Symptoms of Ground Loop Damage

Inputs Stop Working

• This usually affects multiple inputs, rather than a single input.

• If a visual inspection of the board shows no obvious component damage, the issue may be a faulty optocoupler.

• Testing can be performed using the standard optocoupler test procedures for your controller type:

  • Testing MASSO G3 and MASSO G3 Touch optocouplers

  • Testing MASSO G2 optocouplers

Inputs Randomly Going High or Low

• One or more inputs may change state randomly with no apparent cause.

• Begin with a visual inspection of the main board for signs of damage.

• Further testing may require:

  • Measuring the input signal using test equipment

  • Substituting the input source

  • Inspecting associated wiring

USB Stops Working

• One or more USB ports on MASSO stop functioning.

Testing steps:

1. Plug a known good USB flash drive into the affected port and check if MASSO can read it.

2. Test the same flash drive in a known working USB port on MASSO to confirm the drive is functional.

3. If the flash drive is not detected, test the USB port for 5 V output by connecting a USB cable between MASSO and a mobile phone.

    • If the phone starts charging, MASSO is supplying 5 V.

If the USB port does not supply 5 V:

• Ground loop damage is likely.

• Perform a visual inspection of the main board for signs of component damage.