16 years ago the first owner of Artemis ticked a few option boxes on the order form. One of them was the Raymarine navigation system. At that time it included an autopilot with inertial sensor, digital radar, VHF with AIS B mode, overboard warning with bracelets and of course an E120 navigation computer at the navstation and one E80 at the helm. The helm also hade analog rudder indicator and windangle. There was also an ST260 multi-display plus a numerical depthsounder display. Even a remote control for the autopilot was included allowing steering from any location on Artemis. A few direct action panels are also included.
The E120 acts as the master so the E80, being identical but smaller version only, is always slaved and capable of doing whatever the master is doing. One thing that increases this overall system cost over time are the electronic charts. Your investment sort of rises as you travel along and buy charts. Artemis has already been to the Caribbean why we have those charts in addition to the Med.
In other posts I have explained what was done to modernize and simplyfy the wiring and protocols to make the system ST-NG (N2K) centric. So the system got a new lease on life, I liked the Raymarine gear, reliable and rugged, particularly the navigators. Then, summer 2020 the backlight of the E120 failed. I went online and learned pretty quick that this happens with regularity. The backlights are a kind of small flourescent tubes and they simply have finite life. Getting spares looked very difficult and would be expensive. Another thing I learned was that it is possible to refit the backlight with LED´s, actually by using LED-strips.
There were offers from several independent firms to do so but the practicality of shipping the E120 back and forth to some country was no so uplifting. I then found that a fellow cruiser had done this refit and put it up on the web. It can be found here; http://blog.mailasail.com/anastasia/posts/2018/10/31/489-replacing-backlight-with-leds-in-raymarine-e-series-e120-display. Here Phil May on his cruiser Anastasia did this conversion a few years ago.
I picked up;
A TO-220 capsule MOS-FET
LED strip
15k 1/4 watt resistor
Red and black single strand 0,24 sqmm wire
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| After removing the front plastice bezel very carefully a panel is exposed with quite a number of 3mm phillips screw. Take all of them out. Lift off the grey panel and the rubber keys follow with it. Place it away separately in the order it was taken off. Use your phone camera to note how the pieces are placed. Lift off the thick plastic display cover. Place it so it cant be scratched. The display is now exposed, ensure it is not dirtied or even worse scratched. |
Undo the four stainless screws with philip heads. This releases the casting from the PCB assembly. Turn the entire assembly upside down ensuring that the casting and PCB assembly follows as you turn it around. Once upside down on a clean and soft towel, lift of the casting, straight up. It may stick a little on the seal around the back panel.
You will end up with a selection of parts like this.
Now study what keeps the PCB in place, there are screws and semirigid PCB´s to be removed. Be very careful with the connector for the PCB´s.
Removing the PCB is the next step. To do this you need to release a number of flexible PCBs from their sockets. If you are not familiar with this be very careful. It is done by lifting up the tiny black plastic bar on the female connector. The flex-PCB slides easily out now. Make mental note on how far in they go as it will facilitate reassembly. Unscrew the the screws holding the PCB in to the subassembly.
When the PCB is off you will have something looking like this (varies in between the E120 and E80 versions), put it aside for a moment as we are going to first do some work on the PCB itself.
The first job is to desolder and remove the two transformers. They are the ones the "danger" tape is stuck to. You will need a 50watt or more soldering iron and means to remove the tin with (suction tool). All the transformers pins sit in throughplated holes with the PCB sinking up heat making the process slow and tedious.
For the first display, the E120, it required taking it slow and very gradually inching the pins out by iterating with the soldering iron and wedging a screwdriver in at the correct location without damaging the PCB.
Having headmounted magnifyers helps a lot.
With the two transformers off, lots of free space is available. For dimming to work, an N-channel MOS-FET is used. The MOS-FET has its pins from left to right as GDS (Gate-Drain-Source). This is most common but check with the one you have chosen. I stuck the TO-220 MOS-Fet on the PCB with some heavy duty doublesided tape. The + of the LED strip is fed directly from the capacitor pin. The regulation is simply carried out on the negative side of the LEDs. The Gate pin connect via the 15k resistor to the point shown in the picture. This is PWM signal, meaning a pulsetrain of square waves whose duty-cycle varies (on-off period). Hence, the FET acts as a switch and does not sink any current why it does not get hot.
The Drain goes to the LED negative and the Source goes to PCB negative as found on the remaining pin on the capacitor.
Ensure you have a red and a black wire with 20cm´s to spare. Put the PCB aside now and place the screen assembly on your workplace.
Remove, by unclipping from the aluminium chassis, the plastic frame with the flourescent tubes. Remove the tubes carefully and discard them. Take note of the inside white area where you are going to mount the LED strips so that the frame can´t be reinstalled (this picture is from Anastasias rebuild).
Place the LED strips according to this layout. Depending om the LED-strips you can get hold of, your options on the length you cant cut them to may force you to rearrange. Just use common sense such that the light is uniform. Try to get the highest Lumens LED-strip you can get hold of. After placing them, solder in wires to parallell all the strips, this takes a lot of time and may be a bit boring so just relax (this picture is from Anastasias rebuild).
When done, reinstall the PCB and route the black and red wires over to the other side and solder to the LED strip. At this point I ran 12 volts to the LED´s to test them before assembly.
All you need to do now is reverse order reassembly. Go slow and take care to ensure all the seals are in place. Take the opportunity to clean the protective glass. Water and soap only.
As Phil on Anastasia pointed out, there is a software glitch in the dimming code producing a jump in brigthness midpoint. We have to live with it.
I found my LED´s putting out more light than the flourescents and that the dimming did not allow for fine tuning at the low light end. Putting the screen in night-mode helps a lot.
This job took at least three hours, so it is understandable that having this job done by someone else, it would not be cheap.
Feels great to have this done and knowing the units will never have backlights that give up.
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