Suddenly finding himself in possession of a broken Super NES console, my roommate challenged me to follow up on the NES Alarm Clock, natch. The obvious killer feature this time around would be to put the display on a cartridge, and make it removable. So, I got to work.
Our story begins with the gutting of the SNES and the desoldering of the cartridge connector and reset switch from the mainboard. To my great surprise and greater fortune, the cartridge connector's pins were precisely the same pitch as the through-holes for the display ribbon on the alarm clock, and on top of that, the display required 23 connections, which is exactly the size of one side of the middle part of the connector. Display out, cartridge connector in, very smooth. A little dremel work, and a nice shrouded polarized 2-prong AC connector, which I happened to have a cable for, went nicely into what was the "multi out" port.
Then came time for the control buttons. As with the NES, the power button in the SNES is a SPST switch. And as with the NES alarm clock, this posed a problem for switching the alarm and alarm LED, which uses an SPDT switch.
Not wanting to repeat the wall-wart lameness from last time, I drew up a proper circuit to drive a 5VDC relay. I managed to scavenge a rectifier already on a small PCB, but the rest was too big to air-solder and so I went $7 over my budget of free and bought perfboard. The reset button had to be positioned correctly.
The cartridge itself was the tedious part of this project. Unscrewing the cartridge (Paladin's Quest) was rather difficult without a proper bit. Following that, I desoldered everything on the bottom half of the PCB, then dremeled off the top. Goo Gone took care of the sticker and more dremeling and some model glue got a nice green window on the front. I then traced each of the pins on one side of the interface to a through-hole I could solder a wire into and connect to the appropriate pin on the display, which used up my bonus patience for the rest of 2008. Finally, when all was tested, I closed it up using new, non-secure screws.
And, after a greater number of false starts and miswirings than I'm prepared to admit, the base unit came to life. At this point, I am still controlling it by manually shorting the appropriate pins on the controller port.
Rewiring the controller (also known as a paddle, if you ask me) was actually rather easy. The idea is to use one or more buttons to connect a given input line (alarm display, minute set, hour set, snooze) to the common line. The design of the SNES controller is such that by removing the IC, you essentially get a patch bay to all the buttons and to the controller cable. Even more fortuitously, each of the pairs of buttons I wanted to use together (A/X, B/Y, L/R, Start/Select) had pins right next to one another, so I could stick the wire between them and solder. A little delicate for my jittery hands, but it went without a hitch.
As with the NES version, this clock has a shrouded power connector (a proper 2-pronged one this time) and uses the expansion port for battery loading. The port had to be widened slightly with the dremel to fit a 9V, but it doesn't show from the outside.
The SNES alarm clock was introduced to its big brother for a family portrait, and now sits happily across the hall waking my roommate up in the morning.
And of course, here is your video demonstration:
Last modified Tuesday, November 11, 2008 (19:06 UTC)