Theo bài này thì X51v có pin back up nhé.
Nguồn: Aximsite
A few weeks ago, my axim X51v started to lose its date and time setting every time I swapped batteries. Being out of warranty, I decided to open it up and investigate.
Getting the axim open is fairly easy; first you remove the stylus, CF and SD cards (or plugs), then remove the four rubber feet (my two top feet had disappeared long ago).
Under the rubber feet are four small Torx (T5) headed screws. Once the screws are removed, the case can be unclipped by inserting a thumb nail up in the middle of each edge then sliding it up and down. Remove the rear part by hinging up from the bottom (the top is hooked over the ear/mic jack socket)
The back-up 'battery' is actually a tiny rechargeable lithium cell (I found this out after I had removed it). I measured the voltage of the cell at less than one volt, it was clearly faulty (A typical lithium cell should be nearer 3v).
[Edit] It's now been pointed out by jballard that it is not rechargeable lithium cell, but is in fact a Panasonic super-cap type EECEN0F204RK However, the replacement lithium cell should be OK
Replacement caps are available from Mouser Electronics (USA) here:
EDLEN204RL3R3S
Farnell (UK) also list the part, but have a ridiculous £16 US stock surcharge !EDLEN204RL3R3S | CORNELL DUBILIER | Capacitors | Passive Components | Farnell
Removing the old cell is a little tricky. You'll need a temperature controlled soldering iron and plenty of patience.
First I removed the solder from the two cell tabs using Solder-Wick (Solderwick is a fine, pure copper, braid coated in a flux that sucks up the molten solder like a sponge). Then, using a scalpel blade gently inserted under each tab while applying heat, I lifted each leg clear of its PCB pad.
The cell is glued or soldered to a pad underneath the cell to to remove it you have to apply heat to the cell's negative tab while lifting the cell with a fine knife blade.
(I said it was tricky )
With the cell removed I decided to check to see if there was any voltage on the cell terminals at the PCB (I had a suspicion that the cell was a rechargeable type because of its tiny size). With the main battery in place, there was 2.8v on the pads.
Unfortunately, the only available replacement I could find, a Varta MC614 SM from one of my regular suppliers, has slightly different tabs.
60614201501 | VARTA | Tagged (PCB Mount) | Batteries & Power Supplies | CPC
I used a small drop of super-glue to hold the cell in place while I soldered the positive tab, then used a loop of tinned-copper wire to make the negative connection.
I gave the cell a few hours to charge before swapping batteries...
This time, the date and time remained correct
Nguồn: Aximsite
