Citizen 8945 circuit board repair

[gkmaia]

Thanks. That is great help, I know none of these places. Thanks for sharing that.

[AndyHull]

9 hours ago, AlexeiJ1 said:

Watchmakers usually (break one, fit one, keep one).

If we are talking thin glass, that is me on a good day. I only break one. Other days, it can be a complete turkey shoot. I think my record is four.

Actually the other day, not only did I order the correct size first time, but I actually managed to fit it without breaking it. Maybe I'm getting better finally. 

I have to confess I ordered ten though from the cheap end of China, as circular mineral crystals in common sizes are cheap as chips, and I figured ten gave me a very sporting chance of actually fitting one.

[AlexeiJ1]

I just got my replacement one in - so I will fit that and let you know if I have the spare I promised.
Cheers

[gkmaia]

The new boards arrived today. No luck so far... they also do not work.

One thing I know are that the coils are busted. They are at 2Mohm. But, that should not stop the rotor from ticking, at least all the other movements I work on missing coils do not stop the movement from working.

Apart from that I am not sure why it does not work. I am certainly doing something wrong and now sure what. I am following the service manual and connecting everything as per manual also checked continuity in all parts and they are all fine.

 

 

[gkmaia]

It worked!!!! I am so F***** dumb!

The thing really needs a working coil to work. Now I need to buy coils.

[HectorLooi]

I admire your tenacity. I would've given up long ago. 

[gkmaia]

 Thanks!

What I truly want now is to rewind the coils. I got the tools to wind inductors, just don't have the right wire gauge for these coils. Seems something like 50AWG and it is hard to find here in New Zealand.

[gkmaia]

Finally! Got one of the working after 3 or 4 months?! 

Had to fix the coil otherwise another month till a new one arrives. 

Coil is at 1.1k and spec is 1.2k - 1.6k but it is still moving fine.

[AndyHull]

22 hours ago, gkmaia said:

Seems something like 50AWG and it is hard to find here in New Zealand.

You can "unzip" the cores of old power supply transformers. I have done this to make coils for other stuff, but not, so far, for watches. If you have an electric sewing machine, you can unwind the transformer core on to a sewing machine bobbin using the bobbin loading function.

[KOwatch]

Great project, great thread, thanks for sharing. Don't get to read enough deep-dive quartz & digital watch repairs.

@gkmaia, for all your efforts, you might consider swapping a sapphire crystal for your mineral crystal. The 27x2mm are only like £14.70 at cousins, although you'd probably want to make sure you had the size right first.

Wondering if there was no replacement board, would you consider going as far as to redesign a replacement pcb and program a MCU to suit?

[gkmaia]

So after 5 months I managed to have 3 working and restored wingmans. Got all three. The gold, the silver and the black one. Original straps, same from the catalogue. 

If you look closer the black one has black buttons. So those black buttons have been 3d printed in resin and they look really cool. Pretty close to OEM. 

The black one still need the bezel's insert. And for the silver one that is not in the photos still polishing the glass. 

The last thing I need to do in all them after that is just a case back gasket as none of them passed the pressure test.

The black one was painted and backed with high impact ceramic paint. Lets hope it lasts.

But that is it. Was pretty cool work on these guys. I managed to buy 6 boards. But only 2 worked straight and from the other 4 that did not work I could managed to fix the 3rd... mostly likely the other 3 are corroded but still salvageable. 

I really like the black one. Looks like a watch Darth Vader would use... :^P

Edited February 12, 2021 by gkmaia