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Just a side note that you typically won’t be measuring voltage drop across gas valve coils. But you will across other loads like motors.
Going back to Ohms Law, which you learned in the Core course: Voltage is the prime mover in any circuit. Nothing else happens without a voltage source to make the electrons move. If you have voltage from a power supply and a complete circuit from one side of the power supply to the other, electrons will move in that circuit. They have no choice. Unlike voltage from the supply, voltage drop is an effect produced when the voltage difference from the power supply forces electrons to move through the resistance of a load. Some or all of that supply voltage is said to be “dropped” across the resistance of the load and is given by the Ohms Law equation: E = I x R. You may want to review the Basic Electricity section of the Core course. You should watch this webinar recording at Appliantology that goes into detail with multiple examples showing this: https://appliantology.org/topic/72423-voltage-voltage-drop-loads-switches-jumpers-cheaters/
For more detailed information on how the valve coils work in a gas dryer ignition system, watch this webinar recording: https://appliantology.org/topic/63109-mst-office-hours-5222017-gas-dryer-ignition-systems/
Capacitors are reactive devices that change the phase relationship between voltage and current. Don’t worry about what that means exactly for now, just know that if you jump it out, you would be eliminating that function for a circuit that was designed to use it. Bottom line is that jumping a capacitor is not diagnostically meaningful.
You can, however, test a capacitor. The Old Skool way is to first discharge the capacitor by shorting the terminals with a jumper wire. Then set your meter on Rx100 and measure resistance. You will see the resistance low at first and then quickly rise to OL or open as the capacitor charges from your meter. Then reverse your probes and you’ll the see the same action. A better way is to use a meter that has a capacitor testing function. You just select this function, place your probes, and the meter measures the capacitance in microfarads.
Actuators use a small motor. If the motor is a single phase 120 VAC motor, you can use your cheater cord to power the motor. But the best way is to place the machine into diagnostic mode and power the actuator.
I can’t help with the specific problem in this forum but I can help you with troubleshooting strategy. Deploy the Ten Step Tango (TST) troubleshooting procedure that you learned in Core.
1. What’s step 1 of the Tango?
2. What’s step 2 of the Tango?
Step 2 is why I cannot help you with this specific problem in this forum. However, myself and other techs would be happy to help you with this specific problem in the Repair Forum at Appliantology: https://appliantology.org/forum/4-appliance-repair-tech-forum/
Also, you would benefit from watching this webinar recording on applying the Ten Step Tango to various real-world appliance problems: https://appliantology.org/topic/61228-office-hours-webinar-recording-from-12-12-2016/
Complain about no heat…
First thing how to test gas valve coil?First thing I would do is check for proper operating voltage to the gas burner assembly. You can usually do this from the control panel by reading the schematic to see which wire supplies voltage to the gas burner. The coils are part of the gas burner assembly.
There’s a video in the course that explains the gas valve coil operation. You’ve already seen some of this in the midterm exam in the Core course. You may want to review that.
Are you referring to something said in one of the videos? If so, please give timestamps so I can scrub ahead to those points and listen.
Hello sam so I can use jumper wire for only switch and loads
NO! Please watch the video again. I stress that you use jumpers to jump switches, NEVER to jump a load. This is an important concept to understand. If you start jumping loads, you’re going to get arcy-sparky.
Similarly, you would never use a cheater cord on a switch because as soon as you close that switch, arcy-sparky.
Remember the rule I said in the video: Cheat the load, jump the switch.
What about thermostat or thermal fuse
Both of these are SWITCHES, not loads. You should never see a voltage drop across a properly operating switch because a closed switch acts like a wire.
Or measure resistance you said measure amps to know if circuit is open or not
With voltage applied to the circuit and all the circuit components are functioning normally, then there will be amps in the circuit which you can measure. If you have volts but no amps, you know you have an open somewhere. Then you would use test continuity on each component including the load to see which one of them is open.
Make sense?
That’s a manual switch on the console that the customer can open or close (“turn on” or “turn off”) depending on whether they want to silence the buzzer noise at the end of the cycle.
Also, wanted to mention in the video Master Samurai Scott says there is no path to neutral for the buzzer at the 14:47 mark in the video which I think was misspeak but just thought I would bring it to your attention unless I am missing something here.
Good catch! That was a misspeak– should have said there’s no path to Line. I started off showing the buzzer shunted (Neutral on both sides). There was another misspeak– I said the switch is shunted when I was obviously talking about the buzzer. Loads get shunted, not switches.
How do you know when Jazz control boards started going into GE refrigerators? It’s kind of hard to get that info on a google search. I was just curious.
The Jazz boards were only used in Whirlpool-built refrigerators (Maytag, Kitchenaid, Whirlpool, Jenn Air).
More generally, the way you would answer this is by reading the schematic. Remember: the schematic is the FIRST thing you look at when you’re prediagnosing a problem in preparation for a service call. Most techs never even look at the schematic because they don’t know how to read them. Or, if they do look at the schematic (with their eyes crossed), it’s the last thing they do when they’re stumped and flailing around trying to “troubleshoot” an electrical problem without looking at the schematic. How does that work out? Almost always, not well. And without the schematic, they’re not troubleshooting; they’re just guessing and hoping to get lucky. I don’t rely on luck for anything. It’s all analysis and troubleshooting with the Ten Step Tango. Step 2 of the Tango is to read the schematic.
As far as getting the schematic or tech sheet so you can troubleshoot, you’ll download that from Appliantology. If it’s not already on the site, post a manual request in the Appliance Service Manual Request forum and Sam will get it for you.
For clarification I was wondering on newer gas appliances that have control boards, does the hot surface ignitor’s “wire” make an electronic connection directly to the control board (porcelain wire nut) by that terminal and on older appliances it is connected to something else?
Whether older or newer, in hot surface ignition systems with a control board, the board itself is switching one side of the power supply directly to the ignitor and the heater inside the gas valve. You’ll see this on the schematic– there will be a line drawn from one side of the ignitor to the control board (either Line or Neutral). The other side of the igniter goes through the gas valve heater (loads in series) and then to the other side of the power supply. In these hot surface igniter circuits, the board is functioning as a switch and the ignitor and valve bimetal heater are functioning as loads.
Don’t get tripped up just because there’s a control board. We’re still dealing with loads and switches. Boards can function as a load or a switch, depending on the problem. Think of control boards as software controlled switches. The board will make programmed algorithmic decisions about which loads to switch power to and when. This software is programmed into the memory storage chips (EERPROMs- electrically erasable programmable read-only memory). We are not privy to the software code so any of the logic functions that are relevant to troubleshooting must be disclosed by the manufacturer.
For example, suppose you have a dryer motor that’s not running. The dryer has a computer that controls the power supply for all loads in the dryer, including the motor. You have a good power supply for the board but the board won’t close the relay (on the board) that supplies power to the motor. Bad board? Not so fast! You as a sharp tech recognize that the board is functioning as a software controlled switch. So you ask yourself, “What other inputs might the board be looking for before it closes the motor relay to run the motor? Could be Neutral from the door switch or something else. You’ll look at the schematic for sensing lines. I have several webinars where I show sensing lines in different applications. They’re used all over the place in all computer-controlled appliances. General rule: when you see multiple lines doing the same thing going back to a control board (Neutral, Line, doesn’t matter) and one is unswitched while the others are switched, most of the times those switched lines are sensing lines telling the board about something going on in the machine. This blog post has some good discussion on this: https://appliantology.org/blogs/entry/1231-gas-dryer-not-heating-troubleshooting-with-only-a-jumper-wire/
Couple of webinar recordings at Appliantology that you should watch:
Gas oven hot surface ignition systems: https://appliantology.org/topic/62940-mst-office-hours-582017-gas-oven-service-call-after-a-parts-changing-monkey/
Voltage and voltage drop, loads and switches, jumpers and cheaters: https://appliantology.org/topic/72423-voltage-voltage-drop-loads-switches-jumpers-cheaters/
Also, watch this webinar recording at Appliantology: https://appliantology.org/topic/72423-voltage-voltage-drop-loads-switches-jumpers-cheaters/
A belt switch is just a switch like you learned about in Core. Lots of pictures of these types of switches in the Core course or online. The switch is actuated by the tension of the belt. When the belt breaks, this tension disappears and the switch is no longer actuated. The board monitors this switch and can tell when it is no longer actuated. The software on the board attributes this to a broken belt.
secondly,its written that Under normal conditions, the pump will run for 20 seconds at the beginning of a cycle and 20 seconds at the end of a cycle, or if excess water accumulates in the sump area
does it mean that the dryer will automaticly activate the pump at the begining and end of every cycle each and every time i turn on the dryer eventough the pump area is empty? if so why do we need the pump to run on empty?You may have missed the bolded note just below that:
Again – that was an example. Refer to the technical documents for the machine you’ll be working on!
That description from was the operating algorithm for a GE condensing dryer. That description came from the service manual. You will also get the specifics of the operating algorithm from the service manual for whatever condensing dryer you happen to be working on.
I’m not sure how you’re using the phrase “splitting the load.” But you would determine the voltage supply (and your measuring locations) for your load of interest from the schematic. You start at the load and work back to the power supply. For a 120 VAC load, you will be tracing Line and Neutral starting from the load back to the source. Sometimes, you can’t tell right away which side of the load is Line and which is Neutral. Doesn’t matter because it will be revealed to you when you complete the trace back to the source.
For a 120 VAC load, you will measure 120 VAC dropped across that load when it is running. Using the schematic, you can usually find clever and convenient locations for making this measurement, such as at the control board, without having to tear down the entire machine.
If you have your 120 VAC at the voltage supply source but no amps in the circuit, then this tells you that you have an open in the circuit– could be an switch, broken wire, bad harness connector, or an open load. You’ll use the schematic to identify the switches in the power supply circuit for that load and then use your jumper wire to jump out each switch one at a time.
It’s just a variation on the same functional theme. In other words, a different way of doing the same thing. Different valve and regulator manufacturers. The video showing you a common conversion. Many other common conversions involve flipping over the blocking pin. The exact procedure may vary slightly depending on the type of regulator but the FUNCTION is the same regardless of the procedural variation.
But here’s the bottom line: you shall ALWAYS follow the appliance manufacturer’s conversion instructions TO THE LETTER. You shall not turn to the right hand nor to the left. But you shall obey the appliance manufacturer in all their written conversion procedures. BEFORE YOU ATTEMPT THE CONVERSION, you shall obtain said written conversion procedures from the installation guide that came with the appliance. If the customer has misplaced the installation manual, you shall request a PDF of said manual at Appliantology.
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This reply was modified 2 years ago by
Samurai Appliance Repair Man.
Great job! You have snatched the pebble. Just one little tweak…
So, if we test N at T17 wrt L1 at the load and get 120 VAC, that means voltage is present up to that point in N. Then we move our lead to T13 and get 0 VAC, it means that the timer contact at T13 is stuck open and we need to replace the timer.
T13 is definitely one possibility. But Neutral has to complete through two timer switches: T17 to T16 at cam 10 and T16 to T13 at cam 8. So one of those switches is stuck open. As a practical matter, it doesn’t matter which because, either way, the timer is getting replaced. If I have 120 VAC between T17 and L1 but 0 VAC between T13 and L1, I have all the data I need to draw the correct troubleshooting conclusion: replace the timer because one of the switches in Neutral is stuck open.
I think one of the most helpful things you have said is to just focus on the LOI and it’s circuit. In the past, when I have attempted to use schematics and timer charts, I get all distracted and befuddled by processes that have nothing to do with the problem. It seems obvious, but I guess it needs to be pointed out.
Correct! This is true for any schematic analysis you do on the job. A schematic shows lots of different circuits. We don’t need to spend the time figuring out what all those circuits are doing, just the specific circuit for our LOI. We focus like a laser on the power supply circuit for the LOI and don’t let ourselves get distracted by unrelated circuits.
The video begins with a discussion that we were getting a valid L1 but the load was not running. Starting at about 15 minutes in, I list some ways of determining if you’re dealing with an open Neutral. I talk about “junk voltage” (ghost voltage) which indicates an open Neutral. But you would only see this if you’re using a meter without LoZ and measuring with the VAC function. With the LoZ function, you would read 0 VAC because the meter on LoZ bleeds off the ghost voltage and correctly reports 0 usable voltage available for that load. Then I discuss measuring from the L1 side of the LOI (drain pump motor) to a Known Good Neutral (KGN) which is going to be an unswitched Neutral somewhere on the machine (the terminal block, in this case). If I read a good 120 VAC (on LoZ) between L1 on the pump and my KGN BUT I read 0 VAC across the pump winding (again, on LoZ), then I know I’m dealing with an open somewhere in the Neutral circuit for the drain pump motor. And
So we covered several ways of testing for a valid Neutral at the drain pump: read voltage across the pump winding (knowing that we had a valid L1 at the pump); confirming by reading 120 VAC between L1 at the pump and a KGN (unswitched) Neutral elsewhere in the washer; and the ultimate acid test– using our cheater cord to hot wire the load to see if it runs. If the load runs on a cheater cord, then you have proven the load itself is functional and that the problem is in the power supply circuit for the load. Given the components in the Neutral side of the drain pump circuit (switches, harness connectors, splices, wire, etc.) we know one of those components is open.
Given your amazing new knowledge of circuits, how would you track down the location of that open in the Neutral side of the circuit using voltage measurements (that’s a hint)? In other words, we know we have a good L1 at pin 1 of the pump motor. So we can set one of our volt meter probes there. Then we can use our other probe together with the schematic to probe the circuit until we pick up our missing voltage difference.
For example, what if we had one probe at pin 1 of the drain pump (L1) and then put our other probe at timer contact 17 (T17) and we read 120 VAC. Yet we read 0 VAC between drain pump pin 1 and timer contact 13 (T13). What would that reading definitively tell us?
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This reply was modified 2 years ago by
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