Summary

Non-destructive mount to install a UGREEN USB 3.0 SD TF Card Reader (https://www.amazon.com/dp/B01EFPX9XA) inside a (replica) Sinclair ZX Microdrive enclosure (https://retroradionics.com/ZX-Microdrive-enclosure-p246490453), designed in Shapr3D.

Print Settings

Supports:

Yes

Notes:

My settings in PrusaSlicer for the support material to make it a bit easier to remove the supports:
Style: Organic
Top contact Z distance: 0.35
Bottom contact Z distance: Same as top
Pattern: Honeycomb
Pattern spacing: 3mm
Top interface layers: 1 (light)
Bottom interface layers: Same as top
Interface pattern: Concentric
Interface pattern spacing: 0.2mm
XY separation: 100%
Don't support bridges: unchecked

I also turned the brim width off (0mm) for this as it was stable on the bed.

Post-Printing

Opening the UGREEN USB 3.0 SD Card reader

Use a pry tool to open the case of the SD Card reader. There are two tabs on the top and bottom, positioned to the left had side and about 2/3 across when the cable is at the back and the top is where you insert the cards.

Building the microdrive

You might need to open the LED hole with a 3mm drill bit (rotate it by hand inside the LED hole rather than use a drill), and then push the 3mm red LED into the hole. The longer leg is the positive (anode), and the shorter leg is negative (cathode).

Insert the front of the mount into the ZX Microdrive opening first, then it should push down neatly around the two raised lips and with the screw holes lining up. Screw in two of the screws supplied with the microdrive to hold this mount in place.

Inserting the SD card reader board

Slide the SD card reader board into the slot from the back, taking care to insert it the correct way so the larger SD and smaller microSD line up. Push it firmly into the mount, and it should clip in place when you push down on the back of the circuit board.

Coil the USB cable around inside the Microdrive case and make sure the USB connector escapes through one of the microdrive openings on the side. Slide the tab of the bottom of the Microdrive enclosure into the slot of the other part, and screw one of the supplied screws into the hole at the bottom. It should match up with the large pipe of the mount to hold it all in place.

Finishing up

Peel off the backing stips of the tape and stick the metal faceplace on the top to finish it all off. Marvel at how amazing it all looks, and reflect upon how much joy it brings.

Activity LED

(Updated 11 Jan 2025)

The UGREEN USB 3.0 SD TF Card Reader used has a GL3224 controller (https://www.alldatasheet.com/datasheet-pdf/view/1167126/GENESYS/GL3224.html) which has provision for an activity LED, but is not connected up in the UGREEN USB 3.0 SD Card reader.

WARNING: To make the LED light up on activity you will need to do some microsoldering. I take no responsibility if you decide to follow the instructions from here if you (a) hurt yourself or (b) damage your card reader.

From the GL3224 datasheet, pin 21 is card access LED, pin 3 or 12 is GND. We will need to microsolder on some wrapping wire (very thin wire) to pin 21 and either pin 3 or 12. Then, the wire from pin 21 (LED) will be soldered to a 220 ohm resistor, which will then be soldered to the long leg (anode) of the LED, and the wire from either pin 3 or 12 will be soldered to the short leg (cathode) of the LED. A wiring diagram is below.

You only need to solder one of pins 3 or 12 (blue in the diagram above), not both. They are both ground. Thinking about it, pin 12 might be easier as it's on the end.

If the output pin supplies 3.3V, and we expect a 1.8V drop over the red LED, that leaves 1.5V that we will need to drop over a resistor. The datasheet says the current is 8mA, using R=V/I that gives us 187.5 ohms. I'll scale that up to a 220 ohm resistor to be on the safe side.

This is a wrapping wire microsoldered on to pin 21 (LED). If you look closely, you can see that the circuit board does not have any traces attached to that pin. Any 'wet' looking bits is just some left over alcohol used to clean away the flux used when soldering.

Take your time and MAKE SURE THERE ARE NO SOLDER BRIDGES. Pin 22 (which is the third one down from the top right) is 5V! This is the quickest way to damage everything. Use plenty of flux.

Here, I have microsoldered a wrapping wire on to pin 3 (GND). You can also solder it on to pin 12 instead which is the furthermost right pin on this row of pins at the bottom of the GL3224 chip, which might be easier.

This is the board with a wire soldered to pin 21 (right) and pin 3 (bottom)

Here is the wire from pin 3 or 12 (right) connected to the short leg (cathode, -ve) of the LED, and the wire from pin 21 (top) connected to the 220 ohm resistor, which is in turn connected to the long leg (anode, +ve) of the LED.

A quick test with the LED and resistor wired up - the LED lights up on card activity!

Insulate all the bare wires and reassemble the microdrive.

Lush!

NB. I'm not the person selling a USB 3.0 ZX Microdrive SD card reader on the Facebook group "SpectrumForEveryone" or Facebook Marketplace.

Sinclair ZX Microdrive SD card mount