This is a fancy milk frother, apparently almost identical to the Dualit DMF2, but sold at a big mark up as bring particularly suitable for making frothy hot chocolat. It's basically a small jug with a kettle type resistive element in the base, and in the centre of that a small motor holding a magnet which locks on to a magnet in the base of a stirrer inside the jug which spins and froths up whatever liquid is inside.
I've got one and it's not working. I've checked all the obvious things. The heater coil has continuity, as do the two thermal fuses and the motor windings. The temperature sensor changes resistance when I hold it, so that seems to suggest that something is amiss on the main PCB.
Symptoms are that the single led flashes briefly when I press the only button, then it switches itself off. If I wait a couple of seconds then that is repeatable, but if I press it rapicly a few times in succession then only the first press does anything. My guess is that the power supply is not starting up properly and can't power the chip properly when it starts drawing power, so it's going into a shutdown-reboot cycle, but I'm not sure where exactly to look. There are no obvious signs of failiure on the board. Nothing is burned out and the capacitors look and test OK. Everything is covered in a thick conformal coat which doesn't help troubleshooting or even identifying components.
The bridge rectifier looks a bit odd at first glance, but I'm pretty sure that's just the conformal coating. I've run 24v DC into it both ways, and it works ok (sorry, I'm a bit of a coward with AC when things aren't tightly held down in place). Next possible failure chip would be the mosfet/controller, adn I'm having trouble identifying this. I can make out three lines of text which I think say:
MP020
N58294
M8SN33
but searching for these gives nothing. Does anyone recognise this chip or have any suggestions what I could try next.
Attached are some photos. The mains input is bottom right. Left of that is the mains out to the heating element, and left of that the neutral connection. The bridge rectifier is top right and what I think is the mosfet/power controller is between the transformer and the bent over electrolytic capacitor. There is some odd dust around the silk screen markings of R2 and R3, and I have no idea where it comes from. It's definitely not the electrolytics. C2 at the top left is a bodge fix, since I knocked the original capacitor off when dismantling and reassembling the whole unit trying some would be fixes. As far as I can see that capacitor is responsible for filtering, so I hope the value isn't critical. It did not change the nature of the original fault. The white connector is for the temp sensor and the red for the motor.
If you want to see what the whole unit looks like, then someone has documented in great detail a mechanical teardown and rebuild of a similar unit here but his PCB has slight differences and he doesn't go further into the electronics side (because he had no need to, I guess). A couple of commentators there have stated that theirs just died, but again no details.
Thanks in advance for any advice offered.
I've got one and it's not working. I've checked all the obvious things. The heater coil has continuity, as do the two thermal fuses and the motor windings. The temperature sensor changes resistance when I hold it, so that seems to suggest that something is amiss on the main PCB.
Symptoms are that the single led flashes briefly when I press the only button, then it switches itself off. If I wait a couple of seconds then that is repeatable, but if I press it rapicly a few times in succession then only the first press does anything. My guess is that the power supply is not starting up properly and can't power the chip properly when it starts drawing power, so it's going into a shutdown-reboot cycle, but I'm not sure where exactly to look. There are no obvious signs of failiure on the board. Nothing is burned out and the capacitors look and test OK. Everything is covered in a thick conformal coat which doesn't help troubleshooting or even identifying components.
The bridge rectifier looks a bit odd at first glance, but I'm pretty sure that's just the conformal coating. I've run 24v DC into it both ways, and it works ok (sorry, I'm a bit of a coward with AC when things aren't tightly held down in place). Next possible failure chip would be the mosfet/controller, adn I'm having trouble identifying this. I can make out three lines of text which I think say:
MP020
N58294
M8SN33
but searching for these gives nothing. Does anyone recognise this chip or have any suggestions what I could try next.
Attached are some photos. The mains input is bottom right. Left of that is the mains out to the heating element, and left of that the neutral connection. The bridge rectifier is top right and what I think is the mosfet/power controller is between the transformer and the bent over electrolytic capacitor. There is some odd dust around the silk screen markings of R2 and R3, and I have no idea where it comes from. It's definitely not the electrolytics. C2 at the top left is a bodge fix, since I knocked the original capacitor off when dismantling and reassembling the whole unit trying some would be fixes. As far as I can see that capacitor is responsible for filtering, so I hope the value isn't critical. It did not change the nature of the original fault. The white connector is for the temp sensor and the red for the motor.
If you want to see what the whole unit looks like, then someone has documented in great detail a mechanical teardown and rebuild of a similar unit here but his PCB has slight differences and he doesn't go further into the electronics side (because he had no need to, I guess). A couple of commentators there have stated that theirs just died, but again no details.
Thanks in advance for any advice offered.
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