Noisy Intercom

[markejackson02]

Have an older sigtronic intercom in the new M20J.  Right after starting the engine or powering up the avionics, it is unusable due to heavy static.  After about 10 minutes, it warms up and functions perfectly.  Is this indicative of any specific failure?

 

Mark Jackson

M20C N201TK KAXH

[larryb]

Right after startup your alternator has to work harder to re-charge the battery. You could have worn brushes causing noise on your electrical buss. An oscilloscope would identify this quickly. Once things clear up, what happens if you put a high load on the system, like the landing light and pitot heat?

[kerry]

I would call sigtronics.  The techs are really nice and helpful.  They'll help you trouble shoot your problem.  If you send the intercom to them I think they charge you $20 to check it out.  If it needs repair they're very reasonable.

[bumper]

To determine if it's internal to the intercom or caused by a defective alternator (brushes, diodes, or otherwise), pull the field circuit breaker and see if the noise stops. In the perhaps unlikely event that the noise continues unabated, then the most likely problem is woud be leaky or defective electrolytic filter capacitor in the intercom.

 

bumper

[OR75]

start with the most obvious .... make sure that the jacks connectors are tight and snug.

The tend to come loose and loose grouding will tend to create static.  Doubt this is it but never know.   

[markejackson02]

It's not the jacks or the alternator.  It happens on either side and goes away.  It's not the alternator as I can hear slight noise from the gear motor but nothing from the strobes or landing light.  I will get in touch with Sigtronics and probably send it in for fixing.

 

Thx for the suggestions.