SL-30 failure

[N787R]

Has anyone experience comm frequency to change on its own?

I also get comm failure message at the same time.
I check power / ground connections and fuse values which were all correct.
I have seen the previous thread on SL30 failures, but have not seen anyone experience change of comm frequency.

thanks

b

 

[SteinAir]

The "Comm Failure" message usually shows up first with a wiring problem in the RS-232 Rx and Tx being wrong. If that's not the case, a wiring problem with the comm itself can cause it, and lastly it can of course just fail. Is this a new install coupled to an EFIS? If so, make sure you didn't hook the EFIS RS-232 Tx to the Radio Tx and the Rx to the Rx - this is a very common mistake made by people wiring their own stuff together. If it's not a new install and it was working before, then it's probably not the RS-232 lines.

Cheers,
Stein

 

[N787R]

sl30 wiring

thanks stein.
it is a new install. And I have connected the sl30 tx line to Dynon HS34 RX input.
SL30 RX line is connected to ground.
So based on your suggestion I will disconnect SL30 from Dynon and see what happens.

One additional information point : It seems to happen when the unit is warmed up. If I turn it off for a while and then back on, then it is ok for a few minutes.

Regards.

B

 

[n2prise]

SL-30 failure.

I have been flying my SL-30 for three years in my RV-9A. From the beginning, the RS-232 TX line has been tied to my Dynon D10-A via a switch that permits a connection from my Garmin GPS-296 as an alternate. The RX port of the SL-30 was connected to the TX data line from the GPS-296 to input radio frequencies to the SL-30. The TX data line from the GPS-296 also drives my autopilot and the Dynon D10-A. The panel-mounted switch I use to select data going to the D10-A from either the GPS-296 or the SL-30 has a "center off" position to prevent either unit from sending data to the D10-A. I use the center off position when I want to connect my laptop computer to the D10-A for software upgrades.

About a year ago, I had a problem with the COMM radio not staying on frequency, flip-flopping on its own. I had that fixed last year and flew it about 25 hours in the past year. It failed again this fall with the COMM FAILURE message displayed (but not last year). This time it continued to transmit and receive on the last assigned channel until I turned it off and back on. Leave it off for a long time and it would work "briefly" to get on a frequency and then the COMM FAILURE message would return. Pulling the volume knob would not open the squelch during the failure mode. The entire NAV board was changed during the most recent repair. The NAV functions worked just fine, but the problem with serial data communications between the two main boards seemed to be the issue. The unit was just returned to me and I have not yet been to the airport to install it and test it as of this writing.