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I had to make some changes to my 24VDC external power supply, used to power the 250watt ELC lamp in the Elmo GS1200. I found out the hard way that the little digital LCD clock, that I had incorporated into the design to monitor lamp hours run time, uses an internal battery to store data. The problem is that when the battery fails you cannot replace it, as it is sealed into the unit, at which point you presumably throw it away and buy a new one! Mine failed after about 3 months, so realizing what a useless concept that was I set about looking for one which would store run time data and not require a battery to do so.
I found one that met my requirement, and by jumping a couple of connectors you can also zero it out at every lamp change, To facilitate that, I installed a recessed push button switch on the front panel of the power supply. You just need to push on it for about 1 second to zero out the meter. To get all this to work I had to use a larger DPST toggle switch which shifted some of the components on the front panel. So this is how iteration 3 of the design now looks:
I found one that met my requirement, and by jumping a couple of connectors you can also zero it out at every lamp change, To facilitate that, I installed a recessed push button switch on the front panel of the power supply. You just need to push on it for about 1 second to zero out the meter. To get all this to work I had to use a larger DPST toggle switch which shifted some of the components on the front panel. So this is how iteration 3 of the design now looks: