Symptoms of Ground Loop Damage

Inputs stop working

• This would normally affect multiple inputs rather than a single input.
• If a visual inspection of the board does not show damaged components you may just have a faulty optocoupler.
• Tests can be done by using the standard optocoupler test procedure for you particular controller type as per the links below.
• Testing MASSO G3 and MASSO G3 Touch optocouplers
• Testing MASSO G2 Optocouplers

Inputs randomly going high or low

• This may affect one or more inputs changing state for no apparent reason.
• Start with a visual inspection of the main board for signs of damage.
• Testing this may require the use of test equipment to test the input signal, replacement of an input source and the investigation of it's associated wiring.
• Please be aware that electrical noise as well as ground loops can cause similar symptoms.

USB Stops working

• One or more USB ports on MASSO stop working.
• Plug a known good USB flash drive into the affected port and see if MASSO can read it. If possible test the flash drive on a working port on MASSO to ensure that MASSO can read it.
• If the Flash drive does not work you can test the USB port to see if it is outputting 5 volts by plugging a USB cable between the port on MASSO and your phone. If the Phone starts charging them MASSO is supplying 5 volts.
• If you do not get 5 volts on the MASSO USB port you may have ground loop damage.
• Start with a visual inspection of the main board for signs of damage.