Need help for repairing Netgear Meural Canvas digital art frame - Wi-Fi issue

[Koray]

Hi all,

I bought this Meural Canvas (MC227) digital art frame from a major store's ebay clearance in faulty condition. It was described as having difficulty in connecting to Wi-Fi. After I received it I found out that the Wi-Fi antenna cable inside was cut by scissors before. I thought it was a case of return-fraud and since the cable had some slack I was able to solder it back to the antenna board easily.

Once I registered the frame on my account using Wi-Fi, it worked perfectly for two weeks. However, after that it started to drop off from the wireless network. I decided to check what could be wrong and in the process I refreshed the solder joints of the Wi-Fi module (AP6255). After I did that it worked OK again for a few hours, but now it is back to square one.

Here are the symptoms:
- The device powers up properly but fails to connect to the Wi-Fi network. Otherwise all functions work perfectly and the frame displays the pre-downloaded artwork without any issues. Gesture controls work perfectly. Just no Wi-Fi connection.
- In such state you can restore the unit to factory settings. In that case the device has to broadcast its own Wi-Fi network. It sometimes does, sometimes does not. When it does, it is mostly impossible to connect to device's network. If you leave the device to itself (without power) for a few hours and try again, you may have some luck and connect to it. Then you can set it up again and it downloads the albums from the account. However it is not reliable and will disconnect after a while.
- The device is powered by a 12V 2.5A wallwart. The voltages inside the device at different locations are at 11.89V, 5.05V, 3.24V, 1.79V.
- There is nothing that seems to be overheating. The main processor is warm to touch. It has a solid piece of heat regulator thing stuck on it.
- There are two 100mF 16V electrolytic capacitors on the board. One has 12V on it, the other has 5V. I didn't replace them, but maybe the Wi-Fi module is too sensitive about them?
- Cooling the board does not correct the issue.

I am wondering if the issue is main processor or software related, or if the Wi-Fi module (AP6255) is bad. The unit was updated to the latest firmware successfully. The Wi-Fi board datasheet shows that it requires 3.33V for VBAT, but it has 3.24V on the device.

I am trying to understand why the frame worked perfectly for about two weeks and failed.

Probably the snapped antenna cable was a result of customer rage. 

Does anybody have any suggestion on how to proceed?

I am including some photos of the repair and mainboard. The device has a beautiful LG 27" FHD IPS screen (LM270WF7) on it. The mainboard is connected to a central power input board which also manages the I2C connectors of the landscape and portrait mode gesture devices (MGS3030). The power button assembly also houses ambient light sensor.

In the worst case scenario I can just put a regular monitor mainboard that can run the screen and use a raspi to maintain similar functionality. However the Meural Canvas service is top notch and the gesture controls and the user interface are very neat. So I would love to fix the unit.

Thanks in advance!

Koray

[JKKDev]

This is a long shot but do you maybe have an old smart phone or some other device that has a wifi antenna built in? If the plug is the same you could connect that to this board and see if the connection becomes more stable.

[Koray]

Thanks for the suggestion! I have some spare antennas, I will try them tomorrow. Do you think 3.24V that I measured may mean something? It is supposed to be 3.33V isn't it? I also ordered replacement AP6255 Wi-Fi modules, so that will be the last resort. I will keep the thread updated.

K.

[DaJMasta]

If the trace is exposed anywhere, you could try checking continuity of the center conductor of the antenna cable, from the mainboard to the antenna board - those little U.FL connectors are easy to damage so maybe there's a loose joint or intermittent center pin.  There is some chance that your repair has changed the impedance/VSWR of the antenna enough that it no longer performs to spec, so replacing it could be a good attempt as well (and antennas like this should be quite easy/inexpensive to find).

The voltage shouldn't be a worry.  Typical regulation on a regulator will be +- a few percent normally, and often devices will have a 5-10% tolerance to the voltage level before there are real issues with droop.

One last thing, those caps you're describing are definitely 100uF caps, not 100mF caps - seems like a whiny complaint, but 100mF is 1000x larger than 100uF, it helps to be clear.

[Koray]

Thanks! I will try it with a good antenna from a laptop wi-fi. Sorry about the mF mistake, I also was thinking to myself that there was an odd feeling there. 😂

K.