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Any tips on 800k Floppy head?

TheMacGuy

Well-known member
A few months ago I bought 2 external floppy drives for my 512kE, with the intension of putting the one in worst looking case in the 512kE as the eject motor went out on the original drive. The one I choose has a small problem where it tries to inject the disk before it is all the way in, but the heads and eject motor work fine. I lubed the drive with teflon lubricant from Lowes and I think it may have gotten on one of the heads as every disk I insert it tries to initialize, including the System Disk.

I read cleaning the heads with a Q-Tip dipped in rubbing alcohol will clean it, but I was wondering if that doesn't work if there is something else I should try.

 

RickNel

Well-known member
This symptom is very common, but not easy to diagnose or fix.There are several possible reasons why track 0 of the disk is not being read correctly.

1. The diskette can be faulty. Does it work in another drive?

2. There may be an alignment difference between the drive that wrote the disk, and the drive trying to read it. It only needs to be a few microns to cause problem.

3. The top head of the drive may not be making proper contact with the disk surface. As it is attached by a springy metal strip, it can become out of perfect alignment if the metal hinge strip has been bent or twisted, even slightly, during cleaning or lubrication.

I have a drive in that condition, and am still working on a mechanical solution to get it back into alignment.

4. There may be a fault in the electronics on the drive board that is distorting or limiting the read signal. This is an analog stream that has to be interpreted by the IWM controller chip.

5. In some situations, plugging the wrong drive or external enclosure into the floppy drive ports, internal or external, can cause a short-circuit in the Bourns filter (a package of 8 resistor-capacitor networks) that links the FDD sockets to the controller.

Be very careful when cleaning the heads not to raise the upper head any further than it would be raised when the drive is empty.

Rick

 
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