SUCCESS - Repairing Saeco Vienna Espresso machine

Thread Starter

MrChips

Joined Oct 2, 2009
24,651
I post this repair success in case others encounter a similar situation.

We have a Saeco Vienna Superautomatica espresso machine.

1624280311293.png

The brew group was not properly installed and the machine was locked up with the piston in a partially down position.

Photo of brew group:

1624280243197.png

Ordinarily there is no way to open the machine because the mechanism is locked up. There is no way to mechanically turn the gear motor to reverse the piston. The motor has a worm gear with huge step down ratio. This machine would be destined to the dump.

I figured out that the only way to correct the situation was to drive the gear motor directly.
Now the questions were:
1) What voltage to power the drive motor?
2) Where are the connections to the motor?
3) What polarity is required to reverse the motor?

I found a pdf for a similar machine Saeco Incanto Service Manual.
Chapter 10 - Circuit Diagrams, blank pages.

1) First critical information: Chapter 4, Section 4.1 Gearmotor, requires 30-35V.

2) I found a video that show two wires going to the motor, red and blue, 16-18AWG?

photo only:
Saeco Vienna espresso2.jpg

Locating the two wires on the control board is easy. There is a 4-conductor molex connector at the top of the board with fat wires.
YELLOW
YELLOW
RED
BLUE

Saeco Vienna wiring.jpg

With the connector disconnected from the control board I insert jumpers into the female pins connecting to the red and blue cables. I measure 30Ω across red and blue. Good. I need a DC power supply at 30V 1A minimum.

3) What polarity to connect to the PSU?
I have a 50:50 chance of getting it right.
I am going to connect RED to +ve and BLUE to -ve. I will momentarily make a connection and look and listen to see which way the piston moves. If it jams I need to reverse the connections.

Bingo! Works on first attempt.

I apply voltage just long enough to raise the piston and retract the brew group. I have to be careful here because we do not have the benefit of the two microswitches which would normally stop the motor when in the right position.

Final alignment
Now I have to make sure that the brew group can be inserted and removed freely.
In order to accomplish this, the splines on the gear motor mechanism must line up correctly with the shaft on the brew group.
I momentarily power the motor in order to jog the motor to get the splines aligned at the correct angle. I need to reverse the voltage a few times to get the splines aligned.

photo only:
Saeco Vienna espresso1.jpg

Machine is reassembled and checked.
Time to relax with a cup of fresh brew!
 

Thread Starter

MrChips

Joined Oct 2, 2009
24,651
Saeco Vienna espresso machine revisited

The gears driving the brew mechanism broke and needed to be replaced.

Chances are you need to replace both gears at the same time. The two gears are inexpensive compared to the price of a new machine.

SAECO gear 9121_042.jpg

SAECO gear 9121_069_150.jpg

There are different gears for different models. My model is Saeco Vienna SUP018.

SAECO gear 9121_068_150.jpg
Notice that the location of the tabs that trigger the two limit switches are in different positions.
My machine required the 9121.068.150 gear. I learned this the hard way.

In retrospect, if you are going to power the drive motor externally with a power supply you need to interrupt the power to the motor when it hits either limit switch.
 
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