I had a similar issue with a Samsung MS19M8000AS (purchased at from HD in July 2021).
In my case, the fan ran constantly with no heating and the controls were non-functional when the door was closed.
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Upon investigation, I found that the unit had 2 thermostats and door lock mechanism with 3 micro switches.
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Upon investigation, I found that the unit had two thermostats and a door lock mechanism with three micro switches.
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As the blogs have mentioned, my first check was to be the oven ***over temperature*** thermostats. So with the oven ***UNPLUGGED,*** I began static testing with an Ohm meter. First I found that the temperature switches were series wired (with brown wires), making it was obvious that they must operate as normally closed switches, opening the circuit upon activation. This was confirmed by the fact that were wired as part of the power supply feed circuit as well. And with the wires removed, they tested closed ok.
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As the blogs have mentioned, my first check was the over-temperature switches.
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The top switch is mechanically a ***positive door closed*** switch wired normally open that closes when the door is firmly shut and a pin in the door depresses it. This switch has 2 brown wires connected to it that are ***series wired*** with 2 normally closed ***over temperature switches*** located at the air intake and exhaust. This brown wire circuit interrupts one side of the power supply line to the control board and magnetron.This switch tested normally.
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With the oven ***UNPLUGGED,*** I began static testing with an Ohm meter. I located two temperature switches, one on the air intake and the other on the exhaust. These switches are series wired into a brown wire safety circuit that interrupts the power supply when incomplete. With the wires removed at room temperature, each switch tested closed.
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The middle micro-switch is normally depressed when the door latch is engaged, and the door opening button is not being pressed. The moment the door open button is partially depressed and before the door is released, this switch opens a circuit on the control board via 2 orange wires. This circuit remains open until the door latch is fully engaged and the door open button pops out.
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Next, I tested the upper door latch switch that indicates the ***oven door is mechanically closed*** by completing the brown wire safety circuit when a pin on the door operates it.
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The electrical operation of this switch was highly intermittent. Removing the wiring from it produced the same results, so I removed the switch and opened it up. Inside, all appeared to be mechanically OK, but it still wouldn’t close reliably.
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The 2nd switch just below the door closed switch mechanically operates when the door is closed and the door latch is completely engaged. The moment the door open button is partially depressed, and before the door is released, this switch opens a circuit on the control board via two orange wires. This circuit remains open until the door latch is fully engaged again and the door open button pops out.
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With the wires removed, I tested the switch and found it to be highly intermittent, so I removed the switch and opened it up. It appeared to be OK, but it still wouldn’t operate reliably.
[image|2568797]
I placed the switch under our Lab microscope and discovered a microscopic piece of plastic embedded in the contact surface that was almost invisible to the naked eye.
[image|2568795]
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The lower switch operates when the door latch mechanism is not fully engaged. I did not examine this switch, or it’s operation.
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The bottom switch operates when the door latch mechanism is not fully engaged. I did not examine this switch or its operation.
I had a similar issue with a Samsung MS19M8000AS (purchased at from HD in July 2021).
In my case, the fan ran constantly with no heating and the controls were non-functional when the door was closed.
Upon investigation, I found that the unit had 2 thermostats and door lock mechanism with 3 micro switches.
As the blogs have mentioned, my first check was to be the oven ***over temperature*** thermostats. So with the oven ***UNPLUGGED,*** I began static testing with an Ohm meter. First I found that the temperature switches were series wired (with brown wires), making it was obvious that they must operate as normally closed switches, opening the circuit upon activation. This was confirmed by the fact that were wired as part of the power supply feed circuit as well. And with the wires removed, they tested closed ok.
The top switch is mechanically a ***positive door closed*** switch wired normally open that closes when the door is firmly shut and a pin in the door depresses it. This switch has 2 brown wires connected to it that are ***series wired*** with 2 normally closed ***over temperature switches*** located at the air intake and exhaust. This brown wire circuit interrupts one side of the power supply line to the control board and magnetron. This switch tested normally.
The middle micro-switch is normally depressed when the door latch is engaged, and the door opening button is not being pressed. The moment the door open button is partially depressed and before the door is released, this switch opens a circuit on the control board via 2 orange wires. This circuit remains open until the door latch is fully engaged and the door open button pops out.
The electrical operation of this switch was highly intermittent. Removing the wiring from it produced the same results, so I removed the switch and opened it up. Inside, all appeared to be mechanically OK, but it still wouldn’t close reliably.
[image|2568797]
I placed the switch under our Lab microscope and discovered a microscopic piece of plastic embedded in the contact surface that was almost invisible to the naked eye.
[image|2568795]
The lower switch operates when the door latch mechanism is not fully engaged. I did not examine this switch, or it’s operation.
iFixit myself…
[image|2568798]
I had a similar issue with a Samsung MS19M8000AS (purchased at from HD in July 2021).
In my case, the fan ran constantly with no heating and the controls were non-functional when the door was closed.
Upon investigation, I found that the unit had 2 thermostats and door lock mechanism with 3 micro switches.
As the blogs have mentioned, my first check was to be the oven ***over temperature*** thermostats. So with the oven ***UNPLUGGED,*** I began static testing with an Ohm meter. First I found that the temperature switches were series wired (with brown wires), making it was obvious that they must operate as normally closed switches, opening the circuit upon activation. This was confirmed by the fact that were wired as part of the power supply feed circuit as well. And with the wires removed, they tested closed ok.
The top switch is mechanically a ***positive door closed*** switch wired normally open that closes when the door is firmly shut and a pin in the door depresses it. This switch has 2 brown wires connected to it that are ***series wired*** with 2 normally closed ***over temperature switches*** located at the air intake and exhaust. This brown wire circuit interrupts one side of the power supply line to the control board and magnetron. This switch tested normally.
The middle micro-switch is normally depressed when the door latch is engaged, and the door opening button is not being pressed. The moment the door open button is partially depressed and before the door is released, this switch opens a circuit on the control board via 2 orange wires. This circuit remains open until the door latch is fully engaged and the door open button pops out.
The electrical operation of this switch was highly intermittent. Removing the wiring from it produced the same results, so I removed the switch and opened it up. Inside, all appeared to be mechanically OK, but it still wouldn’t close reliably.
[image|2568797]
I placed the switch under our Lab microscope and discovered a microscopic piece of plastic embedded in the contact surface that was almost invisible to the naked eye.
[image|2568795]
The lower switch operates when the door latch mechanism is not fully engaged. I did not examine this switch, or it’s operation.
iFixit myself…
[image|2568798]
I had a similar issue with a Samsung MS19M8000AS (purchased at from HD in July 2021).
In my case, the fan ran constantly with no heating and the controls were non-functional when the door was closed.
Upon investigation, I found that the unit had 2 thermostats and door lock mechanism with 3 micro switches.
As the blogs have mentioned, my first check was to be the oven ***over temperature*** thermostats. So with the oven ***UNPLUGGED,*** I began static testing with an Ohm meter. First I found that the temperature switches were series wired (with brown wires), making it was obvious that they must operate as normally closed switches, opening the circuit upon activation. This was confirmed by the fact that were wired as part of the power supply feed circuit as well. And with the wires removed, they tested closed ok.
The top switch is mechanically a ***positive door closed*** switch wired normally open that closes when the door is firmly shut and a pin in the door depresses it. This switch has 2 brown wires connected to it that are ***series wired*** with 2 normally closed ***over temperature switches*** located at the air intake and exhaust. This brown wire circuit interrupts one side of the power supply line to the control board and magnetron. This switch tested normally.
The middle micro-switch is normally depressed when the door latch is engaged, and the door opening button is not being pressed. The moment the door open button is partially depressed and before the door is released, this switch opens a circuit on the control board via 2 orange wires. This circuit remains open until the door latch is fully engaged and the door open button pops out.
The electrical operation of this switch was highly intermittent. Removing the wiring from it produced the same results, so I removed the switch and opened it up. Inside, all appeared to be mechanically OK, but it still wouldn’t close reliably.
[image|2568797]
-
I placed the switch under our Lab microscope and discovered a microscopic piece of plastic embedded in the contact surface. That was almost invisible to the naked eye.
+
I placed the switch under our Lab microscope and discovered a microscopic piece of plastic embedded in the contact surface that was almost invisible to the naked eye.
[image|2568795]
The lower switch operates when the door latch mechanism is not fully engaged. I did not examine this switch, or it’s operation.
I had a similar issue with a Samsung MS19M8000AS (purchased at from HD in July 2021).
In my case, the fan ran constantly with no heating and the controls were non-functional when the door was closed.
Upon investigation, I found that the unit had 2 thermostats and door lock mechanism with 3 micro switches.
As the blogs have mentioned, my first check was to be the oven ***over temperature*** thermostats. So with the oven ***UNPLUGGED,*** I began static testing with an Ohm meter. First I found that the temperature switches were series wired (with brown wires), making it was obvious that they must operate as normally closed switches, opening the circuit upon activation. This was confirmed by the fact that were wired as part of the power supply feed circuit as well. And with the wires removed, they tested closed ok.
The top switch is mechanically a ***positive door closed*** switch wired normally open that closes when the door is firmly shut and a pin in the door depresses it. This switch has 2 brown wires connected to it that are ***series wired*** with 2 normally closed ***over temperature switches*** located at the air intake and exhaust. This brown wire circuit interrupts one side of the power supply line to the control board and magnetron. This switch tested normally.
The middle micro-switch is normally depressed when the door latch is engaged, and the door opening button is not being pressed. The moment the door open button is partially depressed and before the door is released, this switch opens a circuit on the control board via 2 orange wires. This circuit remains open until the door latch is fully engaged and the door open button pops out.
The electrical operation of this switch was highly intermittent. Removing the wiring from it produced the same results, so I removed the switch and opened it up. Inside, all appeared to be mechanically OK, but it still wouldn’t close reliably.
[image|2568797]
I placed the switch under our Lab microscope and discovered a microscopic piece of plastic embedded in the contact surface. That was almost invisible to the naked eye.
[image|2568795]
The lower switch operates when the door latch mechanism is not fully engaged. I did not examine this switch, or it’s operation.
iFixit myself…
[image|2568798]
[image|2568796]