Image 1 of 52
By Drew McBee
Here we have our Seagate ST-250R and old RLL HDD that sports a 50M unformatted and a 42M formatted capacity. I believe you would use an MFM controller for this. I actually used it in a 286 running IBM-DOS back in the day.
I did power it up and it seems to run properly. Nice to know that before I crack it open.
Note: This gallery was originally published on January 28, 2008. It was republished on October 22, 2010 to be featured in our TR Dojo newsletter. — Bill Detwiler
This fits into a 5.25 bay in the PC.
This will have to come off…
Rubber bushings for the mount points
I found this cool.
As a visual point of reference, I give you an SD card. As another unintentional point of reference, this little SD card holds 10x what our Seagate here holds, and faster.
The MFM tabs.
Fat foam seal
Interesting fat foam seal between the cover and base. Cheap looking, even.
Ground for drive motor
This appears to be the ground for the drive motor — like the brushes in an electric motor. The blue plastic tab in the background was glued to the circuit board on top of it, and held the tab down.
Drive motor and actuator motor
Here we lift the board from the body and get a good look at the bottom of the drive motor, and the actuator motor. There were a total of three connections to the board one for the drive motor, one for the actuator motor, and one for the ribbon that runs the heads, which we’ll see a bit better later.
The board next to the body.
The activity LED
Taking the torx screws out of the cover
But first I take off the label
Don’t ask me why I feel compelled to do it…
It's dark in there
Can’t see much. Disappointing. It did smell like new electronics, though.
Cracking it open, as they say
I was kind of surprised to see only two platters. Interesting actuator mechanism.
The filter/dessicant looks like a cartridge that they expect to be replaceable.
A good look at the actuator mechanism.
This, to me, is the most interesting part of the device. The actuator is driven by opposing metal bands. Over in the next three pictures, you can see how it winds and unwinds…
Midway through its cycle.
…And at the end. You can see the torx screw here that must have been used to do some kind of final adjustment during assembly.
A good look at the head assembly.
This view shows how the actuator extends in between the two platters when fully extended. (I should have had the platters in focus here…)
Irma goes for a ride
Well, I’ve always wanted to power up a big HDD when disassembled, but never got around to it. Here is my big chance. It was going to be hard to demonstrate the platter spinning in a picture, however, so — I give you ‘Irma’, my eight-year-old daughter’s doll. Irma is going for a ride. I glued her feet to the center of the platter for our entertainment.
Irma goes for a ride
On goes the power, Scottie. She spun for about 6 seconds, when the whole assembly began to shake violently and try to walk off of the bench. Just as I went to hold it down…
The aftermath: after a head-first trip into the wall, Irma is face down in a pile of hardware.
Removing the front cover
Okay, on with the project. Here I’m taking off the “front cover.” Notice how the ribbon for the heads was just pinched in between the cover and the seal.
Removing the adjustable stop
There seems to be a lot of adjustable parts.
Taking the actuator bands apart
I wanted to show how thin these were, but they didn’t show at all in the picture. I guess that says plenty. They were .0015″ each.
Another picture of the bands
Taking off the actuator
The mounting screw appears to be one piece and pressed into the bearing.
A nice view of the r/w head, This is a fairly hi-res image, if you save and zoom in on it, you can see the little coil at the tip.
Taking the platters apart
The next four pictures show each step of taking the platters apart. The arrows were initially intended to show the rotation when spinning — but then there was Irma….
Here is the motor itself, a Nidec. I’ve seen that brand in another HDD; I’m sure that is a common brand.
A good look at the bottom of the motor before removal. Also a good look at the carbon button.
The motor removed
Taking out the actuator motor
I noticed a thin plastic seal for the drive motor that I didn’t see before.
I had to pry the black cover off, and there was a wavy washer in the bearing cup to keep pressure on the bearing.
Taking the plastic cover off
Nice. I’m no electrical engineer, but it looks like there are two sets of controls — a start and stop signal for each direction. If you look closely, you can see where each wire taps into its respective coil.
Another picture of this very cool motor
Maybe someone out there knows exactly what this type of motor is called?
Taking apart the motor
After the coil came out, it put up a bit of a fight.
The coil by itself
The motor, cracked open
The Seagate 50 MB RLL drive, cracked open
And finally, the whole drive blown up. If you are wondering, yes, it went back together and ran as it did before, though the heads made a bit of noise, and I’m pretty sure that I wouldn’t try to store anything important on it, even if I did have the right controller.