Silencing the Falcom Twist modem

This is a permanent alteration to the Falcom Twist, and will invalidate the manufacturer's warranty. Do not do it unless you are sure you know what you are doing

Background

The Falcom Twist was a modem we were using at Argogroup for testing mobile networks. Almost every time it interacted with the network (send/receive SMS, make/drop/receive voice calls, establish/tear-down GPRS connections), it would emit a 'beep' - which would be very annoying.

Stage 1 - the tools

You will need the following:

A Falcom Twist:

A small Phillips screwdriver, a smallish flat-head screwdriver and a Stanley blade (or small drill bit, about 1.5mm):

Opening the Twist

Along the side of the Twist, there is a groove:

Near each corner (along the long side), you can see a change inside the groove. These are the clips that hold the lid in place.

Insert the flat-head screwdriver into the first clip position (doesn't matter which one you do), and twist gently:

Do the same for the other 3 clip positions, and the lid will open:

The buzzer is actually the small square black object on the top left hand corner of the board (in this view) - labelled "OW51 BSY 0643D". However, you can't stop it from here!

Near the top-left hand corner, and bottom right hand corner, there is a Phillips screw. Undo these, and the board will come off:

Note the piece of clear plastic - make sure you don't lose it!

Making the alteration

If you look closely at the circuit board, near the antenna, there is a 3-pin surface mount chip on the bottom left hand corner (in this view). This controls the buzzer.

Using the Stanley blade, cut the track coming out of it that goes between a capacitor and a resistor, and ends in a via. To make it clearer, I've highlighted it in orange below:

If you're using a drill but, drill into the via at the end of the track.

Putting it back together again

As always, assembly is the reverse of disassembly:

• Put the PCB back into the bottom of the case
• Put the Phillips screws back in
• Put the clear plastic lens back in
• Snap the top shut

Job done!