Conti Prestina Espresso Machine Restoration 101 (Completed and Indexed) - Page 62

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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drgary
Team HB

#611: Post by drgary »

Thanks, Arcus. Good luck with your search.

Today I'm going to try and install the Sirai PSTAT as the Sopac has a wide deadband at this point in its lifecycle. I'll test that deadband with a steamwand manometer before changing it out. I've looked up PSTAT info online and here's what I'm gathering.

The Sirai is so outsized because it's a commercial unit and is capable of running a much larger heating element than in my machine. No matter. It will work for mine. Paul Pratt's site has a good discussion of PSTATs, and he says the Sirai is rated with a 0.2 bar deadband at first, but that deadband widens as the Teflon membrane stiffens over time. Others have mentioned changing out the membrane every two to three years. Paul recommends mounting the PSTAT low for longevity as a hot environment may stiffen the membrane sooner. There's a rebuild kit that is almost as much as the Sirai itself, but the PSTAT isn't very expensive, $58 if I remember correctly. Paul and erics have both written that one hooks up the hot and neutral leads to the Sirai by simply lining up the incoming lead with the outgoing one, and which terminal is chosen otherwise doesn't matter. In other words, there's a bank of three incoming and three outgoing terminals that pair up. Which pair is chosen for hot or common doesn't matter as each switch is normally closed (NC) or can also be common (C). The drawback with the Sirai is its huge size, but I've determined it can be shoehorned into my machine. As erics noted from the spec sheet the Sirai is best mounted horizontally to retard scaling of the membrane. If only I had an erector set! But I'll figure out something simple.

I also briefly considered switching out my Sopac with a Jaeger that appears almost identical and would simply screw on the existing pipe. Chris Coffee likes the quality of the Jaeger but I've been unable to find specs, including deadband.

In any case, I received my other plumbing parts and assuming they fit I'll attach the vacuum breaker, which will be a big plus from starting up the machine and bleeding off the air once or twice before it comes to temperature. I'll finish securing plumbing pieces in position with some Loctite 567 used sparingly. I'm still deciding whether to fit a steel panel over the front gap. If I do that I'll do something so the steam pipe protrudes less and can allow installation of a flat panel in that place. I've ordered thin ceramic insulation from McMaster-Carr and will have plenty to spare that I'll list on the Buy/Sell forum after this installation and the one for my Coffex (aka Maximatic).
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

jonny

#612: Post by jonny »

Here is what makes me angry:
Why is there not a jaw-dropping emoticon on this forum!?!?

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drgary
Team HB

#613: Post by drgary »

I just tested the Sopac PSTAT and the original manometer using the OE steam wand manometer and determined that the Sopac PSTAT currently has a deadband of 0.5 bar. Putting in place the OE steam wand manometer was tricky. I had to use a spring clip pliers to spread the thick rubber tube over that commercial steam tip. Now that I was watching carefully I also noticed that the original manometer sticks, so it moves upward in jerky movements and sticks in the high position even when the steam wand manometer has smoothly declined to the low end of the range indicated on the original manometer. Although it doesn't show a number scale, the original manometer reads at the start of the red line low reading of 0.55 bar and at 0.9 bar at the outside of the upper red line. This makes me wonder how much difference the pressure will make in shot quality given the temperature stability of the group. Since I have a Sirai PSTAT at the ready I might as well install it and learn to solder fittings in the process. I'll also need to replace the original manometer.

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Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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peacecup

#614: Post by peacecup »

One of the original HB Prestinas can be found somewhere down on Mogo's espresso page:

http://mogogear.webs.com/thingsespresso.htm

Apparently it started in with Bill in Texas, and went through Portland on it's way to Richard Penny's. Just above it is a photo of the first HB Caravel that MoGo imported from Italy. We had some fun discussions about these machines during the dawn of the lever resurgence. Now of course there's the Strega, L1, and the ES2, but the originals still have their charms.

PC
LMWDP #049
Hand-ground, hand-pulled: "hands down.."

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erics
Supporter ◈

#615: Post by erics »

Since I have a Sirai PSTAT at the ready I might as well install it and learn to solder fittings in the process. I'll also need to replace the original manometer.
I would have some second thoughts re that Sirai pstat considering the impact on "space arrangements". A MA-TER pstat is just fine, very easy to adjust, and supports the amperage requirements of that element. That Sirai should be easy to unload on our newly established B/S forum.

The gage should be easy to replace (just measure the case OD - 40 mm?). EPNW probably has the largest selection.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

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drgary
Team HB

#616: Post by drgary »

Eric:

I don't have to jump ahead with the Sirai with its 0.2 bar deadband to start. How much does deadband matter? I'm making delicious coffee with the original Sopac with its 05 bar deadband but obviously haven't spent time fine tuning. I researched the Jaeger PSTAT and it has a deadband of 0.35 bar.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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RayJohns

#617: Post by RayJohns »

drgary wrote:Replaced the gooey electrical tape with Rescue Tape.
Hey Gary,

Is that picture the before or after? Are you aware that when you use splicing tape, you have to stretch it to "activate" it?

I'm not sure if I'm looking at the before or after pic with that connection, but if it's after using the splicing tape, it appears you haven't fused it properly.

Let me know. I can make a brief video if you wish (showing how to employ the splicing tape).

Ray

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RayJohns

#618: Post by RayJohns »

Love the little ice cube tray!

Hope you tidy up those wires.

The nuts are known as "Rectangular Speed Nuts"

Have you ever used that Evap-o-rust stuff? I think you'd love it. I use it to clean rusty nuts and bolts for restoring machinery (like on my lathe and mill, etc.)

Ray

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RayJohns

#619: Post by RayJohns »

Gary, I'd be happy to make you some custom parts on my lathe to secure those Pilot lights a little better, if you like.

The Blu Tac is not "race ready" in my humble opinion.

At a minimum, I would think some sort of Delrin fixture to hold the lights and then maybe the use of a little VHB tape or something.

Project is looking fantastic overall!

Ray

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drgary
Team HB

#620: Post by drgary »

Thanks, Ray. I did stretch the tape and it is bonded together. So I think it's fine.

Fittings for the lights would be great. Should I send you my spare pair so you have something to work with or is it enough to measure the diameter of the studs with calipers?
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!