Garmin 430W blowing fuses and not transmitting

Tmcdavitt

Tmcdavitt

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Tmcdavitt
I'm hoping someone can help point me in a general direction regarding my recently unreliable 430w...

I would like to state the obvious first; I'm not an A/P, nor am I a certified avionics technician. As such, I do not intend on attempting to repair my unit or any of the wiring myself. I wanted to state this so that this post does not stray down the path of "this is not owner maintenance."

My intent is to help the avionics shop with potential issues to avoid as much "hunting and pecking" on my bird as possible. I've had a few avionics shops work on my plane in the past and none of them have impressed me with their ability to troubleshoot certain issues. With that being said; they are extremely good at installing new G1000s or complete avionics packages...

My issue is this: my 430w decided to not transmit the other day without giving any indication (other than no replies from the tower of the controlled field I was trying to land at). It was on the appropriate frequency and the "TX" light was coming on when I depressed the PTT button. It was receiving fine and my headset was plugged in (I actually checked it first thinking that was the problem). I switched to my second radio (SL30) and continued my trip into the towered field. After a brief stop I headed back to my home (towered) field and asked the controller if we could check my radio - this is where I confirmed that even though the "TX" was indicating, the radio was not transmitting.

I searched the net and found some information regarding similar issues with the 430. The first thing I tried was to check the fuses. I found one blown and promptly replaced it. While sitting in my hangar I keyed up the ground frequency for a quick radio check which was responded to affirmatively. I thought at this point I must have fixed the issue and moved on. However; when I went to fly today (first opportunity since replacing the fuse) I found that the same issue was present. Once again I replaced the blown fuse and again that fuse did not last. (Of note, I do have an avionics master switch that I don't turn on until after the plane is running and I turn off the electronics prior to turning off the switch at the end of each flight - while the engine is still running).

Some of the other items that could cause this type of problem seem to be related to bad grounds, failing audio panel (in my case it's an old KM24), bad PTT switch, and/or the 430 is not fully seated in the cage (x amount of turns of the install screw once the power is engaged).

Can anyone provide additional issues to look for? Also, does anyone have good experience with an avionics shop in the Houston area?

Thanks!




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Brazos Avionics at EFD - solved a transponder problem for me when a couple other shops couldn't. The guy has worked avionics for 30 years or so and knows his stuff.
 
Oyy, this one will not be easy. Most likely it is a problem within the box and the only recourse you will have is to send it in. There is a possibility the problem is in the antenna loop, but not likely.
 
Thanks for the recommendation of Brazos. And thanks Henning, I'm hoping that it's not the box itself but we'll see. Doesn't garmin have a serious flat rate for the 430w?


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For effective troubleshooting you must resist the urge to lock yourself into unfounded assumptions. This could be caused by any number of things and one of them is the very shoddy nature of the majority of under panel wiring in general aviation aircraft.

With a good fuse and the avionics power applied try moving wire harnesses around under the darkened panel while watching for a spark. This is how I found a chafing wire causing a similar problem in our brand spanking new Maule. Even if you do not see a spark, if moving the harnesses around causes the fuse to blow there's a very good chance the problem is in there.

If nothing else you can at least eliminate that as a possible source and it will have cost you nothing other than a stiff neck.
 
Tmcdavitt said:
Thanks for the recommendation of Brazos. And thanks Henning, I'm hoping that it's not the box itself but we'll see. Doesn't garmin have a serious flat rate for the 430w?
Click to expand...

Garmin has a "serious" flat rate for everything.. They're not what I'd call a customer service oriented company.
 
I will second the idea of not assuming too much in the beginning and looking for the obvious. Many shops have a tendency to leave old wires in the airframe after upgrade work is completed and it is not uncommon to run across the occasional owner that is more than willing to dive into the panel and work on things without much guidance. You never know what you'll find if you start looking for shorts and stray voltage sources behind that panel.
 
Slide it into someone elses tray and see if the problem persists.
 
FORANE said:
Slide it into someone elses tray and see if the problem persists.
Click to expand...
As a non-tech owner, I would think that's your best approach.

I would suggest getting a hold of the G430 installation manual so you can understand a bit about how it's installed. For example, you have two separate power inputs, I think one for the radio and one for the navigator functions. That would typically mean two external fuses depending on the installer... sounds like you are blowing only one, and possibly at transmit time, etc.

Putting someone else's unit in your tray can be informative too... but you need a good friend for that.

... from an experimental panel builder
 
Like Bill said, there are two power inputs, Nav side and comm. If the whole radio goes dark, you lost both sides at once and most likely the shop that installed it tied both inputs into one fuse. If it doesn't go dark when the fuse blows, but doesn't transmit, it has two fuses, one on each input. I believe the Comm side of the display will be blank also if only the nav side is up.
Good suggestions above, slide it into another aircraft (but not vice versa).
Then follow the power wire(s) up from the fuse examining every inch, and take the D-sub connector apart and look for problems in there. I'd do one or both of these before sending it in to Garmin to pay $900 and be told nothing is wrong.
It could very well be the radio, but I would eliminate the aircraft first.
And.....what size fuse is in there? I ought to be 10 a amp for the comm side and 5 for the Nav. If it has only one fuse feeding both comm and Nav the fuse size is a guess as Garmin doesn't show a fuse size for that configuration, they show it wired with two inputs and two fuses.
Good luck
Tim
 
I doubt you have any records or wiring diagrams in the aircraft manuals for your installation if it's not factory installed. You can get a lot of information by downloading the installation document for your unit. It should be described in the 337, even if you don't have the exact version, you can see what wires and connector pins do what and get a good idea what should be connected where.

Slide the unit out and see what you have on your power and ground pins. Make sure no other (incorrect wire) is supplying a power or ground. I didn't look through all the details in the OP. I can't make myself. I'll be doing it all night after I get to work.

I guess the power input could have an internal short. I don't really know what types of failures are common for these units. Are you sure you are correlating the failure to the correct events in the cockpit. Sometimes the effect of actions in the cockpit take a few seconds to reveal themselves.
 
If no one has already mentioned, perform a very close visual inspection of the pins on the connectors. All the pins should be straight, none laid over. Also try to verify there is no damage (cracks, contamination) in the insulating materials between the pins. Both in the tray and on the unit.
 
I sent my 430W to Garmin once for repair, there was nothing wrong with the unit (problem was elsewhere), but they charged me $900 any way and didn't even update the software!
 
Trying to come full circle...

I brought my trusty 6 to a very reputable avionics shop in town and had a few things done. Amongst all of the additions (new BT audio panel and 330es) I asked the shop to try and find my fuse issue. As most of you replied - it was a bad crimp on one of the power pins in the connector. It wasn't easy to find, either (couldn't shake the harness to look for sparks). It seems as if the crimp was over compressed and it broke several strands of the wire which made the connection intermittent. It's crazy that it just now failed - but it was certainly bound to happen.

As an aside - the shop pulled out all of the intercom jacks and ran new ones (the new audio panel has stereo outputs). The existing wire was telephone wire... Also, the coax for the GPS antenna was RG58 (home cable) as opposed to the required coax specified by garmin. It seems as if whoever installed the antenna last (there's two GPS antennas on the top of the fuselage) was uncomfortable with making their own coax ends so they just installed a pre-made one and zip-tied up the excess cable behind the panel.

I hope that this post helps someone else in a future search. :)

Thanks.


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One other note: the first thing I did was to have the unit bench tested by the avionics shop. It tested fine which then pointed at the installation. Saved $900! Thanks again.


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Thanks for the follow up.

With regards to the RG400 antenna cable, if I recall correctly Garmin mandates a minimum length for that cable of something like 14 feet. So, even if they made their own cable you might still have some excess antenna zip tied behind the panel.
 
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