Old School Casio F-91W Wristwatch Modded with New Features

We’re surrounded by digital clocks these days, which means that wristwatches today mostly act as fashion accessories and status symbols. Like everything else related to fashion, wristwatch fads and trends change with the season. The gold Rolex that said “I’m a rich day trader” in the ‘80s was screaming “I’m a used car salesman” by the late ‘90s. But the classic Casio F-91W has stood the test of time, despite its modest price tag and limited number of features. It was introduced in 1989 and sales are still going strong, with 3 million units produced every year. To bring the F-91W into the modern age, Gautchh modded the retro wristwatch with a handful of cool new features.

The Casio F-91W is not a fancy watch; it is popular because it has an extremely long battery life and a dirt cheap price—about $10 at retail for the standard black color. More importantly, it makes an ironic statement about the wearer’s blasé attitude towards conventional fashion. But even the most indifferent hipsters want to set themselves apart and these mods accomplish that beautifully. Gautchh made four major changes to the F-91W: the strap was replaced, the backlight color was changed, an additional backlight LED was added, and the LCD display was converted to “negative.” The strap and LCD mods are easy enough for most people to handle, but the LED changes will require some delicate PCB work.

Replacing the strap is straightforward, because it’s done the same way as any other watch. Just pull the pin and put the 18mm strap of your choice in. To create the “negative” LCD effect, you simply remove the existing LCD polarizer film and replace it with new film that is rotated to the proper angle. The LED mods are trickier. The existing backlight LED is a pale green that looks a bit outdated. That needs to be replaced with the color of your choice. Gautchh chose to go with blue LEDs, but this is your chance to express your individuality. To add the second LED, you need to run tiny wires from the first LED in parallel. Room is very limited, so you need to use the highest gauge wire that you can get away with. The new LED is held in place with a dab of glue. Then simply reassemble the watch and you’re done. Now you have a retro Casio F-91W that stands out from the 3 million others that were manufactured last year!