ST290 GPS and NMEA issues

[Chuck - Raymarine - Moderator]

Q1. The spliced STng to ST2 coming from the ST1 to STng converter has been removed with no negative impact. (What should be placed in the empty socket?)

A1. Please attach an updated system diagram to this thread in order that we may determine whether you have now corrected powered and terminated the SeaTalkng and SeaTalk2 backbones.

Q2. Disconnecting the RED wire from the S3 Course computer ST1 input removed power from the entire system (ST1/ST2). The ST1 RED wire attached to the S3 course computer is the 12V output, not an input. (Appears this needs to remain wired as-is to operate properly). The S3 main power input (40A fused) and the E125 are both engaged at same time by navigation breaker. It appears the E125 was not supplying any voltage to either the ST1 or ST2 devices.

A2. As has previously been specified by Steve and has been specified within the FAQ referenced in the response to Q3, the current SeaTalk bus must be disconnected from its present sources of power. Per your original diagram, these power sources were the S3 Autopilot Course Computer's SeaTalk port and the ST290 DPU's SeaTalk port. Correspondingly, the red lead of the SeaTalk cable which is presently connected to the red SeaTalk terminal of the S3 Autopilot Course Computer as well as the red lead of the SeaTalk cable which is presently interfaced to the red SeaTalk terminal of the ST290 DPU must be disconnected. The ST290 DPU must be connected to a 12VDC power circuit via the ST290 DPU's power and ground (not to be confused with SeaTalk) terminals. Failure to make the recommended changes which have been specified within the responses to this thread may result in ground loop, unpredictable performance, product damage and/or reduced product life.

Q3. Lastly, if the system appears to be working correctly, is there a reason to add a second ST1 to STng converter? There are more than 5 ST1 devices in the system-is it a hard rule that any more than 5 require an additional converter?

A3. Failure to divide the present SeaTalk bus into busses of no more than 5 devices and add the recommended additional SeaTalk to SeaTalkng Converters may result in too much current being passed via the single SeaTalk to SeaTalkng Converter. Failure to do so may result in premature failure of the SeaTalk to SeaTalkng Converter as well as underpowering the SeaTalk bus. Please click here to view a FAQ addressing this subject.