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I have SMD AC line switch (ACS1207S) on my washing machine electrical board. I need to check if it is faulty, what's the appropriate test?

enter image description here

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  • \$\begingroup\$ The error codes (tones) will be listed in the instruction manual. \$\endgroup\$ – Transistor May 3 '20 at 14:18
  • \$\begingroup\$ It might help if you'd mention the model number and manufacturer of the machine, as well as the part number of the board. There may be some well known defect in it that is documented somewhere on the internet. \$\endgroup\$ – JRE May 7 '20 at 14:30
  • \$\begingroup\$ @JRE It's a Samsung topload, Model number is: WA13F5S4UWA/AS \$\endgroup\$ – Ashraf Alshahawy May 7 '20 at 23:19
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  1. Take it off the board.
  2. Build it into the test circuit given in the datasheet you linked to. Use 220VAC instead of the 2000Vpp mentioned in the drawing.
  3. See if it conducts.

Test circuit:

enter image description here


Once you've done that (or decided it's too much trouble,) stop randomly testing parts.

Your washing machine doesn't work.

WHAT doesn't work?

Figure out exactly what it should do, but doesn't do. Should it first start a motor, or does it have to switch a valve first? Does it have to check some safety switch (door closed) first?

Work backwards from that first action.

If it's a motor that should be turned on, trace the motor leads back to the board. Find the transistor or triac, or whatever it is that switches it. Check that part. If it's OK, check whatever delivers its control signal. Follow it all the way to that controller.

If all the switching elements back to the processor are OK, then maybe the processor is bad or maybe it isn't getting some input it expects.

Check all switches that go to the processor (door closed and similar things.) There will be components between the switch and the processor. Check them. See that the switch signal makes it to the processor.


Be very careful if you have to make measurements of voltages with the power on.

Any part of that washing machine may be at line voltage (220VAC.) It can kill you if you mess up.

If it doesn't kill you, a slip with the meter probes could destroy the controller board beyond repair. A short caused by a probe tip can dump high voltage through things that don't want it. If that happens, you'll have more problems than you can solve.

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  • \$\begingroup\$ I'm really thankful for your help, really appreciated and I learned a lot from it. \$\endgroup\$ – Ashraf Alshahawy May 7 '20 at 23:29

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