PDA

View Full Version : Did some testing of my faulty floppy drive.



per
April 10th, 2010, 07:11 AM
I finally transported my scope to where I store of my XTs, and I have now done some testing of the faulty floppy disk drive.

For those who missed out the earlier topic, this is likely about faulty head-alginment...



Disk a=formated in Drive a
Disk b=don't remember where it was formated
Disk c=formated in Drive b

Drive a=fine
Drive b=bad

Drive a Drive b
Disk a 0.44v 0.1v*
Disk b 0.40v Unreadable**
Disk c 0.30v* 0.43v

voltage levels are peak-to-peak

* = Failed reading data
** = Failed reading data and sometimes sector not found


The thing I saw durning testing was that the voltage level was the same for both heads even on the faulty drive, meaning that both heads on the faulty drive must be out of alginment with the same vector. In other words, it sounds like the entire head assembly is somehow out of alginment, or rather; the stepper-motor is out of alginment...

But the problem is that I have no idea where I should do ajustments. I know there are two screws I can ajust to move at least one of the two heads, but since they are perfectly lined up with each other, this will not do anything good.

Chuck(G)
April 10th, 2010, 09:18 AM
The adjustment varies from drive-to-drive (bitsavers has many maintenance manuals that are specific). Commonly, the positioner stepper is held in place by a couple of screws; these can be slightly loosened and the body of the stepper rotated slightly one way or the other. Tighten the screws down when you've found alignment and re-check.

MikeS
April 10th, 2010, 10:34 AM
<snip>
...The thing I saw durning testing was that the voltage level was the same for both heads even on the faulty drive, meaning that both heads on the faulty drive must be out of alginment with the same vector. In other words, it sounds like the entire head assembly is somehow out of alginment, or rather; the stepper-motor is out of alginment...

But the problem is that I have no idea where I should do ajustments. I know there are two screws I can ajust to move at least one of the two heads, but since they are perfectly lined up with each other, this will not do anything good.As Chuck says and as you surmise, you normally move the stepper motor to adjust the alignment, but I don't understand your second paragraph; are you trying to move one of the head's position relative to the other head?

What make/model are the drives?

per
April 10th, 2010, 10:50 AM
As Chuck says and as you surmise, you normally move the stepper motor to adjust the alignment, but I don't understand your second paragraph; are you trying to move one of the head's position relative to the other head?

What make/model are the drives?

I found the correct screw now, but I still need to transfer a drive-monitoring program to a 360KB floppydisk (I got the program on my modern computer).

About the drive, it's the regular Tandon TM100-2. When speaking about the two screws on the head assembly, I have at least understood that they hold the two head-assembly parts together and by ajusting them, you could move the upper head relative to the other (in cause of radial misalginment). The lower head is stuck on the base of the head assembly, and it can only be rotated.

MikeS
April 10th, 2010, 11:29 AM
I'd leave those screws on the head alone...

On the TM100 you don't rotate the motor, you move the whole assembly; there are two screws on the bottom and one on top that you loosen a bit, and then you use the cam screw beside the top screw to slide the assembly back and forth. Don't forget to check the track 0 adjustment when you're finished.

Good luck!