Recently the EL backlight on my Casio Cognit Schema stopped working. I did some reading online and older EL backlights were prone to failure as they aged since the chemical reaction in them fades the more they are used. My watch was sold as new but old stock which is seemingly legitimate as it was in brand new condition. So I attributed the backlight failing to just age really.
I sent out a few emails to Casio repair companies and an LA based authorised Casio outfit with hope that they could repair the backlight but they said a new module was needed and this is no longer available...
My plan B was to transplant either the donor movement module from a used watch that used the same module bought online or fine one with a similar module and just swap out the backlight panel. I found just the watch on eBay, a 1980s DB-60 which looked the same layout just with a databank capacity of 50 entries instead of the 80 on mine, no bother. It was sold for £19 so couldn't sniff at that really. A brand new (unworn old stock) one with box and papers goes for £90~ for this model too.
The donor watch arrived and everything worked as expected, the module in it is of the same size but it has some physical differences. There are only 2 springs on the back for the speaker, the top gold springs are not there like they are on the module 1475 on mine and whilst it has a white plastic cover between back cover and module, the white cover has no connecting strip of copper for the extra gold springs to short since it doesn't have them.
The donor module also has no pitch change in the beep once you leave the last mode page and return to the time main screen and the tone of the beep is not as cool as the module 1475 in the Cognit Schema. Even though the donor is from the 80s, the Cognit from the 90s sounds more 80s lol.
All other modes seem to be the same but I decided not to just swap the module because of the above and instead look at swapping the EL backlight panel instead.
So off I went taking things apart...
1: The donor watch had its backlight panel removed, I didn't really get any photos of this stage as I was only interested in the backlight... I thought these were metal and quite stiff but turns out it's quite a bendy piece of panel. The circle patches are the contact points for the tiny gold springs that all too easily fly off into the unknown.... Gotta be careful!
2: Took out the 1475 module from the CS, this was rather easy really, the springs are all retained with a little bit on one end that sticks out retaining it in the hole through the mid-section of the plastic module frame.
3: A little closer look inside the Cognit Schema, probably not a sight many will have ever seen, or will likely ever see again?
4: With the module out, I can compare the size of the donor backlight panel just to be double sure it's the right size. The Cognit Schema graphic can be seen on the LCD, more on this later...
5: The graphic sheet removed after taking out the LCD panel: I still have no idea what the graphic is meant to be?!
6: The backlight panels side by side now, the top one is the donor.
7: Close-up inspection of the 1475 module with a loupe to make sure nothing looks burnt out or damaged
8: In goes the donor backlight panel before putting the LCD back in
9: From the underside I forgot to put the springs for the backlight panel back in so had to take the LCD and backlight panels out again to do this as the springs are wider on one side to stop them falling through
Put it all back together and gave it a quick test and you know what? backlight still not working.... Great
So it seems there's a power issue to the backlight from the module mainboard itself. I'm guessing the original backlight panel in the CS was fine too and the issue lies with power to the panel from the mainboard hence why Casio repair in LA said a new module is needed.
It may also be that one of the springs on the backlight panel is not making contact with the mainboard to complete the circuit as one does appear shorter when placed in the holes before the backlight panel goes in so one day when I have more time will dismantle again and stretch the spring out a bit to test this out, otherwise it would appear that I'll just have to put up with not having a backlight.
I also removed the graphic panel and placed it safely with the watches paperwork, it's nice not having a pink blob in the middle of the LCD that looks odd during the daytime now at least without the ability to show it with the backlight, so there is that one positive outcome from all this I guess.
Although alternatively, no working backlight on a ~30yr old watch could be seen as "character" like on a classic car where something electrical doesn't work?
Luckily because of its rarity the value of the watch should not be hurt much by having no backlight, not that I intend to sell it in the near future at least anyway.
