View Full Version : Non-working PS/2 70 Drives

September 16th, 2009, 04:02 AM

As mentioned in an earlier post, (http://www.vintage-computer.com/vcforum/showthread.php?t=17192) I picked up an IBM PS/2 70 the other day. It has a faulty 1.44MB floppy disk drive. I have a similar spare disk drive from another machine. This is also faulty.

The two drives have a similar connector but are different. The one on the left is an ALPS drive from the P/S2 70. The other on the right is a Mitsubishi one from a PS/2 30-286.


The Alps drive seeks and things turn but it doesn't boot off known good disks. In fact, I can't even read a directory. I've done the usual things...cleaned heads, lubed rails etc.

The Mitsibushi drive has a different problem. The drive motor doesn't seem to be working. The flywheel doesn't turn at all (or sometimes just a little). The stepper motor however seems ok.

All connections have been checked. I've scoured through past postings and read of some people's experiences including making up a cable which allows more standard drives to be used.

I've managed to source a replacement from someone who contributes to these forums but before I go ahead and buy it, does anyone have any ideas as to what might be wrong with either of this two units, and what I should check?


September 17th, 2009, 04:13 PM
Well, an interesting development. The Mitsubishi drive (sourced from one of my PS/2 model 30s) suddenly started working!!?. Long enough in fact, to configure my new PS/2 model 70.

Then it stopped working.

It's got an edge connector hence compatible with the Model 70 drive interface. However, it is not compatible with the front bezel, so I'll be seeking a replacement for the original Model 70 drive (the ALPS one) anyway.

I'm mystified as to why the Mitsubishi drive started working for a short period? When it's not working, the stepper motor makes a screeching noise. When it is working the drive is very quiet. Contary to what I wrote above the flywheel does turn. I didn't realise the disk had to be seated. It trips a switch which allows the flywheel to work. It seems to be the stepper that has the problem.


September 17th, 2009, 04:20 PM
That screeching noise sounds a lot like what one of my typical 5.25" floppy drives was doing the other day...it was singing. The r/w heads weren't moving but the stepper motor was clearly turning, causing a terrible high pitched racket. Gave it a light whack and it came back to life.

I'd say you may have spotty circuitry somewhere on the drive...it is "100% operational" but somewhere a circuit disconnects, or possibly contacts somewhere aren't making good contact. Very vague but I wanted to voice that your drive probably isn't dead and therefore shouldn't be junked (if that was on the list of possibilities at all to begin with).

September 17th, 2009, 08:51 PM
No, I won't junk it now. I'll save it and drag it out again at some stage for another look.

I'll get a replacement for the PS/2 M 70 though.