Why this washing machine has microprocessor pins directly connected to the main AC power?

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I'm studying the attached washing machine partial schema in the point in which the main micro activate 2 water elecrovalves.
I would ask:



  1. It seems the micro pins 36,40 are connected by the 1k resistor to the main AC "ground" (which mean phase or neutral). How it is possible, given that the 230V phase and not the neutral could be connected to the pin? From my experience an optoisolator is the correct choice.

  2. The triac is not provided by a snubber. It is correctly designed?

  3. Why in your opinion one of the triac have a voltage divider with 560ohm resistor and the other not?

Thanks a lot



Washing machine scheme (partial)






control triac







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  • 1




    "main AC "ground" (which mean phase or neutral)" does it? Or does it mean PE? Around here washing machines are required to have PE. This thing seems to be russian, if its something older it can also mean "we don't care about safety"
    – PlasmaHH
    3 hours ago










  • If all inputs and outputs of the microprocessor are referred to the same ground potential it is no problem if this ground potential is actually the phase. But all keys and LEDs connected to the microprocessor should be isolated the same way as a wire conected to the phase should be to guarantee users safety.
    – Uwe
    3 hours ago






  • 1




    From my experience an optoisolator is the correct choice. In general opto isolators are needed in devices that have a mains connection and a low voltage, safe to touch connector. Example: a phone charger. Without the opto isolator there would be a direct mains connection so the output would be unsafe to touch. But if there aren't any connections to the outside and the metal case is grounded, then there is no need for an opto isolator.
    – Bimpelrekkie
    3 hours ago










  • Hi plasma, this machine is not old and not only dedicated to the russian market.
    – daigs
    3 hours ago














up vote
1
down vote

favorite












I'm studying the attached washing machine partial schema in the point in which the main micro activate 2 water elecrovalves.
I would ask:



  1. It seems the micro pins 36,40 are connected by the 1k resistor to the main AC "ground" (which mean phase or neutral). How it is possible, given that the 230V phase and not the neutral could be connected to the pin? From my experience an optoisolator is the correct choice.

  2. The triac is not provided by a snubber. It is correctly designed?

  3. Why in your opinion one of the triac have a voltage divider with 560ohm resistor and the other not?

Thanks a lot



Washing machine scheme (partial)






control triac







share|improve this question







New contributor




daigs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.















  • 1




    "main AC "ground" (which mean phase or neutral)" does it? Or does it mean PE? Around here washing machines are required to have PE. This thing seems to be russian, if its something older it can also mean "we don't care about safety"
    – PlasmaHH
    3 hours ago










  • If all inputs and outputs of the microprocessor are referred to the same ground potential it is no problem if this ground potential is actually the phase. But all keys and LEDs connected to the microprocessor should be isolated the same way as a wire conected to the phase should be to guarantee users safety.
    – Uwe
    3 hours ago






  • 1




    From my experience an optoisolator is the correct choice. In general opto isolators are needed in devices that have a mains connection and a low voltage, safe to touch connector. Example: a phone charger. Without the opto isolator there would be a direct mains connection so the output would be unsafe to touch. But if there aren't any connections to the outside and the metal case is grounded, then there is no need for an opto isolator.
    – Bimpelrekkie
    3 hours ago










  • Hi plasma, this machine is not old and not only dedicated to the russian market.
    – daigs
    3 hours ago












up vote
1
down vote

favorite









up vote
1
down vote

favorite











I'm studying the attached washing machine partial schema in the point in which the main micro activate 2 water elecrovalves.
I would ask:



  1. It seems the micro pins 36,40 are connected by the 1k resistor to the main AC "ground" (which mean phase or neutral). How it is possible, given that the 230V phase and not the neutral could be connected to the pin? From my experience an optoisolator is the correct choice.

  2. The triac is not provided by a snubber. It is correctly designed?

  3. Why in your opinion one of the triac have a voltage divider with 560ohm resistor and the other not?

Thanks a lot



Washing machine scheme (partial)






control triac







share|improve this question







New contributor




daigs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











I'm studying the attached washing machine partial schema in the point in which the main micro activate 2 water elecrovalves.
I would ask:



  1. It seems the micro pins 36,40 are connected by the 1k resistor to the main AC "ground" (which mean phase or neutral). How it is possible, given that the 230V phase and not the neutral could be connected to the pin? From my experience an optoisolator is the correct choice.

  2. The triac is not provided by a snubber. It is correctly designed?

  3. Why in your opinion one of the triac have a voltage divider with 560ohm resistor and the other not?

Thanks a lot



Washing machine scheme (partial)






control triac




control triac






share|improve this question







New contributor




daigs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question







New contributor




daigs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question






New contributor




daigs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 3 hours ago









daigs

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New contributor




daigs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





daigs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






daigs is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







  • 1




    "main AC "ground" (which mean phase or neutral)" does it? Or does it mean PE? Around here washing machines are required to have PE. This thing seems to be russian, if its something older it can also mean "we don't care about safety"
    – PlasmaHH
    3 hours ago










  • If all inputs and outputs of the microprocessor are referred to the same ground potential it is no problem if this ground potential is actually the phase. But all keys and LEDs connected to the microprocessor should be isolated the same way as a wire conected to the phase should be to guarantee users safety.
    – Uwe
    3 hours ago






  • 1




    From my experience an optoisolator is the correct choice. In general opto isolators are needed in devices that have a mains connection and a low voltage, safe to touch connector. Example: a phone charger. Without the opto isolator there would be a direct mains connection so the output would be unsafe to touch. But if there aren't any connections to the outside and the metal case is grounded, then there is no need for an opto isolator.
    – Bimpelrekkie
    3 hours ago










  • Hi plasma, this machine is not old and not only dedicated to the russian market.
    – daigs
    3 hours ago












  • 1




    "main AC "ground" (which mean phase or neutral)" does it? Or does it mean PE? Around here washing machines are required to have PE. This thing seems to be russian, if its something older it can also mean "we don't care about safety"
    – PlasmaHH
    3 hours ago










  • If all inputs and outputs of the microprocessor are referred to the same ground potential it is no problem if this ground potential is actually the phase. But all keys and LEDs connected to the microprocessor should be isolated the same way as a wire conected to the phase should be to guarantee users safety.
    – Uwe
    3 hours ago






  • 1




    From my experience an optoisolator is the correct choice. In general opto isolators are needed in devices that have a mains connection and a low voltage, safe to touch connector. Example: a phone charger. Without the opto isolator there would be a direct mains connection so the output would be unsafe to touch. But if there aren't any connections to the outside and the metal case is grounded, then there is no need for an opto isolator.
    – Bimpelrekkie
    3 hours ago










  • Hi plasma, this machine is not old and not only dedicated to the russian market.
    – daigs
    3 hours ago







1




1




"main AC "ground" (which mean phase or neutral)" does it? Or does it mean PE? Around here washing machines are required to have PE. This thing seems to be russian, if its something older it can also mean "we don't care about safety"
– PlasmaHH
3 hours ago




"main AC "ground" (which mean phase or neutral)" does it? Or does it mean PE? Around here washing machines are required to have PE. This thing seems to be russian, if its something older it can also mean "we don't care about safety"
– PlasmaHH
3 hours ago












If all inputs and outputs of the microprocessor are referred to the same ground potential it is no problem if this ground potential is actually the phase. But all keys and LEDs connected to the microprocessor should be isolated the same way as a wire conected to the phase should be to guarantee users safety.
– Uwe
3 hours ago




If all inputs and outputs of the microprocessor are referred to the same ground potential it is no problem if this ground potential is actually the phase. But all keys and LEDs connected to the microprocessor should be isolated the same way as a wire conected to the phase should be to guarantee users safety.
– Uwe
3 hours ago




1




1




From my experience an optoisolator is the correct choice. In general opto isolators are needed in devices that have a mains connection and a low voltage, safe to touch connector. Example: a phone charger. Without the opto isolator there would be a direct mains connection so the output would be unsafe to touch. But if there aren't any connections to the outside and the metal case is grounded, then there is no need for an opto isolator.
– Bimpelrekkie
3 hours ago




From my experience an optoisolator is the correct choice. In general opto isolators are needed in devices that have a mains connection and a low voltage, safe to touch connector. Example: a phone charger. Without the opto isolator there would be a direct mains connection so the output would be unsafe to touch. But if there aren't any connections to the outside and the metal case is grounded, then there is no need for an opto isolator.
– Bimpelrekkie
3 hours ago












Hi plasma, this machine is not old and not only dedicated to the russian market.
– daigs
3 hours ago




Hi plasma, this machine is not old and not only dedicated to the russian market.
– daigs
3 hours ago










1 Answer
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4
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The two pins you mention drive the gates of triacs. Obviously the ground that the cathodes of the triacs are connected to is the same ground that the micro is connected to. One way or another, a low voltage supply is created somewhere to run the micro from, and the negative output of that supply is tied to the system ground.






share|improve this answer




















  • Thanks Olin, but the pin 36 "sense" about 220 V from the 1K resistor, regardless it is in high state (220-5v in this case) or low. Don't this voltage destroy the pin circuitry? Thanks.
    – daigs
    3 hours ago






  • 2




    @daigs: Your comment makes no sense. Pin 36 is going directly to the gate of a triac, with the cathode of the triac grounded.
    – Olin Lathrop
    3 hours ago










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1 Answer
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1 Answer
1






active

oldest

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active

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active

oldest

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up vote
4
down vote













The two pins you mention drive the gates of triacs. Obviously the ground that the cathodes of the triacs are connected to is the same ground that the micro is connected to. One way or another, a low voltage supply is created somewhere to run the micro from, and the negative output of that supply is tied to the system ground.






share|improve this answer




















  • Thanks Olin, but the pin 36 "sense" about 220 V from the 1K resistor, regardless it is in high state (220-5v in this case) or low. Don't this voltage destroy the pin circuitry? Thanks.
    – daigs
    3 hours ago






  • 2




    @daigs: Your comment makes no sense. Pin 36 is going directly to the gate of a triac, with the cathode of the triac grounded.
    – Olin Lathrop
    3 hours ago














up vote
4
down vote













The two pins you mention drive the gates of triacs. Obviously the ground that the cathodes of the triacs are connected to is the same ground that the micro is connected to. One way or another, a low voltage supply is created somewhere to run the micro from, and the negative output of that supply is tied to the system ground.






share|improve this answer




















  • Thanks Olin, but the pin 36 "sense" about 220 V from the 1K resistor, regardless it is in high state (220-5v in this case) or low. Don't this voltage destroy the pin circuitry? Thanks.
    – daigs
    3 hours ago






  • 2




    @daigs: Your comment makes no sense. Pin 36 is going directly to the gate of a triac, with the cathode of the triac grounded.
    – Olin Lathrop
    3 hours ago












up vote
4
down vote










up vote
4
down vote









The two pins you mention drive the gates of triacs. Obviously the ground that the cathodes of the triacs are connected to is the same ground that the micro is connected to. One way or another, a low voltage supply is created somewhere to run the micro from, and the negative output of that supply is tied to the system ground.






share|improve this answer












The two pins you mention drive the gates of triacs. Obviously the ground that the cathodes of the triacs are connected to is the same ground that the micro is connected to. One way or another, a low voltage supply is created somewhere to run the micro from, and the negative output of that supply is tied to the system ground.







share|improve this answer












share|improve this answer



share|improve this answer










answered 3 hours ago









Olin Lathrop

278k28331781




278k28331781











  • Thanks Olin, but the pin 36 "sense" about 220 V from the 1K resistor, regardless it is in high state (220-5v in this case) or low. Don't this voltage destroy the pin circuitry? Thanks.
    – daigs
    3 hours ago






  • 2




    @daigs: Your comment makes no sense. Pin 36 is going directly to the gate of a triac, with the cathode of the triac grounded.
    – Olin Lathrop
    3 hours ago
















  • Thanks Olin, but the pin 36 "sense" about 220 V from the 1K resistor, regardless it is in high state (220-5v in this case) or low. Don't this voltage destroy the pin circuitry? Thanks.
    – daigs
    3 hours ago






  • 2




    @daigs: Your comment makes no sense. Pin 36 is going directly to the gate of a triac, with the cathode of the triac grounded.
    – Olin Lathrop
    3 hours ago















Thanks Olin, but the pin 36 "sense" about 220 V from the 1K resistor, regardless it is in high state (220-5v in this case) or low. Don't this voltage destroy the pin circuitry? Thanks.
– daigs
3 hours ago




Thanks Olin, but the pin 36 "sense" about 220 V from the 1K resistor, regardless it is in high state (220-5v in this case) or low. Don't this voltage destroy the pin circuitry? Thanks.
– daigs
3 hours ago




2




2




@daigs: Your comment makes no sense. Pin 36 is going directly to the gate of a triac, with the cathode of the triac grounded.
– Olin Lathrop
3 hours ago




@daigs: Your comment makes no sense. Pin 36 is going directly to the gate of a triac, with the cathode of the triac grounded.
– Olin Lathrop
3 hours ago










daigs is a new contributor. Be nice, and check out our Code of Conduct.









 

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