NASA MARINE TARGET 2 DEPTH NOT SWITCH ON

[Juri]

The depthmeter Target 2 of Nasa Marine operated successfully on my steel sailboat so far since 2010, but now it unexpectedly does not switch on. Power supply is normal. I ask all those who may concern this problem to post the ideas as to possible reasons of this failure.
Thanks.

 

[Alec_t]

Welcome to EP!
Without a schematic we're unlikely to be able to offer much help .

 

[shrtrnd]

Did you look for a fuse?

 

[Juri]

The fuse is OK. DC voltage exists on the red and black wires of the display box and the alarm.

 

[Juri]

Unfortunately, the manual does not include any electronic scheme. I could not find the scheme in Internet. The connection with the board electric sircuit was made professionally years ago and never changed.

 

[Sunnysky]

so no sign of life?
no method of calibration?
damaged sensor?