Replacing A Clock IC’s Battery

You can find a lot of strange things inside IC packages. For example, the Dallas DS12885 and DS12887 real time clock “chips” were available in a large package with an internal battery. The problem, of course, is that batteries die. [New Old Computer Show] wanted to restore a machine that used one of these devices and was able to repair the device. You can see two videos below. In the first video, he replaces both the battery and adds an external oscillator which would be necessary for the DS12885. However, he actually had the DS12887, which has an internal oscillator, something the second video explains.

The repair used a PCB he ordered from Tindie. However, the board is only part of the problem. You also need to disconnect the dead battery which requires a Dremel and a steady hand.

The board fits on top of the IC — technically, it is more of a module than an IC — and solders to some contacts exposed by the Dremel surgery. It looks like a hack, but then that’s the way we like it.

In the second video, he uses clear nail polish to protect the exposed wires. Someone in the comments mentioned liquid electrical tape, but we might have been tempted to just coat it with hot glue or — if we didn’t want to take it apart — epoxy.