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:
- 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.
- The triac is not provided by a snubber. It is correctly designed?
- Why in your opinion one of the triac have a voltage divider with 560ohm resistor and the other not?
Thanks a lot
control triac
New contributor
add a comment |Â
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:
- 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.
- The triac is not provided by a snubber. It is correctly designed?
- Why in your opinion one of the triac have a voltage divider with 560ohm resistor and the other not?
Thanks a lot
control triac
New contributor
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"
â 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.
â 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.
â Bimpelrekkie
3 hours ago
Hi plasma, this machine is not old and not only dedicated to the russian market.
â daigs
3 hours ago
add a comment |Â
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:
- 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.
- The triac is not provided by a snubber. It is correctly designed?
- Why in your opinion one of the triac have a voltage divider with 560ohm resistor and the other not?
Thanks a lot
control triac
New contributor
I'm studying the attached washing machine partial schema in the point in which the main micro activate 2 water elecrovalves.
I would ask:
- 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.
- The triac is not provided by a snubber. It is correctly designed?
- Why in your opinion one of the triac have a voltage divider with 560ohm resistor and the other not?
Thanks a lot
control triac
control triac
New contributor
New contributor
New contributor
asked 3 hours ago
daigs
61
61
New contributor
New contributor
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"
â 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.
â 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.
â Bimpelrekkie
3 hours ago
Hi plasma, this machine is not old and not only dedicated to the russian market.
â daigs
3 hours ago
add a comment |Â
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"
â 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.
â 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.
â Bimpelrekkie
3 hours ago
Hi plasma, this machine is not old and not only dedicated to the russian market.
â 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"
â 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"
â 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.
â 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.
â 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.
â 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.
â Bimpelrekkie
3 hours ago
Hi plasma, this machine is not old and not only dedicated to the russian market.
â daigs
3 hours ago
Hi plasma, this machine is not old and not only dedicated to the russian market.
â daigs
3 hours ago
add a comment |Â
1 Answer
1
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up vote
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.
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.
â 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.
â Olin Lathrop
3 hours ago
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
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.
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.
â 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.
â Olin Lathrop
3 hours ago
add a comment |Â
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.
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.
â 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.
â Olin Lathrop
3 hours ago
add a comment |Â
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.
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.
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.
â 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.
â Olin Lathrop
3 hours ago
add a comment |Â
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.
â 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.
â 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.
â 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.
â 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.
â 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.
â Olin Lathrop
3 hours ago
add a comment |Â
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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"
â 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.
â 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.
â Bimpelrekkie
3 hours ago
Hi plasma, this machine is not old and not only dedicated to the russian market.
â daigs
3 hours ago