Sorry for the delay, I’ve been busy with other projects, but the winter sprinkler ban just kicked in here so I’ll be looking at this again. I switched over to a 12vdc power supply – this results in one of the master solenoids triggering sometimes, but not reliably enough to depend on. The more distant master solenoid wouldn’t trigger at all (when under water pressure – it works when under no pressure). It’s actually not the holding current that’s the problem – it’s the initial in-rush current. If I turn on the zone, then manually turn on the solenoid (using the manual release), then back off again, the zone will stay on. At 12VDC these solenoids will often trigger even without a higher voltage triggering pulse, so I’m guessing there may be something wrong with the boost circuit – I’ve seen a higher voltage, but maybe there’s not enough stored power in the cap for some reason.