CueCat: De-clawing

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De-clawing a USB :CueCat

De-clawing or modifying a :CueCat is the process of changing it to output code that is plain-text without the encryption or serial number.

Caution: This process works with later model USB :CueCats – those I bought from ElectroMavin, it may not be appropriate for earlier models or for PS/2 :CueCats.

Note: If you have a PS/2 :CueCat, good de-clawing information and photos can be found at http://digilander.libero.it/electrons/CueKitty/68-1965.html. The process is very similar but the connection to cut is different.


Before going any further do check that your :CueCat works correctly. You should see a red flashing light in the nose when it’s at rest – changing to a continuous brighter red light when you put the nose against a sheet of white paper. When you scan a barcode into NotePad (or some other text editor) you should see a text string like this: .C3nZC3nZC3nWCxjWE3D1C3nX.cGf2.ENr7C3v7D3T3ENj3C3zYDNnZ.

If this doesn’t work then there may be a fault with your :CueCat and modifying it is unlikely to make that any better. So stop here!

If all is well and you are happy to go ahead . . .

It’s a simple process but needs a little confidence and some simple tools – a small cross-tip (Philips or Pozidrive) screwdriver to open it up, a sharp craft-knife or fine bladed pair of scissors to cut the single connection. Here’s how to do it.

Opening up

Identify your CueCat
First unplug your :CueCat from your computer, then turn it over and check the type.

If yours is a USB model with the same or a similar Cat.No. then carry on . . .

Fixing screws
Next undo these two screws.

They can be a little tight to start with but should undo if you have the right size of cross-tip screwdriver. Hold the top and bottom of the :CueCat together while you remove them, you don’t want any parts falling out.

Inside a CueCat
When you’ve removed both screws put your :CueCat down on a table with the ‘body shape’ up. Then lift off the top part of the body – it should come quite easily and expose the working parts which look like this:

The parts that interest us are all at the back end here near where the cable enters.

Note: At the ‘nose end’ where you can see that black cover there are some loose plastic parts: the black cover, a clear plastic prism assembly and a tiny plastic lens. You don’t need to remove any of them but if you should accidentally knock them loose you can easily reassemble them as they all drop into place. The black cover goes last and locates under a clip at the bottom and over the round grey lug at the top.

Find the chip
Next, move lift the cable from its guide at the back end of the :CueCat to give you access to the chip (see the yellow arrow).

Then identify the chip you need to work on – in the yellow circle here, it’s the bigger chip near the back end of the :CueCat.


Look carefully at the chip and find the locator marker – a round indent at one corner (marked here with the yellow circle):

Where to snip
Count up from the marker to the fifth connection leg on the chip and cut it, I used a sharp craft knife on this which is a bit messy (sorry about that). It’s possible to use a sharp pair of scissors – like nail scissors - to cut the leg as well.

Note that the connection legs are quite brittle and do not need much force to break. If you decide to use a sharp object to bend the leg out of its place, then be extra careful not to damage the adjacent legs!

Check that the leg is clear of the solder remaining on the circuit board and isn’t touching either of the adjoining legs. If it is then use a small screwdriver to move it gently until it is clear.

Now replace the cable in its guide – the shapes bent into it will show you how it goes; then put the top of the body back in place, turn the :CueCat over and replace the two screws.

That’s it.

Finish up

Check your work area to make sure that nothing has dropped out by mistake. If it has, open up your :CueCat and put it back.

Now plug your :CueCat back in to your computer and check the output. You should find that when you scan a barcode now you get plain text output instead of the previous encrypted string.

The only failures I have had are when I’ve left the cut leg touching one of the legs next to it. Moving it clear fixed the problem.

Good luck!

See also

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