V6 "Stuck PTT"
Posted: Sat Jul 06, 2024 1:00 am
I have an MGL V6 radio that sometimes starts in transmit mode and gives a “PTT Stuck” error. It does not do this all the time. During troubleshooting, I have disconnected the radio from the DB25 connector and found that pin 18 (notated as PTT2 in the manual) is grounded when this happens. A circuit is completed with both pin 14, aircraft ground, and pin 21, audio ground. Both PTT switches operate normally, and the pin 18 remains grounded even after removing the PTT switches from their circuits.
Today I attempted more troubleshooting and for some reason, the radio began to act normally after I removed the stereo input from the panel, thinking perhaps it was grounding through the panel. I thought I had it fixed. I checked periodically as I put the panel back together and operation remained normal. However, after I moved the hinged fuse panel back in place, the radio was in transmit mode when I started it.
It seems there is an intermittent fault to ground through pin 18, as the radio works normally sometimes, and others not. I cannot figure out where it might be. I looked at the twisted pair wiring for PTT2, but it looks OK. Evidently, I did something when I rotated the fuse panel, but the only wire to the fuse panel from the radio is the power.
I recently sent the radio to have it checked, and it was OK, and the firmware was updated. The cable was professionally made in 2015.
Any ideas out there? Very frustrating.
Today I attempted more troubleshooting and for some reason, the radio began to act normally after I removed the stereo input from the panel, thinking perhaps it was grounding through the panel. I thought I had it fixed. I checked periodically as I put the panel back together and operation remained normal. However, after I moved the hinged fuse panel back in place, the radio was in transmit mode when I started it.
It seems there is an intermittent fault to ground through pin 18, as the radio works normally sometimes, and others not. I cannot figure out where it might be. I looked at the twisted pair wiring for PTT2, but it looks OK. Evidently, I did something when I rotated the fuse panel, but the only wire to the fuse panel from the radio is the power.
I recently sent the radio to have it checked, and it was OK, and the firmware was updated. The cable was professionally made in 2015.
Any ideas out there? Very frustrating.