μWatch

[teenix]

(02-28-2019 02:58 PM)Leviset Wrote:  Ian,
I’ve meaus the voltage going to both the +ve and -ve contact points on the main watch PCB - the 2 CR2032s from the battery bay connect directly to them. It shows ≈ 3.3v DC - I do not know if the software is running or not as I can’t get anything on the screen.

Looking at he circuit, most of it runs directly from the battery. The LCD module is probably 5V as there is a simple charge pump circuit controlled by he PIC processor which supplies its power.

Sometimes, LCD modules look the same, but they may have slight differences in their instruction sets or in the procedures for resetting them at powerup and depends on the manufacturer. The module you picked, may or may not have this problem. If it does, the PIC will not be able to drive it properly.

If the circuit is running, you should be able to measure about 5V on pins 1(GND) and 2 (5V) where the LCD module connects.

The ribbon cable is a standard FFC type and should be replaceable if damaged. It looks like it can be repaired though, but would be a bit tricky because you would have to strip off a few mm of the plastic sheath to expose the conductors.

I would then try cleaning the black stuff off, probably with isoporopyl alcohol, clean up the solder pads on the ciruit board and then carefully resolder the ribbon cable back on. You will have to make sure it is the right way around beforehand. If the project is carefully re-assembled and not touched again, you might get away with leaving the black goo off, which is probably there for strain relief to stop the cable pulling off the solder points. It looks like that idea already failed however.

The LCD module will be sensitive to static discharges from your skin, so you need to take a bit of care while handling and repairing it.

cheers

Tony