Upgrades can be made to control units from  Model G onwards to Model K manufactured before January 1996. These units have direct current bells. Such bells wear in time and either stop ringing or have reduced sound output . When this occurs, an upgrade to use alternating current (AC) bells will be required. We modify bells of the later Model K and early Model L units during routine repairs. This modification improves the ringing and extends the life of the bell.

An upgrade of bells with fitting of the standard brass dome is now available. This can be done during the next routine service.

The European Common Market now requires alternating current bells under its electro-magnetic radiation rules. So manufacturers in Europe have discontinued making direct current bells.

An upgrade improves the operating characteristics of these alarms to the latest Model K standard. Upgraded alarms provide a louder wakening stimulus while using less current and so prolong the life of the battery.

Upgrades are usually done during the next routine service. This minimizes the cost as the unit is disassembled in that service.

Early Model H Control Unit. Units with Serial Number 100 or lower, usually require a new front panel. This is a small additional cost which greatly enhances the look of these units.

Model G Control Unit. This alarm can be upgraded similar to later models. This model has obsolete sockets for the Silent Wakener and Remote Buzzer. These may be upgraded if the customer uses the wakener. Also, we would have to replace those obsolete plugs on the wakener and buzzer.

Model D and E  and earlier Control Units. These alarms have obsolete circuits and direct current bells. We have used up all the new direct current bells, so now the prospect is that an upgrade to alternating current bells will be required. We are developing an economic way of upgrading these models as there are many of these alarms still in service.

Key Benefits

	Cost effective
	Louder wakening stimulus
	Lower cost  of routine maintenance for upgraded Model H.