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rigidpatches

FlexSEA-Rigid: Known hardware problems and troubleshooting

Troubleshooting

  • Board powers on USB but not with a power supply/battery: blown fuse, or damaged ATP304.
  • LED blinks red and board doesn't stay powered while on power supply/battery: Low Voltage Protection (UVLO)
  • No LEDs on USB or with a power supply/battery: most likely a TPS2111 issue.
  • Board turns off as soon as you command some motor current: wrong I2t settings.

In-rush current

Patch: the ATP304's gate resistor has to be replaced. It was 0 ohm, it needs to be 510k.

Why? Slowing down the MOSFET's transition lowers the in-rush current. This lowers the stress on the fuse, and on the PCB. This stress was sometimes leading to the fuse blowing shortly after an experiment is started.

Board versions:

  • Rigid 0.1 & 0.2: R78 has to be changed.
  • Rigid 1.0: on the first production batch the patch needs to be applied. Done internally at Dephy. On the second batch the resistor is correct.
  • Rigid 0.2B, 2.0+: integrated, no changes needed.

Self-turn-on

Patch: Add 10nF between the gate and source of the ATP304 MOSFET. There is no footprint, solder a ceramic axial cap across the component's legs.

Why? the ATP304's can self-turn-on when the battery voltage is above 30V. The physical manifestation is a spark when you connect the battery. This lead to a high current, and this current has the same effects as the in-rush current.

Board versions:

  • Rigid 0.1, 0.2 and 1.0: add capacitor.
  • Rigid 0.2B, 2.0+: integrated, no changes needed.

Damaged TPS2111

Failure to follow the instruction on Testing with Real Hardware: Important Safety Warnings can lead to motor current flowing in the USB connector. When that happens, the TPS2111 blows. To prevent this, always use an isolated USB adapter. If it happened, the solution is to replace the chip.

Replacement components

rigidpatches.txt · Last modified: 2019/09/09 13:50 by jfduval