intercom problems, Any ideas?

[Morgan3820]

Background;
I purchased a PA-28-151with a PS engineering 1000II intercom. I went to my local avionics installer (30 yrs. experience) and asked him to add a second ptt switch on the right side yoke.

After laboring on it for a while he couldn't get it to work. Plug into the right side jacks, press the button and the transmit light on the radio (Mitchell MX170) and the intercom indicate transmission but nothing goes out and I do not hear any carrier in my headset. Installer guy says that the relay in the intercom that switches between right and left mike jacks is faulty.

I call PS engineering support. They say that they have never seen such a fault...ever. After doing some mike swapping and testing he feels that the installer has it wired up wrong. That it is wired in parallel. While common for other intercoms, they wire theirs individually to the intercom. Ask the installer to talk with tech support, which he does.

Back to the installer for a second look at the wiring. Installer says that it is wired correctly. Suggests sending unit to PS engineering support. $100 service fee to find out that the unit is working fine. They replace the suspect relay anyway. Back in the airplane, nothing has changed, still showing as transmitting on the radio and intercom but nothing out and no carrier in the headset.

Personally, I like the installer because he will do small jobs and doesn't push $30K full panel upgrades, but I am beginning to doubt his abilities.

Thanks in advance for any ideas.

 

[N801BH]

Background;
I purchased a PA-28-151with a PS engineering 1000II intercom. I went to my local avionics installer (30 yrs. experience) and asked him to add a second ptt switch on the right side yoke.

After laboring on it for a while he couldn't get it to work. Plug into the right side jacks, press the button and the transmit light on the radio (Mitchell MX170) and the intercom indicate transmission but nothing goes out and I do not hear any carrier in my headset. Installer guy says that the relay in the intercom that switches between right and left mike jacks is faulty.

I call PS engineering support. They say that they have never seen such a fault...ever. After doing some mike swapping and testing he feels that the installer has it wired up wrong. That it is wired in parallel. While common for other intercoms, they wire theirs individually to the intercom. Ask the installer to talk with tech support, which he does.

Back to the installer for a second look at the wiring. Installer says that it is wired correctly. Suggests sending unit to PS engineering support. $100 service fee to find out that the unit is working fine. They replace the suspect relay anyway. Back in the airplane, nothing has changed, still showing as transmitting on the radio and intercom but nothing out and no carrier in the headset.

Personally, I like the installer because he will do small jobs and doesn't push $30K full panel upgrades, but I am beginning to doubt his abilities.

Thanks in advance for any ideas.

I have a PS 1000II and I can say.......

He has it wired wrong.... BTDT...

 

[weirdjim]

Background;

After laboring on it for a while he couldn't get it to work. Plug into the right side jacks, press the button and the transmit light on the radio (Mitchell MX170) and the intercom indicate transmission but nothing goes out and I do not hear any carrier in my headset.

You can't hear carrier in your headset. If you mean you can't hear SIDETONE in your headset that is an entirely different matter. Can a portable radio at some distance (say, more than a couple of football fields away) from your aircraft hear carrier when you press the new PTT switch?

Installer guy says that the relay in the intercom that switches between right and left mike jacks is faulty.

Most probably not. PS Eng. (and RST Eng. too) use dry-circuit relays for switching low level microphone elements. That means the contacts are gold-flashed and have lifetimes measured in decades and not years.

I call PS engineering support. They say that they have never seen such a fault...ever. After doing some mike swapping and testing he feels that the installer has it wired up wrong. That it is wired in parallel. While common for other intercoms, they wire theirs individually to the intercom. Ask the installer to talk with tech support, which he does.

Like PS tech support said, a few of us wire the PTT switches individually to the intercom so that the intercom has a fighting chance to figure out which microphone to run "hot" to the transmitter. Wiring the PTT switches in parallel defeats good engineering. Do this ... push the copilot PTT switch and see if the PILOT headset has sidetone. THis is an absolutely foolproof test to see if the PTT switches are incorrectly wired in parallel.

Back to the installer for a second look at the wiring. Installer says that it is wired correctly. Suggests sending unit to PS engineering support. $100 service fee to find out that the unit is working fine. They replace the suspect relay anyway. Back in the airplane, nothing has changed, still showing as transmitting on the radio and intercom but nothing out and no carrier in the headset.

...again, CARRIER is detected with a handheld at a distance from the aircraft SIDETONE is present in the transmitting headset.

Personally, I like the installer because he will do small jobs and doesn't push $30K full panel upgrades, but I am beginning to doubt his abilities.

Thanks in advance for any ideas.

.....

 

[Neal Howard]

Installer has wired it wrong.

Just like Jim says, check to make sure that the Pilot and Co-Pilot side PTT switches are wired to their corresponding _separate_ PTT connections on the intercom's DB connector. They are separate and not equal connections on the PSE intercoms and they are specifically labelled which connection is for which side. Also make sure that the mic input connections on the intercom are correctly wired to the appropriate jacks for the correct sides of the aircraft.

On a PSE intercom, the Co-Pilot PTT switch triggers the intercom's internal relay to select audio coming in only from the Co-Pilot's side microphone and disconnects the Pilot's side mic input while the Co-Pilot side button is pressed. If the installer does not "grok" this concept and is thinking in terms of simpler intercoms where all mic inputs are equal and all PTT switch connections are equal and has simply wired the PTT switches together on the single pilot's side PTT input, it'll never work. It'll also never work if the PTT switches are flip-flopped between Pilot and Co-Pilot sides of the aircraft... in that situation, both sides will only get dead carriers, with no mic modulation on transmit.