I'm hoping the electrical guru's on this most excellent forum will offer some trouble shooting advice. The problem is my old school Narco AT-150 has stopped providing altitude information. After cleaning with electronic contact cleaner and reseating the tray and coax connections, the problem remained.
After visiting an avionics shop, was advised the altitude encoder was likely defective. The Trans-cal SSD120-35C-RS232 altitude encoder was replaced with a new copy of the same encoder, a plug and play replacement and still no altitude information back to the ground station.
A Narco AT-165 of unknown history was installed and powered up and no joy, showing no pressure altitude on the display. Most recently a Narco AT-155 known to be serviceable was installed and again no altitude information to the ground station, in spite of the little green light on the transponder face flashing periodically.
I expect the common advice would be to use the Narco products as fish bait or for paper weights, but would appreciate any suggestions how best to investigate what the problem might be.
How best to access and test continuity of the collection of wires attached to the backside of the transponder tray, or anywhere else I should be checking?
Thank you!
After visiting an avionics shop, was advised the altitude encoder was likely defective. The Trans-cal SSD120-35C-RS232 altitude encoder was replaced with a new copy of the same encoder, a plug and play replacement and still no altitude information back to the ground station.
A Narco AT-165 of unknown history was installed and powered up and no joy, showing no pressure altitude on the display. Most recently a Narco AT-155 known to be serviceable was installed and again no altitude information to the ground station, in spite of the little green light on the transponder face flashing periodically.
I expect the common advice would be to use the Narco products as fish bait or for paper weights, but would appreciate any suggestions how best to investigate what the problem might be.
How best to access and test continuity of the collection of wires attached to the backside of the transponder tray, or anywhere else I should be checking?
Thank you!
