I've been re-animating a UNIC Diva Pro. So far I've had to replace the heating element and a bearing in the pump motor. The dosing / autofill box was dead too, but I couldn't bring myself to spend $500 for a new (old) inferior product so I designed my own with an Arduino. It's overkill right now, but I will add a shot timer, doser, wakeup timer etc. and it only cost $50 or so in parts.
I still have two issues that some of the knowledgable folks here could help with.
The steam pressure gauge works, but the brew pressure gauge is pegged at 15 bar. Is this likely to be a bad gauge or possibly a clog in the tiny copper tubing that feeds it?
The pressure seems adequate, but pulses a bit during a shot. Is that normal for a rotary pump?
Bill, you are true to your user name! Hang in there, and someone geekier than I will most likely come to your aid. I'm more of a lever head these days, and not super hip with coffee machine electronics. Now a recording studio.........
The question of getting old machines to live again is how much do you want to mess with it. In this case, the answer was enough to get it running! These are not complicated machines, even the most advanced ones, when you get down to the basics.
The pressure should be smooth and not pulsing in a rotary pump, there is a pressure regulating device in the pump head and it may be dirty or in need of adjustment.
The gauges on machines tend to not be of the most durable sort, perhaps it is the service that they are performing, I would guess that the gauge is bad, esp in light of the fact that it does not move. You could loosen the fitting at the gauge as see if it drops or remains the same.
Any more questions, just ask!
In real life, my name is Wayne P.
Feed the newbs, starve the trolls and above all enjoy what you drink!
I would think so, as the inlet size of a Procon or Rotoflow etc rotary vane pump is 3/8"-18 NPT. Some people have a small accumulator tank hooked inline as this cushions & absorbs any pulsing. To avoid an accumulator tank, a rotary pump should have a balanced bypass. This equalizes a pressure differential between a possible fluctuating line water main pressure (60 -80 psi) versus the inlet pressure regulated down to 25-35 psi from the standard water mains pressure with a standard bypass valve.
I did disconnect the gauge and it had no effect. I agree it's probably the gauge that's bad.
These gauges use a mechanical half circumferential flexing "Bourdon" tube attached with an arm & small mechanical gears that can break over time. The Bourdon tube can crack/split over years of repeated pressure flexing & unflexing also. Please check my posts as I have answered this a number of times (no sweat again ;) ) & have pics of the gauges internal assembly.
Here's a pic.
fix output pressure regardless of input pressure fluctuation
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