#Arkive PD: Replace internal clock battery GM5

Started Dec 29, 2022 | Discussions thread
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prairiedog Regular Member • Posts: 466
#Arkive PD: Replace internal clock battery GM5

Unfortunately it didn't fix the problem :-(, probably due to my soldering skills! More on that later. I documented my procedure - this may be useful for anyone attempting any kind of GM5 repair in the future.

The original issue was that every time the main battery was removed and reinserted the time would be lost and I would be prompted to set the data and time. So the internal rechargable battery needed replacing.

I'm thinking of selling the GM5 so it would be nice to be in full working order.

There are a few places selling ML-421 batteries but not with the solder tags.

I tried to order from Aliexpress, waited ages then it was cancelled for some reason. I wasn't convinced of the quality anyway. So I sourced a genuine ML-421S/DN from mouser.co.uk. At £1.45 each they were cheap but with Fedex shipping from US plus all the extra charges it was closer to £20, so I ordered 3 batteries just in case.

Mouser.co.uk batteries

I found a copy of the service manual. It's on my google drive, hopfully accessible here:


So, with a bit of spare time after Christmas I tackled it. I followed steps 1-3 of the disassembly procedure on page 40 of the manual.

I used a Philips 00 screwdriver for all the screws and there were no issues. Not all screws are the same size so use a system to track where the screws belong.

I have a cheap amazon soldering iron https://amzn.eu/d/4YEnWPB and practised my skills on an old PCB from a dead gadget. I'm no expert and I've soldered a few things in the past with clumsy but successful results. But I found I was managing fine with my practice PCB.

1. Remove battery and card.

2. Remove 6 case screws, one on each side under the strap loops, and four on the base. Around the tripod mount, only the two near the LCD should be removed.

6 screws

3. Remove hotshoe cover and the hotshoe spring (flat metal springy plate). The instructions show prying it off with a flat bladed screwdriver with arrows to lift and slide at the same time. The screwdriver caused some marking on the case and the spring wouldn't budge. Once I used a pointed tool (a board pin in my case, but a toothpick etc would work well) to lift the spring, it slid out with no effort at all. One of those things you only discover with trial and error.

lift the spring with a pointy tool (green) and the spring will slide out easily.

There are four screws under the spring that should be removed.

4. Remove eye cup. Once I realised which part had to slide, it was fairly easy to use both thumbs to wiggle it forward.

Only the top bit slides so don't try and push the whole protruding eyepiece

5. Pry open the case

I used hands mostly, with a little help from a spudger tool.

This was easy.

6. Remove rear cover

As you tilt the rear case assembly (with tthe LCD) back you will see there are three ribbon cables that need removal. From now on all the connectors are a bit different so I won't go into the details but they are fragile and a lot of care needs to be taken removing them.

With these three removed the rear case assembly can be set aside.

3 flex cables connecting the rear assembly to the PCB

7. Access the rear of the PCB

The biggest pain is that the battery is on the far side of the main PCB. Remove the three screws (circled red) and seven cables (circled blue)

Flex fun

The main PCB is still held by the soldered speaker wires (circled red) and a cable behind the PCB (circled blue)

Pesky things keeping PCB in place.

I had no appetite to desolder the speaker wires, though in retrospect it might have been OK. So I lifted the PCB enough to detach the cable from the connector and tilt the PCB back.

You can now see the released flex connector (blue) and the speaker wires (red - still atached) and the pesky battery (yellow)

Dark side of the PCB

8. Replace battery

I desoldered the battery tags with the help of some desoldering tape.

I tested the voltage of the old and new batteries and they were dead and approx 3V as expected.

I held the new battery in place with one of those little plastic clamps and attempted soldering under a "helping hands" magnifier. This was where the fun began - I really struggled to get the solder to stick. I tried different solders, different temperatures etc but it was tough. Like, I mentioned before, my practice on an old PCB was fine so I'm not sure of the issue here. Eventually I got blobs in place and the voltage seemed OK when I tested on the tabs.

I was so absorbed in this I have no photos of the process.

9. Reassembly

Everything in reverse. The biggest hassle was getting the ribbon cables back into the connectors - first the one on the back side of the PCB then all the others. They spring all over the place and it takes a lot of patience to get them in place and clamped. But I got there in the end.

10. Conclusion

The camera is reassembled and is now fully functional except for the original problem. It was left overnight with the main battery in, so if the internal battery was going to charge it would have. As soon as the main battery is removed the time is lost.

I could have fried the battery, but the voltage measured OK in place on the PCB. I suspect I just didn't get the contact needed when soldering.

Maybe I'll try again in the future when I have a spare afternoon but hopefully this post will be of use to others whether they attempt a battery replacement or some other repair in the future.

 prairiedog's gear list:prairiedog's gear list
Panasonic Lumix DMC-GM5 Panasonic Lumix DC-GX9 Panasonic Lumix G9 II Olympus M.Zuiko Digital 17mm F1.8 Panasonic Lumix G Vario 14-140mm F3.5-5.6 O.I.S +4 more
Panasonic Lumix DMC-GM5
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