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I was a little confused how you unplugged the 120 connector,would that be the same and unplugging the fridge replugging it back in
It would eventually be the same but if you cycle power, you’ll have to wait for the boot up program to finish. I don’t like sitting around waiting so I just disconnect the AC supply to the inverter board (schematic shows which harness is the AC supply), clamp one of the wires with my amp clamp, then plug the connector back into the inverter board so I can monitor amps.
The other problem with cycling power is that you’ll either have to roll the fridge out to unplug it (risking floor damage) or flip the circuit breaker. Easier to just disconnect/reconnect the AC supply harness with my amp clamp on one of the wires. No line splitter needed, either!
There is not comprehensive database of schematic symbols. The reason is that appliance manufacturers will often use schematic symbols that are unique to that manufacturer, like a corporate culture kind of thing.
Fortunately, the schematics we deal with as appliance techs are very simple circuits compared to electronic schematics. We’re mainly dealing with simple loads and switches. So the main question you want to figure out about a schematic symbols is this: Does this symbol represent a load or a switch?
Both sides of a power supply come together across a load. For example, a dryer heating element with have L1 and L2 across it. A drain motor will have L1 and Neutral across it.
A switch is opening and closing one side of the power supply. So L1 and Neutral will never be across a switch because as soon as you close the switch, you have a dead short.
So figuring out schematic symbols first of comes done to answering the question: Is this a load or a switch? To answer that, you have to understand the circuit’s algorithm, or how it’s intended to function. Which means you need to read the schematic.
It’s like a board game, really. You have a “board” (the schematic), the “game piece” is an electron, and the game rules are Ohms Law, Kirchhoff Law and Watts Law. You can’t know how the “piece” moves on the “board” unless you know the “rules of the game.”
Here’s a video from a recent Live Dojo workshop showing the process of “playing the game” where we also had to figure out how an ambiguous schematic symbol functioned: https://appliantology.org/topic/104619-how-to-decipher-schematics-like-a-pro/
Good question, Roy. First, keep in mind that the IR temp reading will not be as accurate as a thermocouple reading because of some inherent deficiencies with getting temperatures via IR. Still, it’s quick and accurate enough (about +/- 5F) for a screening test if you’re trying to get a good idea of compartment temps for any reason. So I’ll use it to get baseline temps in my compartments as well as checking thermistors.
Despite the inaccuracies, there are some tricks you can do to improve accuracy. One is to shoot several jars that have been in the fridge a while. You may get slightly different temperatures based on the color of the contents. This is because color affects albedo, which is light scattering. The more scatter, the less accuracy. Lighter colors scatter more than dark colors. So try to find a jar with dark contents.
Another trick is to use the averaging function on your IR gun (if so equipped). If you have this, you can simply shot the compartment while moving the gun around the contents and then read the average temperature. I’ve found this to be accurate enough, too.
Hi Ron,
I can’t speak to anything Texas-specific but I can talk in the more general sense. The only requirement I know of for techs to do sealed system work on home refrigerator is that they have an EPA Type 1 certification. The so-certified tech can co anything to that sealed system, including replacing the compressor.
The test is super easy, open book, online exam for about $25. They ask regulatory stuff, not technical topic relevant to actually doing sealed system repairs. It’s a joke, really.
For more info, you should post this question in the Dojo forum at Appliantology. Lots of techs there and many more Texas. Can probably give you more info. https://appliantology.org/forum/6-the-dojo/
The normal state (unactuated) of the reed switch is open.
Yes. And it takes a magnet to make the reed switch close.
When the fridge door is closed, the magnet is brought very near the reed switch. The magnet actuates the reed switch thus closing it. When the door is closed, the reed switch is actuated and is therefore closed. Remove the magnet and the reed switch is no longer actuated so it returns to its normal state, which is open.
The way I understand is BLDC fan motors always have a standing DC voltage, like a constant 13vdc. Besides that it has a PWM and sometimes an RPM signal, so there is usually four wires from the board to the fan motor.
Yep, there’s a good article describing the various configurations of BLDC fan motors here: https://appliantology.org/blogs/entry/1095-bldc-motor-configurations-fg-signals-and-pwm-signals/
But keep in mind, the exact same thing– technologically speaking– is going on with the BLDC compressor motors. The only difference between the compressor and fan BLDC motors is where the inverter is located. In compressors, the inverter is external to the compressor casing. In fan motors, the inverter is inside the fan casing.
Watch this video to see an example: https://appliantology.org/topic/58659-web-meetup-weekly-appliantology-tech-training-monday-june-6-2016-7pm-et/#comment-346128
It’s a rule of thumb from experience. It’s a very expensive repair, approaching or sometimes exceeding the cost of a replacement machine. So most customers do not opt for it.
I would. If it stuck once, it’ll do it again. Give the customer the choice.
Hi Anthony. Sounds like it would work as a loading meter. One way you can tell is by measuring the input impedance of the meter using another meter. When you do this, you’ll actually be measuring input resistance which will always be something less than input impedance. But this is close enough for our needs. You will measure something around 3 K-ohms. This is typical input impedance for LoZ. LoZ stands for “Low input impedance.”
Repeat this same test on a DMM set on VAC and you’ll measure something around 50 M-ohms. That’s a very high input impedance.
January 12, 2024 at 11:20 am in reply to: Schematic exercises;appliances with electronic control boards 3 #25549Hi John, I made a short screencast to explain this to you. Hope it helps. Let me know. http://somup.com/cZVlDqkaim
January 10, 2024 at 10:54 am in reply to: Schematic exercises;appliances with electronic control boards 3 #25541Let’s back into the solution. What is the black wire supplying to the heater: Line or Neutral? And how can you tell?
If you’re not seeing this, let me know and we’ll start there.
January 9, 2024 at 10:08 am in reply to: Schematic exercises;appliances with electronic control boards 3 #25529Green
Actually Green/Yellow (green wire with a yellow stripe) according to the legend on the schematic.
In the same test .they refer to the the relay switching line .
Which test are you referring to?
I don’t think that relays can switch ground or neutral . That would defeat the purpose of the thermal fuses.
Relays are switches. Switches can open or close any conductor regardless of what’s on that conductor. So switching Line or Neutral– makes no difference to a switch. Switches simply switch without regard for what they’re switching. You often see DC ground being switched with relays.
I put that the relay switches line . That’s what I put.
Is this in response to a particular quiz questions?
January 8, 2024 at 11:55 am in reply to: Schematic exercises;appliances with electronic control boards 3 #25524After the noise filter. I seem to think the wires go from black (neutral)to white after the noise filter.
Wire, singular. There’s only one white wire on the other side of the noise filter. It is Neutral.
It seems to be white ( live )and blue live ,to the main board.
After the noise filter, if both white and blue are Live, then where is your Neutral?
The blue wire seems to be used as ground?
The blue wire that runs from the noise filter to pin 2 on the connector is Live (L1). The other value wires you see in the schematic are used to supply different inputs to various components like the door lock and the drive motor. They just happen to be the same color but is serving different functions.
Ground is explicitly shown on the schematic. They even give the wire color. What is that color?
January 8, 2024 at 11:42 am in reply to: Mod 5 unit 1,Using the Timer Chart and Schematic to Troubleshoot Open Neutral Pr #25523We have clarified the question to refer to timer cam 10. Does this make is more clear?
You have to kind of interpret what they’re saying. They’re at step 5 where you’ve already ruled out things like solenoid voltage. Now, at step 5, they’re saying that if you do NOT have continuity from the disconnected wire at the P1 connector on the board to the tip of the electrode– and you should have continuity for the reason you pointed out– then at this 5th step, that only leaves a failed DSI board by default. In other words, you’ve ruled out everything else and all you’re left with is a failed DSI board.
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