Hello all,

Long time reader, so I know this topic has been posted a few times but with different symptoms. I'm quite handy but hoping to solicit some advise on how to trouble shoot or next steps as I would like to try to fix it myself as opposed to bringing it in to a repair shop.

I'm having trouble with my Breville Barista (BES870XL). There is no pressure reading on the gauge (zero movement), and it makes a really loud buzzing sound when trying to extract:

• I've tried using single wall with very fine grinds and hard tamper
• I tried using a double walled/pressurized basket
• I tried using the rubber cleaning disc

... all give no readings on the pressure gauge.

I opened it up and checked all the white tubes. They don't seem to be clogged.

My original thought was that it was a bad pump (hoping I can replace the O ring) causing the no pressure. But now that I'm writing this post, I'm guess it's a bad solenoid value given the alarming buzz. Can it be fixed or serviced at home?

What's the best way to diagnosing this issue? Any helps and tips are greatly appreciated.

FYI - this is my first espresso machine (2nd hand). I'm super excited to join the community!

Are you getting any water flow at all?

My first guess when I started reading your post was the solenoid.

Yes, getting water flow through the group head. Steam wand and Hot water also works.

I got a bit ambitious last night and starting removing the solenoid to try to troubleshoot.

I used a multi-meter to test the coil on a solenoid valve - I got 690-693 ohms from each one. I think that sounds about right
Took it a bit further and dissembled, thinking there may be deposit build up that requires a deep clean/vinegar bath.

Pictures of the individual components:
https://imgur.com/a/dLtPKeu

But everything looks pretty clean so I'm a bit stumped on what to do next.

Let's first be sure the pump is good. Remove one of the wires from the vibe pump, then test the vibe pump with your ohmmeter. Do the test twice, by reversing the leads on the pump. What do you get? Most vibe pumps have a diode inside, certainly the ULKA, which I think your machine uses. The diode can fail open or shorted. If it fails open, then there's no buzz. But, if it fails shorted, the pump will still try to move a bit of water, but it won't develop much pressure. The test above looks for open (infinity ohms), shorted (low ohms), or no problem (low ohms one way and high ohms the other). If the coil/diode tests good, then the pump could have internal issues if it isn't developing pressure; best to replace it.

Yes you are correct. My pump says ULKA on it - 120v 80hz

I disconnected the Yellow lead (it has a photo of a diode on top)



Using the Ohm reader, it says 60 ohms. Swapped the leads and I also get ~57 ohms. I'm a little bit more familiar with releys/solenoids than vibration pumps. Is anywhere between Zero - Infinity, good? or is 60 ohms too low?

I'm learning lots - much appreciated!

If you get any conductivity in both directions through a diode, the diode is bad. It should be infinite or over limit or out of range in one direction.

Javabean604 wrote:Yes you are correct. My pump says ULKA on it - 120v 80hz

I disconnected the Yellow lead (it has a photo of a diode on top)

image

Using the Ohm reader, it says 60 ohms. Swapped the leads and I also get ~57 ohms. I'm a little bit more familiar with releys/solenoids than vibration pumps. Is anywhere between Zero - Infinity, good? or is 60 ohms too low?

I'm learning lots - much appreciated!

You found the problem. As the other poster added, the internal diode is toast. In one direction, you should be reading the coil's resistance plus only a tiny bit for loss in the diode; in the other direction, the diode blocks the current flow, which should give you a very high resistance. That pump is not easily repairable. You need to order a new pump. Meanwhile, since your diode failed as a short, you could jury-rig an external diode in series to limp along. Polarity is unimportant, as all you're doing with the diode is creating a half-wave rectifier. I've never done this, so can't advise on the part number for the diode. But, if you look up the fluid-o-tech vibe pump, which uses an external diode, that one would likely work.

Edit: I did a little sleuthing online and found out that the diode in the ULKA is a 1N4007. You don't need this specific diode, just one that can handle a forward average current of at least 1 amp (I'd opt for a bit more). Any radio repair shop should be able to sell you one of these; they cost very little...less than a buck.

Thanks for the tips on how to narrow down the issue to the pump. It makes sense in hindsight that having conductivity both ways with a diode doesn't really make sense any would indicate something wrong with the pump.

I have a salvage Breville Duo-Temp 800ESXL with a leaky thermal block. I was going to see if I could pull the solenoids valves but couldn't find them. That being said it was have the same pump (ULKA Pump Model EFP5 120v 60hz). When I checked the ohms both directions were conductive at around 43 ohms - just my luck - two faulty pumps! I'm curious the this "older" unit has a different ohms reading. Assuming I am to repair one with a diode, which one would be in better shape? Lower ohms or High ohms?

Thanks again for finding the actual part number of the diode (I would have definitely gotten lost in the information). Luckily I found a local electronic ship that carries 1N4007 diodes (4 pieces for $1). I'm going to try to pick it up tomorrow - beats waiting for postmail!

I'm just a bit confused in why the pump it works and gives me hot steam. I'm still able to steam milk. With a failed diode (short), is the pump functioning in some sort of "limp mode". By creating a half-wave rectifier, does it increases the power of the pump?

I took highschool electronics and this is really great stuff - thanks all for the support!

The pump has no bearing on the steam production, other than filling the boiler and the BDB has a separate pump to fill the steam boiler.

With the shorted diode, the pump is basically working against itself and limiting flow/pressure through the brew circuit.

Happy New Year!

I was hoping to give an update sooner but it's been a crazy first week in the new year.

As mentioned previously I was able to source the diode from a local supply shop (4pc for $0.60). I removed the vibe pump and used some alligator clip to test the flow as a benchmark. The results were abysmal - worse than I remembered.

Now I tried jumping the diode in - SUCCESS! - good water flow. I did two measurements got about 700ml/min, which I think is pretty close to spec.

Spent today soldiering and wiring the leads in and now it's working again. I want to send everyone a big thank you for getting my espresso machine working again!

One side note was I noticed the pressure gauge registers a bit lower than I remembered it...

It hits about the 9'oclock of the gauge, which is the lower end of the "espresso range". I tried this with both a pressurized and non-pressurized filter. I know the gauge may not be the most precise, but I'm wondering if there is any other maintenance I could do that may enhance the pump/pressure?

As always much thanks!