Fixing a Hexbright

The HexBright came out as a KickStarter project several years ago. The light features a user programmable Atmega168, solid aluminum body, CREE XM-L U2 LED, accelerometer and temperature sensors. Since the lights are no longer available and are of such high quality I have had the pleasure of undertaking the repair of two of them.

There are 4 common problems with the HexBright flashlight:.

1) Battery will not charge and flash light does not turn on after being left off in storage for a long period of time. This is caused by the battery draining to the point where the internal protection circuitry on the battery will not allow for it to be charged back up.
— symptom: flash light does not turn on

Dropping the flashlight and causing the internal 16mhz 8Mhz SMD crystal to break.
— symptom: flash light does not turn on

USB connector breaking off of the board.
— symptom: can not charge or connect flashlight via USB to computer

Reverse battery insertion. With no reverse polarity protection this can destroy many things.
–symptom: flash light does not turn on, battery was inserted the wrong way, magic smoke.

The solutions:

1) The battery is the easiest to replace. The LGABD11865 18650 D1 3000mAh is a good fit and offers on-board protection. (not all LGABD11865 have a protection circuit, look for a black plastic plate on the positive side of the battery and a metallic ribbon connecting the negative side to the protection circuit.) In this case it is good to remove the 2 screws holding the battery spacer in place, drop the battery in and then put the spacer back in. If you do not do this the battery is too hard to wedge in and the insulation on it can be damaged.

2) The crystal is probably the second easiest to replace. These can be had very cheap on eBay 10PCS 16M 16.000M 16MHz 16.000MHz Passive Crystal 3225 3.2mm×2.5mm SMD-4PIN  “10pcs 8m 8.000m 8mhz 8.000mhz passive crystal 5032 5mm×3.2mm smd-2pin new” You can use a slightly smaller crystal than originally came with the flashlight as the pads extend out quite far. You can also use a 4-pin crystal placed skewed on 2 the pads.

You will need hot air and flux to remove the old crystal and replace it.

3) The connector may need to be fully replaced or the pads may need to just be re connected. This is a delicate procedure as hot air can melt plastic. Plenty of flux helps. With my specific case the pads just needed to be reconnected with the pins. A glob of solder and subsequent solder wick did the job.

4) This is the most complex issue to fix. Because there is no reverse polarity protection on the light I found that 3 ICs were destroyed on the board and 2 pads under the LED driver IC were burned. The parts can be bought on either eBay or DigiKey.

1) TPS63020DSJR, LED Driver IC3

2) MIC5353-3.3YMT-TR, Voltage regulator IC7

3) Mcp73831t-2Ac, Lion charge controller IC5

Hot air and plenty of flux was required to remove the broken ICs. The LED and leads should be removed from the board so that the board can be worked on easier. To repair the 2 broken leads on the LED driver copper tape was needed as well as liquid solder to re-tin the pads after clean up.

All fixed: