Oscar pump starts all the time

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

#1: Post by TalOrbach »

I have a NS Oscar (first model), that's quite old.
Until recently, it would work as intended. When turning the machine on, the pump would start, and after about 10 or 20 seconds, it would stop.
A few months ago, it stopped stopping. It would start with the machine, and then just go on forever.
I tried to take out the water level probe to clean it, but it was clean. I tries disconnecting some of the relevant wires and reconnecting them. Eventually, not sure how - I got it working - I'd start the machine, and the pump wouldn't come on, or it would, for a very short time.
But now, the pump just starts randomly and very frequently. I think it's safe to say that when the machine is on, the pump is running about half the time.
Any thoughts on what I should try to do to get it fixed?

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#2: Post by cafeIKE »

It's likely the control box is failing.

You might try changing out the electrolytic capacitors if you or a pal have the requisite skill.

It's possible a relay controls the pump and it may be failing. Listen closely to the control box and see if there is a click when the pump starts. You can use a wooden dowel as a probe to get to the box if it's deep in the bowels.

If you take the control box out, mark all terminals so there can be no misteak on reassembly.

TalOrbach (original poster)

#3: Post by TalOrbach (original poster) »

Thank you. I'm actually also suspecting the control box, because I did some fiddling around, and now there's another thing, where the water reservoir sensor seems to be acting up (doesn't detect water, even when it's there, and sometimes detects water, even though the reservoir isn't even installed)


#4: Post by WWWired »

TalOrbach wrote:I have a NS Oscar (first model), that's quite old.
. . .
Any thoughts on what I should try to do to get it fixed?
Hello and Happy New Year TalOrbach :)

Consider in this system not running your pump more than 1 minute at a time . . .

As well, worth consideration is a component close to failure, but working intermittently.

Your Machine's functional logic - the operational algorithm - will assist in pinpointing the source of the fault or faults. Here, you have faults described on:
  • Water Reservoir-Level-Sensor Input;
  • Boiler-Water-Level-Sensor input; and
  • A combination of functional anomalies in the Pressurestat and Pump Systems
Both your Water Reservoir Level Sensor (Pin 1) and Boiler Water Level Sensor (Pin 2) share continuity with with Pin 3 in the Control Box.

Pin 3 is Ground (to frame/chassis), shared/divided between Reservoir Level switch, the 2-way Electrovalve (Solenoid), the 3-way Electrovalve (Solenoid), and the Boiler Ground Wire

Your Pump's Neutral Supply (Pin 7), controlled by Pin 2, has switched continuity to Pin 10 (which appears to be Neutral Supply to the Controller with a few other downstream connections that can be discussed later perhaps).

If you are the original owner, we can be sure none of the wires have been tampered with and are where they should be. Saving wear and/or damage there should be nothing too much wrong with them in a properly maintained Oscar. An Oscar that has sat idle for a while will have several issues that could impede function, something for later consideration as needed.

However, as a starting point, before getting into the complexities of the relays and circuit/logic boards and other components, please inspect this area of your Oscar I (the bottom plate for the Oscar I), looking in particular for any signs of water damage, corrosion, etc. (NOTE: BE CERTAIN THE MACHINE IS UNPLUGGED BEFORE REMOVING ANY SCREWS OR BOLTS, EVEN A SMALL AMOUNT OF ELECTRICITY IS DANGEROUS) . . .

There are two types of "Brain Boxes" in the Original Oscar I Models (with varying voltage configurations). Here is a picture of one, a "cubic ricerca" 110V model showing the label . . .

And here's a few pictures, the same Oscar I, with the ground wires disconnected to make them obvious (note: by "right side" it means if you were Oscar itself, that would be your right side, not a Home-Barista's right side when looking at the Oscar lol, apologies for any confusion) . . .

. . . before pointing at the Brain Box function, do a quick inspection of this area (any pictures you have would be much appreciated) :)

Also, If you can, get yourself one of these (an Outlet Circuit Tester) from a Home Depot or other Big Box store (almost any will have them) for about $10-15, and check your Outlet where you plug in your Oscar (there's lots of different makes for these, Mastercraft etc., not just Kleins) . . .