TX will not work

[crxcte]

Anyone have a trouble shooting guide for a PTT not working?  Audio panel and intercom was checked out good on the bench.  I have 2 coms and neither will TX when PTT is pressed on pilot or co-pilot side. 

As I understand it, when the tip and ring are connected (PTT) from the mic plug, TX should occur.

Any help on checks would be great.

layout is 2 coms, Narco CP36 audio panel, Sigtronics SPA400 intercom.

[Piloto]

Does it transmit pressing the PTT on the handheld mic.?. If not the PTT line connection to the CP36 is broken. 

José

[takair]

2 hours ago, crxcte said:

Anyone have a trouble shooting guide for a PTT not working?  Audio panel and intercom was checked out good on the bench.  I have 2 coms and neither will TX when PTT is pressed on pilot or co-pilot side. 

As I understand it, when the tip and ring are connected (PTT) from the mic plug, TX should occur.

Any help on checks would be great.

layout is 2 coms, Narco CP36 audio panel, Sigtronics SPA400 intercom.

Did it ever work?  The radio ptt needs ground to transmit.  You apply ground through the switch, to the tip to the ptt in the radio.  Sometimes you pick up the ground through the sleeve.  If you have it to the ring, you are losing your mic audio to the ptt circuit.  

[crxcte]

Does not work when using handheld microphone.

Verified the plug used for intercom input had continuity with the PTT.  If that is the problem must be between the intercom and audio panel.

[crxcte]

Yes, it has worked in the past.  Started becoming intermittent then later stopped. 

So if I shorted Mic Jack Audio to Mic Jack Key In of the audio panel it should display transmit on the radio?

[takair]

16 minutes ago, crxcte said:

Yes, it has worked in the past.  Started becoming intermittent then later stopped. 

So if I shorted Mic Jack Audio to Mic Jack Key In of the audio panel it should display transmit on the radio?

No, add a ground to the contact that would go to the tip.  That should provide a ground to the ptt if the wire is good.  Since it does not work on either ptt, hand mic, or either radio,   My guess is that the problem is at the audio panel.  Perhaps the key wire broke off or the audio panel is not seated right.  In older Mooneys with the audio panel at the top, they are prone to moisture from the removable panels....you may have corrosion on the pins.  Not much to go wrong inside those old audio panels, pretty bulletproof.