I am a sad owner of a BSNL PentaTab. It is a horrible tablet with a very glitchy hardware/software. Although, enough of the rant..It just gets the job done. I recently had an issue when the tablet stopped charging from its DC jack a week after its official warranty ended ( This always happens 😐 ). The tablet does have a USB-OTG and a Mini-USB for data, but does’nt support any charging via the USB interface. I fail to understand this.
I took it to the local service person, So that it can be handled “professionally” . That guy took some money and got the job done. But it failed again after a few days.In India, they dont give you any guarantee till when the repair would last. So, there was no point taking it back to him.
So, I planned to open it myself. I was surprised to see the board inside. It was hardly populated. :O
I felt heart-broken when i saw the bad soldering on the board. It was probably done by some untrained professional. This makes the board susceptible to shorts. Bad Manufacturer.
Another thing that surprised me was that the onboard storage of 8GB meant there is an 8GB SD card inside. I wished to see some flash chips like the one on beagleboard. huh!
The AIM was to make the USB mini-B charge the tablet, hence by-passing the DC-Jack.
This turned out to be very easy. The grounds of the DC jack and USB Connectors were shorted due to the presence of a ground plane of the PCB. Next i took a small single stranded wire and soldered it shorting the positives of the DC Jack and +VUSB.
And Boo Yeah! It can now be charged by any USB charger >1A.
Update: (13th April ’14)
I did a complete resoldering of the bad joints i saw earlier. The speaker was making insane click and screen too. The wires had gone lose.
Here is the final picture. I desoldered all joints and reduced wire length. The GND pad was a bit hard for my soldering Iron as it needed a bit more power. Then i cleaned the joints and laid out wires a bit more systematically!