u/GloryInKindness

One day, I powered on my ASP Micro, and shortly after the splash screen showed, the screen went dark and has not turned on since. Sometimes I'm able to get it to come up for a split second before it goes dark again, and I'll see the splash screen followed by some black and pink stripes before it turns off completely. My Micro is now well out of warranty, and I picked it up as a package deal with my Rattler, so I took it apart to see if I could fix it. When looking around online, I was not able to find any videos or images or instructions for how to take it apart and repair it, so I figured I would post it here and hope it gets picked up by a search engine for the next person trying to figure out what to do.

SYMPTOMS

• Unit won't boot up.
• When USB is plugged in, it appears to charge and the light comes on.
• Sometimes over USB, my PC can detect it as a storage device.

POTENTIAL CAUSES

• The ASP Micro is not very well sealed from moisture or debris. There is a weather seal around the bottom USB port and 1/4-20 thread, but it broke off quite easily. At one point, the nut also broke off and was rattling around inside of the monocular. It's possible that debris got inside the unit and needs cleaning.
• The battery could have failed due to dendritic growth or other internal shorting.
• Something could have overheated and burned up. If this is true, there's probably not much I'm going to be able to do.

Since I don't have anything to lose, I'm going to give fixing it a try and will update this post with my progress.

Here is how to disassemble the AGM ASP Micro.

1. Use a thin spudger or knife blade to attack the front rubberized cover. It is secured with a very thin layer of adhesive. Go around working it off until it falls away freely. You will then see four Phillips head screws.

https://preview.redd.it/28wvrwy66n0h1.png?width=597&format=png&auto=webp&s=89769d5da24f7a596b95c180cd7db5c67440fbcf

2. Remove the four Phillips head screws.

https://preview.redd.it/apj0k84y6n0h1.png?width=1073&format=png&auto=webp&s=5236b579fd2fb00ff8fd57f71e286d098e628693

3. You should now be able to see two large black Phillips head screws that are horizontally opposed. Remove them. They are holding the entire assembly into the enclosure.

https://preview.redd.it/em6mslsq6n0h1.png?width=1236&format=png&auto=webp&s=d44d7d865c7f1cbac7439bc5ce1f457fad164e4b

4. The entire digital imaging subassembly is self-contained and slides out like a tray. Grab the front of the lens assembly and pull it out.

https://preview.redd.it/y25zqqe18n0h1.png?width=1118&format=png&auto=webp&s=9c871b88e892187edc88651b4ad60d5e73f683bf

At this point, I noticed that D5 was lit solid red on the bottom of my board, probably not a good sign...

https://preview.redd.it/efex96m59n0h1.png?width=768&format=png&auto=webp&s=422ae78023164f30c3f76ae885494c884d1f2c9c

5. Go ahead and disconnect the battery on the side of the main board. Be sure to squeeze in on the connector to release the tension clips. Note that the positive wire lines up with the arrow pointing into the connector for pin 1.

https://preview.redd.it/e8cepydl9n0h1.png?width=757&format=png&auto=webp&s=0733fbbb5a9abc2527ba2222aa48669267e04556

I probed the battery and did a bit of reverse engineering. The total cell voltage on mine appears to be 3.3V, which should be consistent with a discharged 1S lithium battery. I'm going to charge it overnight and see if it is able to charge up. The two middle wires (white and yellow) do not carry any voltage, but I measured 8.6 kΩ across. This is likely a simple 10k NTC thermistor and used for sensing the battery temperature, which is very common for integrated battery packs. Here's the sketch of what I think I'm seeing.

https://preview.redd.it/aubf20a8gn0h1.png?width=738&format=png&auto=webp&s=3cffb977bb97dee76efc1ebf71a4b45369f33d27

And that's all for tonight. Follow along as I continue troubleshooting what the heck broke on this monocular. I will either edit the post or add comments. Hopefully I can get it fixed, but if I can't, then it will be good news for the rats I'm trying to spot before they get introduced to my airgun and develop rapid-onset lead poisoning.

For my next debugging step, I will look into externally powering the thermal using a power supply and try to eliminate the battery as a point of failure. If the battery is what failed, hopefully I can replace it.