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Can You Solve this Schematic Symbol Mystery?


Son of Samurai

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Here's something for you sharp Appliantology techs to puzzle over: what in the world is the circled symbol on this schematic?

2008398185_Frigidairerefrigeratorweirddiodesymbol.png.f5239ea69b3cf0244e4fc38a71c6c27a.png

Is that a wiring harness? Maybe this diagram's strange way of showing a splice?

To figure out what it is, we've got to have a functional understanding of how Electrolux likes to design their water valve circuits. Let's look at a similar configuration that's drawn differently.

Screenshot 2020-11-11 000215.png

There we have it -- on this schematic, the engineers decided to throw us a bone and actually use the standard symbol for what they're trying to depict. Which is, of course, a couple of diodes.

By the way, if you're curious why those diodes are there and what purpose they serve, click here to read my previous blog post about this exact configuration.

So why did they decide to draw those diodes in the most obtuse, inscrutable way possible? Well, Electrolux has always had a special contempt for technicians. The legends say that Electrolux's head engineer has had a grudge against techs ever since he caught one fooling around with his wife. But we'll never know for certain.

The important thing is that we have a functional understanding of these circuits so that we can jump the gaps left for us by shoddy schematics. And that only comes with a grounded understanding of electricity, circuits, and plenty of practice troubleshooting with schematics.

If you'd like to learn these skills, you should check out our courses over at the Master Samurai Tech Academy. Click here to check out our courses and enroll today.

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I knew they did it on purpose, but didn't know that it was a personal grudge... lol. 🤣

Thanks for deciphering it for us.

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Excellent revelation. Diodes are probably the most basic and prominent electronic device in everything. They made a 'digital OR gate' here.    

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Are those valves - DC valves? Asking because power through a diode is only a half a sine.

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  • Team Samurai
Son of Samurai

Posted

1 hour ago, Dragan Panic said:

Are those valves - DC valves? Asking because power through a diode is only a half a sine.

Very astute observation! You're right that the diode turns that those 120 volts AC into 60 volts of pulsed DC.

BUT, that doesn't mean that those valves are DC loads. They are, in fact AC. But AC loads can run just fine on DC, and the main water valve here is also designed to be able to operate properly with only 60 volts rather than a full 120.

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  • Team Samurai
Samurai Appliance Repair Man

Posted

Just to add... The water dispenser and ice maker valves are still receiving the full 120 VAC when each is energized while the isolation valve (also called "primary" or "main") is only receiving 60 V due to the half wave rectification of the diodes. Also, when the dispenser valve is energized with 120 VAC, the ice maker valve gets 0 VAC due to the opposing diodes which, together, block both the positive and negative half cycles from Line. And vice versa when the ice maker valve is energized. 

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