Saturday, January 7, 2017

Wiring fuax pas

A couple of wires got swapped around during a new gear install and the subsequent damage was north of $7000. You had to look closely at the wiring to see what went wrong. This is the terminal block inside a Garmin GSD26 CHIRP sounder module, and the wiring is coming from an Airmar 2kW/3kW r109LH CHIRP transducer. This costly error was made when it was installed and resulted in the failure of two sounder modules, and a very expensive transducer.

In dual frequency CHIRP transducers, there are two sets of transducers. One for high frequencies, and one for low. In the case of the R109LH transducer, there is a bank of 15 low frequency elements, and one large high frequency element.

When the transducer is connected to a CHIRP sounder module two separate transducers are being connected. The blue and its associated black wire is connected to the high frequency terminal block you see on the right side. The low frequency wires, blue/white, and its black wire are for the low frequency side connected on the left side. You can see from the photo, and my annotation this did not happen correctly. They were inadvertently swapped.

I first saw the boat when the owner contacted me about the sounder module not working. This is a working boat used for fishing charters. The boat was new to them, and was bought elsewhere. At the time of purchase the owner wanted a Garmin CHIRP fish finder, and the subsequent system was built around the GSD 26, and the Airmar R109LH transducer.

I stopped by and looked at the GSD 26, and there is zero doubt about the lack of functionality. The owner was really upset. The dialog started with how disappointed they had been with the system's performance, and they should have bought another fish finder brand instead. Bad dock gossip is never good for any brand of marine electronics.

I had a spare GSD 26 set aside for use as an emergency replacement for fishing tournament and working charter boats. Until now it has never been needed.

I leave the boat, pick up the new loaner sounder module, return and get ready to uninstall the non-op module, and that's when I saw the wiring. I leave the boat again to get my good camera and took the picture you see. The old module is then pulled, the new module is installed and I fired the system up.

I was very concerned, but everything initially seemed okay dockside. I played with the system for a while. It appeared to be operating fine, at least as well as I could tell in shallow water dockside and I'm very relieved. It appears the transducer may not have been damaged. The boat goes back to work. I talked to the owner at the end of the day, and there was a vast improvement in the operation of the system, but there was still the lingering shadow of a doubt it wasn't quite as good as they were hoping for. Then a few days later the phone rings, and now there is a problem. The high frequency side of the GSD26 system has stopped working completely.  

It's now time for some modest conjecture about what has happened here. No one to my knowledge has dealt with this wire swap transducer problem at these higher power levels and the potential consequences are not well understood. We however can make some observations, The first one is empirical. The sounder module was not happy with having the high and low frequency wiring swamped. It performed poorly, and  in a short period of time failed outright. It's my understanding that the low frequency elements of the transducer would not be as prone to damage, but the high frequency elements are very likely to suffer in this scenario.

My guess is that after GSD 26 loaner module was installed, the already damaged high frequency transducer element failed completely, taking the loaner GSD 26 to Davy Jones Locker with it. So in sum the original GSD 26 failed along with the loaner and the transducer's high frequency ceramic element has been irreparably damaged, and there still could be damage to the low frequency elements to boot.  

This is not pretty. In the real world the damage caused by swapping the the two wire pairs cost north $7000 thousand dollars to rectify. A third new sounder module, hauling the boat, uninstalling the old transducer, and installing a brand new one all caused by two sets of wires in the wrong place.

There is a one bright spot in this technical conundrum. Garmin, although it's very clear they had no obligation to do so graciously agreed to replace the sounder module, and transducer easing some of the fiscal tribulations for the owner of this working boat who was not well endowed with lots of cash. He still had to pay for haul out and installation of the new transducer. I donated my time for the repair. Pro bono work creates good karma, at least in the long run.

Why did this all occur in the first place? I will never know, and would be the first to say that I have made mistakes myself, but never this expensive. The lesson learned here is to check any work on your boat carefully, and read the directions carefully first. Regardless of whether you do the work, or a marine technician, certified or otherwise does the work, remember the manufacturer is never responsible for incorrectly installed marine equipment. The person who installed it is!


  1. was the owner satisfied with the performance once everything was replaced with known good stuff?

    1. Corey, yes. This same hardware and transducer can hold bottom at over 17,000 ft. I have seen images of swordfish just off of the bottom in over 2000 ft. They were very pleased and for the first time had seen the system operating correctly.


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