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The insulation itself has ribs or raised ridges:
is there another way to jump the connectors neutral to make sure that that was definitely the problem?
First, to check a voltage supply to a load, you should only ever use a loading meter. These meters place a load on the circuit being tested and have a low enough input impedance to deliberately draw current from the circuit. Loads cannot run on voltage alone– they need power, voltage AND current (P=I*E). A loading meter will keep you from getting head-faked by open neutrals and ghost voltages. This post at my blog has more info on this:
https://mastersamuraitech.com/the-low-down-on-loading-meters-and-dmms/
and this video demonstrates using a loading meter on a refrigerator:
https://www.youtube.com/embed/VfZpH2dfQ84
Of course, you could always use a long jumper wire and temporarily run a jumper to the load from a known-good Neutral, such as another load that is running properly.
There is no other way to complete that repair in this scenario because the wires are actually foamed into the cabinet of the refrigerator.
Also, did the customer allow you to drill a hole in the Refrigerator?
When the alternative to a $200 repair is to replace the refrigerator with a new one at $1,100, customers will almost always opt for the repair. This is the kind of repair that makes you look like a magician to customers!
lastly how would you splice the wire from one side to the other? Cut and use a crimp with silicone?
All splices done inside a refrigerated compartment shall be waterproof splices. Period. That means either Drycons or crimp-on connectors with silicone grease added.
Splices outside of the compartment can be either twist-on wire nuts or crimp connectors. I prefer crimp connectors because they are more reliable. Silicone grease is not needed because it is not a wet environment.
The smooth wire is Line and the ribbed wire is Neutral. Ground (if present in the cord) will be a separate, third wire and is a green wire by color convention.
You are right, smack-diddly on, Brother John! I especially like your analysis of the current change using the change in equivalent resistance, which will indeed increase if one of the parallel branches opens (the denominator gets smaller so the equivalent resistance gets bigger).
You have snatched the pebble from my hand. Eggzellent!
And now, please join me in my victory dance…
Many times, you can use the schematic to identify EEPs where you can test things like heating elements from a convenient location without having to disassemble. You don’t see this technique much because most techs who haven’t taken Fundamentals aren’t even aware of the power of EEPs or how to use them to make their job easier. This post at my blog shows the power of EEPs in action:
https://mastersamuraitech.com/using-electrically-equivalent-points-schematic-work-smarter-not-harder/It’s a personal preference thing. I’ve found that the 75-pocket model works best for me. But I hate making extra trips to the vehicle to get tools. Other people may not mind that as much.
Depends how regularly the breaker trips. If each and every time the heating element gets power, there may be a short to investigate. If it only trips occasionally during the heating cycle or at various lengths into the cycle, then I would suspect the breaker itself– not an uncommon problem.
one more question so ur saying that line 1 [hot] and line 2 [neutral]
Line 2 is NOT Neutral! Line 1 and Line 2 are BOTH hot. The voltage difference between them is 240 VAC.
Neutral is a third, different conductor. The voltage difference between Neutral and EITHER Line 1 or Line 2 is 120 VAC.
Have you watched my video in Module 3, Unit 6 where I explain the relationship between Line 1, Line 2, and Neutral?
https://www.youtube.com/embed/zs4HjHhf0x8
Hi Sal,
The screwdriver method (or an insulated jumper wire with alligator clips on each end) works just fine. The reason some people like to use a resistor is because the spark that sometimes results from the discharge freaks them out. There is a theoretical possibility that the sparking discharge can damage the capacitor internally or one of its connection terminals. This can definitely happen on large, commercial or industrial-scale capacitors but not on the sizes we work with in appliance repair.
Hi Jose,
Hot (or Line) and Neutral are two different conductors that complete the circuit to the load. So the load will have Line connected to one side of it and Neutral to the other.
In a situation where the load is completely bypassed and there are no other loads in the circuit so that Line and Neutral are connected directly to each other, then you would have a dead short and, hopefully, the circuit breaker would trip before something burned up!
After testing across the bulb you get a reading of 120 volts but the bulb does not light.
Hi Sal,
The wording on the question is:
You use your meter to test for 120 V AC from one of the terminals of the light to neutral and you read 120 V AC on your meter. You place your probes across the two terminals of the light bulb and read zero.
This is very different from the scenario you posted. It’s also conceptually similar to the last question on the Midterm exam, the difference being that, in the Midterm question, the problem was a dryer heating element on a 240 VAC circuit. But the concept is the same: current needs a complete circuit to flow. You can have all the voltage in the world but if you don’t have a complete circuit, electrons can’t go anywhere. And with no electrons flowing, no work can be done.
Can you figure it out from there?
how do you test a an igniter that is glowing but drawing too much current
Hi Sal,
You will never see an ignitor drawing too much current. They fail due to their resistance increasing over time with age. You would check the current draw using your clamp-on ammeter. The spec for that current draw is printed on the gas valve itself. In general, the specs are:
3.2 to 3.6 amps for gas valves using the flat ignitors
2.5 to 3.0 amps for gas valves using the round ignitorsHere are a couple of articles that talk more about gas oven hot surface ignition systems:
http://fixitnow.com/wp/2008/08/06/how-to-replace-the-ignitor-in-a-gas-oven-a-pictorial-guide/
And this video explains the effects of voltage and current variations on the operation of these systems:
https://www.youtube.com/embed/xsGn-JloxbA
Hi Sal,
This is a great question, thanks for posting this!
Electrically, the two most common ways motors fail are:
1- one of the windings goes open
2- one of the windings develops a high-resistance path or direct short to ground
3- in the case of BLDC motors, in addition to the failures listed above, they can also fail by one of the winding resistances changing so that it has a resistance variance of more than 1/2 ohm relative to the other two windings.You can test the motor windings with your ohm meter and referring to the schematic to identify the appropriate leads on the motor to test the windings.
Since motors are electromechanical devices, they are also prone to mechanical failures. The most common of these is bearing failure so that the rotor shaft no longer rotates freely and smoothly. You can tell if this is the case by simply spinning the rotor shaft by hand. If the rotor shaft is either seized up or doesn’t spin freely and smoothly, then the motor has bearing failure.
I’ll be adding this information to the Fundamentals Basic Motors module. Thanks again for raising this question!
Scott
You are exactly right, Jose– I missed a decimal place in my arithmetic. I’ve corrected the video. Great job for catching that!
Hi Jose,
This video may help you see how to calculate equivalent resistance in parallel circuits:
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