Saturday, April 4, 2009

Fixing a Wacom Bamboo pen

My daughter's Bamboo graphics pad stopped working. Oddly enough the eraser side of the pen was still OK - but the stylus side was dead. This suggested it was the pen - not the pad or the connection - that was at fault.
I found a brilliant blog at
which described my symptoms, and had pictures for a similar pen. But the Bamboo pen has a slightly different design so I thought I would document the disassembly (including what went wrong for me...).

The tip of the pen contains a coil with a ferromagnetic core. This core breaks when you drop the pen - this means it doesn't make as strong of a magnetic field and that means the pad can't sense the pen (or vice versa). To get to the core, you have to take the pen apart (carefully - there is a lot of sensitive electronics inside!)

First step: remove the plastic tab next to the buttons:

Note where I put the screwdriver. Gently ease it under the tab and nudge until you get something like this:

This is where I went wrong and forced the tab off. With a snap something broke, and when I looked closely I saw I should probably have slid the tab (moved in in the direction of my fingers in this picture) rather than pull up and away from the pen - see this picture:

Even better - I could have just left it alone. I later found that the top and bottom half of the stylus are only held together at one point - and so just lifting the tab at one end is enough to free the two halves. With the tab off, careful jiggling allowed me to separate the top and bottom of the pen (it takes quite a bit of force: be careful not to bend it as the two parts separate, or you will break the circuit board inside):

As the two parts separated I could see the little blue tab that I had broken off:

Next, I needed to liberate the electronics board which was still being held by the buttons. I was a bit apprehensive now, but it turns out that this time you can just use a small screwdriver and nudge the buttons straight up and off:

After carefully easing the circuit board out of the barrel I could see the broken coil (it didn't look broken, but when I pulled very gently on the end it came apart, showing a crack):

I pulled out the plastic tip (I needed to turn it to free it - not sure if I could have pulled but with the coil looking quite fragile I decided to play it safe - you don't want to break the little wires that hold it in place). Now, using some Loctite superglue gel (the kind that doesn't go everywhere but still sticks like crazy), and with my daughter's help to hold the crack open as I applied the glue, I was able to put a couple of small dabs in the crack and push it tightly shut - in the process pushing most of the glue out of the crack:

Two more cautions before putting it all back together.
First, make sure there is no glue on the inside - or you won't be able to put the plastic tip back in. Holding the assembly vertical, I moved the tip in and out a few times - it did come out sticky so I kept wiping it clean, until it went in and out without getting sticky.
Second - you want to make sure the glue has time to dry properly, and with the smallest possible gap in the ferrite core. To so this, I held the assembly vertically and let it sit for about an hour - long enough for the superglue to really set. A shot glass and some tissue paper did the trick:

When everything was dry, I put it all back together again. But for the little blue tab that had broken off and the white mark on the blue tab where I had bent it when I should have slid it, it was "good as new". And more importantly, it worked again!

A Great Big ThankYou to Abiyasa - the blogger who inspired me to do this. Let me know if it worked for you!