I recently moved in to a house which has an existing burglar alarm.
The alarm control unit is a white box with 'CPD2' and 'conforms to
BS4737' printed on it. It is key operated with 3 positions - Set, Day
and Test. It has lights for 'Supply Fault', 'Tamper', 'Entry/Exit',
'Zone 1' and 'Zone2' and a button marked 'Omit Zone 2'. Inside the
main circuit board is marked 'Munford & White c1983'.
I have never used it, but there are sensors on the front and back
door, ground floor interior doors, ground floor windows and motion
sensors in 2 rooms (one of which I have removed). I disconnected 1 of
the motion sensors and ever since the 'Tamper' light on the alarm has
come on and I cannot set the alarm. I have tried my own amatuer
attempts to 'Reset' the alarm, unsuccessfully. I have also tried to
find someone to come and fix it. So far, have only found people who
will charge £150 plus just to have a look, not guaranteeing success,
or wanting to sell me a new alarm and service contract.
I want to start using an alarm. The system here would do everything i
want. Any advice on fixing it would be much appreciated. Or
considering it's age should I just replace the conrol box and use the
existing cabling (and sensors?)?
When you removed the sensor, you probably didn't connect the alarm circuit
conductors and tamper circuit conductors together. The sensors work by
breaking the connections, not by making them. The tamper light indicates
that the tamper circuit is in full pelt and it won't set the alarm. The idea
is that if you chop the cables when the alarm is turned on, it will set it
More likely the tamper circuit open. If a fuse has blown it would most
probably be the aux supply fuse. Does the LED on the other sensor
still operate? If so it is more than likely a wiring problem with your
In the sensor you removed you will have six wires. You need to find
out which ones are which and do the following/
The 12V supply, (+ve and -ve), needs to be insulated from all other
cables and from each other.
The tamper circuit, (2 wires), need to be connected to each other and
insulated from all the others.
The zone circuit, (2 wires), need to be connected to each other and
insulated from all the others.
If yours is any different to this then report back.
Take a look inside the control panel at which wires have been connected to
the zones, and which have been connected to the tamper circuit. They should
be obvious inside the panel. Where you removed the detector you'll need to
connect together the same colour wires that are connected to the zone and
tamper circuits inside the control panel, DON'T CONNECT THE POWER WIRES
TOGETHER, OR YOU'LL BLOW ALL THE FUSES, just wrap the bared zone and tamper
wires to each other.
Example 1: If the Blue and Yellow wires are connected to the zone circuit
inside the control panel, then you need to wrap together the Blue and Yellow
wires where the detector used to be.
Example 2: If the Brown and Green wires are used for the tamper circuit,
then you need to wrap together the Brown and Green wires where the detector
used to be.
Example 3: If the Red and Black wires have been used for the power to the
detector, then you need to keep them separate where the detector used to be.
Putting them together will blow the fuses, so keep them apart. Don't
connect them together at all.
Get the idea ?
There goes fatty wallop again.
This time though he may be right and if you have removed the sensor you'll
need to short out the wires as he suggests. If the sensor is removed
permanent then remove that sensors wiring from the panel terminals and use
two wire links to give the necessary shorts.
The bit the fatty didn't mention is that many M&W panels had a small reset
button on the PCB and that may need to be pressed. Some also had a reset
sequence which was Reset button + zone omit button at the same time.
These panels are very old and your guess of 1983 is quite right. There were
very good kit though and M&W sold thousands of them. If you get it working
and providing the electronics don't pack up it'll last a good while yet. The
main problem likely is mechanical failure of the key switch as opposed to
OK, many thanks for the advice all. I have now connected up the
relevant pairs and isolated the mains. However, the tamper light still
comes on when I turn the key to test. I can't find a 'reset' button on
the PCB, is there something else I could try? I must also confess that
the wire to the sensor was just cut when the sensor was removed. Any
help, gratefully received.
p.s. I'm new to newsgroup posting. How do I change my displayed email,
to avoid spam?
Have you tried shorting the actual tamper connections in the panel. That is
disconnect the associated tamper wiring and insert a wire link. That way you
can see if it's the panel at fault or the wiring.
Also take all power off the panel and power up again. Press Bell Test and
Zone 2 together to see if it resets. Try the tamper short as above though
Is it the panel tamper switch? or maybe the bell box?
You have to eliminate the panel first before looking at wiring.
| p.s. I'm new to newsgroup posting. How do I change my displayed
| email, to avoid spam?
AFAIK you can't, on Google. Either use a 'disposable' email address when you
sign up to Googlegroups, or use a proper newsreader (or even Outlook Express
:-) in conjunction with your ISP's newsgroups (NNTP) server.
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