Which short board 1541 Mitsubishi/Newtronics drive do I have?

[qberries]

Hi all. Brand new member here trying to figure out exactly which short board 1541 (oops Mitsumi/Newtronics) I have in order to troubleshoot it. PCB no. is 251830 Ver. A. Is this what some call (from what I have seen in my searches) a 1541A, 1541-C, a 1542 or something else? More importantly which service manual and diagnostic/troubleshooting guide is best for me to use ? Thanks!

 

[VintageVic]

Welcome to the forum!

Looks lika a nice 1541C to me by the case, but that does not really matter.
What matters is the pcb. As you said, you have the 251830. it's not the short board.

Index of /rcarlsen/cbm/1541/1541

I assumme your drive is not working. Does it boot up? (meaning, when you power it up,
spindle turns for a moment, the red led comes on and then spindle stops and red led goes away).

If it boots up, great. But if it does not read floppies (does try but causes ?file not found error),
the very first thing is to measure if that drive has an open head. That link I put above has tons of
information, including how to check the r/w head, if it is "open" - or broken.

If the head is good, it should be fixable, it's just about finding the fault. But if the head is open,
you are going to need another head (from another working drive) or the whole drive mechanism.
Let us know, what is wrong with your drive.

 

[VintageVic]

Oh, and do read fix1541.txt and 1541chip.txt here:

Index of /rcarlsen/cbm/1541

 

[qberries]

Welcome to the forum!

Looks lika a nice 1541C to me by the case, but that does not really matter.
What matters is the pcb. As you said, you have the 251830. it's not the short board.

Index of /rcarlsen/cbm/1541/1541

I assumme your drive is not working. Does it boot up? (meaning, when you power it up,
spindle turns for a moment, the red led comes on and then spindle stops and red led goes away).

If it boots up, great. But if it does not read floppies (does try but causes ?file not found error),
the very first thing is to measure if that drive has an open head. That link I put above has tons of
information, including how to check the r/w head, if it is "open" - or broken.

If the head is good, it should be fixable, it's just about finding the fault. But if the head is open,
you are going to need another head (from another working drive) or the whole drive mechanism.
Let us know, what is wrong with your drive.

Hey Thanks!…and for getting back to me and clarifying. Yes, boots up and sometimes can read the directory and load some programs on the disk and sometimes it get that ?file not found error on another try on that same disk. No open circuit reading on wires on the head so seems ok. It seems to only like to load programs about in the middle of the disk when it does work.

 

[ClassicHasClass]

I wonder about its stepper motor.

 

[Timo W.]

Looks lika a nice 1541C to me by the case, but that does not really matter.

That's a normal 1541, not a 1541-C. It's not a C just because the case is beige.

The 1541-C has a track 0 sensor, shielding around the ports and a shorter pcb with the analog stuff contained in a hybrid "chip".

 

[VintageVic]

Great, so your drive is working, at least partially. PCB is probably fine,
while the problem likely is in the mechanics and/or floppies.

Check that your r/w head moves freely, when power is switched off.
If it gets stuck at some point(s) that would be common on some mechanics. Clean and lubricate if necessary.

Clean the head itself. Some sort of dirt / oxidy / residue is easily transferred from old/dirty floppies
to the head. Then, clean the floppies themselves, or at least one that is partially working and check
if you get better result. Here's one way of cleaning the disks themselves:

Another possible issue is if your spindle is not spinning close enough to 300rpm. But try the above first.
Adjusting the drive spinning speed is possible, but can be a bit more complicated.

 

[VintageVic]

Also another possible issue is slipping disc. Floppy may not be tight enough in the spindle
and it slips, thus the rotation speed becomes an issue. I just happen to have such a drive at my hands
what I'm repairing. Difficult to diagnose and fix. If your floppies have a white ring around the center hole,
those seem to slip easier.

And make sure you don't have any high density floppies. Those will not work, no matter what you try.

 

[qberries]

That's a normal 1541, not a 1541-C. It's not a C just because the case is beige.

The 1541-C has a track 0 sensor, shielding around the ports and a shorter pcb with the analog stuff contained in a hybrid "chip".

Thanks for confirming!

 

[qberries]

Great, so your drive is working, at least partially. PCB is probably fine,
while the problem likely is in the mechanics and/or floppies.

Check that your r/w head moves freely, when power is switched off.
If it gets stuck at some point(s) that would be common on some mechanics. Clean and lubricate if necessary.

Clean the head itself. Some sort of dirt / oxidy / residue is easily transferred from old/dirty floppies
to the head. Then, clean the floppies themselves, or at least one that is partially working and check
if you get better result. Here's one way of cleaning the disks themselves:

Another possible issue is if your spindle is not spinning close enough to 300rpm. But try the above first.
Adjusting the drive spinning speed is possible, but can be a bit more complicated.

Thanks! Will try now that tax day is past and have time again

 

[qberries]

Great, so your drive is working, at least partially. PCB is probably fine,
while the problem likely is in the mechanics and/or floppies.

Check that your r/w head moves freely, when power is switched off.
If it gets stuck at some point(s) that would be common on some mechanics. Clean and lubricate if necessary.

Clean the head itself. Some sort of dirt / oxidy / residue is easily transferred from old/dirty floppies
to the head. Then, clean the floppies themselves, or at least one that is partially working and check
if you get better result. Here's one way of cleaning the disks themselves:

Another possible issue is if your spindle is not spinning close enough to 300rpm. But try the above first.
Adjusting the drive spinning speed is possible, but can be a bit more complicated.

Thank you! Will try those steps.

 

[qberries]

I wonder about its stepper motor.

Is there a way to determine if it is functioning correctly?

 

[qberries]

Also another possible issue is slipping disc. Floppy may not be tight enough in the spindle
and it slips, thus the rotation speed becomes an issue. I just happen to have such a drive at my hands
what I'm repairing. Difficult to diagnose and fix. If your floppies have a white ring around the center hole,
those seem to slip easier.

And make sure you don't have any high density floppies. Those will not work, no matter what you try.

Also another possible issue is slipping disc. Floppy may not be tight enough in the spindle
and it slips, thus the rotation speed becomes an issue. I just happen to have such a drive at my hands
what I'm repairing. Difficult to diagnose and fix. If your floppies have a white ring around the center hole,
those seem to slip easier.

And make sure you don't have any high density floppies. Those will not work, no matter what you try.

Thanks. Yeah I just looked. The floppy that sometimes works does not have the white ring and is a double density not a high density. I saw an old post somewhere that did question if the twist latch mechanism is holding the floppy tightly enough that might cause a problem where it reads only near the middle of the floppy. When I got the drive the latch was not engaging and locking until I saw the pin was not in its right place. But the pin can still slide around. Wondering if I am missing some clip.

 

[VintageVic]

yeah, that pin can slip out of its place. I don't think it has any clip. You can
try to glue it in the right place.