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Finally got my IBM 5150 with 52MB HDD 5.25 360k Tandon and 3.5 Floppy drive working, but

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been having some issues with the 360k IBM Full height floppy drive, I am not sure if it is the alignment or what it might be I have tried cleaning the heads with qtip and cleaner disk with 72% alcohol. I have noticed that when I first tried it with my Ms_DOS 5.25 disks it had trouble reading them but still installed ok from what I could tell and I also tried my original Windows 1.03 disks and some the files when installing it would have issues and I chose ignore when it came up and seemed to install ok though I have to wait until I can install MS-DOS 3.3 so It will work properly to find out if it installed correctly  but I know they read and install fine on my IBM PC Series 350? 

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25 minutes ago, wierd_w said:

Probably head alignment, or rotation speed issue, yes.


360k drives have a rubber belt on the bottom in many models. If the tensioning of that belt is incorrect, the disk rotation speed/torque is not going to be in tolerance, and it will result in read failures.



I actually forgot all about that and I am pretty sure they haven't been ever checked because the guy I bought it from said it had been 10yrs or more since the last time he even took it out of his storage shed to see if it still worked. Is there a way to tighten or would it be better to buy a new belt? If so where would I be able to buy one?

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Order new belts. 


In theory, these should do.



Other issues:

possible bad bearings in transport step motor.


Possible dry slide rails in transport assy.


Head positioning screw incorrectly set

Edited by wierd_w
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There's no way to tension those belts.  I have many full height Tandon and Texas Peripheral drives and I've never had a belt problem.  They're not rubber and are next to indestructible.


Speed is easy to adjust provided you have access to a real fluorescent desk lamp (not easy to find these days).  You need something with the little tin can "starter", modern lamps with electronic starters or curly CFLs won't work.

A neon lamp works good too.  I have a red neon Game Room sign that I use to set the speed on my drives.


There are two patterns on the platter, one for 50hz and the other 60hz.  If you're in the US, the 60hz pattern should look like it's standing still while spinning with the light shining on it.  If the marks are slowing moving, you need to adjust the speed pot until they appear to stop.

There's also software that claims to show speed, but I've not found anything as accurate as using the timing marks on the platter.


There's a stepper motor setscrew that is notorious for loosening up.  You can see it through a frame cutout from the bottom, sometimes there's a clear plastic cover over the cutout.  If the setscrew is tight, leave it be.  If it's loose, tighten it and try the drive.  If you still have issues, loosen it again and slightly rotate the shaft a bit and tighten.  You may need to do this more than once in different directions. 


Alignment gets complicated.  You'll need an oscilloscope, alignment software and a lot of patience.  If you blindly try to tweak things, you'll go down a rabbit hole of no return.  

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