Hi I need help on electrical testing boiler parts and was wondering if anyone would tell me how to test for a ' short circuit on an APS' using a multimeter??? And what readings to look for, this is the only test that I struggle with?
Any replies would be great thanks.
Remove mains from the appliance
Remove the connector at the pcb and measure at that connector. If you do this, you are measuring the loom AND APS i.e. what the pcb actually sees
If you can remove the other end of one of the neoprene pipes going to the APS, do so (you need to be able to suck or blow down it to operate the APS)
Get your multimeter and short the probes togetherto check the resistance of the probes
check the resistance (at the pcb connector) of the normally closed to common contacts should be in the order of an ohm or less
GENTLY suck or blow on the neoprene tube so that the membrane in the APS activates the APS microswitch
Kink the tube so that it maintains pressure (doing this will also test for a rupture inthe membrane) and after a couple of seconds measure the resistance (at the pcb) of the normally open to common contacts , again, ideally should be less than an ohm
That's it
Other than the changeover pressure, which is factory set, that's it tested
contacts on trhe microswitch are written on the side of the switch itself
n /c, n/o, com