Ground Loop Symptoms
Ground loops can damage MASSO's input circuits and USB ports. These are the common symptoms and how to check for them.
1. Inputs stop working
This usually affects several inputs rather than one. If the board shows no obvious component damage, an optocoupler may be faulty – see Testing MASSO G3 and MASSO G3 Touch optocouplers.
2. Inputs randomly go High or Low
One or more inputs change state with no apparent cause. Start with a visual inspection of the main board for damage. Further checks may include measuring the input signal with test equipment, swapping the input source, and inspecting the wiring.
INFORMATION
Electrical noise and ground loops cause similar symptoms – consider both when troubleshooting.3. USB port stops working
1
Plug a known good USB flash drive into the affected port and check whether MASSO reads it.
2
Try the same drive in a working USB port on MASSO to confirm the drive is OK.
3
If the drive still isn't detected, check the port for 5 V: connect a mobile phone with a USB cable. If the phone charges, the port is supplying 5 V.
NO 5 V
Ground loop damage is likely. Inspect the main board for signs of component damage.
