Page 2 of 2 FirstFirst 12
Results 21 to 34 of 34

Thread: Actron AM24-1 Controller Possible Thermistor Replacement.

  1. #21
    Premium Member
    wotnot's Avatar
    Join Date
    Nov 2019
    Posts
    1,291
    Thanks
    495
    Thanked 1,049 Times in 581 Posts
    Rep Power
    478
    Reputation
    20990

    Default

    Hmmm....as you've noted a discrepancy between the temp the unit now displays (as opposed to previously), and what temp is measured by standalone thermometer, one has to make a choice on which data-points might be deemed as accurate.

    If we consider the multimeter reading to be accurate with 8K resistance, we'll guess at one of the more common thermistor values (10K @ 25C);

    (what the unit says)-> 8K @ 20C would infer a 10K NTC thermistor @25C with a delta of 3.9% per degree C

    (what the thermometer says) -- 8K @ 23C ...nothing really 'fits' the standard ranges ..8K2 is the next resistance value down but none have a low enough thermal coefficient, ergo it's likely a 10K @ 25C NTC as well , with a higher delta value...highest I can find is 4.7% per degree C.

    'Just because' the component itself is unmarked, and you've noticed a discrepancy between two different controller boards wrt measuring temperature (with the same unmarked thermistors) -and- your controller has already lunched on one, you're allowed to speculate these thermistors are chinese bespoke, or else factory rejects, or anything else like this, and thus if something like the actual component tolerance is out to +/-20% instead of less than half that, these things would easily account for such discrepancies (and the fact they die in the first place =)

    Of the 2 choices, I'll presume the unit is working in some uncalibrated state due to the board swap, but the part dimensions appear correct wrt thermistor types... ergo, replace dead thermistor with any NTC 10K @ 25C thermistor, and observe results... ie; how closely displayed temp correlates with thermometer readings.

  2. The Following 2 Users Say Thank You to wotnot For This Useful Post:

    Softek2 (11-02-21),tready (10-02-21)



  • #22
    Junior Member RFI-EMI-GUY's Avatar
    Join Date
    Jul 2016
    Location
    Florida USA
    Posts
    227
    Thanks
    134
    Thanked 123 Times in 81 Posts
    Rep Power
    122
    Reputation
    2946

    Default

    He is measuring the part in circuit I would guess. In which case the 8K is probably what in circuit will read on a 10K part. I would solder a 10K 5% or better resistor in the old controller. See what temperature it displays and then measure it in circuit. Probably 8K depending on meter polarity. Then I would buy a pack of 10K thermisters and put one in the old unit to use as a spare.

    Sent from my SM-T350 using Tapatalk
    "Have Spectrum Analyzer, - Will travel".

  • The Following User Says Thank You to RFI-EMI-GUY For This Useful Post:

    tready (10-02-21)

  • #23
    Junior Member tready's Avatar
    Join Date
    May 2011
    Location
    Sydney
    Posts
    26
    Thanks
    13
    Thanked 4 Times in 3 Posts
    Rep Power
    121
    Reputation
    90

    Default

    Thanks wotnot,

    Agree 10K seems most logical when I was researching values. There is no way I have found to adjust the calibration on the controller which is annoying I rang Actron and asked the question and the newer controllers have the ability to plus or minus a 3 degree difference. I guess they got complaints about them being out of spec from junky components want to give changing the thermistor a go just for my own satisfaction and self confidence in soldering, just didn't want to do it without some sort of backup in case the whole thing went belly up. Will report back on the success or failure of my efforts.

  • #24
    Junior Member tready's Avatar
    Join Date
    May 2011
    Location
    Sydney
    Posts
    26
    Thanks
    13
    Thanked 4 Times in 3 Posts
    Rep Power
    121
    Reputation
    90

    Default

    Well time for an update, After a struggle I replaced the thermistor and it worked (note to self get a better iron) Bad result is this one is 2.0/5C out on the reading which is liveable going to order a few online and see if I can get a better tolerance variation then the Jaycar one I used. At least I know its not dead completely though.
    Last edited by tready; 17-02-21 at 04:52 PM.

  • The Following User Says Thank You to tready For This Useful Post:

    wotnot (17-02-21)

  • #25
    Premium Member
    wotnot's Avatar
    Join Date
    Nov 2019
    Posts
    1,291
    Thanks
    495
    Thanked 1,049 Times in 581 Posts
    Rep Power
    478
    Reputation
    20990

    Default

    Uncalculated guesstimation based upon what the jaycar part did -->

  • The Following User Says Thank You to wotnot For This Useful Post:

    tready (17-02-21)

  • #26
    Junior Member tready's Avatar
    Join Date
    May 2011
    Location
    Sydney
    Posts
    26
    Thanks
    13
    Thanked 4 Times in 3 Posts
    Rep Power
    121
    Reputation
    90

    Default

    Quote Originally Posted by wotnot View Post
    Uncalculated guesstimation based upon what the jaycar part did -->
    Thanks, Planned on getting a few different ones as a trial and error but at least its getting closer went from dead to nearly working.

  • #27
    Junior Member tready's Avatar
    Join Date
    May 2011
    Location
    Sydney
    Posts
    26
    Thanks
    13
    Thanked 4 Times in 3 Posts
    Rep Power
    121
    Reputation
    90

    Default

    Quote Originally Posted by wotnot View Post
    Uncalculated guesstimation based upon what the jaycar part did -->
    Thanks for the suggestion I thought of getting a few different ones and trying it out with varying margins. At least were getting warmer went from 0% working to 98& functional and I cant thank you enough for all your info provided.

  • #28
    Junior Member tready's Avatar
    Join Date
    May 2011
    Location
    Sydney
    Posts
    26
    Thanks
    13
    Thanked 4 Times in 3 Posts
    Rep Power
    121
    Reputation
    90

    Default

    Thanks for the suggestion, Was thinking of getting a few different ones with varying margins and doing trial and error. At least we have gone from 0% to 99% functioning and I didn't destroy it during the process will keep cracking at it and see where we end up. I mean I could live with it quite easily but its my OCD that likes numbers to be perfect. Thanks for all the info you have provided would of been lost otherwise.
    Last edited by tready; 17-02-21 at 10:48 PM.

  • #29
    Senior Member
    Reschs's Avatar
    Join Date
    Aug 2010
    Location
    Outside a few schooners
    Posts
    2,769
    Thanks
    654
    Thanked 1,737 Times in 861 Posts
    Rep Power
    721
    Reputation
    25038

    Default

    There must be away of calibrating the unit. Manufacturing tolerances would need to be taken in to account at testing stage.

  • #30
    Premium Member
    hinekadon's Avatar
    Join Date
    Jan 2017
    Location
    still above ground level
    Posts
    1,618
    Thanks
    4,708
    Thanked 1,747 Times in 643 Posts
    Rep Power
    730
    Reputation
    31317

    Default

    dunno but spoke to a mate he told me stick two diodes in series (one fwd/one rev in parallel) then keep adding them to get it right . He works on industrial boilers ?????
    reject religion for the planets safety

  • #31
    Premium Member
    wotnot's Avatar
    Join Date
    Nov 2019
    Posts
    1,291
    Thanks
    495
    Thanked 1,049 Times in 581 Posts
    Rep Power
    478
    Reputation
    20990

    Default

    Quote Originally Posted by Reschs View Post
    There must be away of calibrating the unit. Manufacturing tolerances would need to be taken in to account at testing stage.
    You'd think so, but the Chinese really have re-invented the meaning of the term 'close enough is good enough', and the testing regime (if any) might not extend beyond an accuracy of +/- 2C error margin wrt displayed temperature =)

    Thing is, there's a few ways of achieving such calibration ;

    *change the thermal coefficient factor in the firmware, of the algorithm that's doing the ADC measuring/reporting of the thermistor circuit, at testing time (or based on the tested performance of the unmarked batch of thermistors)

    *install a 'shim' resistor in series with the thermistor, to make the thermistor temp/resistance curve closely match the firmware operations

    If you hold that last thought for a moment, R67 (2K7) in series with the thermistor, may actually be that resistor shim...(or a current limiter...would be worth checking it's actual value with thermistor removed)




    Quote Originally Posted by hinekadon View Post
    dunno but spoke to a mate he told me stick two diodes in series (one fwd/one rev in parallel) then keep adding them to get it right . He works on industrial boilers ?????
    This is a thing, but not applicable here really due to the low temperatures/temp range involved ...tends to be a good solution when you need monitor high temperatures tho' ( >100C), like in boilers =)

  • The Following User Says Thank You to wotnot For This Useful Post:

    Softek2 (20-02-21)

  • #32
    Junior Member tready's Avatar
    Join Date
    May 2011
    Location
    Sydney
    Posts
    26
    Thanks
    13
    Thanked 4 Times in 3 Posts
    Rep Power
    121
    Reputation
    90

    Default

    Quote Originally Posted by wotnot View Post
    You'd think so, but the Chinese really have re-invented the meaning of the term 'close enough is good enough', and the testing regime (if any) might not extend beyond an accuracy of +/- 2C error margin wrt displayed temperature =)

    Thing is, there's a few ways of achieving such calibration ;

    *change the thermal coefficient factor in the firmware, of the algorithm that's doing the ADC measuring/reporting of the thermistor circuit, at testing time (or based on the tested performance of the unmarked batch of thermistors)

    *install a 'shim' resistor in series with the thermistor, to make the thermistor temp/resistance curve closely match the firmware operations

    If you hold that last thought for a moment, R67 (2K7) in series with the thermistor, may actually be that resistor shim...(or a current limiter...would be worth checking it's actual value with thermistor removed)






    This is a thing, but not applicable here really due to the low temperatures/temp range involved ...tends to be a good solution when you need monitor high temperatures tho' ( >100C), like in boilers =)
    I measured it when I was first troubleshooting and I think it was about 273ohms. I thought the value of the resistor is 270 Ohm so assumed it was okay I based the info from this site But your saying its 2.7k? If I was to put a resistor in series what values do you think I should look at?

  • #33
    Junior Member tready's Avatar
    Join Date
    May 2011
    Location
    Sydney
    Posts
    26
    Thanks
    13
    Thanked 4 Times in 3 Posts
    Rep Power
    121
    Reputation
    90

    Default

    Sorry about the earlier triple post I was replying but the post was disappearing when I looked so I kept posting till one stayed the rest obviously posted some time later

  • #34
    Premium Member
    wotnot's Avatar
    Join Date
    Nov 2019
    Posts
    1,291
    Thanks
    495
    Thanked 1,049 Times in 581 Posts
    Rep Power
    478
    Reputation
    20990

    Default

    Quote Originally Posted by tready View Post
    I measured it when I was first troubleshooting and I think it was about 273ohms. I thought the value of the resistor is 270 Ohm so assumed it was okay I based the info from this site But your saying its 2.7k? If I was to put a resistor in series what values do you think I should look at?
    My bad - I was reading it as a 3 digit code -- it is indeed a 270R resistor

  • Page 2 of 2 FirstFirst 12

    Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •