Misbehaving 3.5 floppy drive

[OldAtAtari]

Hello, everyone. I recently acquired a Tandy 1000 TL2, though I don't think the model of the computer is relevant to the problem at hand. That's why I'm posting this in the general computing forum instead of the Tandy forum. 

 

The 3.5 floppy drive at first worked a little bit, though inconsistently. It would read a disk, and then you could try again and it wouldn't read the disk. So I took the drive out and cleaned the heads. I also blew the dust out of it and lubricated all the moving parts.

 

When I put it back into the machine, it had a new seemingly worse problem. Now the head immediately advances to the max position instead of starting at the zero position. And when it tries to read a disk, the head just keeps trying to push forward from the max position.

 

Does anyone have an idea of how I broke this thing? It's a proprietary Tandy drive with the power supply built in to the ribbon cable connector. So I can't just go buy another drive off the shelf and install it here. I would really like to get this one working again. I appreciate any help that anyone can give me. Thank you so much.

 

Here's a link to the YouTube video to see it in action:

 

 

 

 

 

[Almerian]

I don't know the particular drive, but it seems something is wrong with the track zero sensor.

 

[OldAtAtari]

7 hours ago, Almerian said:

I don't know the particular drive, but it seems something is wrong with the track zero sensor.

 

Thank you! Maybe I can find another drive with the same sensor and swap them. It's worth a try!

[+OLD CS1]

3 hours ago, OldAtAtari said:

Thank you! Maybe I can find another drive with the same sensor and swap them. It's worth a try!

You might also try something simple like cleaning it, blowing out any debris which may have collected in it.  Check its alignment with the head carriage, and also its wiring connections.

[OldAtAtari]

Thanks again, guys, but no luck.

I've cleaned the sensor, checked its alignment, and checked its wiring. It's all good, but the drive still doesn't work. I also checked to make sure all the pins are straight in the port where the ribbon cable connects. Everything looks good.

Any other ideas?

[wierd_w]

When you reconditioned the drive, it is possible that grease or dust was blown or otherwise transported into the track zero sensor.

 

This is an optical sensor in most drives. Grease in the throughway might not be readily visible, but will trick the sensor. Run a thick but soft cotton cloth through the sensor throughway, then see if the problem persists.

 

Usually, this sensor is near the head advance motor, or near the worm gear.

 

 

Sometimes the sensor is a mechanical microswitch instead, which gets triggered through contact with the head sled. If this is the case, put a small drop of contact cleaner on the end of a wire hoop applicator, and apply it to the switch, then gently actuate it with a plastic spatula, and wipe it clean. Repeat several times, then test function.

 

Looking at your drive, the sensor appears to be an optical based design, and is to the left of the head assembly, and is contacted by the plastic nub projecting from the left side of the head sled, pointing to the back of the drive. Its hard to see clearly in your video, especially on this phone.  Clean the throughway of the sensor, and then test function.

 

 

Edited November 18, 2021 by wierd_w