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898 si - External GPS Antenna Issues

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chrisfisher:
Not sure if this will help anyone. I've had noticed one common issue with this External GPS Puck! Its the darn plug that I think sort of sucks! Always seems to be the ground wire.. just push it down! (seems to wiggle loose) add a bit of non conductive glue! something to hold em down seems to do the trick. It is nice seeing the  GPS: "Connected" in the diagnostics! Have fixed this on few units already!

fshndude:
As I am in the automotive business, working on vehicles the wiring has went from 18 gauge to 22 gauge. Terminals are even smaller. To help what we call "FRETTING" apply a good dielectric grease to all of your connections. I have been doing this for years on all of my boat electrical connections. Just a thought but I like the pic of the circuit board and how to repair it.

peterv6i:
huh have the same problem with the GPS antenna receiver.
So I decided to investigate what is going on.. My 998 unit is showing that GPS is not connected to it. First have cleaned all the contacts and this was not the reason.
After that, I have opened the GPS antenna and notice that a water/humidity is present inside the case. The main 4 pin connector was totally green (corroded) and also some parts on the printed circuit.
The printed circuit is not even sealed with the epoxy lack  :-X :-X.
My steps were this:
1.) first I have disconnected the connector from the PCB
2.) With a brush and cleaning spray (electronic cleaning solvent) have cleaned the PCB
3.) The next thing that have noticed was the corrosion under the capacitor on the left side of the connector. After a while have replaced the capacitor with the new one
4.) Also, some pins on the ublox module (GPS receiver) were corroded. (cleaned them)
5.) After all this operation I have connected the 10V DC to the power pins and measured voltage on the board.
6.) To test if the ublox module works have connected the pico oscilloscope to the RX/TX pins and notice that the chip is sending data.
7.) Because I was somehow sceptic if the 4 pin connector is ok, have also replaced the 4 pin connector on the PCB
8.) The antenna is now working
9.) After the operation have sealed the PCB board with the (Servisol - plastic seal 60) spray (protective insulator)

that's all

corroded PCB and elements on it :( (crap)


the capacitor was replaced:


some elements trough the microscope


testing the output of the ublox module


Ublox module specifications:
https://d1.amobbs.com/bbs_upload782111/files_33/ourdev_581165TSVA0S.pdf

rnvinc:
That’s some serious troubleshooting  ...

Rickie

peterv6i:
The problem is that the PCB is not coated with protective lack (epoxy)... And the seal under the antenna cap is not enough to prevent humidity to enter into the case.

Anyway, this antenna is a simple GPS module from ublox (it send the NMEA GPS data on the serial port to the Humminbird unit).

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