Need to confirm modern capacitor replacement - Citizen 4110

[dapellegrini]

Is there a modern replacement for this GC920 capacitor?  I am getting the two step sadness, and suspect this has never been changed...

[saldog]

I am seeing that you can use an MT-920, which is readily available.

[inboost]

dapellegrini - does that cell have a tab attached to it? The GC920 I googled seems to but yours appears not to.

I'd bet you the Varta V15H I had you pick up for the older Solar Crystron might just do the trick! Again not a capacitor but rather a rechargeable battery : Manganese-Titanium battery

Manganese-Titanium (Lithium) Cells

Applications: Watches, other ultra-low discharge applications

This technology might be called Manganese-Titanium, but it is just another lithium coin cell. It has "compatible" voltage – 1.5 V to 1.2 Volts, like the Lithium-Iron cell, which makes it convenient for applications that formerly used primary coin cells. It is unusual for a lithium based cell because it can withstand a continuous overcharge at 1.6 to 2.6 volts without damage. Although rated for 500 full discharge cycles, it only has a 10% a year self-discharge rate, and so is used in solar charged watches with expected life of 15+ years with shallow discharging. The amp-hour capacity and available current output of these cells is extremely meager. The range of capacities from Panasonic is 0.9 to 14 mAH (yes, 0.9 milliamp hours). The maximum continuous drain current is 0.1 to 0.5 mA.

[dapellegrini]

Thanks guys.  I will try a Varta V15H tomorrow and update here!

[trilo]

I have used MT920 on these. Works great and is cheap.

And yes, there is a tab attached that needs to be carefully removed to be used with the replacement cell (GC920 came with a unique tab). Intrestingly there is a Citizen movement, that uses the same shape battery tab which can be removed during disassembly and used on these 4110. Can't remember the exact caliber (80's era caliber)


I wrote about my ordeal with this in here:

wristsushi.proboards.com/thread/22211/capacitor-cell-connectors

[dapellegrini]

Thanks trilo - I've ordered one of those and will attempt the swap once it arrives. 

[dapellegrini]

Ok, the MT 920 arrived and it is GO time...

First the WARNINGs



Curious that I am putting this into a solar watch - where the whole point is to expose it to direct sunlight...  I guess the capacitor will stay cool and dark on the other side ... hopefully

So this copper color plate comes off



And you have to kind of pry up the circuit board to get the tab out of it's seat:



I started with a razor blade, but switched over to an exacto knife to finish the separation



Then placed the tab back into its spot





Then I bent it upward so that it was certain to make contact with the capacitor once reassembled.



I wasn't getting any sign of life on the dial side, so I put the copper plate back on.  Still no sign of life, so I closed the case and thought I would just set it aside to deal with later.  I didn't see an AC or other recent to perform while the case was open...

On a whim I popped the crown out and back in - and it's ticking!  Albeit not happily, so under a lamp for a while to see if it just needs some good light...



Thanks everyone for the help on getting this one going again!

[trilo]

I'm afraid that you need to use tape or some other adhesive to keep the prong connected with the cell (I used tape).

It takes a while for them to start up after a new cell is placed.

[dapellegrini]

So I think it must have been at least 36 hours now.  The first 12 were under a bright LED flashlight, the remainder was just leaving the watch in indirect light, in bright rooms of the house.  I was still getting the double step seconds hand things.

Out of curiosity, I put my scorpion black light on the watch and went out to get some sun and time around the pool.  About an hour later and it seems be ticketing normally again.  Is a black light for effective and charging up these solar capacitors, or just coincidence / timing that made it seem that way?

[inboost]

dapellegrini - yes the light source chosen to charge with is critical.

Here's a cool chart from: www.intechopen.com/chapters/32588 and I believe we're using the e-Si type componetry in these solar watches.

As you can see by the green area in the chart, to best absorb the most energy we need a wide spectral range of light from near zero up to about 1100nm in wavelength. I suspect your LED flashlight to have an extremely monochromatic light, probably focused in the 550nm range as shown below in the left panel as I doubt the inexpensive ANKER flashlight is using an RGB chip (expensive, unnecessary).

www.electrical4u.com/white-led/

 

The UV flashlight will come in right around 365nm which if you look at the first chart is more efficient at conversion.

However, none of these new technologies are the best way forward, as you are missing out on the ability to harvest energy from the total range of light wavelengths. That's where an incandescent or the sun will do a better job at charging as they emit all of the wavelengths (at various efficiencies) so the total area under that curve in picture 1 above can be taken advantage of.

Put that thing out in the bright Arizona sun for 8-10 hours and I bet we've got a winner!

[trilo]

I just stick these onto a window with a clear packing tape (peels off clean and doesn't leave marks) and leave them there.

If the connection is solid, it'll be up and running after 3 days, and then I keep them there for couple of days and after that I wear them for a while.

[inboost]

Oh my gosh, could you imagine walking past trilo's house seeing watches taped to the window? if you're a watch person like we are you'd spot it a mile away. I'd have to go ring the doorbell!!!

[trilo]

Solar watch enthusiast walking past: "Sir, did my eyes decieve me or was that Citizen Crystron 8629 on your window, right next to that gorgeous 4110?"

[trilo]

May 28, 2023 11:37:25 GMT -8 dapellegrini said:

So I think it must have been at least 36 hours now.  The first 12 were under a bright LED flashlight, the remainder was just leaving the watch in indirect light, in bright rooms of the house.  I was still getting the double step seconds hand things.

Out of curiosity, I put my scorpion black light on the watch and went out to get some sun and time around the pool.  About an hour later and it seems be ticketing normally again.  Is a black light for effective and charging up these solar capacitors, or just coincidence / timing that made it seem that way?

Have yours kept running?

Both conversions I have done have stopped. I just serviced my brothers 4110 as I thought it stopped due to gunked oils, but it might be that it has a hard time getting charge.

I wonder if the panel is enough to charge the MT920,

Update:

I cleaned the contacts, put it back together, pulled the crown to 2nd click (to clear the setting indicator) and it's now working as it should.

I wonder if it was just a bad contact...

Well, proper cleaning never hurts!

P.s. I was going to make a service thread out of this, but halfway through the assembly at 0030am, I realised that I had forgotten to take the pohotos! 

[dapellegrini]

I will have to dig mine out a check if it recharges.  I think it is in a watch case, sitting in the dark...  with my other solar Citizens

[trilo]

Just for the record.

If the irregular stepping doesn't go away even after charging, put the crown into 0 position, take out the positive battery contact so that the watch stops, put it back, pull crown to 2nd position to adjust it and push it back. Watch should return to normal.

Irregular stepping is both indicator for very low charge and for an unadjusted watch (after a long time in hibernation). Depending on the crown position when assembled, the reset indicator might get messed up and it has to be reset (see the manual).

Not sure if it goes away on its own when the charge is full, but that is one way to clear it.