Noisy whistle from the back

This is a brand new 9.7″ Android tablet purchased via our local New Zealand on-line auction site, Trademe for about NZ$160.

9.7inch Allwinner A20 Dual core \1.5 Ghz, 1GB DDR3, 8GB NANDandroid 4.2 IPS

From first power-on it made quite a loud high pitch whistling noise from somewhere in the back. On the back were two speaker grill slots but the noise sounded like it was coming from inside rather than the speakers.

The first step was to email the supplier, explain the noise and ask what he/she wanted to do about it. After about 2 weeks we had no reply.

Other than the annoying noise, it was working fine. That’s the danger of buying via Trademe or cheap from overseas, you have limited comeback if it goes wrong. Here in NZ, the cost saved over retail generally makes the risk worthwhile.

Repair it here

This noise sounded a lot like a noisy switchmode inductor. The seller was not interested so it was time to look inside. Scrape off the warranty seal and open it up. Two tiny screws and  many small clips around the edge. Not that difficult to open up.

With the back removed it was clear that the noise was from the speakers. Following the wiring immediately showed that the speaker wiring was crossed; soldered with a swap at manufacture. There were also a couple of solder balls stuck to  the board near the speaker wiring.

Re-soldering and a quick clean up solved the problem, No more noise and clear sound from the speakers.

Wifi Antenna connection

The solder connection to the board looked pretty crappy, so it was re-soldered.