HDS-7 Gen 2 / P79 Losing depth at speed

[ncp]

I didn't have any issues with depth readings (at idle or on a plane) for the first 6 months of having the HDS-7 / P79 installed. Now, I lose depth when I'm up on a plane.

-HDS-7 Gen 2
-P79 in-hull, using mineral oil (just what I chose to use initially, haven't tried anything else)
-Purchased 05/02/12, installed mid-summer 2012
-Transducer wire runs along with wire for stern light and battery cable (I mention this because of possible interference but, again, it worked for the first 6 months before crapping out...).

Pic #1
-Aft is to the left, bow is to the right
-Black thingy along bottom of pic is the drive shaft
-Raw water intake is in the middle, just below the transducer
-Black tube hanging into the bilge from the upper left is manual bilge pump (pump handle is above deck level at transom)

Pic #2
Just showing that it did work on a plane before!!! (left is speed in mph and right is depth in feet)

Checked so far:
** Fluid level in transducer reservoir. Full! I figured that maybe the fluid was sloshing backwards while I was on a plane but the reservoir was full.
Need to check:
** Higher rpm's at neutral at dock to see if it cuts out

I would like to figure it out in the next week and a half in case of needing warranty work from Lowrance prior to my one year expiring. Besides checking depth at a higher rpm at the dock, what else to check before sending it in?

(Talked to Lowrance tech supports today and their only advice was to try high rpm at dock)

[Peter_C]

My recommendation would be to call the manufacturer and start a case with a number since your warranty is coming up fast. Plus they usually have good advice and really do want the components working and a happy customer.

Most of the time it is a transducer issue. Either by lack of connectivity to the water, from being knocked lose etc, or flat out failure. I have had both issues in the past and Hummingbird in my case took care of the issue. I did have to send my head unit in for them to confirm it worked, and they sent it back along with a brand new transducer.

[jyasaki]

Originally Posted by ncp

-Transducer wire runs along with wire for stern light and battery cable (I mention this because of possible interference but, again, it worked for the first 6 months before crapping out...).

Both DC signals, so that should not be an issue, unless you've got a ton of noise on your battery cable (a voltmeter set to AC should give you a rough idea.)

Can't really think of a reliable method of isolating the problem. Unless you can pull the ducer and hang it over the side or back while running (didn't really think so)?


jky

[ncp]

Originally Posted by Peter_C

My recommendation would be to call the manufacturer and start a case with a number since your warranty is coming up fast. Plus they usually have good advice and really do want the components working and a happy customer.

Did that yesterday. Didn't get the brightest tech on the phone. He didn't know that a P79 was an in-hull!

Originally Posted by jyasaki

Both DC signals, so that should not be an issue, unless you've got a ton of noise on your battery cable (a voltmeter set to AC should give you a rough idea.)

Can't really think of a reliable method of isolating the problem. Unless you can pull the ducer and hang it over the side or back while running (didn't really think so)?

1. Test at full throttle in neutral to see if it goes out.
2. Change the fluid? Everyone says mineral oil is ok but now airmar is recommending "Propylene glycol (non-toxic antifreeze/coolant)"
3. Cut zip ties and route wire away from everything?
4. I could hang it over the side but only when idling along....probably can't do that at 20 mph!