Question on 5.25" drives

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Last seen: 8 months 1 week ago
Joined: Mar 15 2021 - 23:14
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Question on 5.25" drives

I have two slim 5.25" drives.  One is from a Laser 128, the other is a Maple drive.  They both seem to basically work (drive spins, light comes on) but the stepper motor doesn't move the head.  When off, I can manually move the heads without issue.


On the Laser drive, if I slide the head back to track 0, Copy2Plus can verify track 0 but then cannot advance the head for the rest of the tracks.  The Maple drive's head can also move but I can't get it to read track 0.  Maybe that head is dead.


From the Disk II schematics, it appears the ULN2003 drives the stepper motor.  With an oscope, I can see activity on the 4 channels of output on that chip but haven't replaced it yet.  The Disk II schematics also seem to make it look like the stepper motor signal flows from the controller to the 2003 right to the motor.  It would be nice to find schematics for the Laser and Maple drives since the layout seems a bit different.


Would a good course of action be to try and replace the uln2003?  Maybe both stepper motors are bad?  Is there a good way to test the stepper motors?  I tried searching for the motor on the Laser drive and google didn't return anything.


Just curious if anyone else ran into similar drive issues such as this.



Wizard1969's picture
Last seen: 7 months 1 week ago
Joined: May 26 2016 - 02:17
Posts: 4
The issue you're describing,

The issue you're describing, where the stepper motor doesn't move the head, can have several potential causes. Let's explore some steps you can take to diagnose and potentially fix the problem:

  1. ULN2003 Replacement: Since you've noticed activity on the ULN2003 outputs, it's a good idea to replace this chip as a first step. It's a relatively common component and can sometimes fail over time. Ensure that the replacement chip is compatible with your specific drive model.

  2. Stepper Motor Testing: You can test the stepper motors themselves to see if they are functioning correctly. Disconnect the motor from the ULN2003 and measure its resistance across the coils with a multimeter. You should see a relatively low resistance value (typically in the range of a few ohms). If you get an open circuit (infinite resistance), the motor coil may be damaged.

  3. Verify Wiring and Connections: Make sure that all wiring and connections are intact and secure. Over time, wires can become loose or damaged, which can prevent the stepper motor from receiving proper signals.

  4. Seek Mechanism: The Laser 128 and Maple drives may have slightly different designs for their seek mechanisms. It's possible that there's an issue with the seek mechanism preventing proper head movement. Inspect the mechanical parts for any obstructions or damage.

  5. Controller Board and Components: Check the controller board for any visibly damaged or burnt components. Capacitors, resistors, or other components may have failed over time, affecting the drive's operation.

  6. Drive Alignment: Ensure that the head alignment is correct. Misaligned heads can cause reading and seeking issues. You might need a special alignment tool for this, depending on the drive model.

  7. Lubrication: If the drives haven't been used in a long time, lubrication of the moving parts might be necessary. Be cautious with this, as using the wrong type of lubricant can damage the drive.

Last seen: 8 months 1 week ago
Joined: Mar 15 2021 - 23:14
Posts: 12
Thansk for the suggestions! 

Thansk for the suggestions!  I will give them a try!

Last seen: 1 hour 22 min ago
Joined: May 31 2022 - 18:18
Posts: 267
Not sure if you've seen this,

Not sure if you've seen this, but really got some good stuff including details on how to check the stepper motor, see the peliminary checks on II and then dig deeper.Disk II vs the drives you mentioned, parts may be different but they all response to the same commands and troubleshooting flow should be good.Sam's CompufterFacts - Disk II

Last seen: 8 months 1 week ago
Joined: Mar 15 2021 - 23:14
Posts: 12
Quick update.  While looking

Quick update.  While looking for stepper motors, I came across this topic:


This was exactly what was wrong with my Laser 128 drive.  I disconnected the sensor and jumpered it and the drive works fine.

The Maple drive had some corrosion on the control board so I cleaned that up and plugged and replugged the 20-pin connector and that one started working again too.

Thanks to everyone for the suggestions!

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