MGL Avionics User Forum

I have recently installed a new V6 radio in my DR-107 One Design aircraft. The aircraft has a 12V Odyssey PC680 battery and no alternator. The problem I am having is that the V6 radio does not turn on when 12V aircraft power is applied to Pin 1 of the DB25 connector. Here are the details:

1. When the aircraft master switch is turned on I measure 12V at Pin 1, but the radio does not turn on (display remains blank).
2. If I add an electrical load to the system with the master switch on, the radio turns on and functions normally. If the load is then removed the radio continues to function until the power is removed, after which the radio will not turn back on. The load I am using is a 12V cooling fan from a power supply.
3. The radio turns on and works fine if an external switching 12V power supply is attached to Pin 1.
4. All of these observations were made with the engine off. There are no other radios or avionics installed in the aircraft, and no EFIS displays.

In summary, the radio seems to respond to only certain 12V supplies. If the 12V is from an independent switching power supply, the radio works great. If the 12V is from the aircraft battery and harness, the radio does not even turn on. If I add a small load (cooling fan) to the aircraft harness, the radio turns on and functions normally.

Any troubleshooting advice would be much appreciated.

Rick

I think you have a very fundamental issue your volt meter should be able to tell you easily.

The V6 radio is not made or distributed by us anymore - we broke tries with the manufacturer South West electronics more than three years ago due to supply and support issues. We then developed the V16 which we manufacture ourselves. The V6 and V10 radios were based on a design I did some 17 years ago but never put into production as we where too small at the time to handle the work load. The design was eventually passed onto South West electronics which then converted it to fit the new housings and produced it.

Thank you so much for the rapid response. I should have clarified that I have measured voltage at the radio input for all these scenarios. The voltage from the battery (measured at the radio input) is approximately 12.8 V, depending on battery charge state. The voltage from the external power supply is approximately 14 V. Applying a small load (fan) to the battery does not change the measured battery voltage at the radio input, but does cause the radio to turn on.

12.8V from battery applied to radio -- RADIO INOP
12.8V from battery and load on system (fan) -- RADIO OPERATES
14V external switched supply -- RADIO OPERATES

I purchased this radio from Michigan Avionics. Do you recommend that I seek support directly from South West Electronics?

Sadly South West electronics does not do customer support.

I cannot see that this a radio issue though - it would be most unusual. There must be something else.

OK, Thank you.