Last April the unit was serviced with I believe an OpAmp to allow RPM and Fuel Flow reading. Recently I got around to replacing my Dynon CHT/EGT Probes with ungrounded and removed the Dynon gear and installed the Advanced 4500.
I bench tested the unit and all was good with CHT/EGT functioning correctly. Replaced the unit in aircraft and powered up and everything was fine. On a subsequent power up the screen was unstable then stable/unstable. Even Altitude and VS were giving huge fluctuations. The voltage was indicating 6.9 on ships power but also changing. I removed the unit and bench tested on a 12 volt battery. Once again I had issues with the baro instruments erratic indications. It appears that the external power is not getting into the unit and it's attempting to run on the internal battery as the unit began to cycle on and off on the internal battery power. It must be sensing external 12v power but is running on the internal battery.
I'm not sure if the attachment will show the problem

Thanks

Rocky

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