Marco 85-16M Practical - Page 3

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

Postby nick2000 » Apr 14, 2019, 6:17 pm

robdmngz wrote:I do not have any voltage at the flow solenoid. I also tested at the Board and I do not get voltage. The right button also doesn't work when in automatic mode.
I also removed the solenoid and tested it outside the machine and it does work when a voltage is applied. So I know its not the solenoid itself.
I took it apart and everything looks good just no voltage.

I would visually check the electronics on the board to see if something is off. With the assumption that the board is robust enough so that if something is indeed broken it would be visually obvious, I would trace the whole circuit for any connectivity issues. As in, from the button, to the closure of the solenoid circuit. More specifically ,I'd trace the connection from the solenoid to the board as the lights on the buttons work per your video. More often than not, I noticed the culprit is usually bad connections, corroded wires, or other more obvious stuff.

The far right button on the front panel doesn't work either, right? I know you said the brew buttons don't work, but wanted to confirm that specific button. It's the non programmable dispensing button. If it doesn't work either, it would confirm that it's not a programming issue.


Postby robdmngz » Apr 15, 2019, 5:53 pm

The button on the far right works. and the buttons all work if I have the switch in Manual mode. it's just when I switch it to automatic.

I tested the continuity with a meter and it all checks out okay.

Even when in Manual mode and the thing is brewing and coffee is coming out of the group, I still don't get voltage to that fill solenoid.

I just can't seem to find what the inputs should be on that board that triggers the voltage to that solenoid.

with the help I got from here I am able to at least brew.

The other issue is someone mentioned that my auto/manual switch is in backward, however, I have never had that off and the wires on the back are fairly short and don't allow for me to rotate. I looked for a picture but can't find one for that exact model to verify that it is backwards.

Mad Scientist

Postby Mad Scientist » Apr 15, 2019, 6:14 pm

So, when the light is green, it's NOT in automatic mode. (the programmed buttons will NOT work). It's what the operation manual calls that switch "emergency switch for deactivation of automatic coffee brewing system". So, when you flip that switch On (universal symbol "-", the top buttons work. Your video shows it working normally!



Postby robdmngz » Apr 16, 2019, 8:47 am

I talked to the people in the bookstore (original location) and they said the guy who serviced the machine while it was in use was "strange" and they didn't think it was a stretch to assume he must have changed it and put it in backward.

Thank you all for your help. I feel like I now have a fine working machine and its ready to be used again.

One more question. It seems to work to just have the hose going into the pump in a 5-gallon water jug. Does it need the additional pressure from a water faucet? Or can I just use it as a mobile machine on a cart?


Postby nick2000 » Apr 20, 2019, 10:50 pm


Great to hear and congratulations that it's up and running! Weird about the button, but super happy that all is well.

Regarding pulling water from a tank, a very good question. These espresso pumps are used to operate with pressure from the tap, estimated at around 3-4 bar, but people can correct me. Lack of pressure puts undue stress on the pump and may cause additional wear and tear. There are numerous top notch articles and posts out there on this.

Many people end up taking a large water jug, connecting a Flojet (most popular) or a vevor, etc, pump which gives the low water pressure (3-4 bar) into the espresso water pump, which then pumps at the ~9 bar (or whatever you set it to). This is a straightforward solution, and you just have to worrying about keeping the water tank topped up. FYI, rule of thumb, I mix 1:1 of spring water and distilled water. Extremely non scientific, and we have brilliant people here that I'm sure can describe a better way to mix and control water mineral content. Another option is distilled water plus an espresso water tablet (forget the brand, "3rd wave" or similar name) which gives the optimal mineral content for water. Haven't used that, so I can't vouch.

Personally, I have a pressurized corny keg connected to an automatic airpump that maintains pressure of 4 bar.

Hope this helps.