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  1. #1
    Click avatar for tech links/info, donation request K447's Avatar
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    Arrow What is inside a Polaris Ficht EMM - 45 volt & 12 volt power section

    For those with background or experience designing or repairing electronics at the component level, this may be interesting.

    Note; the other EMM circuit board is described in this thread;
    What is inside a Polaris Ficht EMM, computer/logic/ignition/injector driver board

    Attached and linked are images and a partial circuit diagram (schematic) for the EMM power circuit board from a Ficht EMM. This is the section covered by a thin black plastic cover. The other side of the EMM has a much larger and heavier metal cover plate, which is also used to mount the EMM.

    Polaris Ficht EMM 4010408A (2002 Virage i) Power section
    Part number 586734 Serial 0000045133
    From the factory the Ficht EMM internal circuit boards are encapsulated with a thick gel sealant. It takes time and effort to remove the gooey stuff.

    This is, I believe, a fully operational power section. The logic board was serviced by DFI, who deemed it unrepairable, but the power section appeared untouched before I began taking it apart.

    This is a partial circuit trace extracted from the board. All the power devices are shown. Despite checking the diagram against the actual board, errors may be present.
    See the attachments area for a PDF version of this diagram.


    The large rectangular area with four oval holes is where the circuit board is clamped against the water cooled heat sink that runs through the center of the EMM metal casting. A film of heat transfer compound was sandwiched between the metal surface and the circuit board. This area of the circuit board has no circuit traces, just a flat copper area with typical green PCB coating. A portion of the coating peeled off when the board was lifted up.


    The 'back' side of the circuit board has a single large electrolytic capacitor. C26 is 3300uf, rated for 25 volts. It was glued to the circuit board.
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    Last edited by K447; 05-05-2016 at 08:27 PM.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Arrow Ficht EMM power section Components

    This circuit uses a lot of diodes and SCRs. If you are only familiar with simple bridge rectifier circuits powered from single stator coils, this circuit is going to seem very weird

    Power devices
    21 - 8EWS08S Diode, Vishay (formerly International Rectifier)
    6 - 16TTS08S SCR, International Rectifier
    6 - TN12 SCR, International Rectifier
    1 - L3705NS MOSFET
    1 - 32CTQ030S Dual diode array, International Rectifier

    To understand how the EMM power section functions, see this description cribbed from the Kawasaki 1100 STX D.I. watercraft Service Manual, page 1-16;
    6.1 ... The flywheel houses magnets that work in conjunction with the stator to provide battery charging (12 volts) and injector operation (45 volts).
    Within approximately one crankshaft revolution, the EMM will learn crankshaft positioning to enable it to fire the cylinders and control spark advance.

    6. 2 Stator
    The stator, in conjunction with the flywheel and rectifier/regulator, makes up the DFI system alternator.
    The stator consists of 12 poles with 5 sets of windings that are all connected to the EMM (10 wires). Switches are located in the EMM switching circuit.
    (1) The ignition system receives its operating voltage from the stator (45V), not the battery.
    (2) During engine starting, a switch closes and connects all 5 windings in series. This maximises the available power for the EMM and injectors.
    (3) The battery operates the starter, fuel pump, and instrumentation during starting.
    (4) At approximately 500 r/min (rpm), the switch opens isolating the battery charging windings from the EMM and injector windings. This is normal operation.
    To satisfy power requirements at higher rpms, the stator switches windings 3 – 5 from series to parallel at 2500 r/min (rpm).

    6. 3 Capacitor
    The capacitor is a dampening device that prevents erratic operations of the injections.
    A faulty capacitor will cause the engine to surge or sharply miss.
    The 'switches' referred to above are the twelve Silicon Controlled Rectifiers within the EMM power section.

    In order to deliver enough DC voltage to actually start the engine while it is cranking on the starter motor at 300RPM or so, the EMM must combine the AC voltage output from all five stator windings. Shown on the circuit diagram are the typical AC voltages from the stator coils during cranking. The fuel injectors need something over 20 DC volts to actually deliver fuel, typically something around 23-25 volts DC.

    As soon as the engine starts the RPM will rapidly increase towards the target idle RPM of 1150. Above 500RPM the EMM power section will reassign the two 'battery charging' stator coils back to battery charging duty, and the battery voltage will increase to the typical 14.5 volts required for normal battery charging.

    The EMM will maintain the three 'injector power' stator coils in an effective series mode to deliver the required 45 volts for stable Ficht operation.

    As engine RPM rises the voltage output from the stator coils also increases. Above 2500RPM (per the Kawasaki Ficht document) the EMM changes modes to allow the stator coils outputs to run in parallel. This maintains the injector voltage and provides plenty of reserve amps as the engine runs up towards max RPM and/or redline.

    When you first look at the circuit, the high RPM mode with three bridge rectifiers connected for parallel output seems obvious. All those SCR are there to do the magical series modes needed for voltage boosting in the lower RPM ranges (starting mode and running sub-2500RPM mode)

    Related note, also cribbed from the Kawasaki STX 1100 D.I. service manual;
    5. Ignition
    5. 1 High-Frequency Multi-Strike DC-CDI system
    The DFI ignition system is a high frequency, multi–strike DC-CDI system that generates a variable spark profile to exactly meet combustion requirement.

    5. 2 Coils are rising field type.
    (1) Primary voltage is approximately 250 volts.
    (2) Secondary voltage is 35 – 40 kV.

    5. 3 Variable spark count
    (1) Spark timing is determined in conjunction with injector timing. The ribs on the flywheel time the injector (through the EMM), ignition timing is on this EMM map.

    (2) Stratified mode
    (a) At idle and low engine rpms, combustion takes place as the fuel spray contacts the spark plug’s tip.
    (b) There are about 10 sparks in this mode. [per cylinder, per power stroke]

    (3) Homogeneous mode
    (a) The engine starts in this mode to conserve voltage for the injectors. At approximately 500 r/min (rpm) the [EMM] switches to stratified [mode].

    (b) The homogeneous mode starts [switches from stratified mode combustion] at approximately 5500 r/min (rpm) [up to engine red-line].
    (c) There is one spark [per power stroke, per cylinder] in this mode.
    (d) Ignition occurs after the fuel has contacted to the piston and has atomized.
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    Last edited by K447; 06-29-2014 at 08:55 PM.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    If you are looking to replace a burned out component, these closeups may be helpful.

    There may be more than one version of this circuit board in use, so cross check yours carefully. Do not assume all components and part numbers are the same, or in the same location, as yours.
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  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Click image for larger version. 

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    The 12-pin Deutsch connector from the stator has an interesting pin labelling on the circuit board. My guess is that the stator coils and flywheel magnets are arranged so that the AC outputs are all in phase. This would almost be a requirement since there is but a single storage capacitor in the Ficht system, that big soda can sized unit mounted external to the EMM.

    C26 is in there, as best I can tell, merely to provide power filtering for the smarts within the EMM power circuit board. I dont think C26 has anything to do with power filtering for the 12 and 45 volt outputs. I have not yet traced the 12 volt circuit enough to determine if this section powers itself from the battery at all or entirely self-powered from the rectified S1/F1 stator coil.

    Note that there are no internal connections between the EMM power section and the EMM engine control section. The only link is via the 8-pin output connector, which feeds through the wire harness to the EMM 40-pin connector on the other side (pins 7 [diagnostic loop through] and 32,33).

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Perhaps someone would like to review the schematic and post up a concise description of how the SCR circuits actually function to deliver the series mode voltage boosted modes.

  6. #6
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    C27 and C28 are a pair of series connected Tantalum capacitors.

    See this thread for comments regarding replacing them with AVX TAJD106K050RNJ
    Digi-Key part number 478-2380-1-ND
    10uf 50 volt rating



    Last edited by K447; 10-07-2013 at 10:02 PM.

  7. #7

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    great job

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by rr44red View Post
    great job
    Just getting started ...

  9. #9
    thank you very much

  10. #10
    do u know what c23 is? its missing in my emm too.

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