American Dryer OPL

Discussion in 'General Electronics Chat' started by R!f@@, Sep 23, 2011.

  1. R!f@@

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    Apr 2, 2009
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    Any one Using this type of OPL unit or have any info on the technical details.
    I am attempting to fix the μC controller of a typical, Model is ADE120ES. The electrical type.
     
  2. SgtWookie

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  3. R!f@@

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    Thanks Sgt.. I did get the service manual after filling the request. I like those type that gives the manual on request.

    There are 3 units in the our Hospital. One out of service for a long time. The controller missing and the mechanics, all taken apart but they say they can put it back together. And I said I can make on controller with the default Drying cycles they like.

    Two were working till last week, now 1 controller not functioning properly.
    They called me when it stopped. After the long document procedure, which I totally hate, I got to check it. The heater was not turning on. The controller is pretty simple enuf and very well put together. I say this of the well thought of output indicator Led's on the circuit. It was easy enuf to pin point the exact fault by looking at the function Led's. The problem was fixed but it did had another issue with the keypad. The unit being near the harbor vicinity and due to long service life, the flex cable lines had worn out and the keypad is not responding the way it is supposed to.

    I changed all the caps and the relays plus the IC sockets after cleaning the μC & memory Pins. As like the rest, oxidization was a major issue.
    I can get it running but the default six program is not running. Only 1 works, even though I replaced the keyboard with push button one which I made after studying the keypad layout. The remain time of the dry cycle is not displayed, only 00 is displayed, but the rest like displaying the interna heat templ is displayed every other second and shows an increase in temp as the tumbler rotates.
    At first after fixing it works for a few minutes and gives the DsFL error which as per the manual says the thermistor circuit fault. But as it shows an increase in temp at the reading I figured it could be a loose. It corrected itself when I gave a rather strong tug at the connectors.

    As before the time does not decrease.
    And when I press some keys, the some display digit turns off which definitely say it is a fault. The digit should not turn off when I press the user key's.
    I figured it could be a uC software issue and the default cycle could be a memory corruption. As per the manual I can very well make another controller with the cycles they regularly use. But here is the main issue I am asking for help.

    Sgt, If you have read the service manual, I like you to explain me the details of the factor A & B mentioned in the manual page 54 to 58. No matter how many times I read it, I cannot figure it out.

    Here is what bothers me about the "factor" issue.
    The manual says tht the μC monitors how temperature increases in factor A & B slopes. which means I cannot duplicate those cycles into a PIC but I can very well put in a heating cycle and cooling cycle times to switch on the relays.

    I have an issue here excepting the things said in the manual about it's heating feedback mechanism.
    As per the unit wiring the motor and heater are switched via heavy duty contactors. The contactors are switched via onboard SPST relays on the controller, it has relays for Heat, 2 for Tumbler direction rotation and 1 for blower motor. As per this config the heaters are not voltage controlled to regulate heat and I can guarantee you tht the heater relay does not switch on or off during a cycle to regulate heat. As the cycle is turned on the heater turns on till the cycle ends, it turns off before two min of that typical to cool down the garments.
    But the service manual says it regulates the heat increase. could it be that it turns on & off the heater to regulate and that I have missed somehow to monitor the off cycle

    The only way I can think of is that switches off the heat for a few minutes and then turns it on, rather than controlling the voltage via it. If this is the cause I don't see a reason I cannot make a program to do it. As I see it the controller simply switches on and off the relays as per software times and thermistor input.

    I like you to confirm my findings.
    I will update the μC and memory number and some photo's later tonight

    {ed}
    I forgot tht u have to file a request. Here is the service manual.
    Correction.
    The service guide does not have all the details but the user manual has. The manuals are uploaded for reference, not for distribution, if mod sees this unfit please feel free to remove them
     
    Last edited: Sep 23, 2011
  4. colinb

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    Jun 15, 2011
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    Perhaps the Factor A and Factor B parameters define control loop tuning parameters relating to heating. Machine size and burner power output will affect the way in which the controller operates, although I would think the algorithms could use closed-loop feedback to make control decisions.
     
  5. R!f@@

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    :confused: HUH!!
    I'm a dummy :D

    Oh ! by the way, what's with the "patent"
     
  6. R!f@@

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    Here are some pics of the μC

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  7. colinb

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    Jun 15, 2011
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    The dryer attempts to predict the dryness of the clothes based on the heat required to maintain the set temperature. This Factor A and Factor B appear as a and b in equations on page 9 of the patent document (section DESCRIPTION OF THE PREFERRED EMBODIMENT). Actually despite my ranting about the ridiculousness of many patents, it is nice to have a written description of how your dryer functions!">) is mentioned a ridiculous number of times in the user manual (I consider it a sort of logical fallacy to equate a patented invention with goodness).

    Even my 20-year-old Maytag dryer has a moisture sensor and a mode that dries until the clothes are dry.

    The dryer attempts to predict the dryness of the clothes based on the heat required to maintain the set temperature. This Factor A and Factor B appear as a and b in equations on page 9 of the patent document (section DESCRIPTION OF THE PREFERRED EMBODIMENT). Actually despite my ranting about the ridiculousness of many patents, it is nice to have a written description of how your dryer functions!
     
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  • R!f@@

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    You too found the patent thing annoying huh!! :p

    Well, here is what I think. It's a sort of a rip off kinda thing..how do you say in ur words,umm.....I think the atmel does not have that much sophisticated program but rather timed on off cycles and that patent thing is to keep other companies ( from USA ) from duplicating the so called "Factor" thingy.

    I figured you guys are afraid of copyright and law suite over this patent thingy.
    ADC registered a simple program and patented it so no one else has the guts to go and make something similar...:D

    What do you think?
     
  • R!f@@

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    Son of a gun..that patent has the circuit. :D
    What kind of patent is tht.....Now I can definetly figure out what is wrong with it.
    Screw the patent, I am going duplicate it so tht the third one will be fixed.

    Hey thanks colinb buddy..I owe u one. :)
     
  • colinb

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    While patents are often obnoxious, one of their purposes is to document the workings of the inventions, while they (in an ideal world) let the inventor exclusively profit from the invention for 18 years or whatever, the second and ultimately the most beneficial to society is that it puts the invention's ideas into the public's hands. Companies often have the choice between making an invention a trade secret or making it an invention, with very different consequences: trade secrets mean the company gets to keep the invention's design confidential, but if it is leaked or somehow figured out, then the trade secret is nullified and others can appropriate its ideas; on the other hand, a patented invention is put into public knowledge unconditionally, but only the inventor is permitted to profit from the idea. BUT, don't get me started on software patents and patents on mathematical ideas... which are total crap.

    Anyway...
    Glad to help you find the solution. Make sure to update us when you get it working... it sounds like it's still going to be some work to figure out the exact problem and solve it. Are you going to try to diagnose and repair the existing control circuit or are you going to try to design a replacement?
     
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  • colinb

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    Bunnie had a perfect illustration of how hardware makers have changed over the years in his last blog post. Consider the example of the page from an old service manual with circuit diagrams to the modern Apple Mac Pro manual's “how to sit comfortably” diagram. It is always amazing when I find an old product where the manual has full circuit schematics and BOM! (E.g., my old 20 MHz Hitachi analog oscilloscope, or my old tube-powered ham HF transceiver.)
     
  • R!f@@

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    Of course I will keep u guys posted, I luv this place.
    Today I am planning to copy the EEPROM from the working one.
    I tried to read the memory 24WC02 from the faulty one and it says cannot ID device. I think the memory is dead.

    So what I am trying to do is to give them an instant solution so tht their workload will be minimized, since one is working the bedsheets are over loading. I need to give them a quick workable solution so tht the drying can be continued, it is a hospital for Pete's sake.
    One of my friend has an EEPROM duplicator, so I thought I would take it and copy the working one and see if the default cycles work or not.
     
  • R!f@@

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    This thing definitely is giving me the run a round. managed to duplicate the memory but still it does not work...The copied new memory is in the working dryer now.

    So now I know it ain't a memory fault, could be the atmel or other cmos acting up.
    Right now my hunch is on one of the two buffer IC's used at the Atmel outputs.

    Several hours later:

    So I tried to run the controller by substituting pots and switches instead of thermistor and door switches, but still this thing is giving a dsfl error. Checked the 555 and surrounding components .
    Fault lies in the Atmel.
    So today I studied how the dry cycle works.
    For 40 min drying time, the heater is ON for 10 min. The tumbler reverses every other minute continuously thru out the cycle. The blower is on too.
    After 10 min the temp reaches to around 200°F. The μC tries to keep the the temp around that value thru out the cycle by switching the heater. Feedback is thru the thermistor coupled to 555. Hysteresis window is from 188°f to 195°f.

    Now I am going to see if I can write a simple program to do tht for the time being.
     
    Last edited: Sep 25, 2011
  • R!f@@

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    [​IMG]

    See the pic...It's my programming skills in use :D.. this PIC stuff is pretty good.

    Story:

    The Desk jockeys at the hospital want a quick solution for the time being. So I gave them a quick solution after a week :p.
    What to do...too much work and not enuf hands.

    I said to them ht I can make a controller for the grounded one with a keypad and all, they wanted to make two so to cut cost and less hassle, and for the time being needs to run the second one.
    So, I just simply note down the heater, tumbler and blower on off periods and use the 12F629 leftovers I had to good use.
    I cannot yet write complicated programs, so I simply used one PIC for each element.
    One to switch the heater, another to switch the tumbler and one for the Blower. All uses it's own cycles.

    One main one to control the 40 min cycle and this one enables the other PIC'S MCLR.

    No feed back for now, just an on switch and it will stop in 40 mins.

    It works perfectly on my bench. The cute little green leds on off accordingly.
    Now to test on the machine.
    Wish me luck.:p
     
  • R!f@@

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    And it works...for now.

    {ED}
    Update.

    See the prototype pic above.
    #The relays and the transformer and regulators are from the original Assy.
    The 3 12F629's are the new parts.

    See the harness connector.
    This is the I/O. Nothing else is there. I will be using the same connector in the new PCB.
     
    Last edited: Oct 3, 2011
  • debjit625

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    Apr 17, 2010
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    First of all you should learn assembly,it will help you to understand the architecture of the microcontroller better and in small scale microcontrollers the instruction set is not too large to learn, just couple of days....

    When I am programming for microcontrollers I always use C,but some times C compilers can't optimize your logic to the expected level ,then its time to tweak it with a bit of assembly for example some times if you are using delay routines in some compilers they cant do it properly so I do that part using assembly.

    Long ago their was no high level programming language, that time people used assembly but as programs started to grow larger and complex the instruction based assembly failed to run properly, in big programs all the goto and jump statements of assembly made the code jumbled up and it is called spaghetti code.So people came up with high level language like C.C is a high level structural based language and still in 2011 its the predominant system programming language in the industry. One of the most useful stuff of high level languages are their code are maintainable and manageable. Learn it once and all most program any microcontroller or microprocessor.

    It’s like to get married to any girl from Maldives and she will give you permission to get married again... and the next one will give permission for another and this will continue....
    2012 1st Jan I will be 23, I think I should get married to any(beautiful ,sexy) girl form Maldives.:D
     
  • R!f@@

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    U knowwhat. I really like you. Drop in to Maldives and gimme a call. I'll show you around and the girls too.
    :D
    If you wanna marry, I can arrange that too. This I guarantee
     
  • Markd77

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    Sep 7, 2009
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  • R!f@@

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    I've been thinking about how to increase the visual effect and use lesser pin PIC's.
    Here is my Idea.

    First to use less coding and 7 segs, I could use bar meter using LM3914 to show temperature rise. Since the temp is measured using a thermistor, wouldn't it be easier to show the resistance variation with an amplifier coupled to the bar meter.

    This way the temp display is far better I think. The Fahrenheit indication can be printed next to the led just to give out a rough idea on the level. Just for indication. Actual heater control can be via PIC ADC. So I guess a 16F88 would suffice for the job.

    All I need to code is the count down timer and the delays which I have already done. Just need to Mux the count down timer, which I believe is a bit difficult for me.
     
  • Markd77

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    Should be just about possible, here's my idea of the pin requirements from thread:
    http://forum.allaboutcircuits.com/showthread.php?t=60129
    10.........3+7 for multiplexing 3 7 segment displays
    1...........3 user input switches (multiplexed with the above)
    1...........3 sense inputs (also multiplexed)
    3...........relay outputs (assuming the two direction relays can be driven by one pin)
    1...........analog thermistor input
    ________
    16 pins total
     
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