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DC Ceiling Fan Motor Controller / receiver

Discussion in 'Troubleshooting and Repair' started by 265chemic, Jan 14, 2020.

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  1. 265chemic


    Jan 14, 2020
    Hi All,

    I'm having a problem with a DC ceiling fan controller (from a Mercator Trinidad fan). This operates via a remote. The light works fine, as does re-pairing the remote (an audible beep is emitted). The fan function itself however does not. This leads me to believe the issue is more than likely with the DC power control part of the circuit. I have another known good controller for comparison.

    When it first started having issues - and this might be key to forming a theory from someone more experienced than I - it initially wouldn't work until after the AC isolator wall switch was on for some time - sometimes even taking a few hours from pressing a fan speed button on the remote until the fan actually started turning.

    I suspected capacitor issues originally, due to it having some lag time before it would work. Here are some pics - visually all seems okay.


    Electrolytic caps;

    - The big 68uf 450v cap tested ok. Had .29ohm esr and .7% vloss.
    - 100uf 16v tested ok, .49ohm esr and 4.1% vloss
    - 100uf 35v tested ok, .07ohm esr and 1.4% vloss
    - 47uf 35v tested ok

    Film caps;
    - cx2 - .1uf film cap tested at 70.3nf .40 esr
    - cx1 - same as above, 89.1nf .29 esr

    Interestingly, I swapped these over and the fan had not worked even being on for hours like it did before, even after swapping them back.

    *The whole input bank (inductors(?)+film caps) in circuit from the AC input wires (brown/blue) to the bridge rectifier measures 164uf (vs 154uf on the good fan control )) - 8.4/7.4 esr respectively, so I'm not sure that even though the film caps are >10% outside spec that this would fix it, particularly as the bad one has a higher capacitance reading.

    - Tested all surface mount diodes okay, however. D7 was open both ways.
    - D7 is S1J. removed from circuit - tested ok - reinstalled.

    Bridge Rectifier;
    - bridge rectifier is KBP08. Tested 240vac in, 318vdc out.

    Test Points;

    Tp0+tp1 = 15vdc (correct supply voltage for PCM as per PDF below)
    Tp0+tp2 = 3.5vdc
    Tp0+tp3 = 320vdc (correct DC bus voltage)
    Tp0+tp4 = continuity, GND(?)
    Tp0+tp5 = .5vdc ***Noted that this on the good controller is 3.5vdc - this is the only difference I've measured.
    Tp0+tp6 = .5vdc
    Tp0+tp7= 15vdc (when light is 'off' only, activates light relay)

    Has irsm836-025ma dc power control module

    Tp5 and Tp6 correspond to pins 5 and 6 on the dc power control module, and the description from the datasheet is;

    5 | /FLT | Fault Output Pin
    6 | Itrip | Over-Current Protection Pin

    Focussing on pin 5, and the description for fault in the datasheet "Once the fault condition occurs, the FAULT pin is internally pulled to VSS and the fault clear timer is activated. "

    VSS is described as " 9, 39 | VSS, COM | Ground for Gate Drive IC and Low Side Gate Drive Return "

    Should I be interpreting that as it's been pulled to ground (hence the .5v reading vs the 3v on the good controller) therefore it's detecting a fault?

    I've hit a bit of a wall here - any suggestions that may help me out?

    Also - for the DC motor feed wires (U/V/W) I get 2v out of U/V/W +gnd and 26v from tp3(dc bus voltage)+U/V/W.
  2. kenny256


    Jan 4, 2020
    That sure seems like an excessive amount of ICs just to operate a fan motor--why do they need all that?

    To troubleshoot and repair a board like that would require a schematic. Chances of failure are increased with so many components. A replacement board could get the fan working again. A schematic could be drawn from a traced-out board, but is it worth the time?
  3. Bluejets


    Oct 5, 2014
    It's a (normally) 5 speed DC fan operated on AC supply via remote i.e. r/c and having light control and sometimes even light dimming.
    Many are also addressable....Do the math.....

    For the Op...I think it's time to bite the bullet and get a new one.
    These are way too complex for those in the know without service data let alone DIY.
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