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Kaypro II drive problem

modem7 said:
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.
Click to expand...

Hmm..it keeps spinning though until CP/M itself stops it? Also, would a faulty track 0 switch be consistent with the stepper motor returning the head to a start position (edge of disk) on boot then doing nothing, and simply doing nothing if the head is already positioned at the start position?

I've swapped around the smaller card on the back of the drives and it seems both cards are fine too. So the "electronics" as such seem ok.

While I always like to know exactly what's wrong, I think the best course for me at this time is to look for a replacement FH SSDD drive.

Tez
 
On power up, the heads could be anywhere. There is no way for a floppy controller to ask the floppy drive as to which track the heads are over. The TRACK 00 line is the only form of feedback. And so on the first operation of the floppy drive after power up, the floppy drive controller (FDC) initially takes the heads back to track 0 and from then on keeps a track (pun intended) of which track the heads should be over by monitoring the step commands (direction and count).

Also, would a faulty track 0 switch be consistent with the stepper motor returning the head to a start position (edge of disk) on boot then doing nothing
Click to expand...
Look at this scenario:

* Heads on track 2 at power on.
* CP/M asks floppy controller (FDC) for first sector on floppy (or asks for 'recalibration').
* FDC sees that HEAD 00 line inactive and therefore assumes that heads are not on track 0.
* FDC selects floppy drive (motor, etc.), issues a step in the direction of track 0.
* Floppy drive moves heads to track 1.
* FDC still sees that HEAD 00 line inactive.
* FDC issues a step in the direction of track 0.
* Floppy drive moves heads to track 0.

At this point, the heads are on track 0, but because of the faulty switch, the drive cannot inform the FDC of that.
The FDC will believe that the heads are still past track 0.

* The FDC will continue to issue steps waiting to see the TRACK 00 line toggle at some point. In intelligent design, there's no point issueing more than 40 steps. Whether or not you will hear the stepper motor straining at this point comes down to stepper motor design I guess.

* FDC gives up on drive (TRACK 00 line did not toggle as expected).


and simply doing nothing if the head is already positioned at the start position?
Click to expand...

* Heads on track 0 at power on.
* CP/M asks floppy controller (FDC) for first sector on floppy (or asks for 'recalibration').
* FDC sees that HEAD 00 line inactive and therefore assumes heads are not on track 0.

At this point, the heads are on track 0, but because of the faulty switch, the drive cannot inform the FDC of that.
The FDC will believe that the heads are still past track 0.

* The FDC will issue steps waiting to see the TRACK 00 line toggle at some point.
* FDC gives up on drive (TRACK 00 line did not toggle as expected).
 
A track 0 problem could be the problem, but then I'd expect it to try stepping when you power it up while already at track 0. Easy to check: pin 26 should go from high to low when it restores the head to track 0.

Might be a selection problem, but you've checked that; I assume the LED does light while all this is happening? Have you tried grounding pin 20 a few times while the LED is on?

Not much goes wrong with the electronics on these drives in my experience; out of the dozen or so that I've used and still have the only problems have been analog, i.e. heads, alignment &c. except for one track 0 switch AFAIR.

So it may just be the most obvious, that it can't read the boot track and just sits there trying until it times out. Try formatting it; most formatters will merrily step through the disk whether it's OK or not until the end.

m
 
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MikeS said:
Might be a selection problem, but you've checked that; I assume the LED does light while all this is happening?
Click to expand...

Yes, it is.

MikeS said:
Try formatting it; most formatters will merrily step through the disk whether it's OK or not until the end.
Click to expand...

I did this tonight and the exercise may have offered a few more clues. Here's what happened.

1. A disk in drive B (which was the original A drive) could be formatted AND verified without errors
2. A CP/M System disk in drive A could be copied to the disk in drive B AND verified without errors.
3. switching to >B, I could list a directory, run programs and list text files from the newly created disk in Drive B
3. However the new system disk made in drive B would not boot in drive A. Nor could I list a directory when used in drive A. It exibited the same symptom when the B drive (configured as A) tried to boot the original CP/M disk. In other words nothing. No seeking...just spinning.

Guys, this suggests to me an alignment or speed problem, would you agree? The disk is fine FOR THE B DRIVE (the drive it was created on) but it's speed and/or alignment is too much out of wack with the A drive for it to be recognised. Is this how you would read it?

If I get a moment tomorrow I'll see if the new system disk made on >B will boot on the B drive, when I've configured it as A. I guess if it does, that will strengthen the theory above.

Regarding speed, I've had a look at the strobe patterns on the drive platter as they are spinning. One drive appears a fraction slow, the other a fraction fast. Not by a lot, but maybe enough so that disks made in one won't read the others? Should there be an adjuster somewhere which fine tunes a drive's rotation speed? I couldn't see one anywhere?

Tez
 
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Ok, I've done some research on this.

It seems that I need an analogue calibration disk, some software and some instructions.

I don't have such a disk and I imagine they are rare and expensive.

The drive reads and writes to itself just fine. The pragmatist in me says I just should let it be. After all, it's only going to be used for demonstration if at all. I shouldn't spend a lot of money on it. However, I like to have all my systems working 100% and it niggles at me if I don't. (Given that maybe I shouldn't be playing with vintage computers :) )

Is there any "quick and dirty" way to attempt re-calibration without the special disk? Perhaps disk diagnostic CP/M software which can be used for testing after turning the calibration screws? I might have a bit to lose though, as the drive may then stop working completely.

What do you think?

Tez
 
I've adjusted the timing so both drives run at exactly the same speed. No difference.

Some more info gleaned from a run today...

1. A boot disk made in the faulty drive (drive B) does boot the machine when booted from the faulty drive.

2. The faulty drive has trouble formatting high numbered tracks. On five disks (all new) the format with verify failed on tracks 34 upwards with increasing errors. The most errors were on track 39. I noticed this yesterday with two disks, but the third one seemed to format ok. I used this one to make the new boot disk copy in B. However, reformatting that disk today threw up those track errors, then 2 more new ones I tried. It seems pretty consistant then.

More evidence of an alignment, or at least a head problem?

Tez
 
It seems that I need an analogue calibration disk, some software and some instructions.
I don't have such a disk and I imagine they are rare and expensive.
Click to expand...
The service manual for the TM100 is at http://maben.homeip.net/static/S100/tandon/diskette/Tandon TM100 Operating and Service Manual.pdf
The overall alignment procedure is on page 19. You'll note that an oscilloscope is another required tool for the head alignment. I have both an oscilloscope and the specified Dyson 224/2A alignment diskette.
An option for you is that if you will pay for shipping to/from Australia, I will do a head alignment on your drive for you.

If you have an oscilloscope, another option is that I loan you my alignment diskette. I can also provide a BASIC program for the PC that will allow you to step to a specified track.

The faulty drive has trouble formatting high numbered tracks. On five disks (all new) the format with verify failed on tracks 34 upwards with increasing errors.
Click to expand...
The higher the track number, the tighter the bits are packed. Heads still slightly dirty perhaps?
 
billdeg said:
It does not matter which drive has the terminator, as long as one of them does.
Click to expand...
The drive at the end of the cable is to have the terminator, to stop/reduce signal reflection occurring at the end of the cable (refer to transmission line theory).

Note that that doesn't mean that the setup won't work if the terminator is positioned somewhere other than the cable end - signal reflection can occur from the end of the cable and that can interfere with controller to drive communication. Play safe.
 
Inner track & r/w amplifier

Inner track & r/w amplifier

This is a bit of a stretch, but perhaps the read amplifier circuit is faulty ? The fact that reads on outer sectors (lower bit rate) but not on inner sectors (higher bit rate) almost sounds like there's a lpf or band-pass in the read amplifier that's shifted it's spectrum due to a leaky cap or something similar.
Ok, I know it's a stretch, but...
patscc
 
Pc

Pc

Another off-the-wall thought. Put the drive in a IBM-PC, and run something like Drive Probe against it, if you have it. or, barring that, see if the same behaviour manifests itself( or another Kayro, for that matter)
patscc
 
modem7 said:
I have both an oscilloscope and the specified Dyson 224/2A alignment diskette.
An option for you is that if you will pay for shipping to/from Australia, I will do a head alignment on your drive for you.
Click to expand...

I'll PM you about this.

modem7 said:
The higher the track number, the tighter the bits are packed. Heads still slightly dirty perhaps?
Click to expand...

Yes, I thought of that. I gave them yet another clean but no improvement.

Tez
 
Hi
With problems on the inner tracks, it could be dirty heads,
as was mentioned, or azimuth. If it is an azimuth problem,
there is little that one can do except check that the
rails are in the right place relative to the heads. If
the heads are a little off center or crooked they would
fail at the center tracks.
It could also be that you are using the wrong type
of disk. if they are 1.2M disk, they will have this problem.
360K disk usually have donuts on the hub but I've
seen them on 1.2M disk as well.
Dwight
 
Tandons aren't bad drives for their time.

If disks you format in the "bad" drive don't work in "good" drives, but boot in the "bad" drive, then your alignment is probably off--and, as Dwight suggested, so might be the azumith. Take a good look at the head and the springs that hold it against the medium--are they corroded or deformed?

How's the spindle speed? If it's low by more than 10 percent, you're going to have problems interchanging disks between drives. Be sure to measure the spindle speed with a diskette inserted and the heads loaded.
 
Hi Dwight, Chuck(G)

Dwight Elvey said:
It could also be that you are using the wrong type of disk. if they are 1.2M disk, they will have this problem. 360K disk usually have donuts on the hub but I've seen them on 1.2M disk as well.
Dwight
Click to expand...

They are definitely not high density disks. Double Sided, Double Density is what it says on the label.

Chuck(G) said:
If disks you format in the "bad" drive don't work in "good" drives, but boot in the "bad" drive, then your alignment is probably off--and, as Dwight suggested, so might be the azumith. Take a good look at the head and the springs that hold it against the medium--are they corroded or deformed?

How's the spindle speed? If it's low by more than 10 percent, you're going to have problems interchanging disks between drives. Be sure to measure the spindle speed with a diskette inserted and the heads loaded.
Click to expand...

The spindle speed was just a little fraction slow but is calibrated now and is dead on when accessing or writing a disk. However, I'll have another good look at the heads and springs.

Thanks for the thoughts.

Tez
 
Tez

I can help you with drive alignment & speed - and I'm local too :)

As it happens, I need to delve into my TRS-80 Model III. I can offer to plug in your drive & set the speed plus check the alignment. I have a scope, but no alignment disk (looking for one, thou). I do a 'poor man's' alignment by moving the heads to get the best signal on a floppy that was written to by the *other* drive in the machine. My Model III has TM-100s as well. One of my drives had a similar problem to yours and this technique solved the problem.

The TRS-80 Model I/III has great Disk Drive diagnostic powers. The program 'Floppy Doctor' set's speed digitally, steps by user input and boasts a heap of tests to work-out a drive. You can run it on your System-80.

So I must visit you (as we've discussed previously). After the New Year, I'll phone you. Dying to check out some of your collection - particularly the PET.

Philip
 
pavery said:
Tez

I can help you with drive alignment & speed - and I'm local too :)
Click to expand...

Hi Philip,

Great! Yes, you are just down the road relatively speaking. Good to see you on the forums here

pavery said:
As it happens, I need to delve into my TRS-80 Model III. I can offer to plug in your drive & set the speed plus check the alignment. I have a scope, but no alignment disk (looking for one, thou). I do a 'poor man's' alignment by moving the heads to get the best signal on a floppy that was written to by the *other* drive in the machine. My Model III has TM-100s as well. One of my drives had a similar problem to yours and this technique solved the problem.
Click to expand...

Excellent. It's a date! I have a feeling it might be more than just alignment though. There are some other issue, possibly damaged heads or a azimuth problem as the drive has problems reading and writing inner tracks. If it is one of these two it can't be fixed.

It's a strange symptom. It's never consistent. You can format/verify a disk and (very rarely) it shows no errors. Format it again and it has errors. Format a third time and it also has errors, except these are not the same. The only consistant thing is they tend to be the higher tracks and there are more errors the higher the track number.

I've cleaned the heads thouroughly with a cotton bud and isoproply alcohol. I've also swapped drives and formatted/verified disks in the "good" drive just to check it wasn't the disks themselves. They formatted perfectly. I've also swapped over both sets of circuit boards. Same result.

pavery said:
So I must visit you (as we've discussed previously). After the New Year, I'll phone you. Dying to check out some of your collection - particularly the PET.

Philip
Click to expand...

Sure thing. However, in case you've got high expecations don't expect a well ordered display. :) They are all in an untidy stack of cardboard boxes. However, we can rummage through whatever you're interested in.

The PET isn't in a box as it's still a work in progress. It's still not going but I HAVE got around to thoroughly cleaning the motherboard. Driud (on this forum) has given me some tips and Carlsson is keeping his eye out for a possible replacement board. Externally at least, it's a fine looking machine.

Tez
 
Tandon disk drives on Kaypros

Tandon disk drives on Kaypros

Hi!

Many of you know me and Kaypros and my web site www.kayprosts.org.

From my great experience in this area, just replace them with Teacs!

I have never had any issues with Teacs over many years.

Tandons have always been an issue, even with my software to align them, diagnostics, etc. Spent a lot of money having a repair service trying to keep them running until I decided I would learn to do it myself.

I can sell / give you many Tandons, spare parts, etc., but your time is not worth it.

If you are a 'purist" and want to stick to the Tandons, fine. Just know what you are getting into.

Teacs are half height so you have the cosmetic issues on the front panel.

But if you upgrade to 4 disk drives, this issue goes away.

Next issue, is trying to upgrade Kaypro II's. Microcornucopia does not exist any more.

But for later Kaypros, after 1983, there is still an upgrade. Check with "Sharkonwheels" the expert in this area on this site.

All the best in whatever you decide.

Frank

P.S.

So glad you finally got your Kaypro II! Great machines.

No word from Andy Kay and his web site recently, so I guess he finally retired, although he had many health issues.

They were built like the Tucker Cars of the 1940's - very rugged - but time moves on and the market shows not much loyalty.
 
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