Raymarine chart plotter intermittently showing GPS NO FIX position lost alarm

While anchored near the red “X” on the chart image above I looked down at the E120W chart plotter and was a bit alarmed when the chart plotter showed our vessels position as being on the opposite side of the island we were anchored by.  

Following the track back to our original position by the “X” you can see the Raymarine GPS also placed a track traveling directly over the island.

According to the Raymarine E120w Chart Plotter and RayStar RS125 GPS receiver out boat traveled over the island and back several times.  Again our actual position while anchored was near the red “X”.

Clearly there was an issue with the Raystar 125 GPS receivers.  Once underway heading back to the dock there was no position fix lost. Never displayed a NOFIX alarm and E120 chart plotter did show our position accurately based on visual references of the surrounding the area to our position visually.

Note: Raymarine E series chart plotters do not have any internal GPS systems and rely completely on an external GPS receiver being hooked up to the units to relay GPS position.

There are two GPS receivers in this picture because there are two E120W chart plotters on this boat.  Each chart plotter is assigned its own GPS receiver.

On the top of the Raymarine RS 125 GPS receiver there is a single LED light, with the chart plotter and GPS receiver on check the light.

– Green blinking light means the GPS unit has a fix
– Yellow blinking light means No FIX
– Red blinking light means it is trying to boot up but is unable to
– No light after several minutes means the unit has no power or is damaged and is not working properly

Once at the dock I started to take apart the Raymarine Raystar RS125 recivers. And below will show you an easy way to fix the GPS issue without replacing the GPS receiver.

Unscrewed the GPS receiver from the mounting pipe, then removed the caulking filling the two screw holes.

After getting all caulking out of the screw holes (if applicable) unscrew the 2 screws that hold the Raystar 125 GPS receiver to the mounting base that is used to mount the unit to the threaded pipe base stand. 

The lower section is only used when wanting to raise the unit higher as you can flush mount the top section directly to the hard top if desired but having a raised position is preferable such as in this situation.  Bottom base is a 1″-14 pole mounting adapter that can be used to attach the Raystar to any standard antenna extension pole or rail mount with 1″ – 14 threads.

After the 2 screws holding the top section to the base are removed I noticed the amount of cord that could allow the unit to move freely was very short.  So I screwed the GPS receiver back onto the pipe mounting stand so more wire cord was available for when removing the top section of the Raymarine RS 125 GPS receiver.

Pulling the two sections apart you can see the cord mounts via a plastic nut system to secure the GPS sending cord to the GPS receiver.

Before unscrewing the GPS sending cord nut from the top section of the RS125 GPS receiver I first wrapped some electrical tap to the cord so that it wouldn’t fall down into the pipe stand base.

Then I unscrewed the plastic nut system to remove the cord connecting the top to the bottom.  Again in this situation the cord didn’t have much slack so made this step a little tricky.

Note the 5 pins on the bottom of the GPS receiver (in my hand now upside down) This shows this unit is a Raymarine Ray Star (or RS) 125.  A Raymarine Ray Star 130 will have 6 pins like the picture below.

This image above is only to show the difference between the Raymarine Raystar 125 and the 130 GPS receiver antenna / sensor.

You can see above the RS130 has 6 pins.  While the RS125 unit in the picture above this one has 5 pins.

Important to note this if needing to order a new GPS unit, however both the Raymarine Raystar RS 125 and Raystar RS 130 are both discontinued and are no longer available from Raymarine.  Most places that have any of these for sale are found on ebay.  Some units are new, but most as in probably 90% are used units from people who put all new electronics on the boat and had a GPS receiver unit that worked when removing the old electronics. 

Again most of the “non working” RS 120 and RS 125 units can be fixed by simply following the steps below.

But if you absolutely need a new unit many of the used and new RS125 and RS130 GPS receiver units are selling on ebay for $120 to $450 depending on condition.

This is the cable end which the 5 pins that stick out from the GPS receiver plugs into. This cable then travels to the sea talk bus or directly to the GPS depending on how it was installed.  Then the plastic nut screws onto the threads to secure the cable to the RS 125 GPS receiver.

Pull the black foam gasket off with the clear plastic backing at the same time so the sticky residue comes with it.

Raymarine RS125 GPS receiver is held together with six screws, carefully remove them and set aside. 

Once they are removed you can start to wiggle the top cover off the bottom section.  There is a rubber gasket that keeps these two sections held together quit firm.  If you use a very small flat head jewelers screw driver to start seperating the two halfs it really helps.

After the two halfs are apart you will see the circuit board and where the battery is held in place. 

With the GPS receiver apart and viewing the circuit board you can see there is a slot for a small flat battery.  Remove this battery and volt meter test it to see what it reads.  If the GPS receiver is losing fix with a NO FIX alarm it is usually due to this battery reading 0 volts.

No need to replace the entire GPS unit if this is the case, only replace the battery with a new CR2032 battery.

Sometimes this battery will be soldered into place, if this is the case and it is not just placed in the metal clips simply remove the solder carfully from the battery with pliers and you can usually place the new battery in position without having to solder it again, but if the spring tension of the metal is not strong enough to just hold the new battery in place you may have to solder a new one in position.  Just make sure to not overheat the battery and use plenty of flux.

In this example soldering a new battery in place was not needed.  Often you encounter having a soldered battery on the Raymarine Raystar RS 120 GPS receiver units. Thankfully most of the Raymarine raystar RS125 units use only the metal bracket to hold it in place and no solder was used.

The battery easily slides out of the compartment and is held in place just with two metal prongs.

If the battery is soldered in place as often found on the RS120 and sometimes the RS125 see the picture and text above this picture for more information on dealing with this issue.

After taking the old battery out you can then volt test the battery, usually it will show .5 volts or 0 volts when having the issue as described in this article.

The new battery will produce 3 volts. 

You can buy new CR2032 batteries on Amazon at this link:

Link to buy new CR2032 Batteries

Put the GPS receiver back together, then continue to reverse the steps until the unit is back in its original position on the boat.

Note: Raymarine E series chart plotters do not have any internal GPS systems and rely completely on an external GPS receiver being hooked up to the units to relay GPS position.

There are two GPS receivers on this boat because there are two E120W chart plotters on this boat.  Each chart plotter is assigned its own GPS receiver.

On the top of the Raymarine RS 125 GPS receiver there is a single LED light, once the chart plotter and GPS receiver is turned back on check the LED light.

When power to the GPS receiver is first turned on the LED light will first blink RED, then after a few minutes will then blink YELLOW.  After 3 to 10 minutes of blinking yellow it will then blink GREEN.  Once blinking green the GPS reciever has a fix and is relaying the position to the GPS chart plotter, which in this case is the Raymarine E120W.

– Green blinking light means the GPS unit has a fix
– Yellow blinking light means No FIX
– Red blinking light means it is trying to boot up but is unable to
– No light after 15 minutes means the unit has no power, so first check the power into the unit form the cable. If power is going in from the cable to the gps receiver but still no light turns on the unit may be damaged and is not working properly, or a separate issue is causing the unit to not power up.  After checking the boats battery voltage then check that the cable going into the unit has a good connection and the threaded nut is tight.  If it is and still no light take the GPS receiver back off and check that the new flat battery was not installed upside down.

Why does the Raymarine RS 125 and Raymarine RS 120 have a battery?  The design of this unit makes it so that the last known position is stored in the GPS receiver on a small memory chip. This Random Access Memory or RAM memory for short makes it so that the GPS can acquire a signal faster on the next power up as the unit does not have to search through as many possible GPS satellite positions.

Have you ever turned on a hand held GPS unit after an international flight?  The unit once turned on will first try to acquire the satellites the unit last used to find its position.  Once those can not be found it will then start searching for other GPS satellites.  This often takes a long time, but once it find the new satellites to use and if you turn the unit off and back on while still in the same area it will acquire a signal faster the second time.

The same thing is happening in the RS 120 and RS 125 with the stored information in the GPS receiver.  This battery is allowing the unit to acquire the next satellite fix faster.

This is also why the unit will intermittently lose a fix to the position as it is “forgetting” the last known satellites and sometimes cant reacquire them fast enough without causing a GPS NO FIX alarm to show up.  Sometimes the receiver can so it won’t show a NOFIX alarm and other times it cant so the alarm will sound and show on the cart plotter.

Once the GPS receiver is showing a green blinking light the associated chart plotter should now show a position fix and no alarms.  

This boat has two GPS receivers, one for each of the chart plotters.  Two GPS recievers, and two Chart plotters.  

Again Raymarine E120 chart plotters and all E series chart plotters from Raymarine do not have internal GPS units so rely completely on outside GPS recievers for a GPS fix and signal.

In the event that you need to replace the entire GPS receiver this diagram from Raymarine will help you understand a bit of what is needed to convert the connection to your needs.

Most will need a seatalk NG connection as that was the main connection type with these GPS receivers were in production. 

But some may have to use a Raymarine RS 125 to connect to a seatalk cable.  Or may have to NMEA connection.

You may have to change the Raymarine RS 125 or Raymarine RS 120 GPS receivers out for a new version if replacing the battery does not work.

The E Series Widescreen displays do not have an integrated GPS and therefore require an RS130 connected via a SeaTalk^ng backbone.

Follow the below diagrams for more information on how to switch a RS 125 or RS 120 to a Raymarine Raystar RS 130 GPS receiving unit.

Check your external GPS requirements in the chart above.

Again the RS 120, RS 125, and RS 130 are all discontinued but finding a new or used RS 130 may be easier than the 120 or 125 versions.

Graphics above show what types of connections you can use to connect the GPS receiver to the chart plotter.

Graphic above is for use for typical connection systems with a RS130

Due to the fact that Raymarine has discontinued many products that people are still on the water using you may have to upgrade the GPS receiver for what is available.

Trying to find a new Raymarine Raystar 120 or 125 is almost impossible and usually comes at a steep price. Some are available used from ebay and other places online but those too are at a steep price.

Some Raystar RS 130 and RS130 plus units are available new, and many used but you may opt to just go with the new Raymarine RS150.

Doing so however you will have to adapt how the unit hooks up to the older existing network.  More on that below if you need to go that route.

Getting your older chart plotter to be able to use a newer GPS receiver may be an option with various adapters, but expect to have to replace some few connections, cables, and sea talk type bus bars.  

We will come out with an article on how to do this soon.

Now you know a few different ways to:
– test your gps unit
– fix the unit with a cheap simple effective solution (hopefully replacing the internal battery of the GPS receiver is all it will take to get the unit working again without any NOFIX alarms showing up)
– Replace your Raymarine RS120 or RS125 GPS receiver with a newer version Raymarine  Raystar RS130
– Or replace your GPS receiver with a even newer version Raymarine RS150

Any questions feel free to message us or leave a comment below