The content of this topic has been archived on 30 Apr 2018. There are no obvious gaps in this topic, but there may still be some posts missing at the end.
I am currently working with an Nexx WT3020 (SoC MT7620n) and have a really weird problem.
With a short 5V micro USB cable (1 meter) everything works just fine. However with cables longer than 1,5 meters the box crashes and reboot constantly if wifi is enabled (works fine with wifi disabled).
Have tried:
- different types of cables
- shielded/unshielded cables
- twisted/straight cable pairs
- different power sources
- toroids
Has anyone else experienced these problems? Any ideas?
maybe you know it already but sometimes cheap cables works bad. if all your cables are cheap one's, maybe you just aint lucky.
have you tried with an "expensive", power cable? which intensity did you use (1200ma, 500ma, 250ma..)?
Thanks for your response.
No, have not tried "expensive" cables. As I am connecting to a heat pump with 5V from an RJ85 connector I need to make my own cable. Will consider a test with an "expensive" cable.
Forgot to mention that other units like WR703N, HooToo TM02 and noname MIFI-router works fine with the long cables.
Still a mystery to me.
Why is that a mystery for you ?
Longer cable = higher resistance
Enabling Wifi is causing a higher power consumption and more Ampere means a higher Voltage drop on the cable
And it seems that your Nexx seems the be unstable if the Voltage is a little bit to low.
Either use a better cable or a PSU with a little higher Voltage like 5.2V
Have tried cables with greater area without success. However I think you have a point here. The Nexx unit seem to be more (very) sensitive to voltage drops. Will do some additional tests as soon as I receive more connectors.
Could you please clarify what you mean by trying "different power sources"?
Are you connecting this to a computer's USB port for power? If you, try another computer or a powered USB hub.
If you're connecting your USB cable to an phone charger (aka AC adapter), the adapter might not be providing decent power. I just bought a batch of wall wart adapters and they're "interesting" when you connect them to an oscilloscope. Try plugging into a computer instead.
In the meantime, I would buy another NEXX (or two!) to see if it's simply a faulty unit. They're cheap enough.
Have tried the following power sources.
- My heat pump
- USB ports on 3 different PC's
- My iPhone charger
- My iPad charger
All with the same result.
Bought a batch of 5 units. Same problem with all 5 units.
Finally solved. A "high quality cable" made it. I guess that some brands are very sensitive to voltage drops below 5.0V.
The discussion might have continued from here.