Hall Sensor Bypass for Coffee Grinder

[millicurie999]

Hi all,

I am seeking help with an annoying problem for my coffee machine. It's one of those "super automatic" that grinds whole beans and then dispenses it in the brew unit to make a fresh cup of coffee.  The problem is the dosimeter uses a Hall sensor mechanism to determine if there is enough ground coffee in the brewer unit. If it senses there is not enough, it will discard all the freshly grounded coffee without brewing.  In theory it ensures accurate dosage of ground coffee and consistent taste of the brew. In practice, the Hall sensor often misdiagnoses, and throw away a good amount of freshly grounded coffee. So it's a big waste. Is there a way to bypass the Hall Sensor logic so that the machine will continue with the brewing process even if it "thinks" there is not enough ground coffee (i.e., no bean error)?  This has been driving the coffee machine community nuts so any insight from you is appreciated.

Please see p. 20 of the attached service manual on how it works. The actual sensor and the motor gear with the magnet is shown here

 

Thanks so much for checking in.

BRERA_Service_Manual.pdf

[HarryA]

I gather the machine has  a fixed number of pulses it expects for each type of brew. It counts these via the two magnets. It also monitors the current draw by the motor. If the motor current drops off (no longer grinding) while it has not reach its count of rotations it "thinks" it is out of beans.

If  it is not out of beans and the motor is really working then it is missing counts at the hall effect sensor is what you are thinking? If it is really is out of beans it would discard the grounds that it has so far also?

On second thought if it is missing counts it would run longer and grind to much coffee.  So it must be that there are more counts to go and the current to the motor has fallen off?

[millicurie999]

Thanks for taking the time to respond. I think that's exactly what you said (I don't have any electric engineering background). The 2 pages of the manual where it talks about the mechanism are shown here. If there is a way to hack the system so that it would continue with the brewing process even if the machine thinks it doesn't have enough beans (or somehow bypass this step altogether so that it would just grinds a fix number of cycle), that would be amazing. 🙏

[HarryA]

I think it would be a worth while experiment to increase the current flow in the motor circuit by say  200ma. From the next to the bottom table above that would push it above the 200 ma minimum for mild coffee but not put into the 800ma maximum. One would need to find the motor voltage in order to calculate the required added shunt resistor (across the motor terminals.

I gather the beans never hang up within the machine so that the flow to the grinder is interrupted.

[bidrohini]

 Bypassing the Hall sensor is not recommended. You can check the manual for instructions on how to calibrate the sensor. 

[Olivier Hudon]

Hi bidrohini,  what do you mean by calibrate the sensor?!?  I have the same issue and sometime (each 8 or 15) coffees the grinder miss a turn and drop my coffee without breewing it…. I tried to recalibrate the grinder running it out of bean about 20 times but without success…. By the way i have a saeco incanto.

[Beans320]

On my Saeco Intellia HD8753, there are two inputs to the “out of bean” indicator. The first is the hall sensor (counts rotations) and the second is a current sensor (on the circuit board??). I have found that if one properly calibrates the grinding wheels, and holds the grinding shaft, I can bypass the out-of-bean indicator. My working hypothesis is that the additional load on the motor increases the current required to turn the grinder. Increased current means there’s beans.

further, this technique only works 3 times in a row before consistently coming up “out of bean” I suspect it’s an over temperature problem. After some time… the technique it works again.
 

So, does anyone know how to increase the current draw of the motor? Or point to the relevant current sense circuit on HD8753 board so I can add a heat sink? 
 

otherwise I’m switching to pre-ground beans

[csmith]

I have a slightly different issue and that is my coffee grinder only grinds for 1/2 the required time.  I have two of these machines (one decaf on caf) and if you time the grind cycle, one of them is exactly half the time of the other and brews too weak a cup of coffee.  It may be this sensor but why would it be double counting rotations? 

[buymode]

On 10/18/2022 at 10:47 PM, millicurie999 said:

Hi all,

I am seeking help with an annoying problem for my coffee machine. It's one of those "super automatic" that grinds whole beans and then dispenses it in the brew unit to make a fresh cup of coffee.  The problem is the dosimeter uses a Hall sensor mechanism to determine if there is enough ground coffee in the brewer unit. If it senses there is not enough, it will discard all the freshly grounded coffee without brewing.  In theory it ensures accurate dosage of ground coffee and consistent taste of the brew. In practice, the Hall sensor often misdiagnoses, and throw away a good amount of freshly grounded coffee. So it's a big waste. Is there a way to bypass the Hall Sensor logic so that the machine will continue with the brewing process even if it "thinks" there is not enough ground coffee (i.e., no bean error)?  This has been driving the coffee machine community nuts so any insight from you is appreciated.

Please see p. 20 of the attached service manual on how it works. The actual sensor and the motor gear with the magnet is shown here

 

Thanks so much for checking in.

BRERA_Service_Manual.pdf 4.2 MB · 2 downloads

millicurie999,

I understand how frustrating it must be to have your coffee machine waste good coffee due to sensor issues. While bypassing the Hall sensor isn't generally recommended, a potential workaround might involve adjusting the motor's current draw. Increasing the current flow by about 200mA could help, as suggested by HarryA, ensuring it stays within safe limits. Alternatively, calibrating the sensor as mentioned by bidrohini and Beans320 might resolve the issue. If these methods prove ineffective, consulting with a technician for a more precise solution might be your best bet. Good luck!