Impulse QT-204 Depth Sounder trouble shooting

[Capn Crunch]

Wasn't sure if I should add to (felt like I'd be hijacking) the previous post from mbenner, I am having issues w/factory installed sounder on my "das boot'" as well... Impulse QT-204. One day worked fine, next - when I turn it on it shows 0.0 for a few (10-20) seconds and then starts flashing the 0.0 reading without end. Not sure if this is my head unit or the transducer... or maybe as simple as a wiring/short/ground issue?

Any one have any suggestions?

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[Viper]

If you've checked the obvious things such as source voltage and wiring, usually the best thing to do with older units is simply replace both the head and ducer with a newer model. Usually you can tell if the ducer is working by putting your ear next to it and listening for a clicking sound. But if there is no sound, is it a failed ducer or a head that's failing to trigger the ducer? Buy a replacement ducer and you could find that you have the same problem if the real failure is the head. Replace just the head and you may find it was the ducer all along. Even if you get it right, you've now put money into a system where the other major component is still decades old and may fail shortly as well.

Does this happen at every depth? I assume you checked the ducer face to ensure it is free of marine growth?

[Capn Crunch]

Qr Bbpost Does this happen at every depth? I assume you checked the ducer face to ensure it is free of marine growth?

First, Thanks Viper for the reply!! It does happen at every depth... from the time I turn the unit on... when I first turn it on it shows only "0.0" and then after a short period of time it starts flashing the 0.0. The transducer is mounted to the internal side of the hull... I don't think it protrudes thru-hull, although I never checked while it was trailered... being a new to us boat and having no previous experience w/cabin cruiser (bowrider doesn't even have a fishfinder, let alone sounder) I didn't think to check that aspect of boat - total noob here lol. The sounder worked when we purchased it and had just fine, until last week. That's when this started.

I buy into your explanation of replacement of both ends of system... it does however bring up other questions from the noob in me. Was considering adding a lower end chartplotter of some sort so I could cruise down river to Portland Ore from my Marina (about 220 miles as crow flies)... so mounting a new transducer - worried about poking a hole in the transom for the transducer first... second, stringing wire to bridge seems a bit problematic as wiring appears to be between ?hulls? not sure if that's the right terminology -

At any rate... just wondering how big a job this'll turn into?

Thanks again,

Mark

[Viper]

Mark, if your current unit shoots thru the hull rather than an assembly that protrudes thru the hull, these are typically filled with fluid. If the fluid has leaked out, you won't get a proper reading.

If you're thinking of upgrading, you can go with a ducer that shoots thru the hull so no holes needed though that wouldn't be my first choice, you can go with a ducer that mounts in a hole at the bottom of the hull, or if you have sterndrives, you can opt for a transom mount. The transom mount only requires a few small holes for a mounting bracket and a small hole above the water line where you would run the cable from the ducer to the inside of the boat. Then it's just a matter of finding a way to run the cable to the bridge. Following your engine harness and shift/throttle cables will lead you in the right direction.

[Mikep2389]

Not to bring up older thread but I'm looking to buy an Impulse qt-204 if somebody has one lying around. Screen on mine broke.