Page 1 of 6 1 2 3 ... LastLast
Results 1 to 10 of 57
  1. #1

    Join Date
    Jul 2009
    Location
    Constanta, Romania
    Posts
    41
    +1
    1

    Unhappy Polaris 750 MFD Type 2 repairing help

    Hello everybody,

    I try to fix my MFD Type 2 and i really need your help.
    The previous owner removed the fuse in the electrical box and conected the MFD directly. That is probably the cause of MFD board burning.
    The MFD does not start at all right now.

    I added some pictures of the board and a part the was found disconected from the board (its place was above the middle capacitor).

    The suspected burned parts are noted as:
    M427 (the part that was disconected from the board, it is shorted)
    i could not found this part in internet by its code, but i suspect it is an 1N4427
    M448 (similar part found on the board and seem to be shorted), i also could not found this on internet and i suspect it to be 1N4448.

    This parts seem to be interlaced as current limiters for the board. One is conected directly on +, the other on - .

    I am also thinking to replace the 3 capacitors with new ones.

    But there is something that worry me. I shorted the missing diode from the board and feeded 12V on the board and it does not seem to start at all.

    Any help would be apreciated.





  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,575
    +1
    1,272
    Welcome

    Sounds like you have an electronics background. I hope you stick around these forums - we could use more people that know their way around this stuff

    My guess is that someone connected the battery polarity backwards at some point, and with the wrong fuse, or a by-passed fuse, the excess current flow damaged the MFD at multiple points.

    If the main ASIC has failed, there is no way to repair it.

    When I dug into the failed unit I have, I traced enough of the power input circuit to determine that once the protection from the diodes and inline filters failed, the damage went deeper.

    If you figure out how to get it going again, let us know. I see at least one burned out trace on the back side of your PCB, and I think you will find other failed components.

  3. #3

    Join Date
    Jul 2009
    Location
    Constanta, Romania
    Posts
    41
    +1
    1

    Talking

    thnx for your warm welcome, you have brought me luck as i don't have much electronical background, but i found it ,

    there was also a broken trace hidden by the capacitor, it was linking the two diodes and it was the power source for the voltage regulator. i directly feeded the voltage regulator with +12v and the lcd seem to work normaly , i attached a picture for better understanding

    I now need to find 2 diodes suited for circuit protection as i cant find those codes.


  4. #4

    Join Date
    Jul 2009
    Location
    Constanta, Romania
    Posts
    41
    +1
    1

    Smile final fix

    hmm, i was expected more feedback on my succes, as i read that there are many people having this kind of problems with their mfd-s

    i also belive this fix should also be in http://polarispwcknowledge.shorturl....nction-display

    anyway, i'll post a final pic of my mfd fixed, all i used was 2 diodes, one is in series with + for reverse voltage protection (i used 1n4007, it can be 1n4009), and the other one is a 16V zener diode in paralel with the - for over voltage protection (any 16-18V or even more zener diode will do it), you can look at the original one to figure out their orientation.

    .sry for the unclear picture,
    .. and use silicone to close mfd back



    cya

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,575
    +1
    1,272
    Quote Originally Posted by townkat View Post
    hmm, i was expected more feedback on my success, as i read that there are many people having this kind of problems with their mfd-s

    i also believe this fix should also be in http://polarispwcknowledge.shorturl....nction-display

    anyway, i'll post a final pic of my mfd fixed, all i used was 2 diodes, one is in series with + for reverse voltage protection (i used 1n4007, it can be 1n4009), and the other one is a 16V zener diode in parallel with the - for over voltage protection (any 16-18V or even more zener diode will do it), you can look at the original one to figure out their orientation.

    .sry for the unclear picture,
    .. and use silicone to close mfd back



    cya
    Glad to hear you got it fixed

    I will have another look at my own dead MFD, see if the same trace under the capacitors is burned out.

    Only a few guys are willing to do component level repairs on these MFD units.

    Thanks for documenting your process

    BTW, what do you think was the failure sequence?

  6. #6

    Join Date
    Jul 2009
    Location
    Constanta, Romania
    Posts
    41
    +1
    1
    I belive that the zener is the one that failed first (become shorted). Its function is to take out all the voltage spikes induced by sparking plugs and probably it gets old pretty fast.
    After that the circuit become shorted and starts to burn fuses. At this point usualy someone install a bigger fuse. This will overload the shorted zenner and also destroy the other diode and some traces on the board.

    I also do not think that someone feeded a reversed 12V to the board. In that case, if the reverse protection diode is working nothing would happen, but if it is shorted (low probability), it would destroy much more. Probably the first ones would be the voltage regulators, but main ASIC may not escape too.

    cya

  7. #7
    TownKat,
    I have the exact same thing. So the diode on top of the capacitors is the zener? That is the diode that is cracked open. Both of the diodes are shorted. My middle cap is bulged. The notch on the chip is the anode? I am not familiar with the surface mounted diodes.

  8. #8

    Join Date
    Jul 2009
    Location
    Constanta, Romania
    Posts
    41
    +1
    1
    yup, that is the zener, mine was cracked open too, as you can see in the picture
    also loock at the final fix picture for the polarity of the diodes, the zener is the one in the left
    http://img31.imageshack.us/i/imag0366.jpg/

    edit:
    actualy a much beter explanation i gived at the time o fixing few posts upper

    "one is in series with + for reverse voltage protection (i used 1n4007, it can be 1n4009), and the other one is a 16V zener diode in paralel with the - for over voltage protection (any 16-18V or even more zener diode will do it)"

  9. #9
    On mine, the diode that was split was above the three caps. There is also another diode to the left that is shorted as well. In your pic it looks like it is still there.

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,575
    +1
    1,272
    There is also a circuit for sensing over and under battery voltage at the power inputs, which then triggers warnings on the display.

    Multi-Function Display (MFD)

    MFD, MFI, NGI pin connections, functions

Page 1 of 6 1 2 3 ... LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. 95 polaris 750sl mfd needed or need repair help!
    By mc150 in forum Polaris Open Discussion
    Replies: 0
    Last Post: 08-28-2016, 07:31 PM
  2. 94 polaris 750 mfd. will my jetski start without hte mfd pluged in?
    By srt8charger in forum Polaris How To & FAQs
    Replies: 1
    Last Post: 05-26-2012, 02:40 PM
  3. 95 Polaris 750 sl vent tube routing help please!
    By mogyver69 in forum Polaris How To & FAQs
    Replies: 16
    Last Post: 05-25-2010, 03:43 PM
  4. Polaris SL650 Oil Type! Help!
    By kepneriphone in forum Polaris Open Discussion
    Replies: 2
    Last Post: 07-27-2007, 11:33 AM
  5. 1994 Polaris 750 Help ASAP
    By sgshore in forum Polaris PWC Performance
    Replies: 6
    Last Post: 04-15-2007, 11:13 PM

Posting Permissions

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