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It's alive!
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Discussions > Espresso > Espresso Mods > It's alive!  
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TRUgEEk
Senior Member


Joined: 6 Aug 2012
Posts: 20
Location: east coast
Expertise: I love coffee

Posted Wed Sep 5, 2012, 5:05pm
Subject: It's alive!
 

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?

Thanks for any help!!!

TRUgEEk: diva lives.jpg
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IMAWriter
Senior Member
IMAWriter
Joined: 4 Jul 2002
Posts: 5,862
Location: Brentwood, TN
Expertise: I live coffee

Espresso: Bezzera Strega
Grinder: Forte, OE Pharos,...
Vac Pot: Adcraft SS, Yama 8 cup
Drip: Brazen, Kalita, Chemex,...
Roaster: Behmor 1600, CO/UFO combo
Posted Wed Sep 5, 2012, 8:07pm
Subject: Re: It's alive!
 

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.........

 
Rob J (LMWDP #187)
My Music Production web site:
www.robertjason.com
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calblacksmith
Moderator
calblacksmith
Joined: 25 Nov 2007
Posts: 7,726
Location: Riverside, Ca, U.S.A.
Expertise: I live coffee

Espresso: ECM Vene. A1, La Cimbali M32
Grinder: Azkoyen Capriccio, Major
Vac Pot: 40s era Silex
Drip: Msl. Com. brewers
Roaster: gave it a try, decided no
Posted Thu Sep 6, 2012, 5:55am
Subject: Re: It's alive!
 

Congrats on getting her to live again.

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.
Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

Feed the newbs, starve the trolls and above all enjoy what you drink!
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TRUgEEk
Senior Member


Joined: 6 Aug 2012
Posts: 20
Location: east coast
Expertise: I love coffee

Posted Thu Sep 6, 2012, 9:38am
Subject: Re: It's alive!
 

Thanks Wayne.

I'm running the pump from a FloJet BW4000. I used the supplied hose which is 1/4" I think. I'm wondering if that's restricting the flow causing the pulsing? I'll invetigate.

I did disconnect the gauge and it had no effect. I agree it's probably the gauge that's bad.

BTW, I asked the question in another topic about the autofill sensing and your reply helped me get this working, so thanks again!
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CraigA
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CraigA
Joined: 19 Dec 2001
Posts: 11,241
Location: Rexdale, Toronto, Ontario, Canada.
Expertise: I live coffee

Espresso: PID/PressureMod 2001...
Grinder: BUNN FPG-2 DBC, Baratza...
Vac Pot: Bodum Santos manual, Yama 5...
Drip: Behmor BraZen, BUNN VPR-APS,...
Roaster: Refurb Behmor 1600, BBQ...
Posted Thu Sep 6, 2012, 10:04am
Subject: Re: It's alive!
 

TRUgEEk Said:

Thanks Wayne.

I'm running the pump from a FloJet BW4000. I used the supplied hose which is 1/4" I think. I'm wondering if that's restricting the flow causing the pulsing? I'll invetigate.

Posted September 6, 2012 link

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

CraigA: Bourdon tube.jpg
(Click for larger image)

 
http://twitter.com/CoffeegeekCraig
http://www.facebook.com/craig.andrews.169

Excellent coffee doesn't just happen!
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calblacksmith
Moderator
calblacksmith
Joined: 25 Nov 2007
Posts: 7,726
Location: Riverside, Ca, U.S.A.
Expertise: I live coffee

Espresso: ECM Vene. A1, La Cimbali M32
Grinder: Azkoyen Capriccio, Major
Vac Pot: 40s era Silex
Drip: Msl. Com. brewers
Roaster: gave it a try, decided no
Posted Thu Sep 6, 2012, 2:12pm
Subject: Re: It's alive!
 

On the mark again Craig, nice pic of the workings of a gauge, thanks again for posting it, a pic says a whole lot when it clearly shows the works of something.

 
In real life, my name is
Wayne P.
Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

Feed the newbs, starve the trolls and above all enjoy what you drink!
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TRUgEEk
Senior Member


Joined: 6 Aug 2012
Posts: 20
Location: east coast
Expertise: I love coffee

Posted Thu Sep 6, 2012, 9:20pm
Subject: Re: It's alive!
 

Thanks for posting again Craig. My pump does have a bypass, but Im not sure if it's the balanced type or not.
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