Comfort 1 System 12v Fail

[Campbell]

I know it\'s old, but my trusty Comfort 1 (Action 4.233) has seemingly got big trouble....I would appreciate some pointers in fault finding...

Today the system called me saying intruder alert...However on checking CCTV I saw this was untrue. However when my son came home, and opened the front door...he could not switch off the alarm as the keypad was dead...therefore the alarm went off and he could not switch it off...

He called me and I eventually managed to switch it off, after the system had released the telephone line...it took a time.....

Unfortunately when investigating....using phone to put into engineer test mode, my son, hung the phone up.....which sent the system into overdrive, presumably as the tamper on the panel box was removed.....It was a nightmare to switch off....

I have put a voltmeter on the 12v (recording 1.44v) and S12v (recording 1.41v) connections and they are recording less than 1.5v, however if I put the meter on the Siren 12v it is recording 13.64v and appears healthy.

In the short term, I suspect  I can connect draw power throught the Siren 12v....or direct from battery to enable keypad use....

Can you or anyone advise possible fault finding route or cause....and solution.

I have not checked any other components yet.
many thanks in advance

Campbell

[ident]

If the 12V supply is showing a very low voltage, it may be that there is  a short circuit or high current from a device on the bus. Check if the Black heatsink on the edge is very hot - this indicates that this may be the case.
Disconnect everything from the 12V, and see if the voltage recovers. There is a resettable fuse which protects the 12V output when there is too much current drawn

[Campbell]

Many thanks for advice, I have disconnected the plug with S12v, com, 12v. Then checked voltage on S12v and12v. The voltage remains at less than 1.5v. Is the resettable fuse self resetting or do I have to power down the system.

The black heatsink is touchable warm.

Can you advise what other components share the 12v.

Any further advice appreciated

Campbell

[ident]

The resettable fuse does reset itself if the load is removed. If you have removed all the wires from S12V and 12V then it should not be the fuse overloaded.

Can you disconnect everything, including keypads and all other wiring, and measure the 12V? If it is still low then the board may have developed a fault unfortunately