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.

WP_20140315_10_16_36_Pro

So, I planned to open it myself. I was surprised to see the board inside. It was hardly populated. :O

WP_20140315_003There were so many reflow-able spots.Maybe they use the same board for all their products. The empty spots “might” just be for SIM Module,Bluetooth or GPS (# Hidden Gold)

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.

Bad soldering by manufacturer inside the tablet

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!

8GB SD Card So, this is what the manufacturer meant by onboard storage.

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.
Adding #USB #Charging #Capability to an #Android #Tablet #Hack

And Boo Yeah! It can now be charged by any USB charger >1A.
Yeah! It #Works . So now it gets charged via USB too. #Juggad

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!

Cleaning up some joints inside the tablet.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s