Nuova Simonelli Oscar having heating problems!

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
ricky analog

#1: Post by ricky analog »

Hey everyone, I have been having a problem with my Oscar that has been getting a little worse it would seem each day. It has an issue where whenever the heating lamp comes on, the empty water tank light flickers on and off a bunch. When you run water while this is happening, the water shuts on and off with the blinking of the empty tank light. This really is annoying when pulling shots. The only way to pull shots was to trigger the behavior, wait for the boiler to heat up to temp, and then quickly pull the shot before the issue resurfaced. I have included some footy to help explain what I mean:
Then today I wake up and the heating element won't even turn on! Is my machine dead??? It still pumps water. It just won't heat up. The friendly people at Elektros informed me that they think the electrical board may be defective. They suggested I try to "short-circuit" the water-level probe and to "short-circuit" the pressure-stat. I am assuming by "short-circuit" they mean bypass (italians english is cute). I included another clip to show what the issue "looked" like this morning:
Does anyone here know what is wrong or have any advice? Should I try to bypass the water-level probe and the p-stat? If so, how do you do that??? I really really really need a shot of spro right now!!!! This is killing me. Any help would be greatly appreciated.


#2: Post by fredk01 »

I'm now electronics whiz, but...

Bypassing the water level probe is easy. Just pull the connector off the probe. Your pump should start immediately and pump water into the boiler. As soon as you touch the connector to your boiler (ground) it should stop. If it does that, your level sensor should be good.

Have you looked at the tips and tricks section of the Electros site (found at the bottom of the home page)? He really does a good job of showing how to trouble shoot common Oscar problems.

Hopefully someone with more electronics knowledge will chime in soon.

ricky analog (original poster)

#3: Post by ricky analog (original poster) »

So here is an update. I woke up this morning and went to try and diagnose the problem, and when I turned the machine on we were back to where the empty tank light was on. I thought to myself, hmmm, maybe we are gonna be able to get the heating lamp to come on too. When I removed the water-level probe connection the boiler began to fill and then stopped when I replaced the water-level probe wire. I decided to leave the machine on for an hour and see if the heater kicked on. It never did and now we are back at square one. I am really frustrated. Does anyone know what could be wrong? Can anyone explain how to bypass the p-stat so that i can see if the heater kicks on? If I bypass the p-stat and the heater kicks on, does that mean I have a defective p-stat or does it point to a problem with the electrical board? I have included 2 video clips showing what happened this morning as well as the photos Elektros provided me to show how to "short-circuit" the water-level probe and the p-stat. The picture is a bit confusing to me because I believe that is a different p-stat than the sirai that i have on my machine. Any help is greatly appreciated as always team!

ricky analog (original poster)

#4: Post by ricky analog (original poster) »

So I did the bypass of the p-stat and water-level probe and filmed the whole thing. I realize that the 2 previous videos I posted in this topic are included in the beginning of the video, but that was done so that when i send the link to the guys at Elektros they can see it as well. So if you have already watched the previous 2 videos in the prior post, you can skip ahead 1 minute in this video.

Can anyone verify that what I did in this video was actually correct? I have never done this before and electronics is hardly my forte. Also, if what I did was correct, does anyone know what the results tell me? Since the machine is still behaving the same way, I tend to think that means that it isn't the electrical board, the p-stat, or the water-level probe that is causing my problem. Is this correct reasoning?


#5: Post by fredk01 »

Good job on making the bypass wires for your tests. You want to be careful with the circuit that goes through the pstat and heater coil as that is 110v.

Bypassing a faulty pstat should allow your heater to turn on. Well, unless the low water condition also turns off the heater. I don't know what all the low tank water sensor controls.

The water level light staying on when you bypass the tank water sensor puzzles me. That should tell the 'brain' that there is water, even when there is not.

Do you happen to own a multimeter? The next thing I would test is the heater coil itself to make sure it is good. Elektros shows how to do that at the bottom of its tips page.

After that, I think the next thing to check is for corrosion on the control board/brain.

ricky analog (original poster)

#6: Post by ricky analog (original poster) »

Thanks for the reply. I pulled the brain and looked. Doesn't seem to be any corrosion. But I'm gonna run out tomorrow and grab a multimeter. There is some corrosion around the seal of the heater coil.


#7: Post by fredk01 »

Here is where you reach the limits of my trouble shooting abilities. You actually need to pull the black outer cover off to get a good look at the circuit boards inside. Failed or failing capacitors are relatively easy to spot because they bulge as they fail, other components are not so obvious.

It could be that you have something like a bad solder joint that is failing or has failed. I'm not so good at spotting those unless it is from a really obvious short.

From your symptoms, my guess it there is an issue with something relating to the tank low water sensing circuit. I have no idea how to further trouble shoot that though. Hopefully Elektros gets back to you.

ricky analog (original poster)

#8: Post by ricky analog (original poster) »

Here are some pics from the inside of the electronics box. Does anything look problematic? I have circled in red the one capacitor I think could be causing a problem. But I am far from skilled in this department, so I'm not sure it is blown.

I also was able to see what looks like corrosion on the outside seal of the heating coil. What I actually think it is is thread sealant that heated up and expanded for some reason. I used the correct food safe sealant that is recommended throughout the forums, so I can't figure out why it would have done that. Is that possibly from not letting it sit long enough before turning the machine back on after the last tear-down?


#9: Post by fredk01 »

I just went through the first video again and each time that low water light turns on you can hear an audible click. Do you know where that noise was coming from? That may give you some clue as to where the issue is. It could also be the low water relay turning on and each time the low water circuit is broken.

You've reached the end of my limited diagnostic skills. From the machines behavior it looks to me like something in the low water circuit, but I have pretty much no experience with espresso machines, so who knows...

If you have someplace local that services Nuova Simonelli equipment, they can probably figure this out in short order.


#10: Post by LukeFlynn » replying to fredk01 »

The loud click is the pressure stat, most Oscars have a full on Sirai that is pretty loud. The intermittent click sounds like the pump is biting the dust to me.

A lot of Oscars start experiencing weird problems like this as they age, mine was always really finicky about sensing water in the tank. This one seems to be some sort of electronics issue though. I think the pump might be the cause of that continuous click, but it could be the relay too.