[CPAP] Luna 3B (G3 A20) stuck in reboot loop

[snelson44]

The other night I pulled on my device (Luna 3B G3 A20) too hard with my tubing and it fell to the floor on its side.  I recovered it as soon as I could, but water had already worked its way through the device.  I was able to gently shake it out and turn it on.  The pressure was inconsistent until I unplugged it several times, then it evened out and worked properly for the evening.  

The next morning I unplugged it and disconnected everything to let it dry.  That night when I turned it on, it started up, got to the home screen and then immediately went black, then just started rebooting on its own, over and over.  Starting up, reading SD card, home page, boom, restart again.  If I unplug it and air it out, later it will work for maybe 5 minutes before starting to reboot again.  

I can't afford to replace this right now, but at least I own it and can do whatever I want with it.  Since its not working, I'm ready to get aggressive with the troubleshooting.  If anyone can help, it'd be much appreciated.  I have a strong IT background, so I'm comfortable doing advanced things like updating firmware or whatever - lay it on me!  I have a Windows PC with SD card reader.

Thanks in advance everyone.

[eok361]

if it seems to get better the longer you let it air dry, then you're going to have to wait it out. but something probably went bad on the motherbaord. have you reached out to luna? maybe they have a recommended service center near you.

in the meantime, i'd check your local craigslist for an older remstar, or equivalent machine. they can be found in my area for less than 50 bucks.

i think i read in here some while ago that there is a cpap community that helps find low cost (probably pre-owned) machines for a discounted price.

[TechGuy]

I think these machines are robust and rarely give defects, but when turned over, water from the humidifier easily reach in the tubes of the flow sensor. Open it (it's hard to open, because of the clips), disconnect the blower, take the blower assembly out, take a picture, disconnect the silicon tubes and blow away all the water from inside the tubes and from the sensor. Then reassemble the machine and try it again.
(There is a small lid under the machine, where sits the communication module. If you remove the communication module, you will see the silicon tubes, maybe without opening the machine you can see if there is water in them. But if there has been water in the humidifier, I'm almost sure you will have to open the machine anyway.)

[snelson44]

Thanks for the responses.  I would've replied sooner, but I didn't think anything would come of the thread!

Anyways, yeah, I got impatient the night I created this post and took the thing apart.  There wasn't really anything jumping out at me, like say a bad capacitor or loose wire.  I did disconnect all of the hoses and got the water out of them. And reseated anything that could be. Disconnected the battery inside to wipe everything (seemed to be just the clock). No luck.

I understand what you mean about how there isn't any protection for the motherboard if it falls upside-down.  My guess is some water got into the processor or something and caused permanent damage.  I planning to get some canned air to really blast any leftover moisture out of the motherboard and try one more time.

Unless I can figure out what that USB port is for.  I know there's software to connect to this thing and troubleshoot this, but I don't think I'll ever find it.

I like the advice to look for used equipment though.  It seems like that could be gross, but maybe all I need is a replacement motherboard...

[Phaleronic]

Yep, go used on this one, I found locally for $100 (for the G3).   It was basically new with 76 hours.  And if you swap out the humidifier air chamber and pull the motor and blow it out/wipe down all the tubing/grommet inside it's really like a new machine, I remediate and sanitize all brands of machines.   Obviously swap filters too.

[TechGuy]

I hope you will repair your machine, but it's a good idea to meanwhile look for a cheap spare G3, because you see it's easy to get it out of order by some water.
And this applies to almost all CPAP machines, so it's always good to have a backup machine on hand.
The mainboard itself is mounted in such a location, where water can not get easily. Did you see any obvious water damage on the board - oxidation, etc? Water enters the airways, so most often you will find water in the flow sensor (because it is of the pass-thru type and water, once in the tubes, easily passes through it). If there is enough water, it will also reach to the blower motor. So first you have to disassemble the machine and look for water in the tubes. If there is, then blow the tubes -and- blow the water out of the flow sensor, because in the flow sensor there will be water too. If you use a compressor, don't blow too hard in the flow sensor passage - Sensirion's datasheet says it will withstand 1 bar differential pressure max. Then look in the blower assembly: if there is any water in it, better put it at a hot place (for example at summer put it on the dashboard of a car to stay for several hours) and dry it completely. I think spinning the motor at high RPM with water in it will wash out the lubricant in its bearings and they will start making noise and fail soon. You can open the blower assembly, but after you remove the screws you will find the rubber gasket is sticky and the plastic lids will not come out easily. You have to put some moistener (water, alcohol) on the rubber and pull/pry it gently. So better try to shake most of the water out of it, then put the whole assembly at a really hot place and dry it for several hours.
If the blower doesn't turn at all, it's also possible to have a defect in the blower motor or its driver part. If the machine says "Starting..." on the display, but do not start the blower, then disconnect the blower connector (the one with the three wires, that comes out of the motor) and use a multimeter to check for continuity between the three outputs and the big capacitor nearby. If there is a short circuit between the outputs and the capacitor then you have a blown transistor, but the motor can also be bad (so to overload the circuit and to blow the transistor).
I didn't understand from your explanation what exactly happens, but you said that sometimes it starts and works for a few minutes, that's why I think the motor driver part is working ok.
The small lid at the bottom side of the machine, where you see the USB connector is for the communication module. I don't think you will find any service software for the G3 (actually I think such software doesn't exist), but you see the readings of the pressure and flow sensors displayed directly on the screen. So in this aspect the G3 is much better and much more serviceable, compared to other manufacturers, where you have to use a special top-secret service software just to check the sensors are working ok. On the G3 anytime, without any service software you can compare the displayed values with an external pressure and airflow meters to confirm the machine is working fine and within specs. Here is an example of water in the flow sensor and you see the wrong readings instantly, by just starting the machine: 
https://www.reddit.com/r/CPAP/comments/1...g3_broken/
It displays impossible flow readings of 6451 liters/min., and you know that such big amount of air can not pass through the machine.
[url=https://www.reddit.com/r/CPAP/comments/1efk0kd/is_my_cpap_machine_luna_g3_broken/][/url]

[snelson44]

Thanks for the help TechGuy. I did some further troubleshooting and have decided to go the used route.

Does anyone have any resources or know where to point me for used equipment? Eok361 mentioned something earlier.

[Crimson Nape]

Supplier #2 is a very good place to look.  My go-to site is dotmed.  It's an eBay for medical equipment.  I have purchased 3 machines off of the site.
- Red

[snelson44]

I'll check those out.  Thank you!

I liked supplier 2 as well. I already requested a Physician Authorization Form from them. I hope my doctor will complete it for me. Any tips for getting around any prescription requirements I might encounter? Any suppliers not require these?