Jump to content
  • 0

Citizen 8945 circuit board repair


gkmaia

Question

I've go a couple faulty wingmans from ebay. 

And they both have no life. 

Did fix some of the tracks and tested continuity in each track, front/back.. all good. 

Hooked them on my oscilloscope and got absolutely no signal, nor noise. Just stable positive voltage across the rails and some current usage. No shorts between positive and negative rails, in fact impedance is very high.

As per manual the IC drives everything. It has a built-in oscillator to drive the crystal but I get no signal on the crystal and coil. 

My assumption is the IC is fried... 

Any hope? ideas?

Screen Shot 2020-09-25 at 10.01.35 PM.png

8943.pdf

Link to post
Share on other sites
  • Answers 60
  • Created
  • Last Reply

Top Posters For This Question

Top Posters For This Question

Popular Posts

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

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 fin

Who needs schematics when you have nitric acid? https://zeptobars.com/en/read/Luch-quartz-wristwatch-IC-at-sc-tuning-fork Generally they do have a clamping diode or modified transistor junct

Posted Images

Recommended Posts

  • 0
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.

  • Haha 1
Link to post
Share on other sites
  • 0

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.

 

 

Link to post
Share on other sites
  • 0

😆 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.

Link to post
Share on other sites
  • 0
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.

  • Like 1
Link to post
Share on other sites
  • 0

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?

Link to post
Share on other sites
  • 0

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

IMG_0771.JPG

IMG_0772.JPG

IMG_0769.JPG

IMG_0770.JPG

IMG_0773.JPG

IMG_0774.JPG

Edited by gkmaia
  • Like 3
Link to post
Share on other sites



  • Recently Browsing

    No registered users viewing this page.

  • Topics

  • Posts

    • Hello Not really a watch question, however I thought I would it it a try. I have a couple of Silver Beer Mugs that are tarnished and all I have to clean them with is the L & R Ultrasonic Watch Cleaning Solution (ammoniated) and a ultrasonic machine. I also have the L & R Ultrasonic Watch Cleaning Solution and an Ultrasonic machine. Does anyone know if I can use these two products on the silver beer mugs or should I get another type of cleaner> Also should I be diluting the cleaning and rinse solutions?  Thanks in advance for any help that can be provided. Michael
    • Hi JDM - Thanks for the detailed reply. The Bezel only looks like a rotating time ring, but it's just a "faux" divers watch, only rated to 50m. I think the Seiko "Solar Power" version actually had a rotating ring and Tritium on the hands and numbers and was rated to 200m or something. But, the bezel is fixed. Also, there are no "indent" or any indication that you could use a Snap Back knife to open the bezel. If this is not indeed a screw off bezel (using a screw type base wrench), then a 4 blade bezel tool is likely the only thing that will remove it. Then I'll need to figure out how the stem is removed so I can remove the whole movement to get to the Cap which I assume is underneath. Other owners on some other watch forums have reported the same experience I had with my Lorus/ Seiko 851 model, the Capacitor fails after only 8 to 10 years and nothing like the "promised" 80 years (Life Time Warranty they refuse to obey). Quite a few owners wrote that they had the Capacitor replaced, but no details on HOW. Read my response above to "watchweasol". There's been some conflict about which capacitor to use as well since the original 2023 24T / MT920 was discontinued 30 years ago (probably the reason all these Lorus Solar watch never met the 80-year promise. Supposedly the replacement Cap is a 3023 24T now. The word in some forums is that this Maxell Cap will last 30 to 40 years. The Seiko Kenetic watches supposedly also use this same Capacitor. Have you ever worked on the Seiko Solar version of this Lorus? Thanks.    
    • @watchweasol - I  know that was the Seiko "company line" for both the Seiko and Lorus branded "Solar Power" versions, but there are an awful lot of folks that bought both and found the Capacitor died, like mine, only after 8 to 10 years and did have the Capacitor replaced with at first the original 2023 24T version and then the 3023 24T, which is apparently a much longer lived replacement. Seiko's "promise" of an 80-year life for this Capacitor was all hooey and likely the reason Seiko quickly dropped both their own branded model and the Lorus ones after just 10 years on the market. Both Seiko and Lorus (who is no longer in North America) refuse to honor the "life time" warranty. One of the reasons I now trust Casio more than Seiko for warranty promises. The movement in the Lorus is literally the exact same one that was in the 3 "Solar Power" Seiko mens models, a Seiko NA tech admitted that to me almost 30 years ago when mine stopped charging. I bought it new in 1986 or 87, and I still have the original paper manual and box and "Life Time Warranty" card (good for nuthin'). I've been a watch and clock "collector" since a teenager, prefer early American pocket watches, but who doesn't love early American MADE and Japanese and Swiss made wristwatches? So I've also collected all the tools a watch and clock tech uses, many pretty vintage too, and learned how to work to a certain degree on most any watch or clock, restoring and fixing, to my limits. I already have that (another version) Bezel removing tool, am just trying to confirm that the bezel is NOT a screw on, or absolutely IS a press-fit. Was hoping to find someone that has either worked on the Lorus version or the sort of same looking Seiko versions that also had the one-piece "tub" body. The Bezel only looks like a rotating time ring, but it's just a "faux" divers watch, only rated to 50m. I think the Seiko version actually had a rotating ring and Tritium on the hands and numbers and was rated to 200m or something. This Lorus/Seiko is an odd-ball and there is absolutely no repair info on them, so that makes me want to fix it more myself.
    • Very, very nice production.  Really outstanding walkthrough!
    • I assume that this is made after Aaron Lufkin Dennison time. I consider this as treasure. 🙂 Case Opener (i should have cleaned it first I see 🙂 ):
×
×
  • Create New...