SmilingJack

SmilingJack

Well Known Member
Hello all,

I have 2 questions on the GMA240 fail safe mode:

1 - turning the left volume switch to off should place it into fail safe mode, on mine when doing this I can't seems to hear anything on the radio, which then causes me not to try to Transmit, which is the second test.

2 - if I can figure out number 1, I would like to know if there if a jumper inside the GMA240 to switch the fail safe mode from using com 1 to making com 2 the fail safe radio.

Why? Because I have a backup power circuit from my VP100 to com 2.

Thank!
 
GMA240 Fail Safe Mode

John,

In reviewing the failsafe operation section from the GMA240 installation manual, I am reminded that the COM1 audio is provided to the pilot headphone's left earpiece in failsafe mode. You might check to see that your headset volume is up on the left side when you do this check.

You might also try removing power from the GMA240 and see if this invokes the failsafe mode, but either method should work to cause the failsafe relay to change state.

I checked the internal jumper list and didn't see any jumper to allow you to change the failsafe radio from COM1 to COM2.

Steve

3.5.2 Failsafe Operation Check
1. Turn the unit off by rotating the pilot intercom knob fully counter clockwise.
2. Check the failsafe operation by exercising the COM 1 microphone, microphone key, and monitoring received COM 1 audio over the pilot headphone's left earpiece.
3. If installed, check that the failsafe warning is heard in the pilot headphone's left earpiece.
4. Turn the unit back on to continue testing.
 
I'll check that tomorrow Steve.

In re-reading your post on the procedure, I now am wondering if "keying" the mic after turning off the GMA240 places it in the fail safe mode. I haven't keyed the mic during my test.

Thanks,
 
I have been reading the manual on the GMA 340 quite a bit. Sounds like they function just about the same. One option you might have would be to rewire your radios so that your current COM2 radio is switched to COM1. This would give you the electrical redundancy you would like to have. It might be a fairly easy switch.

George
 
George, I may do a swap "sort" of as you suggest.

I have been searching through the archives and see many people do not separate the 2 powers for the SL30 Nav & Com, I did and maybe what I will do is combine them so I can use #1 Nav/Com with my back up power pin on my VP100.

Now I just have to figure out if my fail safe is working on the GMA240.

Thanks,
 
No-Joy!

I tested the fail safe mode today and it almost appears to work, I just can't be sure.

When I turn the GMA240 off and listen real carefully I can almost hear audio from a radio.

I tried turning up all the volumes on my radio and headset and still came in very weak.

Anyone know if there is another volume adjustment?

Thanks,
 
GMA240 Fail Safe Mode

John,

Do you have the pilot headset jack wired for stereo only, mono only, or mono/stereo using a switched right output?

HeadsetWiring.jpg


Are you using a stereo or a mono headset? If stereo, are you sure the headset switch is in the stereo position? What brand/model headset are you using?

The following three possibilities exist for the Fail Safe mode to not work correctly:
  1. The left/right audio outputs are wired backwards on the stereo headset jack and a mono headset is being used (or a stereo headset with the mono/stereo switch set to mono).
  2. The jack is wired correctly for stereo, but a headset is being used in mono mode that shorts left and right together to achieve this mode (some headsets operate this way).
  3. The jack is wired for mono, but is using the right output instead of the left output, so you don't hear the fail safe audio output on the left side.

Hope this helps to troubleshoot your problem. Let me know if you need additional help or have questions.

Steve
 
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