DIR showed all those programs. However, I can't get any of them to load. The disk just spins and spins. So either..

1. This drive is also faulty (but it boots no problem, every time and display a DIR???).
2. The programs did not write out correcty onto the disk, from the PC containing the image. (although it was a 360k drive and all tests seemed fine).
3. The image itself was just a CP/M boot disk and those programs were not actually on the disk. However, their directory entries were.

Anyone got any ideas? I only used one image of Dave Dunfield's and that was KAYPRO1.IMD . I made three duplicate disks and they all behave the same way in the Kaypro. Has anyone used this image before and does it really have those programs on it?

I will look at the other images when I get some more time.

Hopefully it is hypothesis number 3.

Tez

 

[Terry Yager]

Did you only try to run the .com files? See what happens if you TYPE one of the text files (.asm or .bas). The syntax is the same as MSDOG: TYPE [FILENAME.EXT]<ENTER>.

--T

 

[MikeS]

Have you tried STAT?

 

[tezza]

Yes, I only tried the com files. I'm pretty sure I tried STAT but will give all two suggestions a go when I boot the machine up again.

Tez

 

[Erik]

Quick thoughts:

1. Clean the heads.
2. Check the belt and pulleys on the drive bottom. If they are out of spec (dirty, loose, etc.) the drive speeds will be off and reading disks will fail. (The drives should have a pattern that can be used with a strobe, if you've got one.
3. The drive(s) may be mis-aligned. You'd need an alignment disk and software, dedicated hardware or a 'scope to figure and fix.

Good luck!

 

[billdeg]

We had a similar problem with MARCH's Kaypro II. You can swap in any Tandon 100 or compatible drive that fits (IBM PC for example). It does not matter which drive has the terminator, as long as one of them does. If you have a spare IBM PC use that drive temporarily.

Edit:
In fact, I suggest that you compare and contract the A and B drive from a working IBM PC to see what differences there are, if any between these two systems. I bet they're fully compatible.
http://vintagecomputer.net/itemsavailable/ibm_full-height_tandon100_qty-2_parts.jpg
Bill

 

[tezza]

Quick thoughts:

1. Clean the heads.
2. Check the belt and pulleys on the drive bottom. If they are out of spec (dirty, loose, etc.) the drive speeds will be off and reading disks will fail. (The drives should have a pattern that can be used with a strobe, if you've got one.
3. The drive(s) may be mis-aligned. You'd need an alignment disk and software, dedicated hardware or a 'scope to figure and fix.

Good luck!

Thanks for those thoughts Erik. The first thing I did before testing them was clean the heads. When I removed the drives I also checked the belts. They are clean and tight.

I guess mis-alignment is always a possibility. I've no equipment to check that at the moment. The unit is quite pristine though and doesn't look like it's been abused (dropped etc.).

I'm puzzelled about the drive that DOES boot though. Why can it boot and show a DIR so successfully yet not be able to run any of the programs listed? I'd like to verify the disk image is sound.

I'll be doing more investigations on that but it may need to wait until the family mania of xmas is over. However, I welcome all and any thoughts.

Tez

 

[tezza]

We had a similar problem with MARCH's Kaypro II. You can swap in any Tandon 100 or compatible drive that fits (IBM PC for example). It does not matter which drive has the terminator, as long as one of them does. If you have a spare IBM PC use that drive temporarily.

Edit:
In fact, I suggest that you compare and contract the A and B drive from a working IBM PC to see what differences there are, if any between these two systems. I bet they're fully compatible.
http://vintagecomputer.net/itemsavailable/ibm_full-height_tandon100_qty-2_parts.jpg
Bill

Yes, I'm sure they are compatible Bill. I guess this will show if there is any disk controller issues. I don't think there are though, because the Kaypro B can boot and show a directory whereas A doesn't work at all. That suggest it's the drives that have the problem(s).

Unfortunately I don't have any spares. About eight month ago I HAD a spare tandon full-hight I used to use on my System 80. I threw it out thinking it was faulty. I now know more about hardware and I suspect it wasn't the drive at all, but rather the machine it was attached to. (grrr...never throw old stuff out!)

Those full-height drives are quite rare here. You almost never see them on our local auction site.

Tez

 

[Ole Juul]

t

ezza: ... (grrr...never throw old stuff out!)

W00t!! another convert.

 

[Yzzerdd]

Wow, too bad those drives don't work, as you said it is an otherwise nice system.

My Kaypro II had a similair problem. One drive would boot and thats it, the other didn't work at all. But my booting drive was A: not B:...isn't there a key combo where you can switch the drives? Or is that the Osbourne?

I can't reccommend more than what the others have, although I can suggest that if you have a voltmeter, use the IBM 5150 Hardware Service Manual to diagnose your drives. I assume that the voltages and chips should be pretty much the same. I've never noticed a difference between Kaypro drives and IBM Tandon T-whatever drives, other than the faceplate.

Hmm...lets see where that manual is... Oh, thats right, Eric's site is down...Hmm...Well, if you can find another online or have an IBM Harware Service Manual, I wish you luck.

--Jack
BTW, poking through my data archive, I do indeed have the IBM 5150 HSM in a few different PDFs. Ask me nicely and I will grudgingly try to split them into 10MB pieces and e-mail them to you. PMs of course.

 

[tezza]

More progress on this.

I had a couple of hours spare from Xmas-preparation duties so I did some more testing. I wanted to know if the disk made from Dave's images contained all the programs it said it did.

First I hooked up to the Kaypro the same 1/2 height DD/DS drive that had MADE the disks. The disk worked just fine. All programs ran!

But then I thought maybe they would only work on the drive that make the disks so I hooked up my full height SS 40 track System 80 drive (see photo). It also worked perfectly. The kaypro booted and all the programs loaded.

So the disk and the Kaypro drive controller was fine. It must be the drives.

I then looked at the drives again starting with the one that would boot, but not load programs. Listening to this trying to load a program is seemed that the stepper arm was trying to scan the disk but somehow not moving very far down the rail. I could hear it trying to move. I booted with the circuit board folder back from the top so I could see what was going on. The arm would move a bit but then stop.

Hmm..I looked at the rails again. I didn't want to use too much oil but maybe the rails were still dry and sticky. I cleaned it again, finding some more black gunk underneath and in less accessible areas of the rails. I gave it a good oiling this time and pushed the head arrangement back and forth many times until is seemed very free.

Guess what? It worked!!! When I re-assembled and booted, it not only ran CP/M but booted ever program on the directory and could read all the text files using the TYPE command!

That drive (the original B drive which I've configured as A) was certified as working and OK

I turned my attention to the second drive. I gave it another clean but no joy with this one. I think it's something else. The stepper motor doesn't even TRY to move the heads on boot. There is no movement at all! If the head is manually moved from the rest position before switching the machine on it moves back there on boot (so there is electricity there), but then doesn't seem to attempt to pan the disk at all.

Oh well, at least I know know that I DO have one good drive, a boot disk that's fine and one broken drive. The computer itself (apart from just one drive) seems to work flawlessy.

So it's not so bad. I might be able to fix the drive with a bit more tinkering, but otherwise I'll look out for one. I could always poach my System 80 drive (it's external) but I want to keep the components of a disk-based System 80, as part of the collection.

Tez

 

[MikeS]

I know, I know, it's obvious, but just in case: you did set the jumpers properly and install the terminating resistor when you checked that second drive?

And shame on you: You of all people should know that the FIRST thing you do with any drive is clean and lightly lube the rails... ;-)

m

 

[tezza]

I know, I know, it's obvious, but just in case: you did set the jumpers properly and install the terminating resistor when you checked that second drive?

And shame on you: You of all people should know that the FIRST thing you do with any drive is clean and lightly lube the rails... ;-)

m

Yes, certainly checked the jumpers and terminating resistor etc. In fact, it's the B drive that works, which I've now configured (by shifting the resistor and changing the jumpers) to act as A.

Ah but, cleaning the rails and lubing WAS the first thing I did (see an earlier post).

However, it obviously wasn't cleaned and lubed well enough the first time. The second time I did a proper job, including cleaning all those hard-to-get places including the bottom of the rails. That worked.

Moral of the story. Take your time and do a careful and complete job the first time.

 

[chuckcmagee]

Whew, you saved me from digging out one of my Kaypros. I was thinking maybe it was some sort of single density/double density type problem but thinking about that now, that doesn't make much sense.

I can't remember which ones but some of my floppy drives have this stupid hard rubber cam that rotates. Then a metal finger follows a groove in the cam to move the heads. Pretty stupid system, if you ask me. Tends to get dusty and the metal finger jumps out of the track.

 

[Dr_Acula]

That photo brings back memories. Lots of brown disc bypass capacitors. And the green screen. Part of me says "so old fashioned" and another part says "I want one of those. I always wanted one of those..."

Is that how vintage computer addiction starts?

I just finished building a batch of 10 N8VEM CP/M boards. They are a bit old school in that they use eproms instead of eeproms, but they have LCD displays and an interface to a standard PC keyboard and it is really cool to get them chatting via wireless. I like to set my terminal programs to green screen for that true retro feel.

But one thing that strikes me in comparing these old systems with newer ones is that the newer ones have no moving parts. That appears to be the weak link - a computer stops working for lack of a bit of grease.

Restoring old systems certainly is a labour of love.

 

[Yzzerdd]

Nice job, Tezza!

I've had some problems with IBM 360K drives not reading disks, etc. But the ones I've tried fixing are the ones that used to work then started giving me trouble. Anyhow, I've found it to be the top circuit board on two occassions. It's not that hard of a test. Just take the circuit board off one working drive and hook it up to the drive that doesn't work. If the drive starts working again, then the problem is on the circuit board somewhere. Bad chip? Broken trace? Wrong switch settings? Could be anything.

--Jack

 

[tezza]

Nice job, Tezza!

I've had some problems with IBM 360K drives not reading disks, etc. But the ones I've tried fixing are the ones that used to work then started giving me trouble. Anyhow, I've found it to be the top circuit board on two occassions. It's not that hard of a test. Just take the circuit board off one working drive and hook it up to the drive that doesn't work. If the drive starts working again, then the problem is on the circuit board somewhere. Bad chip? Broken trace? Wrong switch settings? Could be anything.

--Jack

That's a good idea Jack. I'll try that.

Tez

 

[tezza]

That's a good idea Jack. I'll try that.

Tez

After cleaning up after Xmas festivities last night I swapped the top circuitboards over. They both work.

For some reason the stepper motor is not being activated although the motor itself can move the head; if it's not in the resting postion before boot, the motor will activate and return it there.

There is a secondary ciruit board on the back on the unit. I might try swapping that too. If that works it will narrow the fault to the stepper motor itself maybe? I'm assuming that if the electronics (i.e. circuit boards) feeding the motor and heads are all ok (because they can be successfully exchanged between the two drives) then it must be the stepper motor itself which is not working as it should.

Or it could be the heads but am I right in thinking if there is something wrong with the heads themselves, they would still "seek" (i.e. move down the disk looking for the boot track) assuming everying else is ok?

Tez

 

[frozenfire75i]

The board on the back of the drive as far as I know dose the moter speed/contral for the spindle or the main motor.

After cleaning up after Xmas festivities last night I swapped the top circuitboards over. They both work.

For some reason the stepper motor is not being activated although the motor itself can move the head; if it's not in the resting postion before boot, the motor will activate and return it there.

There is a secondary ciruit board on the back on the unit. I might try swapping that too. If that works it will narrow the fault to the stepper motor itself maybe? I'm assuming that if the electronics (i.e. circuit boards) feeding the motor and heads are all ok (because they can be successfully exchanged between the two drives) then it must be the stepper motor itself which is not working as it should.

Or it could be the heads but am I right in thinking if there is something wrong with the heads themselves, they would still "seek" (i.e. move down the disk looking for the boot track) assuming everying else is ok?

Tez

 

[modem7]

A faulty 'track 0' switch is a possibility.

On initialisation, the floppy controller will look at the TRACK 00 line from the drive, and if that line indicates that the heads are not at track 0, will step the heads in the track 0 direction until the TRACK 00 line activates.
If the 'track 0' switch is faulty, then the TRACK 00 line will never activate. I would expect that after the floppy controller has issued 40 steps in the track 0 direction, and sees the TRACK 00 line still inactive, that the controller would then assume the drive to be faulty and stop any further operations with it.