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Reviving a 512K Hyperdrive - Error Code 0F0100
Posted by: techknight on 2016-12-14 07:36:15
Thats actually a good idea and I have thought about that myself. Modern processors these days can easily do that. 
Posted by: techknight on 2016-12-14 07:37:14
This damn MMI M112 is near impossible to find. The MiniScribe 8425 (Hyperdrive 20) on the other end, is all over the place on ebay. 
Thats because MiniScribe got in with alot of the OEMs and sold the crap out of those drives. Problem is, they are far far from reliable. Just about every one I have is dead. I was able to revive one though. the Stepper was stuck. 
Posted by: BadGoldEagle on 2016-12-14 08:20:10
Got a question here for you techknight

I'm no hard drive expert, but some drives apparently have something called a "head track motor" of some sorts. It's supposed to move the arm around, right? 



I'll open my dead MMI up to see what's inside. It's already been opened before, and since it's supposedly dead, I'm not risking anything.
Posted by: bibilit on 2016-12-14 08:43:38
It's supposed to move the arm around, right? 
yes, the motor is driving the arm back and forth.
Posted by: BadGoldEagle on 2016-12-14 09:09:35
So perhaps that motor's just dead or needs a slight tweak? Maybe I can mend this or find another one to fix my drive? Who knows? It really depends on how the disks and the heads look. 

As long as it doesn't look like this...
Posted by: techknight on 2016-12-16 15:40:43
Yea, thats the actuator arm stepper motor. 

The last picture is a BAD sign. haha, thats a head crash. 

Those old hard drives sometimes the head actually rides on the platter. 
Posted by: BadGoldEagle on 2017-06-08 04:36:31
It's been a long time but I'm still trying to get it to work properly.

So I went on and bought another drive which apparently is defective too... I'm a dumb@$$, I know and I should have listened.

I'm going to buy the DREM emulator (even though it's the cheapest MFM emulator out there, it costs $250). If it doesn't work, I can get my money back so it's worth a try. 

I'm still a little worried about that capacitor though... We know it's 0.1uF, 5V and that you can't get a new one of those anywhere. 

I want to replace it just to be sure... Should I go for a higher/lower capacitance or for a higher/lower voltage? I can't seem to find any of the "through hole axial" type, only SMD... So I dunno how this is going to work.
Posted by: bibilit on 2017-06-08 08:05:21
Always higher.
Posted by: Themk on 2017-06-08 08:12:28
keep the capacitance (0.1uF) the same, but go higher on the voltage. It will be fine.
Posted by: BadGoldEagle on 2017-06-08 09:33:01
Thanks guys. Will go for the 6.3V one then. But it's SMD... Can I solder that on top of traditional holes?
Posted by: Themk on 2017-06-08 09:38:03
You can always make your own leads for the component, by soldering on a small un-insulated solid wire to pads on the capacitor.
Posted by: BadGoldEagle on 2019-11-06 02:35:19
More than two years have passed... But here's a small update. 

I recapped the 512k and the Hyperdrive PSU (albeit a few months ago) because both had gone bad. I was able to test the second hard drive (again) before the Mac died (again). This time, I'm suspecting one of the diodes on the analog board. But this has to do with the video circuitry, not the logic board. Both power supplies output the correct voltages. 

Anyway, with the second hard drive, before the video started collapsing, I was getting the same error code. The capacitor still had not been replaced so I think it's definitely the culprit. Or ROMs... or the Hyperdrive board altogether...

To be continued.
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