Anyone understand Icoms?

[trevelyan]

Have a problem with my Icom IC A22E, and would like to see if anyone can help before i send it of to them for investigation!

I fly a PFA aircraft that has a Lynx Headset system. This sytem has special headsets that plug into a junction box under the dash, out of this box comes the wiring to the PTT switches on the sticks, and the power and 2 pin adapter to plug into the Icom.

The system was connected up prior to a recent flight and was fine for half an hour, then after getting into the aircraft, and without touching anything, the wires that lead to the Icom started to overheat and smoke to a point the some of the external sheath melted. I unplugged the system rather sharpish and everything calmed down. Turns out that a small 1.5a fuse had been replaced by a piece of foil, which must be the reason that it overheated.

The Icom only had the 2 pin plug into the top of the unit (which I assume is for the headsets), I wasnt using the power adapter, just the Icoms own battery power.

Now when I plug My DC`s into it using a headset adaptor, I can hear ATC but so faint that it is useless. As soon as I unplug the 2 pin headset adapter, normal external volume is restored. Ive tried another headset and had the same results. This has ended up with ATC being able to hear me, but due to the engine noise I cant hear them.

Has anybody else had a problem with the volume with a headset plugged in? Im not sure if the 2 pin plug on the top of the Icom carries a voltage, so Im not sure if the events of last week could have affected the unit?

The lynx headsets have a battery in them, so you have comms full time even without the master on, not sure if this is related?

Long shot I know, but I thought id at least ask as im a comms numpty. (ive only just started flying this a/c and havent used Icoms before)

Cheers for your time.

:ok:

[Genghis the Engineer]

Not absolutely sure, but my best guess is that your battery pack may be knackered - they don't live forever I'm afraid.

But, venturing outside that - if there is a connection to a rectifier/regulator on the aircraft, you can damage the circuit if it's direct - rather than having a (separate) battery in the circuit. If not, you tend to get large power spikes off the rectifier that do sensitive electrics no particular good.

That said, there was probably a pre-existing fault, otherwise why would some numpty have inserted a piece of foil - presumably because the fuse kept blowing? But again, my money's on the battery pack - possibly damaged by a messy power feed into it (not necessarily at the time you were using it).


That said, I may misread you - are you saying that the headset leads became heated? If so either the headset or the Icom has an internal short. Put a resistance meter (multimeter) across the various headset plugs and see if it's giving about the resistance reading it should (the headset manual should tell you what to expect).


G

[trevelyan]

otherwise why would some numpty have inserted a piece of foil - presumably because the fuse kept blowing?

Agreed! Unfortunately tucked away and out of sight it became evident as part of the post event check, rather than part of any pre-flight.

The Icom is brand spankers, so the Battery should be ok.

:confused:

[Genghis the Engineer]

Not necessarily - if somebody has shorted it out or overcharged it it could be nearly new and completely knackered.

G

[yakker]

"This sytem has special headsets that plug into a junction box under the dash"
Not just a junction box, has a power unit and amp, this is probably where the fault lies, return it to Lynx for them to check it.