USB connection via MTP broken

[DMcCunney]

I have an Azpen A746g Android tablet. It has a 1.3ghz quad core Allwinner CPU (ARM Cortex 7 design), Mali graphics, 1GB RAM, 8GB Flash, Wifi but not Bluetooth, a front facing camera, and a slot for a microSD card with a 32GB card inserted. It ships with Android Lollipop 5.1.1, and was rooted with Kingo Root.

The principal use for the tablet is eBook viewer, using the open source FBReader for Android app. My master eBook library is on my desktop, maintained by the open source Calibre application. Books get added to the tablet from Calibre via USB cable. When Calibre is active, and the tablet is connected by USB, Calibre sees it, examines the content to see what eBooks are already present, and those that already exist are checked in Calibre. I can select books not already on tablet and send them to the device.

At least, that's how it used to work, up until a few days ago. Now Calibre doesn't see the device. Win10 thinks there's a device called Android, but that there is a driver issue. I dual boot Ubuntu Linux as well as Win10, and Ubuntu pops up a series of notifications about being unable to mount an MTP device, so this isn't a Windows issue, it's a problem on the tablet end. (I had the same issue plugging the tablet into a laptop running Win10 which hasn't been used in a while and where this also previously worked.)

I've gone over my configuration with a fine tooth comb, and looked at recently added apps, but see nothing that might have caused the issue.

Before I bite the bullet, backup, pull the microSD card and reset to factory defaults, then rebuild my config, does anyone have suggestions on how I might identify just what the problem is and address it without reset to factory default?

Thanks in advance,
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Dennis

 

[B. Diddy]

Welcome to Android Central! Just to be sure--when you connect via USB and swipe down the notification panel, do you see a USB icon? If you tap it, is MTP selected?

If that's all set correctly, then the next thing to try is a different USB cable, since cables can fail unexpectedly.

 

[DMcCunney]

Just to be sure--when you connect via USB and swipe down the notification panel, do you see a USB icon? If you tap it, is MTP selected?

Yes, it is.

If that's all set correctly, then the next thing to try is a different USB cable, since cables can fail unexpectedly.

I tried several, since I have half a dozen or so.
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Dennis

 

[B. Diddy]

Another quick thing to check is the microUSB port. Make sure it's clear of debris by blowing it out with a can of compressed air, or rooting around with a toothpick.

 

[DMcCunney]

That shouldn't be the problem. The microUSB port appears fine.

I am configuring an identical device for a friend. When I plug it in via USB, a device called azpen appears in Computer in Win10, and I can drill down into it to see the content. On mine, nothing shows in Computer. I do see a device called Android in Devices and Printers, but Windows isn't seeing the manufacturer or model number.

I find that significant, but don't offhand know what might have happened or how to the the device properly recognized. As mentioned, this used to work up till a few days ago,
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Dennis

 

[B. Diddy]

Hmm, not sure. My guess would be either firmware corruption or hardware defect.