• Please review our updated Terms and Rules here

IBM XT hard drive woes

Yep you're right modem7, with the head recalibrated and the arm secured tightly it should keep operating.
I just suggested it as an option in case the OP didn't feel motivated enough to do the full repair - but if he's keen then all good - no point wasting potentially good kit.
 
modem7 said:
Aren't we all jumping the gun?
Photos/info provided by the OP may indicate that the drive is repairable (by the OP, possibly under instruction).
Click to expand...

I will still try to fix this one in the morning. I'll post about that drive then. I don't know much about how these drives operate so I may need help.

The main reason I was interested in the seagate was for double the disk size, and the other controllers actually have documentation.
 
miniscribe.jpg


OK I got the cover off. Not really sure what do to.

Now I get a different error code. fast flashing, long flash, fast flash, long flash.
It spins up, the head doesn't move, then it spins down and flashes.

Do you want a video of it with the cover off?

******EDIT*******

I must have a bad molex on my test power supply, I changed to a different plug on the PSU and now I get the same thing as before.


OK what happens is, the head will start from outer side of the disk, then go toward the center. When it reaches the center it stops and unleashes the error code.
 
Last edited:
Video would be great - I'm interested in where the arm (on the side) is positioned in relation to the head.
If the arm is preventing the reset, it can be loosened with a tiny torx driver - but before doing anything it'd be good to wait for another opinion.

I'm thinking I might need to crack open my Miniscribe again (its a junk spare, but it does work).

Keep the lid on as much as possible.
 
The outer cylinder is 0. With the head assembly at that position, expect to see the stepper motor positioned as in the photo located [here], the arm sitting in the cylinder 0 sensor.
Is that the case?

As you move the head assembly (very slowly) inwards towards cylinder 612 (a MiniScribe 3212 has 612 cylinders), the stepper motor will rotate. I'm expecting you to see significantly more than 90 degrees of rotation.
 
Here's the video. Modem7, when i turn the arm all the way to get the head on the outmost part of the disk, the stepper motor does appear to be in that position.
Here's the video.

 
The first time you powered the drive on, all looked as I expected it to, but the second time showed a problem.
The drive appears to be getting confused about what cylinder it is on.

Per what SpidersWeb wrote, verify that the stepper arm is firmly gripped on its shaft.
If it is, then I don't think there is anything further you can do.
 
I'm starting to think it's not as repairable as I'd hoped too.

Best of luck, if you get a replacement Seagate or NEC are my picks for 'least likely to die'.
 
Last edited:
modem7 said:
Per what SpidersWeb wrote, verify that the stepper arm is firmly gripped on its shaft.
If it is, then I don't think there is anything further you can do.
Click to expand...
yes, it appears to be... :( Looks like it's hosed then... :(

Well, I'd say 28 years is fairly reliable anyway.

At least something good came out of it, I finally built and installed my XT-IDE card and got it working.

xtide.jpg
 
Last edited:
You might check the power transistors in the positioner driver circuitry. They handle a fair amount of power and any one may be bad, which would result in the motion you see.
 
Chuck(G) said:
You might check the power transistors in the positioner driver circuitry. They handle a fair amount of power and any one may be bad, which would result in the motion you see.
Click to expand...
Also, if you haven't already done so, I suggest that you inspect the drive's circuit card with a magnifying glass. The cause of the problem may be visible (bad solder joint, leaking capacitor, etc.)

The cabling from the stepper motor will plug into a connector on the circuit card. Reseating that plug is worth a try.
 
Chuck, by power transistors, do you mean the ones that look like this type? Forgive my ignorance. I didn't find any schemes or anything so I will have to just randomly test some. I imagine doing the standard multimeter transistor test will work.
 

Attachments

  • image.jpg
    image.jpg
    12.3 KB · Views: 1
Yes, but if those are what's driving your positioner (entirely possible), they arent BJTs (Bipolar Junction Transistors--i.e. what Shockley, Brattain and Bardeen invented in 1947), but MOSFETs (Metal Oxide Semiconductor Feild-Effect Transistor, a type invented by Julius Lillenfield in 1925) and they're tested differently:

http://howtoblogpost.blogspot.com/2011/09/how-to-test-mosfet.html

It's always seemed a little odd tiwst of history that Shockley et al. got the Nobel prize in 1956 for the junction transistor and Lillenfield got squat (although Shockley et al. were aware of his invention). I'd say that today's application of the FET over the BJT must be something like 1,000,000 to 1, since almost all ICs, including memory devices and microprocessors use the FET exclusively. It's sort of like giving the inventor of the UJT a Nobel and ignoring the developers of the BJT. But the Lillenfield was Canadian, and they're usually modest anyway...
 
Chuck(G) said:
My money's still on a problem in the actuator electronics, rather than a mechanical failure.
Click to expand...

Now that I know a little more about the drive, I agree. Too bad I'm not good at troubleshooting electronics. Always something that appealed to me.
I can usually fix something when someone tells me what to do, but sadly it's rare when I fix something that isn't visibly defective.
 
You must log in or register to reply here.
Back
Top