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Hamilton-Beach Dehydrator - thermal fuse?

Discussion in 'Troubleshooting and Repair' started by Johnnyanglo, May 30, 2020.

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  1. Johnnyanglo

    Johnnyanglo

    3
    0
    May 30, 2020
    Thermal Fuse2.jpg I believe the thermal fuse needs to be replaced after the dehydrator motor overheated and the unit died. I think if I could find the right part I could just snip and solder in a new fuse. Here's a picture of the offending part. Any ideas on the replacement?
     
  2. Martaine2005

    Martaine2005

    3,417
    928
    May 12, 2015
    Although very similar to diode, it is probably a silicon PTC thermistor.
    What makes you think it’s blown?. Have you tried heating and cooling to see whether the resistance changes?.

    Martin
     
  3. 73's de Edd

    73's de Edd

    3,085
    1,302
    Aug 21, 2015
    Sir Johnnyanglo . . . . .

    Look around that unit and find at least 49 other components being associated with its electronics and then suspicion ANY of them and THEN you hold out testing and suspecting THIS unit as being your 50th unit and with its being your actual problem.

    Obviously it is being a common 1N914 /4148 switching diode, that is being mounted within that heating elements air flow path, so that its diode juntions variance to subjected temperature will feed back to thermal control circuitry.

    You certainly did not provide much other info . . .photographically . . . . so we might suspicion the visible heating element as receiving a botttom mounted fans airflow thru it and then being switched on / off, accordingly, by a SCR electronic switch.

    A failure mode then might be a failure or sluggishness of that fan,downright stopping or hindering airflow, such that this heating element THEN starts overheating and finally pops open a thermal cutoff fuse and THEN all operation ceases.

    Provide more info and relevant pictures.

    Thaaaaaaaasssssssit . . . . .

    73's de Edd . . . . . . .

    Somedays I absolutely amaze myself . . . . . then, on other days, I put laundry in the oven .


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  4. Johnnyanglo

    Johnnyanglo

    3
    0
    May 30, 2020
    I can add that there is no power to the unit at all. It had been assembled incorrectly so that the airflow was blocked and it apparently shut off. So I assume there is a blown fuse. This apparent switching diode lays across the fan stream with the heating elements below it. It seemed like the most likely culprit to be replaced. Perhaps the issue is in another place further down inside the unit, some kind of fuse, and the diode was not affected by what I believe was an overheated blower motor.
     
  5. 73's de Edd

    73's de Edd

    3,085
    1,302
    Aug 21, 2015
    Sir Johnnyanglo . . . . .


    This apparent switching diode lays across the fan stream with the heating elements below it. It seemed like the most likely culprit to be replaced.
    ( L A A A A A AST thing to fault . . . )

    Well . . . .still not enough usable info coming forward . . . being specifically relevant to your unit.
    Hamilton Beach provides no info their HOME site as being forthcoming . . . ¿ assuming ? . . . that this is just expected to be a $60 toss away unit . . . considering any developed operational problems.
    Can I assume that Hamilton Beach consumer model # 32100 is being the unit involved ?

    A . . .la . . .

    [​IMG]

    If I DO go to their commercial product area and research their commercial dehydrator , there I can at least get into their minds and see exactly how their engineering heads are being screwed on . . . .CW ? . . . CCW ? . . . Coarse . . . Fine . . . Metric . . . SAE ?

    Viz . . . .

    http://partsapp.hamiltonbeach.com/files/540096600B.pdf


    Now, on that unit, you can see that an AC power line fuse is being involved in its power input flow at bottom right corner.
    Then there is the air supply fan., the heating element and the control panel.
    I might suspicion that the shown thermostat is just being for an UPPER heat limit protctive precaution.
    And if temperature control aspect is involved, it will also be using your same silicon diode junction for temperature sensing in the air flow stack and being wire remoted to the control / display electronics portion.

    Then there would likely be a thermally coupled one shot thermal fuse *** being associated with the heater element and possibly the fan motor proper.

    *** They look-a-like-a-dis . . . . and are being CRIMP CONNECTED into circuit just as your is diode as shown, BECAUSE soldering heat applied to the one lead that is set in ceramic frit, might damage / ruin / melt / blow the internals of the unit on its initial install.
    PLUS . . . . you just might find this unit being HIDDEN, in the respect of being nestled INSIDE of a woven, electrically insulative fiberglass sleeve .

    upload_2020-5-31_4-21-24.png

    So finally now, give some feedback, as to whether the now thermally and air flow DEAD unit is being totally devoid of any digital display or associative indicator lamps ?
    Since . . . with that digital display, some power supply electronics is involved with it, whereas the separate and isolated heater and fan aspects may now be the non powered up units.


    What say ye ?


    73's de Edd . . . . .

    I don't have A.D.D., it's just that . . . . . oh LOOK ! a squirrel ! I wonder where it lives . . . . will it run away if I approach it ? . . . .




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    Last edited: May 31, 2020
    Martaine2005 likes this.
  6. Johnnyanglo

    Johnnyanglo

    3
    0
    May 30, 2020
    Heating board.jpg Circuit Board Control Panel.JPG Yes, it' H&B Model 32100. The repair center for H&B would not provide any info or schematic and said go buy another one. Anyway, there is absolutely no power going to the unit so I was looking for a replaceable fuse but didn't see anything obvious when I took it apart. I assume it overheated when the airflow was blocked. So I'm thinking something associated with the heating elements? That silver diode crimped between the red wire and the coiled heating element might be my new culprit. Not sure what to test or how?
     
  7. 73's de Edd

    73's de Edd

    3,085
    1,302
    Aug 21, 2015
    Sir Johnnyanglo . . . . .

    AHHHHHHHH YES ! now you have just experienced your EUREKA moment . . . . and have FOUND it.

    NEXT STEP . . .

    You say . . . . .NO A.C. line power going to the unit and . . . .

    The use of an ohmmeter being set to its lowest range and probing across that fusible unit see if its open / blown, or a dead short indicates that it is still good.

    Additionally . . . . .to know . . . .that the fan motor might not be a full A.C. line voltage motor, but of a lessor voltage and is relying upon a tap off point from that nichrome heating wire coil set, in order to get a reduced voltage to power the fan.

    Therefore . . . .an explanation for an / the additional loss of fan action, if that thermal cut out opens up.

    You are now being reliant upon the case markings of the old unit to sort out its temperature rating . . . which is to be expected marked on as three digits of its C ( Celsius) temperature value.

    Mouser or Digi Key have replacements.

    https://www.digikey.com/catalog/en/partgroup/sdf-series/24120

    You say . . . . . I was looking for a replaceable fuse

    On your photo of the control electronics there is Fuse 1 on that boards far right side.


    73's de Edd . . . . .

    Hey ! . . . . I just got into some deep depth thinking . . . . . . . shouldn't a radioactive cat have 18 half-lives?



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