Depth Sounder Problem

[Doug]

Looking for a little help with a depth problem.
My boat came with a SIGNET depth sounder/ knotmeter. The knot meter worked, but the depth did not. The previous owner said he had trouble with the depth sounder and had both the had unit and the transducer tested and found to be good.

I've already:

Sent the head unit to Signet for testing (unit is OK)
Traced all wiring, the pulled all wiring.
Hooked the unit direct to a good battery and a short, new wire to the transducer.
Adjusted gain

Still get a -0- depth reading. 

Can't think of what else to do, and any suggestions would be welcomed.

Long shot question: Could bottom paint applied over the through hull effect it?

[Jeff Kaplan]

doug, not supposed to apply antifouling paint over the transducer. this might be where your problem is, if not, at least a starting point to look. there is a special transducer paint, black, looks like a nail polish bottle and goes on with a brush attached to cap. sold in all boat stores. try to carefully remove the old paint and apply new transducer paint, which btw, is antifouling...jeff

[Ron Hill]

Doug : If you don't have SPECIAL transducer paint on the face of the depth transducer- that could be your problem??
However, with another boat I learned that if you have problems with any instrument, that you send the instrument and the transducer back to the manufacturer - so they can check them as a MATCHED PAIR!! 
If the boat's in the water, find someone that also has a Signet and check your instrument with his transducer and your transducer with his instrument. 

[Tom Lanzilli]

If removing the paint does not fix the problem my guess is their could be a ground issue or the sensor is just bad.  My speed sensor whent bad on me last year, in the process of troubleshooting I was told they loose strength over time (8 to 10 years) the manufacturer worked through a test process with me to help narrow the problem down.

[Jeff Kaplan]

doug, my guess is that the transducer is bad. you didn't state whether you sent both units back to the factory for test or only the guage. as ron stated, both should be sent back. my thought was to remove any anti-fouling paint first, to see if that made a difference. if the guage showed good by the mfg. the fault lies with the transducer...jeff

[Gary Ambrose]

Doug,

Jeff has good advice.  I had a similar problem and it was the transducer.  They have an element that sends a signal to the bottom and they do tire after awhile.  I found that purchasing a new transducer and hanging it over the rail, into the water, and then connecting to the instrument immediately located the problem.  I then waited to haul out before removing the old transducer.