NS Oscar 1 - Diagnosing issue - Page 2

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
Quirquincho (original poster)

#11: Post by Quirquincho (original poster) »

WWWired wrote: (1) Steam:
(a) How does your steam wand work?
(b) Is there a lot of pressure like a bull snorting in Spain running the streets?
Works great, at least compared to my Gaggia Classic Pro (don't have much else to compare to). The pressurestat is set at 1.5 bar.
WWWired wrote: (2) Group Head:
(a) After you run a shot, is your grounds puck dry?
They looked pretty dry to me... easy to knock off the portafilter. Not at all soupy.
WWWired wrote: (b) How many cc's or ounces of water do you get in 30 seconds from the group (once it flows)?
Hard to tell as the flow generally pauses at about 20 secs after the flow starts. I happened to catch this in the video.
WWWired wrote: (3) 3-way Solenoid or 2-way Solenoid?
(a) Did you install a new 2 or 3 way solenoid?
(b) Can you provide the specifications written on the solenoid?

. . . is the writing on your 3-way Solenoid like this? ↓
I just realized that the replaced solenoid was the 2-way solenoid. The writing on the new 2-way solenoid looks like this:

The 3-way solenoid was already there when I got the machine, but I did not see the flow issue until after the rebuild and several days of using it. This is what it looks like:

The writing is a bit hard to read and it was hard to catch a good pic, but it's mostly legible if you zoom in. Main difference I immediately notice is the pressure specification at 15bars.
WWWired wrote: . . . are your 3-way coloured wires connected like this? ↓
Not quite. As you can see in the pic below, the terminal triad is in a different direction. The wires were reconnected in the same way they were when I obtained the machine.

Does your Pressostat look like this? ↓
I couldn't catch a pic because the vacuum breaker prevents me from completely removing the cover. My Sirai pressurestat looks similar, but the writing on the right side is slightly different:


Thanks for any insights!

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#12: Post by WWWired »

Hi :D

Just took an initial quick look at the great pictures (that will help everyone who has an Oscar I).

Just working on some ideas/pathways now. Do you have a photo of the old 2-way solenoid (showing specifications) that was replaced by any chance?

Best of health to everyone reading this thread :D


#13: Post by stanp »

ceme is still in business making what looks to be the same valve.
there are a lot of used ceme valves on ebay. if you don't
hear/feel a click, try a used coil first for $25.

http://files.cemegroup.com/elettrovalvo ... 996750.pdf

Quirquincho (original poster)

#14: Post by Quirquincho (original poster) »

WWWired wrote: Just took an initial quick look at the great pictures (that will help everyone who has an Oscar I).

Just working on some ideas/pathways now. Do you have a photo of the old 2-way solenoid (showing specifications) that was replaced by any chance?
Thanks for taking a look! Here's the pic of the old 2-way solenoid:

stanp wrote: if you don't
hear/feel a click, try a used coil first for $25.
Also, thanks for the suggestion about the used coil, Stan!

Quirquincho (original poster)

#15: Post by Quirquincho (original poster) »

The past couple of days, I fired up the machine again and took a closer look. I took out the 3-way solenoid and disassembled it. It looked clean and unobstructed, as I expected given the recent through cleaning. At the same time, I did not see any bits or pieces of plastic, which I saw could be evidence of a broken retention valve. Without the solenoid in place, water flowed unobstructed out of the lower hole of the group, indicating no obstructions in the HX (as expected).

Next, I took a closer look at the 2-way solenoid. I tried the test recommended by Elektros to check proper functioning of the 2-way solenoid (https://www.elektros.it/it/en/tips_tric ... paragrafo2). Interestingly, some drops of water did come out of the solenoid line to the boiler. I made sure the boiler was full before doing this. So, it looks like there's some evidence of malfunction in the 2-way solenoid.

While taking a closer look, I also noticed leaking from the steam wand valve. Could it be evidence of an overfilled boiler due to the 2-way solenoid malfunction?

Based on some old forum threads, the combination of symptoms seems to also suggest a failing retention valve.

Nuova Simonelli Oscar faulty retention valve
Nuova Simonelli Oscar with brewing trouble

I now wonder what is the most likely culprit. Is it an electrical 2-way solenoid issue? Or, is it a failing retention valve? Or, is it both? Could it be both? And, is the fact that the intermittent flow of water only happens when the machine is up to temp consistent with a failing retention valve?

My machine is now with my (more savvy) buddy who is helping me troubleshoot and helped me with the restoration. Still, any insights would be much appreciated!


#16: Post by WWWired »

Hi . . . just finishing up a more comprehensive reply to your recent post and trying to put together an annotated/symbols electrical diagram for the Oscar 1 series. For now just wanted to put some initial ideas forward to consider as its been a bit since was able to get back to your fascinating original post and replies. Your original video seems to show unusual pressure/flow at the group. Often, a person's ear is the best diagnostic tool as listening for the switching and various activations of the pump, solenoids, and noting how they coincide with the flow/pressure will identify the systems involved. Switching does appear to be occurring between the electrovalves and thermal systems and also proper engagement of the group electrovalve (3-way solenoid) and switching of the 3-way appears to be occurring well.

The 2-way solenoid seems to have drawn some attention but as the boiler is getting water and heat, and your boiler water level sensor and GICAR brain-box are seemingly regulating and switching current to your pump/solenoids (2 and 3 way)/and boiler heating element properly, the electrical logic in your Oscar seems sound up to those stages. A "Normally Closed" 2-way Solenoid usually doesn't fail in open position (unless the spring or piston fails inside the armature - the post inside the black solenoid block). It is possible a small piece of debris is blocking one of the channels in the 2 or 3 way solenoid(s). The water channels in some of these solenoids can be extraordinarily tiny and a small blockage could interfere with normal opening and closing of the solenoid's piston. This could be a situation that just requires a bit of fine-tuning/adjustment. If it is something in one of the solenoids, it could possibly be a stubborn armature and piston or spring and testing the coil will narrow that diagnosis to begin with (see the multimeter video below for a 2-way solenoid coil test). A first adjustment, however, might involve the following:
  • Adjusting the new OPV to see if it makes a difference to flow/pressure and how that might affect function. Your Elektro OPV kit is wonderfully ingenious designed bit of technology, factory calibrated to 10 bar. That said, even a perfectly calibrated OPV can produce some unusual pressure results throughout a system like the Oscar dependent on a few variables such as your pump (and a few other components)
Here's a screenshot of the Elektro OPV kit with a few notes . . . by "left" it means counter-clockwise and "right" is clockwise" (picture credit to Elektros online):

And here's a quick link to a brilliant youtube video by Elektros (which I hope is ok to link to here) about adjustment of the OPV:
A pressure gauge is not strictly necessary at this point, as this is just about trying a few 1/4 turns (tightening and loosening turns) on your Electro OPV kit screw/nut to see if a difference is perceived at the Group . . . be sure to mark your OPV position with a marker or something so you can return it to that position if OPV screw/nut adjustment makes no difference. Side Bar:
Your Sirai pressostat is something that can be considered later, and usually about 1 full turn of the screw on a Sirai equates to 1 Bar of pressure increase/decrease depending on direction . . . maybe later after a bit more troubleshooting (I am always careful around a pressostat as you can see massive arcing of electricity strong enough to weld normally lol . . . the amps in a Pressostat (10+) can be enough to pop out teeth fillings and put us clumsier folk in a whole other bracket of disability needs so no touchy when plugged in is my thoughts i.e. unplug, then adjust, then plug in again).
It appears a little more pressure/flow is needed. Tightening the OPV nut/screw a bit at time, will provide an opportunity to see if the Oscar can gain performance at the Group.

If you do want to test your 2-way solenoid, take a multimeter and set it to ohms Ω/continuity and then check for resistance (do this with the black solenoid block disassembled from the machine). In the CEME 6610 series the resistance in mine was 184 to 185 (which I believe is correct for this 22VA (+- 5). If your reading comes back with something near zero, then the coil could be defective:
Here's a picture of the settings on the multimeter: