Miniscribe 3650 Revival

[compaqportableplus]

I managed to pull this off. I successfully replaced the bad spindle motor in a Miniscribe 3650! I had a lot of fun with this, and seeing an old Miniscribe come back to life warms my heart.

I got a really nice looking Miniscribe 3650 for cheap on eBay but when I first plugged it in, it didn’t spin and I got a flashing error code on the LED. I figured it had stiction, so I removed the PCB to turn the flywheel and found it was not stuck at all!

If I applied power and gave the spindle a manual turn it would start spin up VERY slowly, and the drive would always give up long before it reached speed.

My first assumption was the main PCB was bad, so I hooked a known good one to it and got the same result!

So at that point I knew the spindle had to be bad. The drive has an Ontrack data recovery sticker on top, so I’m assuming this drive failed many, many years ago, possibly not long after it was made. I suspect it had a factory defect, because a failed spindle is quite rare. I’ve seen drives that look like they’ve been under water that will still at least spin.

I found a good donor drive on eBay that was missing the PCB and stepper motor, but appeared to have an intact spindle, so I jumped on it. This is the craziest hard drive repair I’ve ever taken on and I’m so glad it worked.

Here’s pics of the donor drive in different stages of dissasembly (forgot to get one before taking the lid off).

Donor ready for disassembly.



Heads unloaded and top platter removed from donor drive.


Heads and platters completely removed from donor drive.


Good spindle liberated from donor drive!

 

[compaqportableplus]

And here are pics of the recipient drive.

Recipient drive before disassembly. (That Ontrack data recovery sticker is awesome. Definitely leaving that intact!)


Recipient drive with cover removed.


Heads and platters removed from recipient drive.


Bad spindle liberated from recipient drive!


Good spindle from donor installed in recipient drive.


Platters reinstalled into recipient drive.


Heads reinstalled into recipient drive.


Recipient drive reassembled and running factory test!

 

[compaqportableplus]

Last chapter.

Low level formatting the newly repaired drive.


Dos formatting!


Newly repaired drive successfully booted DOS!



Wow, that was fun! It has a few bad blocks but nothing major. This is a fully usable drive now.

Sorry for multiple posts, I can only attach 10 photos per post so I had to split it up.

 

[modem7]

OMG. You voided the warranty. 😱

 

[powerlot]

How did you safely remove the heads? I want to try to replace the index sensor on one of my MiniScribes.

 

[compaqportableplus]

How did you safely remove the heads? I want to try to replace the index sensor on one of my MiniScribes.

The Miniscribe 3650 has a unique head setup where the top and bottom rows of heads are offset from each other, so because of this, I just removed the without doing anything special.

So instead of them clamping together like heads would normally do, they just bend down slightly and nothing touches. Getting them back in was a little tricky. I actually held them in position with my fingers to get them back on (wearing gloves and being extremely careful). I have never done this before so I was just winging it.

I assume you’re referring to the sensor on the stepper motor? Good news is you shouldn’t have to remove the heads (or even open the drive at all) to replace that.

 

[Al Kossow]

There is a whole class off little combs you can buy for rotary actuator drive.
I guess something like that must have existed for linear motor drives.

 

[compaqportableplus]

There is a whole class off little combs you can buy for rotary actuator drive.
I guess something like that must have existed for linear motor drives.

Yeah, that would be awesome to have something like that for these old MFM drives. I’m sure they existed at one point but finding one these days would probably be damn near impossible.

 

[powerlot]

I assume you’re referring to the sensor on the stepper motor? Good news is you shouldn’t have to remove the heads (or even open the drive at all) to replace that.

I'm referring to the index sensor on the spindle which if faulty prevents starting up the drive as the microcontroller thinks the spindle doesn't get up to speed.

https://forum.vcfed.org/index.php?threads/miniscribe-8438-flashing-error-code.1239327/

Don't know how to disassemble or reach that sensor wiring below the spindle without taking it apart and I don't want to apply force where I'm not sure I would permanetly destroy something.

There is a whole class off little combs you can buy for rotary actuator drive.
I guess something like that must have existed for linear motor drives.

Yeah, that would be awesome to have something like that for these old MFM drives. I’m sure they existed at one point but finding one these days would probably be damn near impossible.

That's cool, didn't know about those. Looks like something that can be 3D printed

 

[compaqportableplus]

I'm referring to the index sensor on the spindle which if faulty prevents starting up the drive as the microcontroller thinks the spindle doesn't get up to speed.
https://forum.vcfed.org/index.php?threads/miniscribe-8438-flashing-error-code.1239327/
Don't know how to disassemble or reach that sensor wiring below the spindle without taking it apart and I don't want to apply force where I'm not sure I would permanetly destroy something.

Oh, I don’t know how easy that will be to replace. You would have to partially disassemble the spindle itself to get to that, which I’m not sure how to do. The index sensor is internal to the spindle.

 

[Pickelhaube808]

This is pretty insane and something I don't feel comfortable to do unless I had some sort of filtered fumehood/cleanroom. Hoping not a single speck of dust got stuck to that platter, but if the low level format was 100% successful, you should be in the clear.

 

[compaqportableplus]

This is pretty insane and something I don't feel comfortable to do unless I had some sort of filtered fumehood/cleanroom. Hoping not a single speck of dust got stuck to that platter, but if the low level format was 100% successful, you should be in the clear.

It is definitely the most in-depth hard drive repair I’ve ever attempted! These old drives aren’t nearly as sensitive to dust as newer drives are, so it’s not as much of an issue as you might think.

Any dust left over will typically get blown into the air filter upon power up.

The drive is still working absolutely fine, so this was definitely a successful repair!

 

[Pickelhaube808]

It is definitely the most in-depth hard drive repair I’ve ever attempted! These old drives aren’t nearly as sensitive to dust as newer drives are, so it’s not as much of an issue as you might think.

Any dust left over will typically get blown into the air filter upon power up.

The drive is still working absolutely fine, so this was definitely a successful repair!

Oh, I had always assumed that HDD filters only filtered air coming in/out of the drive. Is there an internal filter that filters recirculated air?

 

[compaqportableplus]

Oh, I had always assumed that HDD filters only filtered air coming in/out of the drive. Is there an internal filter that filters recirculated air?

Yes, there is!


I outlined the filter in this drive (top left). That white folded piece is the filter.

 

[3lectr1c]

Great work! How did you get the platters out without getting them all fingerprinted up? I do suppose with a drive this old you could just polish off the fingerprints, but I'll bet you had a better way.

 

[tradde]

Didn't he say he wore something like surgical gloves? Or whatever they wear in a clean room?

 

[compaqportableplus]

Great work! How did you get the platters out without getting them all fingerprinted up? I do suppose with a drive this old you could just polish off the fingerprints, but I'll bet you had a better way.

Thanks! I wore latex gloves to keep fingerprints off of the platters. They can certainly be cleaned if you accidentally smudge them though, but that can be a bit tedious so it’s best avoided.

Didn't he say he wore something like surgical gloves? Or whatever they wear in a clean room?

Yep, I wore latex gloves!