How to fix your older Raymarine MFD showing 'NOFIX' for GPS status

[Rich]

*** Frugal Yankee Alert ***

I thought I'd document what I found, in case anyone else goes through this as many people on the lake may have some of this older equipment.

I have a 2005 boat that has Raymarine C80 MFD and a RS-120 GPS sensor on it. Mine are probably 2004 vintage considering the build date of my boat.

Just two weeks ago I had a problem where I could not get my MFD to display my position. When looking at the GPS Status page, it displayed 'NOFIX', which means that the GPS can't lock onto enough satellites to get a good location fix. Thinking that I had a GPS failure, or a wiring failure, or all sorts of things, I was thinking this was going to cost me a lot of money (after all, this is a B.O.A.T.).

After trying to reset the power to the GPS, the MFD, and other things, I was about to give up, but then I tried the 'RESTART GPS' button that is on the GPS Status page. This worked! But every time I restarted my MFD, I would end up with the same problem again.

I checked online and read many posts, as well as reviewing my documentation and the Raymarine web site. My GPS is a RS-120. It seems this unit contains a lithium battery that has a projected life of 10 years. Yes, it's been just about 11 years for mine, so if we guess that it was manufactured in 2004, Raymarine's 10 year life prediction is about right!

The battery is used to maintain the internal clock on the GPS when the power is off, as well as to maintain data about the locations of the satellites. Without the ability to remember this information, it takes too much time for the GPS to find from scratch the satellites (cold start). The battery allows it to do more of a 'warm start' and have an idea on where to start looking.

Raymarine's solution to this failed battery issue on the RS120 is to replace the GPS, as they don't service the RS-120 anymore. The new GPS's are probably more accurate, quicker, etc. but I'd rather not pay $300 plus if I can get my GPS working again, because if I need to replace the GPS, I'd rather put the money into newer technology such as a new MFD which includes many more features and greater accuracy.

So I decided to take a chance and disassemble my RS-120 GPS to take a look (it's a habit that I've had since I was about 5 years old, and I can't kick this habit now). Sure enough, inside the RS-120 was a 3V CR-2032 button lithium battery manufactured by Varta. Yes, this is a very common coin type battery used in many devices! The problem is that it was soldered in place by tabs that are welded onto the button battery itself. I'm sure Raymarine soldered it in place to be sure that corrosion wouldn't affect a battery socket over the life of the GPS. This complicates changing the battery a bit.

Here are the pictures with some instructions if anyone else wants to try to replace the battery in their Raymarine RS-120 GPS. © Rich 2015 !

Note: This is only a solution for a failed battery. If your GPS will work OK after issuing the 'Restart GPS' command from your GPS Status screen, and your GPS is about 10 years or more old, then this procedure may get the GPS working again as it was before the internal battery went dead.

It was easy to disassemble the RS-120. First there were two screws holding the mount to the bottom of the GPS sensor. Then there were 6 small screws that had to be removed. After the 6 screws are removed (don't lose them!), pull the top off, but be careful not to damage the gasket under the circuit board. There is also a large O-ring used to seal the case, but this one doesn't look easily damaged.

Here is the original battery as installed by Raymarine, it was a Varta 2032 3V Lithium button battery. In this picture the positive terminal of the battery is facing down or away from the circuit board, the negative terminal is facing 'up' or towards the GPS circuit board:


Original Varta 2032 3V lithium battery can be seen under the circuit board

I checked the voltage on the original battery and it was down to about 0.3 VDC. This should be at 3.0 VDC or higher.

I went to a local Batteries+ (or may be known as Batteries+Bulbs). They built me a new battery 'pack' using a CR2032 Lithium battery. Basically they spot welded two wires onto a CR2032 battery for me, and then covered the battery in heat shrink tubing to insulate it. It cost me $14.99. A bit pricey, but it was built while I waited and at least I know it was built properly, and also has a fresh battery. Note that if you try to solder wires or tabs to the CR2032 battery yourself, you will probably over heat and damage the battery. It's best to buy one that already has solder tabs on it (or get one built for you as I did). Alternatively, you could install a CR2032 battery socket, but then you could have problems with corrosion over time.

To remove the old battery from the GPS, first confirm that there is no power to the GPS by checking at the red and black leads that come to the circuit board with a volt meter. If there is 12V power here, find the breaker for your MFD or electronic accessories to turn off the power and confirm that it is off before proceeding.

I then used some scissors (or you can use wire snips) to clip the battery tabs, but leave enough of the tabs on the circuit board to allow you to solder the new battery wires. Don't flex these tabs too much, or cut too close to the circuit board, you don't want to stress the circuit board traces too much and they could be fragile, so be careful. This way you're not taking the chance to damage the circuit board when trying to solder the new battery wires.


Raymarine RS-120 GPS with its original battery clipped out. Take note of the positive (to the left) and negative (to the right) terminals before you remove the original battery.

Next place the new battery (be sure it's fully insulated) into the base of the GPS, then route its wires to the tabs and solder them to the tabs taking important note to see that the positive and negative leads are installed properly.


Raymarine RS-120 GPS with the new battery installed. You can see the new battery insulated and installed to the left of the cable clamp. Its wires are soldered to the clipped tabs of the original battery (red is positive, black negative).

Then check the voltage at the old battery tabs after installing the battery. The one that is to the left in the photo (closer to the center of the circuit board) should be positive, and the one closer to the edge of the circuit board is negative. You should read about 3.2 VDC here with a fresh battery after it is installed. If the voltage is correct, you are done, re-assemble and re-install the GPS.

Restore the power to your GPS. Turn on your MFD. You may need to use the GPS Status page to issue a 'Restart GPS' command. Once this is done, it may take a couple of minutes to fully lock onto the satellites. Once this occurs, you should get quick lock-ons in the future.

I just saved you about $375 USD as Raymarine wants you to buy a new GPS and SeaTalkng converter kit to retrofit a new GPS into the older MFD systems that used RS120s:
http://www.amazon.com/Raymarine-Rays...aymarine+rs130

You're welcome! If you're happy with this procedure, feel free to send me a donation! © Rich 2015

IMPORTANT WARNING: If you're not comfortable with working with electronics, get someone that is to help you! As you could easily damage your GPS for many reasons, and then it WILL cost you $375 (plus installation) to replace your damaged GPS.