An old game revived

Last summer I cleaned up our old copy of MB's Dark Tower, a hybrid electronic/board game from 1981.

Thanks to a repair service for the game on eBay, I was able to perform some diagnostics and decide on a probable cause for our problem and a fix.

To understand the problem, you have to know that the board game is basically a race around the board between up to four players, all the while fighting obstacles controlled by the Dark Tower in the center of the map.

The tower is a sturdy plastic construction, with a window along its side allowing the players to look at a single
column containing a two-digit LED display on top of three back-lighted icons. The icons are actually on a plastic cylinder that can rotate inside the tower. There are 5 x 3 icons in total.

The tower keeps track of the players' progress and inventory of soldiers, food, and equipment.


....


I finally checked the motor separately, and found it was running well. But the tower would not even start the motor - maybe because of a problem with the light sensors? If one of the two diodes were broken, we were
hosed, but I checked the circuit board, and found some reddish gunk around the light sensors.

The stuff tracked two circuits and I found some of it between two soldering joints - when I scraped off most of it and cleaned the space between the two joints I connected all components and switched on the tower.

The display showed the single [0_], followed by two blinking dashes [--]

So far, so good. So I did not break anything that worked before.

I pressed a key on the membrane, and the tower started whirring... BINGO!

The tower positioned its open window in front of the three bulbs and lit each of them in quick succession - it started its test sequence!

We played a game with the kids, and put the thing to rest again for next time.

Next project: Find a way to get rid of the batteries and replace them with an external power supply.