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Hello there,
I am trying to understand if the dryer is not working properly or just misunderstanding of this feature.
When set up to Cotton and Sensor, I believe that after the clothes dried off, the operation of the dryer should stop. This is not the case. That is, it is turning and turning while the clothes are well dry.
Is this a setting issue?
I checked the dryer moisture sensor connection all good. When operating under "timed cycle" it works well.
Any hint will help.
Thanks,
AmDek
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Does the timer advance at all during auto dry cycle? or does it advance part of the way but never goes to OFF? If timer never advances at all in auto, you may need to clean the moisture sensor bars.
Eric
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Well - It seem to be standing still at the point in which I set that up to start the drying cycle. And the sensor's contacts are sparkling clean, this dryer, although 18 months old only operated 10-12 times...
Still scratching my head on this... Any help will be appreciated!
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Rank: Advanced Member
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Probably a bad sensor board. This pc board drives the timer during auto dry based on input from the sensor bars. When wet clothes fall across the bars, they are shorted out and this is detected by the board. As the clothes dry out, there is less shorting of the bars and the board starts advancing the timer. If the bars are shorted out due to gunk buildup, the timer will never advance but if they are clean and the area between them is clean, then it looks like a faulty board. GE WE04X10103 Pc Board-No Buzzer - AppliancePartsPros.comEric
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Rank: Member
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Eric - Thanks for taking the time to respond.
I was suspecting the PCB and tried to reverse engineer it and to understand how it works... Do you know where can I get a schematics of this board? I know it has an LM393 comparator on it and some other components, but because it is a SMT board it was difficult to really figure that out. A schematics will help. I would not want to buy the board if it works OK and the problem is elsewhere.
Thanks again for your help.
AmDek
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Rank: Advanced Member
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There's no schematic available for it but it looks simple to reverse engineer. I've done that to far more complex circuit boards before. If you buy the part from APP, you can return it if it doesn't fix the problem. If you have electrical troubleshooting skills, it's pretty simple to determine if the board is the problem. All it does is provide a neutral connection to the timer. If you disconnect the sensor bar input, then it should connect neutral to the timer all the time just as in timed dry.
Eric
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Hmmm, excellent hints!
Let me make sure I understood - The moisture sensor change its' conductance according to the humidity inside the dryer's drum - Nothing complicated with that. That is being measured by the PCB (I believe by way of comparing to a preset threshold represented by the comparator I noticed there), and then, when the moisture level is low (when the air is dry = clothe are dry), the PCB allow the Neutral line into the timer motor and thus advances it to complete the cycle (and actually to stop the dryer) - Is this correct?
If indeed, the trouble shooting technique you suggested is clear and clever.
Thanks again, I will do some work tonight on this and then order the part.
What still puzzles me is how did this circuit died (if indeed) when it was only operated 10-12 time so far... Being and Electronics Engineer, I cannot accept that a brand new circuit, which I am sure was tested before put into the dryer, would be dead... Oh well, it is what it is, and I mainly appreciate your kind help!
AmDek
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Rank: Advanced Member
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Close. It's not the humidity that is detected, it's wet clothes laying across the bars as they are being tumbled. When the pcb is powered, the large capacitor starts charging up. Each time wet clothes short the sensor bars (one of the bars is connected to ground), the charge is reduced. Eventually, the charge gets high enough to reach the threshold and the board passes neutral to the timer. I'm not an engineer but I spent 37 years as an electronics technician at the Naval Academy before retiring and now doing appliance repair for the fun of it. Washers and dryers are easy :-)
Eric
Tried to upload the wiring diagram of your dryer for you but it won't accept for some reason. Your diagram should be in the control panel.
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You are great! Chris. thanks. I also appreciate your service to our country!
I have the machine diagram, and I will reverse engineer the PCB later this week and post the schematics here. I am surprised nobody did it before. I already know they have a TRIAC device there to control the Neutral going to the timer motor and I am collecting hints from everywhere... Unlike you I am not even close to appliances repair, but I can fix anything if I can put enough time and attention to it.
Also, if the PCB is indeed broken, I am tempting to design one myself and build it. From your explanation it should be a rather simple circuit to design, I may even utilize a small micro processor for that. Should be fun and will cost a lot less than the $45.- they charge. Of course, I did not add my time, but this is like a hobby for me and one never calculate how much a day on lake, fishing, costs...
Again - Thanks!
AmDek
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