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Handset Testing
Clip one battery lead clip onto one battery terminal. Connect a test meter, set to the 200mA DC range, between the other battery lead clip and the other battery terminal, so that the meter is in series with the battery. After an initial surge the meter should read zero, or possibly 1mA. Switch down to the 2mA range to obtain a more precise reading, which should be less than 0.010mA (10uA). The reading may initially be higher than this, and gradually reduce as the chemical composition of C2 reforms.

Set the test meter back to the 200mA DC range, and press one of the remote control buttons. With a fresh alkaline battery the reading should be between 40mA and 60mA. If the readings obtained vary greatly from these, the cause should be investigated. If all is well the battery may be fitted properly and the cover clipped into place.

Motherboard Construction
The motherboard is constructed on a single sided PCB, which is shown in figures 6A and 6B. Do not fit anything into the module positions (pads J101 to J120), or in the test link position (TP101 to TP102) at this stage.

Fit the terminal blocks (TB101 to TB104) with the wire entries towards the edge of the PCB. C103 must be a Class X or X2 rated component, suitable for direct connection across the mains. D101 is be fitted with the curved side towards the edge of the PCB as shown.

A terminal pin (Veropin) should be fitted in the pads at each corner of the rectangle around U1 and surrounding components. These are used to hold a screening can made from a 30mm wide strip of tin sheet. Take care when cutting this as the edges can be very sharp.

A small aperture is needed so that the IR can reach D101. It may be easiest to join the tin sheet at this point. The tin plate can easily be soldered to the terminal pins and itself with a larger soldering iron (above about 30W).

It is advisable to fit a lid to the screening can. Do not do this until the unit has been tested, in case you need to get inside! Clean the PCB with suitable solvent to remove any flux residues.

Motherboard Testing
WARNING. DURING THIS TESTING PROCEDURE THE ENTIRE MOTHERBOARD IS LIVE AT MAINS POTENTIAL. SWITCH OFF AT THE MAINS BEFORE TOUCHING THE MOTHERBOARD, TEST METER OR ANYTHING ELSE CONNECTED TO IT. FAILURE TO HEED THIS WARNING MAY RESULT IN A POTENTIALLY FATAL ELECTRICAL SHOCK. THE USE OF A RESIDUAL CURRENT CIRCUIT BREAKER (THE TYPE USED FOR GARDEN POWER TOOLS) IS RECOMMENDED.

Connect a length of two core mains cable to TB101, with the live (brown) wire to the terminal closest to FU101. Connect the other end to the mains, such that it can be readily switched on and off. Do not switch on yet.

Solder a short piece of tinned copper wire to TP101 (one of the test link pads). Connect the positive terminal of your test meter to this wire, and the negative terminal to the screening can. Test leads fitted with crocodile clips are essential here. Set the meter to the 20V DC range. Place the PCB on a clean dry insulated surface - a plastic videocassette box is ideal.

Ensure you cannot inadvertently touch anything, and then switch on the mains. The meter should read between 4.7V and 5.5V. Switch off, and wait a few seconds for C103 to discharge. The meter may continue to read a voltage, or may drop slowly, due to the charge stored in C110. This is not cause for concern.

Fit the test link between TP101 and TP102. Solder short pieces of tinned copper wire into the pads marked J101, J102, J103 and J104. Connect the positive meter terminal to J101 (leave the negative on the screening can). When you switch the mains on the meter should read below 0.5V. Hold the remote control about two metres away and point it towards the curved face of D101. Push the left button and the meter should read at least 4.5V. Release the button and the reading should drop back to below 0.5V. Repeat this for the other three channels. Remember to switch off at the mains when transferring the meter connections.

If these tests are successful the motherboard assembly is working correctly. Disconnect it from the mains and remove the pieces of tinned copper wire in J101 to J104. The test link between TP101 and TP102 must remain fitted.