Replacing the 1541-II / 1571-II/ 1581 drive power supply

Having drives without a working PSU doesn’t make sense. So this years #DiskDumpingDecember (on twitter) went a little haywire, although I did dump some EPROM to .bin files using an eprommer.

First I sourced a replacement PSU, which handles at least 12Vdc/0.5A and 5Vdc/1A, from our local recycling site. I ended up buying a TRSF, model TR-05HHD, power supply which is able to deliver 12Vdc/1.5A and 5Vdc/2A.


Now this power supply sports a 6 pin mini DIN  male connector and the 1541-II/1571-II/1581 are equipped with a 4 pin regular size DIN female connector. So this is an very easy job. Just replace the plug!

The output pin out is noted on the power supply so figuring out the pin configuration on the drive shouldn’t be a drag. Using i multimeter i figured that the internal cabling uses the industry standard.

Browsing famous FTP site i found the following diagram:

drive_power_supplyNow it’s just a matter of soldering the corresponding wires to the plug.

  • Yellow – 5Vdc -> pin 1 on the drive plug
  • Black – ground -> pin 2 on the drive plug
  • Red – 12Vdc -> pin 4 on the drive plug
Posted in 1541-II, 1571-II, 1581, Hardware | Tagged , | 2 Comments

Installing µIEC in a SX-64

Wanting massive storage and a minimum of soldering in your good old Commodore SX-64? I just found the solution by using the UIEC 3.2 without the daughterboard (article: UIEC-SD-BA) supplied by Jim Brain / Retro Innovations!


I made a little dual IEC connector to plug in between the internal drive and the controller board allowing you to add a secondaty internal IEC driver. The µIEC only emulates the IEC protocol so it’s not a real 1541 replacement and does not allow fast loader and most common trackloaders (which sends a binary to the drive’s memory and cpu) to function properly. If you need full 1541 emulation i would recommend the 1541 Ultimate 2 cartridge.

So this is what i have done to accomplish the additional drive space;

The only pin which needs to be soldered to the expansion board is pin 2 on the user port. This is the 5V feed for the protocol emulating uIEC card (see SX-64 schematic diagram)


Next thing is to make a dual IEC board. This was very simple, just a 6-pin female and two 6-pin male pin headers soldered to a little PCB.



Now when this is done just plug it in to the header P11 of the I/O board (see page 13 of the schematics) and connect the other wires accordingly. To figure out the pin assignment for the µIEC i used the following scheme:

P11 I/O ------------------- µIEC
pin 1 -------- SQR -------- pin 4
pin 2 -------- GND -------- pin 1
pin 3 -------- ATN -------- pin 7
pin 4 -------- CLK -------- pin 5
pin 5 -------- DATA ------- pin 6
pin 6 -------- RESET ------ pin 3

User port ----------------- µIEC
pin 2 -------- 5 volt ----- pin 2

If you like you can peek here for some hints.



Now the internal drive, number 8, and the SD card is accessible via drive 10 (default setting of the µIEC).

As this SX-64 already been modified (to sport a Teletron 1200 modem internally) the storage bay was already altered. I decided to use double-sided sticky-tape to mount the µIEC to the right upper side of the storage bay.


Everything worked out just fine even at first start up!

Posted in Hardware, SX-64, µIEC | Tagged , , , , , , | Leave a comment

Reproduction of the SX64 parts by Erwin van Betten


Erwin van Betten has succesfully reproduced the handlebar caps and the keyboard clips for the Commodore SX-64. Those handlebar caps are really sought after as they are relatively the most missing part on the first executive computer sporting a built-in colour screen. Also the keyboard clips tend to wear out over the years. It’s almost 30 years ago when the first SX-64 passed by the cash register.

Keeping this in mind, Erwin van Betten took the opportunity to fuse the old school computer together with today’s technology of reproducing your own parts made from thermo-plastic filament. After (re-)measuring and (re-)jamming for several hours on the FreeCAD application to create a 3D model as a blueprint for the actual reproduction of the parts the idea come to a product.


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The 3D files (.STL format) can be downloaded so you can 3D print the actual parts yourself. The .STL files can be opened using FreeCAD the parametric 3D modeler.

Download link: SX64 repair parts (beta) – Erwin van Betten

Please note the license details:

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

To view a copy of this license, visit

These parts are designed with surgical precision to match as close the original parts and to provide a snug fit into and onto the casing. When the actual drawing are done it’s to time to process there files for the 3D printer. The software used for the actual printing is: Slic3r and Printrun/Pronterfac.

Amsterdam’s Hackspace “Technologia Incognita” a.k.a. TechInc provided the actual hardware to print the 3D models. The used hardware is a LulzBot TAZ 3D Printer equipped with a Budaschnozzle 2.0 w/ 0.35mm nozzle for a higher resolution.


Here is the printer plotting and dotting the PLA filament to the surface. As you can see the outline of the keyboard clip is already clearly visible. Preparation and patience are the key for a good result.


Showing the difference between the black original clip and the rendered shows that Erwin did an incredible job in the complete process.

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To make sure the quality is consistent Erwin decided to also to a batch of red clips and caps. I think that the red variant looks really amazingly good on the SX64 and the blue ones match the original colour scheme perfectly.

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A big applause for Erwin van Betten for arranging this all for giving the opportunity to create and repair our well beloved Commodore SX-64.

The items are not for sale (yet) however Erwin states regarding the design; “When I’m completely satisfied with them I will release the STL files and GCODE files (for a Lulzbot with PLA filament and 0.35mm nozzle) under the Creative Commons ( Attribution-NonCommercial-ShareAlike 4.0 International ) license.”

So join your local hackspace so you can make use of their 3D printer of look for commercial 3D printing service.

Posted in Hardware, SX-64 | Tagged , , , , , , , , , , | 7 Comments