Most Lexicon units have back up batteries to supply enough voltage to hold memory in SRAM chips. The SRAM chip holds all user settings. For these settings to be store on this chip it must have a constant voltage to hold the data that has been written to it. When you disconnect power from the 110 power, a circuit sees power has been disconnected and the 3V battery applies voltage to the SRAM chip, so data written to it is saved.
The SRAM chip is like a hard drive in that you can write to it. If you modify a program, or create a new one, by pressing "Save" this info is written and stored in the SRAM chip. Unlike the EPROM chip where the only way it can be written to is it has to be plugged into a ROM burner. The program information is burned into the chip, so when the unit is powered down it does not need any voltage to maintain any info that is stored in it.
The 3V batteries used in Lexicon units have a life of about 10 years. After 10 years all bets are off as to the reliably of the battery to supply enough voltage to maintain and keep the info stored on the SRAM chip intact. Also an aging battery can leak. A leaking battery can cause damage to the PC board that can end up being a costly repair. The leaking acid can literally eat tracers away.
If you have saved settings or programs loaded you will need to back them up via MIDI to USB cable to your computer, using software such as Bob's Dump Tool. Once the battery is removed, any saved data will be lost. It is good to have a back up anyway just as you would have a back up of your computer drive. Info on how to dump and load programs on your unit can be found in your user manual.
To replace the battery is simple but if done wrong you can damage the PC board. The back up batteries used in Lexicon units are button type lithium batteries that are soldered to the PC board. Lexicon PC boards tend to be fragile in that they will not take allot of heat, also care must be taken when lifting any component off the PC board as the pads components are soldered to, including the battery, can be easily destroyed.
There is a fine line between to much heat and not enough heat. To much heat can damage a pad and or component the pads adhesive can separate it from the PC board, not enough heat when lifting the component off the board if the solder is not completely liquefied can still be fused to the component and pad. lifting the component in this state will for sure rip the pad off the PC board. Also to much heat can explode the battery.
Lexicon uses a low temp solder. Depending on your experience I would not recommend using a solder iron over 25 watt. Also I do not recommend using rosin core solder or paste as rosin is corrosive. I recommend using a solid 60/40 tin-lead solder and a water soluble flux. At the bottom of this article I have provided some links to give an idea of what is best to use (in my opinion).
Items needed to replace battery:
1. Solder iron and a cleaning tip sponge, to clean tip. (any clean wet clean sponge will do)
4. Solder sucker
5. New battery
6. Good lighted area
7. In some cases if hot glue or silicon adhesive is used to secure battery an exacto knife
8. Tweezers if adhesive was used tweezers will be help-full to remove adhesive NOTE IF YOU DO THIS PROCEDURE, YOU DO SO AT YOUR OWN RISK. WE CAN NOT BE RESPONSIBLE IF YOU MESS SOMETHING UP. THIS IS ONLY A GUIDE FOR THE DO IT YOURSELF-ER. IF YOU DO NOT HAVE ANY EXPERIENCE SOLDERING, WE RECOMMEND YOU HAVE A PROFESSIONAL DO THIS PROCEDURE.
First you will need to remove the cover of the unit (for the MPX R1 the bottom cover on some units such as the LXP's remove the 4 screws on the face plate, the PC board will slide out of the housing) locate the battery on the board. First note which lead of the battery is Positive (+) and which is negative (-) also note on new battery which lead is positive and negative, you do not want to replace the battery in backwards. If adhesive is present you will need to very carefully cut it away using your exacto knife with the aid of tweezers to pull it away and off the battery area.NOTE HERE, CAUTION!, ONCE COVER IS REMOVED BE AWARE STATIC ELECTRICITY CAN DAMAGE CHIPS. ALL IT CAN TAKE IS JUST ONE LITTLE ZAP AND YOU CAN FRY A CHIP. IF YOU DON'T HAVE A GROUNDING SET UP AT THE VERY LEAST ALWAYS TOUCH THE CHASSIS SOME WHERE BEFORE TOUCHING ANYTHING ON THE PC BOARD TO HELP INSURE YOU DO NOT HAVE ANY STATIC BUILT UP IN YOUR BODY.
Next power up your solder iron, when it gets to operational temp, (you can tell when you can melt solder to the tip by touching the end of your solder from your roll to the tip of the iron) You will want to get some solder on the tip of your iron. Then apply some water soluble flux to the battery leads. Using the iron melt the solder on one of the leads to the battery. You will see the solder liquefy, gently wiggle the battery to lift the lead out a bit. Do not try to lift it all the way out. Just lift it a bit, then go to the other lead and lift a bit. Alternate between leads back and forth, keeping heat in mind, if you feel the battery is getting warm give it a rest to let it cool. Alternating between leads back and forth ever so gently, eventually the battery will come out.
Once the old battery is removed, apply a drop of flux on each pad. Using your solder iron heat the solder till it liquefies and suck the solder out of the hole. If done correctly the hole will be clean, then do the same for the other hole.
Set the new battery leads in the holes, making sure you have the correct polarity in each hole, put a drop of flux on each battery lead. Wipe the tip of your solder iron on the wet sponge to clean the tip and apply a bead of solder on the solder iron tip. Holding the battery so that it is fully seated to the PC board and fully vertical put a dab of solder to one of the leads, just enough to tack it in place to hold it, Then go to the other lead put your solder iron to the pad and the tip to the battery lead, apply solder from your roll, you will see the solder flow onto the lead and pad. Once the solder starts to flow, If you count 1 second (one-thousand-one), that should be plenty of solder. Feel the battery if it is hot let it cool, then solder the other lead (the one you originally tacked) in the same manner you did the other one. Both solder joints should appear shinny, if not this indicates a cold solder, if this is the case, apply another drop of flux to the lead and using your iron re-flow the solder.
I then suggest you put a small bead of silicon adhesive all the way around the battery to secure and reinforce the leads to prevent vibration from breaking the battery leads. I have seen many batteries that snapped off or their leads and end up just floating around inside units, this step will help prevent this.
Once your new battery is in, replace the cover. You are now ready to power up. Some units will re-initialize automatically when you power up other units such as the G2 you will need to do it manually. With the G2 you will see no gain selected, tap the gain button, then do a reinitialize all. Once initializing is done you can re-load your programs.
Hopefully this info will help the do-it-your-selfer successfully do a battery replacement. Take your time, don't try to rush the job especially when removing the battery to not damage the pads, and keep heat in mind, to much heat can be one of your worst enemies. Below are some links on items to use as an example of what you will need to replace your battery.Solder ironSolder suckerFlux SolderNew batteryBob's Dump ToolMIDI to USB cable