Hi all,
over the last weeks/months I have come across several EME-150A floppy drives that all suffer the same problem. The motor that positions the head has become worn and it is impossible to calibrate. This happens because of "play" on the worm-screw, which means that the head goes to a different position depending on whether the head was moving forwards or backwards. I now have three of these drives with exactly the same issue.
The EME-150A is the drive that was used in most FD-1 drives and can also be found in the 664 (not sure about the 6128). It looks slightly different to the other drives and the drive rotation speed is adusted on the PCB rather than directly on the motor. I intend tearing one of these apart to see if there's any way of repairing the problem, but the motor is much more difficult to take apart than the other versions, so I don't hold up much hope of fixing them. This version of the 3in drive may be on its way out...
Bryce.
R.I.P. my dear old drive. You were with me for many many years and helped me greatly with my amateurish BASIC development.
All three examples are in the "nothing to loose" category, but I will use a different drive to test my repair methods. If they work, then yours and Silkworms drives will be used to confirm the repair method.
Bryce.
Any findings?
Haven't had a chance to look at them any further so far, but I have some other "practice" drives to keep me busy for now.
Bryce.
You must apply some specific oil for micromecanism. This helps tremendously those old drives :)
Unfortunately the problem is the plastic parts in the motor that moves the head. The plastic has worn down too much and have too much movement now. No amount of oil is going to solve that.
Bryce.
Would it be possible to build replacement parts with a 3D printer?
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Quote from: robcfg on 22:14, 25 January 17
Would it be possible to build replacement parts with a 3D printer?
Sent from my iPhone using Tapatalk
Unlikely, they need to be very precise and very smooth to work properly.
Bryce.
Quote from: Bryce on 20:42, 25 January 17
Unfortunately the problem is the plastic parts in the motor that moves the head. The plastic has worn down too much and have too much movement now. No amount of oil is going to solve that.
Bryce.
Basically, i have an EME-150A floppy drive. I more or less have the same problem as you do, but i've oiled the drive parts. This helps against this problem, or prevent it.
In your case it's simply 'too late', shame.
Which drive is used on the Plus?
I replaced the belt on my plus drive a few years back.
The drive sometimes gives not ready.
I ran some tests on it.
One test formats the drive so that the ids match the physical track numbers. I then go through all step rate values (slow to fast), and do a seek from 0 to 39 and again 39 to 0. I then look at the track it reached when the fdc thinks it completed.
Drive performs fairly well seeking 0-39 but is not so good on 39 to 0.
I plan to take it apart to lubricate it and put another belt on it... I hope it's not gone the way of the EME-150A!
The plus CPCs use an EME-157, this is a 5V only beige coloured drive, but it's very similar to the EME-155/156 drives used on the Classic CPC. The electronics are different, but the mechanics are very similar and they use the same head movement motor. This motor is known to acquire a different issue where the Nylon bushing inside the motor cracks and no longer grips the shaft properly. This causes the shaft to slip in some situations, possibly when faster steps are used, this could be what you are seeing in your test.
Bryce.
What is the correct type of lubricant for these plastic parts? I could imagine a fossil based oil or grease degrading the material..
I call these parts "plastic" but in reality they are probably nylon, I've never tested. I use sunflower oil for plastic/nylon parts and vaseline for metal parts.
Bryce.