NASA MARINE ST50 TRIDATA

[serendipity9]

Hi,



I have a Tridata NASA MARINE and the depths are not showing the right values for some days. Is there someone who can help me to repair these instruments?

Many thanks!

 

[kellys_eye]

Probably the sender unit rather than the display.

 

[serendipity9]

Probably the sender unit rather than the display.

For sure is PCB, the display is OK.

 

[Alec_t]

Can you post a schematic of the device?

 

[serendipity9]

Can you post a schematic of the device?

Unfortunately, I don't have one.

 

[kellys_eye]

and the depths are not showing the right values for some days.

First, how do you know? What is your reference for the ACTUAL depth? and on that/those particular days? How great is the error?

Secondly, is the error a constant or variable? If it's not erroneous digits (i.e. LCD segment error) then either get another sender and place it in a fixed, known depth of water and observe the results or remove the sender completely (disconnect it) and see if the display remains 'still' (zero?).

It's possible to fake a depth signal - I designed and built an echo sounder simulator for servicing such device many years ago but left it with my last employer nearly 25 years ago A simple pulse generator can do the same thing.

 

[kellys_eye]

For sure is PCB, the display is OK.

The SENDER is the device fitted to the hull of your vessel, nothing to do with the display or PCB. It could be something as simple as a fish lying under the vessel or even seaweed. Sure you know the basic principles of how these things work?

 

[serendipity9]

First, how do you know? What is your reference for the ACTUAL depth? and on that/those particular days? How great is the error?

Secondly, is the error a constant or variable? If it's not erroneous digits (i.e. LCD segment error) then either get another sender and place it in a fixed, known depth of water and observe the results or remove the sender completely (disconnect it) and see if the display remains 'still' (zero?).

It's possible to fake a depth signal - I designed and built an echo sounder simulator for servicing such device many years ago but left it with my last employer nearly 25 years ago A simple pulse generator can do the same thing.

It shows 00,00 the word DEPTH is blinking. I've tried it with other PCB and it is working, so the sensor is ok. The display is very OK, it shows the temperature.

 

[Alec_t]

It shows 00,00 the word DEPTH is blinking.

Is the blink rate a fault code? Do you have a User Manual for fault identification?

 

[serendipity9]

lost signal from sensor, or cable demaged. But with other PCB is working.

 

[Alec_t]

lost signal from sensor, or cable demaged. But with other PCB is working.

If the signal is lost, how do you know the other PCB is working?

 

[serendipity9]

If the signal is lost, how do you know the other PCB is working?

It's what the manual error code said.

 

[kellys_eye]

You say the fault occurs on certain days so, presumably not permanently. When you tested it on a different display (PCB) and it worked then maybe it was a day there wasn't an intermittent fault.

Check the cable back from the display to see if there are any junctions or joints in the cable. Also check the connections at the display for corrosion etc. Typical issue in marine equipment.

 

[Alec_t]

Does the sender/sensor work ok with 'the other pcb' (pcb 1) without any error code showing?
If so, and the error code using 'your' pcb (pcb 2) is telling you that the signal is lost, then the fault must lie in (a) the connection of the sender/sensor to pcb 2 or (b) pcb 2 itself, most likely in an early stage.
Are the display readings for pcb 2 correct for the other two sensed variables of this Tridata device?