Squelch on 650

A friend of mine is having a squelch issue with his 650 radio that wasn't there and all the sudden appears to be there.
We pushed the volume knob to put it to squelch and then changed to auto squelch again with no change in the static sound in the headset.

I was wondering if anyone has seen this or idea where to go look next.

Com configuration

Installation manual 5.5.1.10
COM RF Squelch
This setting configures the RF squelch threshold for the COM radio. This field may be set to any value between 0% and 100%. The default is 0%. 0% is the most sensitive (i.e. the weakest signal level necessary to break squelch). Increasing the value will require a stronger signal to break squelch.
Mic 1 Gain
The MIC 1 Gain can be adjusted from -12 dB to +30 dB in 6 dB increments. The default is +12 dB. For mics with low signal levels, this can be adjusted up to increase the signal strength. For mics with high signal levels, this can be adjusted down to decrease the signal strength.
Sidetone Volume
This parameter sets the audio side tone output level. Side tone refers to the audio spoken into the COM microphone. This setting only affects the volume of the side tone for the GTN COM during PTT. This value may be set to values between 0.0 dB and 63.0 dB in 0.5 dB increments. The default is 17.5 dB. The higher the setting, the louder the side tone will be. The side tone is only generated in the COM headset (low level) audio output.

Good luck

Have you tried a different headset? Make sure the headset you are testing with is the only one plugged in. Had a similar problem with my 650 and the problem was a rear seat heaset still plugged in and the rear vent was blowing directly on the mike. ( Cherokee 235 )

Thanks folks. I guess I should have said that he is seeing the issue on the ground and in the hanger and he has verified that the headsets are not the cause by pulling each and the problem continues.

One interesting thing I learned today as part of the troubleshooting today which I can not explain. The 650 has two CBs (one for COM and one for NAV), pulling the NAV CB will powers down the whole unit. However, if we pulled the NAV CB (unit shut down) he could still hear the squelch and it would go away only when the COM CB was pulled.

Now, honestly if someone else had described this to me, I say he is pulling my leg but it seems it is working that way.

I will go to help him troubleshoot soon and would really like to see this for myself.

Any Fluorescent or LED hangar lighting involved. Twice now I've done radio work and then when tried it out have said "WHAT THE HECK OF I DONE, IT IS NOTHING BUT STATIC!!!!" and once I turned off the overhead lights presto all is well.

Bavafa said:

One interesting thing I learned today as part of the troubleshooting today which I can not explain. The 650 has two CBs (one for COM and one for NAV), pulling the NAV CB will powers down the whole unit. However, if we pulled the NAV CB (unit shut down) he could still hear the squelch and it would go away only when the COM CB was pulled.

Click to expand...

The 430 (assume 650 si similar) has both a nav Circuit Board and a Comm Circuit board. The nav board controls the general unit I/O's and display and the Nav receiver. The com board controls the entire Com function, however, all of the I/O run through the nav board, so nothing can be changed when the nav board is down. Each board has it's own connector, so the com function will work even when the nav board is down, you just can't change or adjust anything. I believe this is done in part for redundancy and a way to keep costs down for supporting the different models (with and without comm), as the entire comm board can be left out.

lr172 said:

The 430 (assume 650 si similar) has both a nav Circuit Board and a Comm Circuit board. The nav board controls the general unit I/O's and display and the Nav receiver. The com board controls the entire Com function, however, all of the I/O run through the nav board, so nothing can be changed when the nav board is down. Each board has it's own connector, so the com function will work even when the nav board is down, you just can't change or adjust anything. I believe this is done in part for redundancy and a way to keep costs down for supporting the different models (with and without comm), as the entire comm board can be left out.

Click to expand...

The 650 is the same in terms of circuit boards, I had always assumed that since I don't see the unit booting up with the NAV CB pulled, that they whole unit is not functional anymore.
I appears the unit boots up but since the display is not powered, it will appear to be all shut down.

It makes sense now and thanks for explaining.