I originally tried to post this to https://www.reddit.com/r/Filmmakers/ but evidently I'm not turtley enough for the turtle club to post there. So I'll put it in my obscure blogspot post so maybe some search engines will catch it.
So I ran into a situation where my mic hadn't been used in probably near half a year, maybe even closer to a year. I took it out thinking it would be fine but it wouldn't work at all. Here were my symptoms:
- Plugging in the light goes immediately green and it can be used in this way. However, no indication of charging, the light didn't change between green and red at all.
- Unplugging the power and attempting to turn the mic on doesn't do anything, having something plugged into the 3.5mm makes no difference on the experience.
So the thing to remember on the Pro models is that they have an internal battery. And in my case I ended up tearing down the mic (more on this down below) and got to the point I could get to the battery. When I took a multimeter and read the volts on the battery I read 0.6V. Considering the battery is a standard 3.7v this is not good. Although I don't know the lowest point these will charge at, I would assume its somewhere around 2v, give or take a half a volt.
The fix: I charged the battery in the mic up to about 3.4v and now it behaves normally.
The fix, detailed: Okay, so now the how I fixed it. First I must put a shout out to this video which helped with the teardown and will be my reference points in explaining it:
https://www.youtube.com/watch?v=yMK8WWqICXU - Thanks DensiKen!
1:00-1:03 - Do everything shown.
1:03-1:07 - You do not have to tear off the metal screen, in my opinion this makes re-assembly harder.
1:08-1:12 - You do not need to pull the entire piece off as he shows here, however, the screws do need removed as shown in the next section.
1:12-1:35 - Pull back or just push your screwdriver through this material and get these two screws out.
1:36-2:21 - Skip.
2:21-2:25 - What wasn't shown in the video is that there is a small flathead screw between 0 and 10, remove that screw first, then remove the end of this knob. I accidentally pulled my entire shaft out missing this bit. It still works though, just much harder.
2:27-2:33 - This is a 10mm nut if you happen to have sockets around to use.
2:34-2:45 - Do everything shown. There is another screw not shown, there is one just under the charge and output ports, this will need to be removed before the casing will come off.
2:46-3:09 - Skip.
3:10-3:20 - What he started showing but doesn't finish is that there are 3 screws on the edges holding the circuit board down, you will need to remove all 3 to get to the battery.
3:21-3:32 - This is where the battery gets exposed but he doesn't go into more detail.
At this point you need to pull off the protective coverings (a foam pad and a cardboard on the positive and orange tape on the negative). Once you have that done measure your voltage. If your battery isn't a dead 0v, you can probably recover it (my experience with 18650 batteries has taught me this). The next step is getting a charge on the battery. I happened to have bench power supply that I tuned to 3.6v (just to be safe), I don't know the limitations on the battery but .5a would also probably be the safest, I let the battery pull whatever it wanted, which turned out to be close to 1.5a to start and dropping down to .5a within a minute or two. If your battery is at a dead 0, you would need to replace it. The battery marker on this unit is 10440, you might be able to replace it with another 10440 battery and solder in a replacement. I would probably replace the leads with a short bit of cable and hot glue the battery to the board.
There are a few solutions on amazon if you don't have something between (guessing on the lower voltage) 2.5v and 3.7v that you can destroy or be able to pull the positive and negative leads from. If you happen to have a desktop power supply lying around you could also use the 3.3v leads to get the battery up to a certain point and let the standard charger do the rest. Below is a diagram I found. Any of +3.3v and ground sets pins you can use any of the to start charging the battery. The important thing here is to not exceed 3.7v on the battery. To turn the power supply on you also need to put a cable between the green and a black as well.
Desktop Power Supplies
Either way, pull power from a power source and attach the positive to the end away from the mic (closest to the knob we removed in 2:21) and the negative toward the mic (the mic is the section in 1:36 I said to skip).
Using a plastic and rubbert clamp (clamp cannot be conductive!! No all metal touching the ends of the battery!) I left mine charging for around 5 minutes and it was at about 3.4v when I took it off the bench and tested it again. After doing this I pressed the button that is the LPF button (pictured below) on top for 2 seconds. The light below it lights up orange since i didn't have anything connected to the 3.5mm.
Button to push and hold for 2 seconds
This told me that the mic was working as normal. I reassembled it after this point and charged it as normal.
