Connecting PC Case Supply to 1541 Drive

[fig1: external power for
1541]    The graph at figure_1 describes how to connect +5V, +12V voltages and ground to 1541 PCB. Note that 1541-II drives are different, and its easy to power up them with PC power supply. But you cannot put 1541-II mechanism into a tower case. Thus, use this schematics for old 1541 drives. It's also good to know that Commodore followed some standards once. That is, if you try to insert old 1541 mechanism into a PC tower case, you will notice that even screw holes matches with the tower case.

You can connect ground connection easily, but I soldered it to negative leg of C1 capacitor, since it is close to the border of the PCB. And, best place to attach +12V DC voltage is positive leg of the C2 capacitor. It,s also close to the border. Connecting the +5V is also easy as concting the ground (gnd = 0V) line. I chose positive leg of the CR4 (1N4001) diode. Please be careful if you are not experienced in soldering. Beware of short-circuits. Also clean the solders with a brush to remove metalic particles. Furthermore please keep in mind that this connection description is for old type 1541 drives. If your 1541 has different PCB layout, do not try this in case you don't know what to do.

[fig2: PC power supply
connector]    After soldering the three power wires (+5V, +12V, and gnd) to the 1541 PCB, we need to connect them to corresponding pins of PC power supply cords. In figure_2 you can see one of these standard cords. There are four pins/holes at these connectors, with four wires to the supply. Black wires are ground ( 0V ) levels. The yellow is +12V, and red wire is +5V. Now, all you have to do is making necassary connections. That's it. From now on, your 1541 will be powered up with the switch of PC case. As I stated in the introduction, the mechanism is compatable with the PC cases. So, I hope you can easily screw the mechanism of the drive to one of the 5.25" ports of your C64-Tower.

March 1998
Ilker Ficicilar