Avionics master relay bad

[bmcconnaha]

Any help is appreciated.  We flew 500mi to pick my plane up at the avionics shop.  We did our first shakedown flight and when we landed I shut the avions master down.  It was normal.  When I turned the master switch back on, all avionics powered.  Shop thinks it's the avionics relay after some testing.  Any ideas? I've glanced at the other threads.  Still not sure where to source one.  It's a 1990 28 volt J.  

Thanks! 

[PT20J]

According to the service manual it appears to be a Kissling 26.64.01 28V 100A relay: https://www.te.com/content/dam/te-com/documents/industrial-and-commercial-transportation/global/kissling-documents-data-sheets/Data_Sheets_Documents_Kissling/contractors/KI-Relay26-100A-ds-a4-K1166685-en-2012.pdf

You might call the the manufacturer (TE Connectivity) and see if you can find out who stocks them or if they are special order.

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[Aerodon]

I have one for you, Aerodon supercub180@gmail.com

 

[flyboy0681]

I had the same problem a few years ago and it did turn out to be the avionics relay.

[PT20J]

Since you said that the shop did troubleshooting, I presume they know that the avionics master switch is wired so that the OFF position actually powers the relay to remove power from the avionics bus. This is a failsafe design so that a switch or relay coil failure will turn the radios on. So, the symptom you describe can also be caused by a failed switch or a broken wire. The relay is powered via the Aux Bus, so pulling that breaker will also cause the radios to turn on. However, a number of other items are powered off the Aux Bus depending on the airplane and you would probably notice that other things weren't working if that was the problem. But, it is still worth checking.

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[carusoam]

+1 for being familiar with the fail safe operation of the avionics master…. And it’s wiring 

If it isn’t working properly… they probably get replaced… older relays may have had a clean and re-use ability….

Expect that there is a phenolic part inside that may have failed….

PP thoughts only,

-a-