Phil123 Posted December 12 Report Posted December 12 Hi, I am trying to troubleshoot a new squawk in our M20C, our COM2 radio does not work properly anymore. We have a KA134 audio panel, PM1000 intercom, Garmin 430 COM1 and Icom IC-A200 COM2. The radio seems to be working just fine and I confirmed that it is still sending, but I can’t receive anything, and I also won’t hear myself when I send. When I switch the panel to both with both radios on the same frequency and COM2 as sender, I can hear the transmission on COM1. It might be the something wrong in the connection between the radio and the audio panel, or maybe the panel itself as it looks quite old… Any troubleshooting tips on how to narrow down the problem? Thank you Philip
AndreiC Posted December 12 Report Posted December 12 I have the same KA134 panel and the old switches do not always work as they should. Try to push them in/out a number of times. The weird thing is that a button unrelated to the one you care about may be causing the problems. (ADF or DME or one of the NAVs…) On mine, once I got the radios to work well, I never touch the other buttons.
Echo Posted December 12 Report Posted December 12 I have a similar intermittent problem. I found that powering off the intercom and powering it back on FIXES the problem ever time.
Phil123 Posted December 13 Author Report Posted December 13 Thanks for the tips, I will give it a try tomorrow. Are there any drop-in replacements for the KA134?
AndreiC Posted December 13 Report Posted December 13 1 hour ago, Phil123 said: Are there any drop-in replacements for the KA134? None that I could find. I bought a used KA134 from ebay that was marginally better than the one I used to have. But this equipment is 55 years old, so my next upgrade will likely be a modern audio panel.
Phil123 Posted December 15 Author Report Posted December 15 On 12/12/2025 at 1:38 PM, AndreiC said: I have the same KA134 panel and the old switches do not always work as they should. Try to push them in/out a number of times. The weird thing is that a button unrelated to the one you care about may be causing the problems. (ADF or DME or one of the NAVs…) On mine, once I got the radios to work well, I never touch the other buttons. Switching the buttons helped. Let‘s see for how long
Phil123 Posted December 15 Author Report Posted December 15 On 12/13/2025 at 1:24 PM, AndreiC said: None that I could find. I bought a used KA134 from ebay that was marginally better than the one I used to have. But this equipment is 55 years old, so my next upgrade will likely be a modern audio panel. Do you know if anybody does overhauls on these old audiopanels?
AndreiC Posted December 15 Report Posted December 15 20 hours ago, Phil123 said: Do you know if anybody does overhauls on these old audiopanels? I strongly doubt it. My avionics shop said the switches in these units are not serviceable, so probably they would need to find new ones and solder them back out/in. Doubt that is worth the effort, even if the switches can be found (which is highly doubtful). 1
Andy95W Posted Tuesday at 08:58 PM Report Posted Tuesday at 08:58 PM On 12/14/2025 at 10:17 PM, Phil123 said: Do you know if anybody does overhauls on these old audiopanels? @Phil123- try the usual places for KA-134 overhaul like Sarasota Avionics, Gulf Coast Avionics, and Bevan ( @Jake@BevanAviation). I bet a good cleaning will probably fix 90% of your issues. Those audio panels are fairly bulletproof. 3
AndreiC Posted Tuesday at 09:05 PM Report Posted Tuesday at 09:05 PM 5 minutes ago, Andy95W said: @Phil123- try the usual places for KA-134 overhaul like Sarasota Avionics, Gulf Coast Avionics, and Bevan ( @Jake@BevanAviation). I bet a good cleaning will probably fix 90% of your issues. Those audio panels are fairly bulletproof. I for one would be very happy if this audio panel can be cleaned up and restored to full functionality, I am happy with it otherwise. @Phil123 please keep me posted if you find someone who can work on it.
Bob E Posted Tuesday at 11:16 PM Report Posted Tuesday at 11:16 PM I agree that it's probably the audio panel. Before you spend $$$ to fix anything, you might try removing the audio panel and spraying all the switch contacts with some silicone contact cleaner and lubricant. Spray liberally while you're working the switches, and see if that helps.
AndreiC Posted Tuesday at 11:34 PM Report Posted Tuesday at 11:34 PM 16 minutes ago, Bob E said: I agree that it's probably the audio panel. Before you spend $$$ to fix anything, you might try removing the audio panel and spraying all the switch contacts with some silicone contact cleaner and lubricant. Spray liberally while you're working the switches, and see if that helps. I tried that on my panel, and it did not help. The issue seems to be that the switches are supposed to be sealed, so not much of the cleaner, if any, gets in.
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