A friend has a 1-group Nuova Simonelli Mac Cup automatic with a fried brain box. She doesn't want to spring for new electronics (~$700), and she wants me to convert it to a semi-auto; plus she'd like me to convert it from a rotary pump to a vibe pump for weight savings (she drags it around to lots of
charity functions).
I did this mod for a Bunn ES-1A and it wasn't too difficult - IIRC, $130 for the parts to make up an auto fill circuit & ~$100 for a vibe pump with an adjustable OPV on it. A lot cheaper than a new brain box!
I believe the 7 liter boiler capacity could cause damage to the vibe pump if it's relied on it to fill the boiler (it's drained after every gig). The Mac Cup has a manual fill valve on it, so it can be filled with fresh water using the line pressure. But I'm not sure I trust this user to remember to do this.
Can anyone suggest
a way to set a timer on the vibe pump circuit to interrupt it if the pump is run for too long (maybe 45 seconds??) and then automatically reset itself for the next shot? This would give the users time enough to pull shots and hopefully the shutting off of the pump would remind them to use the manual fill function when its empty.
Or some other way to remind the user that the vibe pump isn't for filling the boiler?