I have been recently wanting a 24 hour clock in my office set to UTC so I have less chance of screwing up my radio logbook (Yes, despite having multiple computers in my office, I still keep a pen and paper log). Since my “geeky stuff” budget is next to nothing I was pretty much out in the cold, until this message by Howard, VE4ISP floated into my INBOX by way of the AMSAT-BB listserv. I was intrigued, since this was more or less exactly my situation and I had an old clock I could experiment on. Inspired by Larry from PSW I decided to try it my luck.
I cracked open the clock and surveyed the circuit board:
We’re not interested in the IC in the upper right. That’s the FM receiver. What we’re interested in is the IC in the lower left:
Behold, the LM8560! From Howard’s e-mail I know that I was supposed to jump pin 15 to pin 28, however, I wanted to be doubly sure those numbers were correct . So, I found the LM8560 datasheet online and found the pinout (page 2). You can tell which way the chip is orientated by seeing which way the notch is pointing (on the left in the above picture). I also found out that Pin #28 is the 12/24 hour selection and pin #15 is “Vss”, which is IC-speak for “ground”. So, essentially, we’re grounding the 12/24 hour selection pin so it’s it makes the IC, and thus the clock, go into 24 hour mode. Should be easy right? Well, it would be if I were good at soldering, but after 15 minutes of abortive attempts I was finally successful.
Notice the scorch marks on the corners of the IC and cap right next to it! Hey, stop laughing! The soldering was made a touch easier by the fact that I could fit the wire into the little holes that the pins go down through. This made it slightly easier to solder together. After checking with my multimeter to make sure that the connection was good and that I didn’t accidentally solder another pin. I was pleasantly surprised and somewhat shocked when it told me that I only got the pins I was supposed to. So, I closed it up and plugged it in.
OK. No smoke. Now, let’s adjust the time…
Booyah! Success! Using parts I had around at home, I made a clock that was more-or-less useless to me into a clock that isn’t and also saved about $25 in the process! Huzzah!
This goes to prove that you too can do hardware hacking. After all, if I can, anyone should be able to…