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A210 and Sigtronics SPA-4S - Help Please

D

Darinh

Well Known Member
Guys,

I have got my intercom (Sigtronics SPA-4S) wired up to the radio (A210) using the Sigtronics wiring diagram for the A200 they provide on their website as a guide. The pin assignments looked to be the same between the A200 and the A210 at least for the connections called out. I have it wired for music also.

Now the issues..I can listen to music and hear radio transmissions all clear as a bell but when nothing is being received all I hear is static. I can obviously send a transmission as I can activate the runway lighting but when I hit the push-to-talk, no voice is transmitted...the static goes away but no voice.??

Any ideas? I would guess it would be something with my mic wiring or jacks based on the above mentioned performance but I am a novice at best with electrical troubleshooting and was hoping someone had either experienced this and new a fix or could help me out based on my description of the problem. Any help is appreciated.

Thanks,

Darin
 
Some things to try

Hi Darin, I don't have this setup but I am an E.E. so lets try a few things. If you look at the A200 wiring diagram as shown for the sigtronics they show pins H and 7 coming from the A200 (210 in your case). This is the audio (and sidetone you hear) when you key the mike or just listen to the radio. They show a separate headphone jack connected to the radio and then to the intercom. Do you have this type of set up? If yes, try plugging in to that jack and see if you can hear radio transmissions. If yes, this eliminates the radio as being the problem. If no, very carefully check that pin H is not swapped anywhere. Pin 7 is ground and usually one side of the phone jack is grounded. If you have pin H going to the wrong side of the phone jack you have it shorted out. If you don't have this setup (only have the jacks from the sigtronics) then unplug the sigtronics and make a temporary connection from the radio pin H and pin 7 to a pair of headsets. If you can hear the radio now, the problem might be that you have pin H swapped in the sig connector.
What you want to do is break the system into simple parts. Check the radio, get it working, then connect the sigtronics. It sounds like you are part way there since you can key the transmitter. (bring up the landing lights). I hate to say it but don't forget the "duh" items like the volume for the radio, squelch etc. and lastly the built in functions. If you are using the sigtronics I suspect the A210 ICS is not needed and would be turned off. Hope this helps, if not let me know and we can try the next step.

Paul

pczar3
N694BP reserved
 
Let me try again

Hi again Darin,
Sorry I mis-read your post. I thought you could not hear the radio. If it is the mike circuit that is the problem, look at the mike jack connections. In particular check the tip and ring connections to make sure you don't have it shorted. The push to talk just keys the transmitter. It still needs the audio from the mike. If you plug both headphones in can you "talk to yourself"? That is speak into the co-pilot mike and hear it in your headset? If yes, then the problem is in the wiring from the sig to the A210. If not, then it is in the wiring of the jacks.

Paul

pczar3
N694BP reserved
 
Darin,

Paul brings up a good point. The plugs are supposed to be isolated from the panel by insulating washers. Check the drawing.

The other possible problem may be your headsets, are they stereo? If so, are they set to stereo?
 
pczar3 said:
Hi again Darin,
Sorry I mis-read your post. I thought you could not hear the radio. If it is the mike circuit that is the problem, look at the mike jack connections. In particular check the tip and ring connections to make sure you don't have it shorted. The push to talk just keys the transmitter. It still needs the audio from the mike. If you plug both headphones in can you "talk to yourself"? That is speak into the co-pilot mike and hear it in your headset? If yes, then the problem is in the wiring from the sig to the A210. If not, then it is in the wiring of the jacks.
Click to expand...

Paul,

Thanks for the reply...I have not tried to speak into the passenger mic and listen on the pilot headset so I will try that. I do know that when I speak into the pilot mic, the static stops and I can hear my voice in my headset just fine. I will also double check the jack connection to see if there are any shorts. Thanks again for the info and I will reply with my findings.

Darin
 
Jacks are fine

Paul,

I double checked the jacks and they are fine...mic jack is insulated from the airframe. I also plugged in the other headset and I can communicate with passenger headset just fine. Everything is clear as a bell...reception, communication in the cabin between headsets, I can key the runway lights but still can't transmit voice over the radio.

I have not yet check the wiring because I want to eliminate everything possible before I start tearing into the wiring. Given the above symptoms can I reasonably assume the problem is between the intercom and the radio? Or possibly a wrong connection dealing with the mic at the radio?

Thanks again,

Darin
 
Time to check some wiring

Hi Darin,
according to the Sig website, the brown wire from the intercom (J1-6) goes to Pin J on the radio. Also note that not all the letters are on the connector. That is there is no G and there is no I so make sure you count the pins correctly. You have eliminated the mic jacks because you can talk to yourself and you have verified you can hear the radio so the only thing to do is get the mike signal to the radio. Also check that you have your mic hooked to the white/black wire (the pilots input) on the sig J1-1.
Let me know what you find.
Paul

pczar3
N694BP reserved
 
Verified the Wiring

Paul,

I have verified the wiring to the radio and it is as stated in your post. This is getting very frustrating to say the least. I have no idea where to go next.

Darin
 
One thing to try.

Darin,
if you can break out the audio leads (brown and white wires) you could hook things up as if the Sig was not in the circuit. If you look at the picture on the Sig website you can see what they call the " aircraft hand mike jack" If you wire in a temporary jack like that (or disconnect the connector on the sig and temporarily connect a jack) you can make sure the radio works without the sig attached. I'm starting to think there is a problem either with the radio or the setup options for the radio. Did you check the wiring on the back of the radio connector? Remember the missing letters! If you would like to call me directly send me an email and I'll give you my home phone number. We'll get this figured out.
Paul

pczar3
N694BP reserved
 
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