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Commodore 8050 Floppy Drive - Stepper Motor / Head stuck?

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phil.bischof

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Feb 10, 2020
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I have a Commodore 8050 that I just recently purchased. The drive arrived very well packaged and showed no sign of damage. When I turn it on, I get the self test and the light goes green, which I believe indicates the power on self test process returned zero errors. I am trying to find a way to test the drives though, as I don't have any pre-formatted floppies. So I used the HEADER"TEST",D0,I80 command and the drive spins and attempts to format, but quickly returns "Bad Disk" error. When I try the same command in Drive 1, it spins and spins for about 45 seconds and then dies with the same "Bad Disk" error. However, the head does not move at all during the process, on either drive.

Shouldn't it be moving? I would expect it to seek back and forth or at least do something, but the disk just spins and the stepper motors does not engage. I don't hear anything from it either like any knocking sounds. When I try to manually move the head on the rails, it won't budge, and I mean it's stuck solid as a rock. I know on my TRS-80 Tandom drives I can move the head assembly on the rails manually back and forth, so shouldn't I be able to on these drives too? Or is this normal? If this indicates the stepper or head assembly is seized up, what could I try to safely break it free? Is there a command I can issue that will simply make the stepper move the head so I can see if it moves?

Any ideas or assistance is greatly appreciated. Thank you!
 
With the power off, You should be able to carefully rotate the head stepper motor and the head will move freely along. It is common for the grease on that drive screw to go hard so it may need cleaning and fresh material applied.

A photo of the drive internals would help identify what make of drive you have in the 8050. I only know the micropolis variant.
 
AndyG said:
With the power off, You should be able to carefully rotate the head stepper motor and the head will move freely along. It is common for the grease on that drive screw to go hard so it may need cleaning and fresh material applied.

A photo of the drive internals would help identify what make of drive you have in the 8050. I only know the micropolis variant.
Click to expand...

Thank you for your reply. With your instruction to rotate the head stepper motor, where do I do this? There is a small round control to the right of the head assembly, which appears to be what controls the stepper motor movement, but I'm unsure if this is what you're referring to.

I've uploaded a full set of photos showing my drives, as well as the rest of the 8050. They can be found on link below.
https://imgur.com/a/MasFXJX

I greatly appreciate any help you can provide! I checked the RAM at UJ2 as suggested in the documentation I found in the service manual for the 8050, and I can confirm it's getting approx 5V. I'd like to check the stepper motor itself to see if it's receiving the 12V, but I'm unsure WHERE to connect my multimeter to check this.
 
First see if it's a mechanical issue: with power on the carriage will be very hard to move; try to move it in with the power off (it should move fairly freely)and note whether it restores when you turn power back on.
 
MikeS said:
First see if it's a mechanical issue: with power on the carriage will be very hard to move; try to move it in with the power off (it should move fairly freely)and note whether it restores when you turn power back on.
Click to expand...

With the drive completely disconnected, I can't get the head assembly to move at all. I mean it won't budge. I'm afraid to apply too much pressure because I don't want to break it. Looking at the images I posted, do you think it's safe to gently apply more pressure behind the carriage to see if it will "break free"?
 
These are MPI floppy drives and not familiar with them. On mine you can rotate the clamp on the stepper motor spindle with your finger as the carriages are directly driven via What looks like a long screw.

These look to be driven by a different motor setup but can you gently slide the carriage forward or back ?
 
phil.bischof said:
With the drive completely disconnected, I can't get the head assembly to move at all. I mean it won't budge. I'm afraid to apply too much pressure because I don't want to break it. Looking at the images I posted, do you think it's safe to gently apply more pressure behind the carriage to see if it will "break free"?
Click to expand...

Just noticed that it's a screw drive so the carriage will probably not move; a little harder but you should be able to carefully turn the drive screw by hand. Any signs of crud or corrosion on the rails?

Do both drives have the same issue?
 
AndyG said:
These are MPI floppy drives and not familiar with them. On mine you can rotate the clamp on the stepper motor spindle with your finger as the carriages are directly driven via What looks like a long screw.

These look to be driven by a different motor setup but can you gently slide the carriage forward or back ?
Click to expand...

MikeS said:
If you have sensitive fingers and wiggle the carriage a bit can you tell whether it's the carriage rails or the motor itself that's seized? Any signs of crud or corrosion on the rails?

Do both drives have the same issue?
Click to expand...

Yes, both drives have the same issue. However, I carefully tried to wiggle the head carriage back and forth and voila! It broke free! Drive 0 now seeks back and forth, although it's pretty loud - and when I try to format a disk I still get the "Bad Disk" error. But at least that part seems to be working now. When I manually move it all the way out, it seeks back to track 0 and attempts to format. I guess the disks I have may truly be no good. I'm using DS/DD disks I bought on eBay.

Drive 1 though broke free, but the darn metal strip that runs along the right side of the carriage and which is attached to the stepper motor top cylinder to the right of the carriage broke. I'm wondering if I can find some clever way to fix this.

See photo here of the broken metal band (https://imgur.com/a/HJk9pT0)
 
phil.bischof said:
Yes, both drives have the same issue. However, I carefully tried to wiggle the head carriage back and forth and voila! It broke free! Drive 0 now seeks back and forth, although it's pretty loud - and when I try to format a disk I still get the "Bad Disk" error. But at least that part seems to be working now. When I manually move it all the way out, it seeks back to track 0 and attempts to format. I guess the disks I have may truly be no good. I'm using DS/DD disks I bought on eBay.

Drive 1 though broke free, but the darn metal strip that runs along the right side of the carriage and which is attached to the stepper motor top cylinder to the right of the carriage broke. I'm wondering if I can find some clever way to fix this.

See photo here of the broken metal band (https://imgur.com/a/HJk9pT0)
Click to expand...

If the carriage "broke" free then i would clean the rails and put some lubrication on them. move the carriage back and forth many times to ensure its truly free.

OK. You may also need to send an Initialize command to the drives - sometimes the 8050 loose there way ... and this resets them. There is an article somewhere that discussed this. you will find it in this pdf

https://www.vintagecomputer.net/commodore/IEEE_drives/CBM_IEEEDriveNotes.pdf

open 1,8,15
print#1,"I"
close 1

This will Initialize both drives, substitute I for I0 for drive 0
 
Last edited:
AndyG said:
If the carriage "broke" free then i would clean the rails and put some lubrication on them. move the carriage back and forth many times to ensure its truly free.

OK. You may also need to send an Initialize command to the drives - sometimes the 8050 loose there way ... and this resets them. There is an article somewhere that discussed this. you will find it in this pdf

https://www.vintagecomputer.net/commodore/IEEE_drives/CBM_IEEEDriveNotes.pdf

open 1,8,15
print#1,"I"
close 1

This will Initialize both drives, substitute I for I0 for drive 0
Click to expand...

Excellent, I will try this command and see how happens. I'm hoping to find some way to repair Drive 1 with the broken drive band.
 
Many times I found that mechanical devices don't work simply because of old and dry grease... because somebody applied grease when there shouldn't be grease at all, or because of a bad quality grease, or excess of dirt.

In this case, and this case only, I use to clean dirty mechanisms with an accurate use of WD-40, gently and carefully applied only where and if needed (it helps a lot for oxide removal too); WD-40 solve the grease, so you can clean it with some toilet or kitchen paper and re-apply grease if needed. Most times, no lubrication at all is better than excess of lubrication.

Also, in case of severe oxidation, I clean it with sand paper (800 - 1200 or thinner)... but this should happen in extreme case only.

Heads should run freely on their sleeves, so I suggest to clean everything and keep it a little lubricated if needed (oil and grease tend to keep dirt and, even if it seems to work better in a first moment, later could make things get worse), at least for an initial test. Keep the heads clean and protect from WD-40, oil, an so on.
 
AndyG said:
If the carriage "broke" free then i would clean the rails and put some lubrication on them. move the carriage back and forth many times to ensure its truly free.

OK. You may also need to send an Initialize command to the drives - sometimes the 8050 loose there way ... and this resets them. There is an article somewhere that discussed this. you will find it in this pdf

https://www.vintagecomputer.net/commodore/IEEE_drives/CBM_IEEEDriveNotes.pdf

open 1,8,15
print#1,"I"
close 1

This will Initialize both drives, substitute I for I0 for drive 0
Click to expand...

I ran this command and it did cause Drive 0 to "bump", but I'm not sure how to call this for my Drive 1. It doesn't do anything when I run this.

However, I was able to repair my broken head carriage metal strap that the stepper motor on Drive 1 uses to move the head back and forth. The drive will now move the head from the first to last track on a disk when I call HEADER"TEST",D1,I01 ...however after it completes, it finishes with "? Bad Disk" error.

Drive 0 throws the Bad Disk error almost immediately, but I have not lubricated it's stepper motor as I did with Drive 1, so I'm going to try that and see if that changes anything there.

Does you know any good ways to troubleshoot "? Bad Disk" error? Why does it happen, what can I test to diagnose, etc.?

As always, thank you!!!
 
Ok to bump Drive 1 change I0 to I1

clean and lubricate the rails on Drive 0 and also gently clean the heads on both drives with IPA.

Then if it still errors, type PRINT DS$ from the command line (And when the error light is red) and it will report an error message with numbers.
 
AndyG said:
Ok to bump Drive 1 change I0 to I1

clean and lubricate the rails on Drive 0 and also gently clean the heads on both drives with IPA.

Then if it still errors, type PRINT DS$ from the command line (And when the error light is red) and it will report an error message with numbers.
Click to expand...

AndyG, thank you!! I've done the PRINT DS$, but all I've ever gotten was the DOS version printed. Now I know I need to send that command when the light is red after getting the Bad Disk error. I'll do this today and report back! Thanks!!!
 
AndyG said:
Ok to bump Drive 1 change I0 to I1

clean and lubricate the rails on Drive 0 and also gently clean the heads on both drives with IPA.

Then if it still errors, type PRINT DS$ from the command line (And when the error light is red) and it will report an error message with numbers.
Click to expand...

So, I when I tried to format a disk in Drive 0, it immediately fails with ?Bad Disk error. This was the drive I had not cleaned out and lubricated yet, I only cleaned the head. I removed it and fully cleaned and lubricated the rails, spinner motor, stepper motor, cleaned the belt etc. Now after putting everything back in and re-running the HEADER command, it formatted a disk successfully. I can run DI_D0 (or LOAD"$",8) command and pull a directory off the disk. Yay!

Drive 1 though, this is the drive I cleaned first, and when I run the HEADER command there it steps through and moves the head to the end and back and forth, taking about 45 seconds to 1 minute to complete, but then fails with ?Bad Disk error. When I run ?DS$ I get 24,READ ERROR,38,00,1.

What's really strange though, is I can call DI_D1 to pull a directory off of D1 and it works. I mean there are no files, but it shows an empty directory listing with 2054 blocks free message.

I'd like to try and write a super simple BASIC program like just a 10 PRINT "HELLO WORLD" 20 GOTO 10 and save it to disk. Then clear it using NEW and load it back to test the drives read/write functionality.

Am I correct in assuming that what I would do is
10 PRINT "HELLO WORLD"
20 GOTO 10
DSAVE "MYTESTPROGRAM",D0 -- to save to drive 0, D1 to save to D1

Then to load it back in I'd do
DLOAD "MYTESTPROGRAM",D0 (or D1)

I tried this, but it kept saying "File not found MYTESTPROGRAM".
 
phil.bischof said:
So, I when I tried to format a disk in Drive 0, it immediately fails with ?Bad Disk error. This was the drive I had not cleaned out and lubricated yet, I only cleaned the head. I removed it and fully cleaned and lubricated the rails, spinner motor, stepper motor, cleaned the belt etc. Now after putting everything back in and re-running the HEADER command, it formatted a disk successfully. I can run DI_D0 (or LOAD"$",8) command and pull a directory off the disk. Yay!

Drive 1 though, this is the drive I cleaned first, and when I run the HEADER command there it steps through and moves the head to the end and back and forth, taking about 45 seconds to 1 minute to complete, but then fails with ?Bad Disk error. When I run ?DS$ I get 24,READ ERROR,38,00,1.

What's really strange though, is I can call DI_D1 to pull a directory off of D1 and it works. I mean there are no files, but it shows an empty directory listing with 2054 blocks free message.

I'd like to try and write a super simple BASIC program like just a 10 PRINT "HELLO WORLD" 20 GOTO 10 and save it to disk. Then clear it using NEW and load it back to test the drives read/write functionality.

Am I correct in assuming that what I would do is
10 PRINT "HELLO WORLD"
20 GOTO 10
DSAVE "MYTESTPROGRAM",D0 -- to save to drive 0, D1 to save to D1

Then to load it back in I'd do
DLOAD "MYTESTPROGRAM",D0 (or D1)

I tried this, but it kept saying "File not found MYTESTPROGRAM".
Click to expand...


How did you fix the broken drive band ?
 
phil.bischof said:
I have a Commodore 8050 that I just recently purchased. The drive arrived very well packaged and showed no sign of damage. When I turn it on, I get the self test and the light goes green, which I believe indicates the power on self test process returned zero errors. I am trying to find a way to test the drives though, as I don't have any pre-formatted floppies. So I used the HEADER"TEST",D0,I80 command and the drive spins and attempts to format, but quickly returns "Bad Disk" error. When I try the same command in Drive 1, it spins and spins for about 45 seconds and then dies with the same "Bad Disk" error. However, the head does not move at all during the process, on either drive.

Shouldn't it be moving? I would expect it to seek back and forth or at least do something, but the disk just spins and the stepper motors does not engage. I don't hear anything from it either like any knocking sounds. When I try to manually move the head on the rails, it won't budge, and I mean it's stuck solid as a rock. I know on my TRS-80 Tandom drives I can move the head assembly on the rails manually back and forth, so shouldn't I be able to on these drives too? Or is this normal? If this indicates the stepper or head assembly is seized up, what could I try to safely break it free? Is there a command I can issue that will simply make the stepper move the head so I can see if it moves?

Any ideas or assistance is greatly appreciated. Thank you!
Click to expand...
How did you fix it? I have the same issue with a CBM 8050 - clunking sound but not reading drive 0.
 
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