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Author Topic: Converting Wacom XD-0912-R from Serial to USB  (Read 13566 times)
gordon13
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« on: September 15, 2011, 04:30:38 PM »

Alright lets do this.
Firs things first, checking continuity according to the table made by Bernard:
http://forum.bongofish.co.uk/index.php?topic=1927.0

First thing I noticed, the boards are slightly different. TR1R on this board is on the right side of the serial connector (assuming the board is oriented like in the other thread I linked). Also the serial connector is the other way around. The pins are marked 10, to 1  from the left side as shown in the following pictures.

http://dl.dropbox.com/u/4249784/P1150946.JPG
http://dl.dropbox.com/u/4249784/P1150947.JPG

Also, serial driver chip connections doesnt seem to match the table in the other thread :/

Where to go from here? Is the circuit still similar enough that removing TR1R and IC2R going to work? Also, how do I work out which pins will need to be soldered to the teensy?

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bernard
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« Reply #1 on: September 15, 2011, 05:06:35 PM »

The important stuff to test is the DB9 connector pins to the serial driver chip pin.  The special internal connector we do not really care.

Let me put the important thing to test here:


             
  PC DB9  |  ADM202
 ---------+---------
  2 (RXD) |  14
  3 (TXD) |  13
  4 (DTR) |   8
  5 (GND) |
  6 (DSR) |   7
  7 (RTS) | R2R



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gordon13
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« Reply #2 on: September 15, 2011, 06:06:24 PM »

Thanks for the clarification. That works! I was test on the internal connector and getting confused, when i realized db9 was the connector on the end of the cable, i felt stupid^^.
Anyway I wasnt sure what R2R was so I didnt check it, but I assume its fine.
Now I had a look at this thread:
http://forum.bongofish.co.uk/index.php?topic=1928.0

and it looks like the circuit is exactly the same. I guess the next step is to remove the serial chip and the transistor?
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bernard
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« Reply #3 on: September 15, 2011, 06:20:04 PM »

R2R stands for "Resistor #2 - seRial component" it might be the R02R on your board -- the marking is a little bit off -- near the internal connector (because of limited space, they often put markings a little bit away from the component, but you can always figure out which is which).  Maybe try the "checkpoint CP1" (there is a little arrow that points to a little round copper pad).  Try anything in that area -- we want to know if it  connects to the RTS pin. 
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gordon13
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« Reply #4 on: September 15, 2011, 06:26:38 PM »

RTS pin connects to checkpoint 1.
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bernard
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« Reply #5 on: September 15, 2011, 06:55:10 PM »

ok, then it matches.  You can proceed to unsolder the serial driver and the TRansistor on the side.

Make sure your tablet was somehow working before destroying stuff.  Else we will ask ourself if it fails because of the patch or because it was broken to start with.

Now we have to plan how we are going to patch things exactly.  For example, getting ground from the various places we need to connect to ground.
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gordon13
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« Reply #6 on: September 16, 2011, 02:18:01 AM »

Right thats done. I ripped the solder pads under the chip, so ill have to find somewhere else to solder the wires. Should be easy using multimeter.
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bernard
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« Reply #7 on: September 16, 2011, 06:13:25 AM »

ripped all solder pads???  yipes.  Please take a picture.
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gordon13
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« Reply #8 on: September 16, 2011, 01:15:03 PM »

Oh no now youve got me worried!

http://dl.dropbox.com/u/4249784/P1150950.JPG
http://dl.dropbox.com/u/4249784/P1150951.JPG

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bernard
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« Reply #9 on: September 16, 2011, 04:42:58 PM »

I am just surprised how many you ripped.  Maybe your solder was too hot or you kept it too long.  Did you try to cut the legs before removing them?

We will find ways to fix this do not worry. Now try to be extra careful.  I do not have this exact board in my hand, so I cannot search for good soldering points myself.  You will have to do it yourself.  If none is available, then you will have to ***gently*** scratch the green compound on top of a trace to expose the metal.

First you need to find exactly which pins are required to be soldered (most of them must be kept unconnected).

Now for the 5V power regulator, you need to lift (of better: cut) one of the leg. You will then have to solder on the pad (or the little remaining leg piece).

Actually, you should solder the power (and ground) first and test that.  (the led must lit when playing with the pen).   When that works, you can look at soldering the serial signals.
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gordon13
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« Reply #10 on: September 16, 2011, 07:51:59 PM »

I couldnt get rid of enough solder for it to come off easily so i forced a bit and didn't realise just how fragile the tracks are. I think the main problem is, i dont really have the best equipment. only a swiss army knife and a soldering iron with a flat 45 degree tip.

Alright so ive cut one of the legs of the regulator and soldered a wire on the pad. Ive also soldered a wire on the internal connector pin 9(DB9 pin 6).

Right so those wires now go to the ground and 5volt pins of the teensy i assume and if I plug the teensy to the computer, and touch the board with the pen i should see the light come on?
Are there any other pins that need to be grounded?
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bernard
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« Reply #11 on: September 16, 2011, 08:25:44 PM »

I assume you picked the good side of the regulator (check pictures in other threads: this is the same regulator in all Wacom boards since the Ultrapads).

GND: you just need to hook the Teensy GND at one spot (for now).    You can check that your ground is okay by testing the vias (holes) on the side of the board where you have a "ground plane" or "ground area" -- this is a big large trace covering all the "holes" -- this is typically ground.  So check that the Teensy GND pin connects with theses vias with your multimeter.

Plug the USB and pray -- if you see something weird, (your computer instantly shutting down, tablet not responding, smoke) -- disconnect right away.  Have your pen ready to try it quickly and have the Wacom tablet led in sight.  Your pen must be touching/tapping the sensor board (the bare PCB is fine) to have the led blink.

« Last Edit: September 16, 2011, 08:29:39 PM by bernard » Logged
gordon13
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« Reply #12 on: September 17, 2011, 02:40:15 AM »

We have power! Connected it up and the board (led) responds to pen clicks.
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gordon13
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« Reply #13 on: September 17, 2011, 03:54:04 PM »

I think Ill be lucky if it still works.. I now realize that some of the pads were in the middle of tracks which are now broken since they were ripped off. Its very messy and cant see where the tracked were meant to go. But Ill try and fix them, maybe find some points along the tracks and solder single copper wire or something.
I hope its not dead
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bernard
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« Reply #14 on: September 17, 2011, 04:00:46 PM »

it is most likely not dead -- I say more than 75% chances that you can make it work.
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