Garmin Fishfinder 90 broken - can I use the sensor with another instrument?

[pouch]

Our boat has a Garmin Fishfinder 90, this was fitted about 2 years ago, but is not working. The unit has been mounted to the bulkhead and the screen looks like the water ha got in and I assume thats the reason for failure.

Question
Can I change the fish finder for a simple and clear to read depth guage such as a NASA?
Will the Garmin sensor work with another instrument, or must I replace both?

 

[mainmarine]

My Garmin 100 is wired to an old raymarine ST30 transducer that was already fitted to my hull. if you check the Airmar cross reference pages here
:http://www.airmartechnology.com/airmar2005/ex20/RMProducts/RMMain.asp?LinkID= it should tell you the frequency of your fish finder. Airmar supply most sounder transducers.

 

[TYKE]

I had a fish finder with a Japanese sounding name for which I could find no information whatsoever. I connected a VDO depth gauge to the existing transducer and it worked perfectly, even the same connector!
Whilst asking the same question prior to trying it I found that there appear to be 2 frequencies used for depth transducers - 150 & 200khz, I dont know what mine is but it worked.