News

Mondial Fan Speed Controller

Discussion in 'Mondial' started by AndruL, Jan 11, 2019.

  1. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
  2. DavidJ

    DavidJ Formula Junior

    Feb 12, 2012
    385
    Northern NJ
    Full Name:
    David
    The problem usually is the semiconductor mounted in the air vent (of all places).
    This is assuming the fan speed control is either off at all positions or only full on at the max setting of the potentiometer.

    DavidJ
     
  3. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    Yes, checked that one. Still good.
     
  4. BillyD

    BillyD Formula 3
    Silver Subscribed

    Feb 28, 2004
    1,571
    Pacific Northwest
    Full Name:
    Bill
    Can you get to the transistor without pulling dash and Hvac box?
     
  5. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    Yes, remove the air vent, bottom right
     
  6. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    OK, the PNP transistor in the picture is shot. The Emitter and Base junctions shorted together. Sourcing replacement part...
     
  7. DavidJ

    DavidJ Formula Junior

    Feb 12, 2012
    385
    Northern NJ
    Full Name:
    David
    I suggest getting a higher rated PNP or it will blow again.

    DavidJ
     
  8. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,853
    The big TO3 package transistor is mounted on a metal plate/heat sink that's riveted in place. Drill out the rivets, undo the plastic connector, and remove the whole plate through the center vent as mentioned.
     
  9. BillyD

    BillyD Formula 3
    Silver Subscribed

    Feb 28, 2004
    1,571
    Pacific Northwest
    Full Name:
    Bill
    Got any testing instructions and a reasonably priced source if it’s bad?
    Thanks
     
  10. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    You can do that however you’ll need to match all relevant transistor parameters of the first stage pnp and second stage npn transistors such as gain, hfe, Ice of first stage into Ibase of second stage etc. Otherwise the second stage transistor would not be properly biased and can conduct current event when the fan speed knob is turned off causing the fan to run even when you click the knob to off. My fan control knob is working perfect now with matching pair. I have full control range from 0 to max speed.
     
  11. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,853
    Common symptoms are that the fan works on max, and turns off, but won't throttle. If the transistor is shorted, it will cause this. Short = zero ohms (or close) between the base, emitter, or collector. Base and emitter on this package are the protruding pins. Collector is the case. Generally a working transistor has 400 - 800 ohms between the base and emitter, and base and collector one way. The other way should read open. Between emitter and collector should read open either way. Use the diode function on you meter.

    https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=2N5886&_sacat=0

    https://www.ebay.com/p/Ferrari-512-Testarossa-Mondial-Power-Transistor-OEM-127014-60930200/593880657?iid=113403554747
     
    gsfent likes this.
  12. BillyD

    BillyD Formula 3
    Silver Subscribed

    Feb 28, 2004
    1,571
    Pacific Northwest
    Full Name:
    Bill
    I too am chasing this fan problem, I just finished testing the Transistor in the HVAC vent and it checks out according to Spicedriver instructions. When I had the console apart and checked the pots with a VOM only one of the pots showed a variance over its travel. Can you help me figure what to do next. Did you replace the pots? My fan only works on max and you have to constantly move rheostat to keep it running.
    thanks
    Bill
     
  13. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    It's unlikely that the pots went bad. They're just mechanical variable resistors. Did you take the fan speed controller apart as I did in the picture and checked the pnp transistor?
     
  14. BillyD

    BillyD Formula 3
    Silver Subscribed

    Feb 28, 2004
    1,571
    Pacific Northwest
    Full Name:
    Bill
    The lower pot showed a variable resistance thru its travel , the top one showed open/nothing thru its travel.
    Ill take the console back apart and test the transistor there, are the collector, emitter, and base marked?
    My father who was an Avionics/Electronics/Ham guy would shoot me for not knowing this stuff.
     
  15. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    No, they're not marked. Looking at the front of the part (the side with marking on it), left pin is Emitter, center is Collector and right is Base.
     
  16. BillyD

    BillyD Formula 3
    Silver Subscribed

    Feb 28, 2004
    1,571
    Pacific Northwest
    Full Name:
    Bill
    #16 BillyD, Jan 12, 2019
    Last edited: Jan 12, 2019
    Image Unavailable, Please Login

    Tests BAD, you have a source for a replacement?
    thanks
    Bill
     
  17. BillyD

    BillyD Formula 3
    Silver Subscribed

    Feb 28, 2004
    1,571
    Pacific Northwest
    Full Name:
    Bill
    Image Unavailable, Please Login

    The Big Transistor in the Vent looked as if it had been replaced and obviously someone worked on this board before I got here. Not that my soldering will look any better. :)
     
  18. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    How and what were tested?
     
  19. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    Never mind. I can see the damage on the part zooming in. Search ebay for BD680.
     
  20. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    And I would also suggest that you solder jumper wires across those damaged traces
     
  21. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,853
    A pot is basically a resistor with a tap in the middle. So the outer pins should read the total resistance value, while the middle pin will vary between total resistance and zero. So when the pot is turned all the way, you will read the total resistance between the middle pin and one of the outer pins, and zero between the middle pin and the other outer pin. Also, it looks like the value is printed on the cases. K is 1,000 so 10K would be 10,000 ohms. I can't see it clearly enough to know what it is. To get an accurate measurement of the components, they should be removed from the circuit. Also, I would make sure that none of the diodes are shorted. Diodes read like a single transistor junction. So 400-800 ohms one way, and open circuit the other way.
     
  22. BillyD

    BillyD Formula 3
    Silver Subscribed

    Feb 28, 2004
    1,571
    Pacific Northwest
    Full Name:
    Bill
    New transistor ordered from EBAY, since its clearly BAD, I'll replace that before I screw up printed circuit by unsoldering pots from it. Any idea where to get the siamesed pots if bad?
    Thanks Spicedriver and Andrul. It will be nice to have heat as its in the 30s up here in the frigid NorthWest!!!
     
  23. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    Good luck. You’ll get it fixed. Report back on progress and will go from there.
     
  24. spicedriver

    spicedriver Formula 3

    Feb 1, 2011
    1,853
    Sometimes pots get corrosion inside. Try spraying the inside with WD-40. Also you might be able to disassemble it, to see what's going on.

    It will probably be hard to find new replacements, because these were made some 30 years ago. Write down the numbers printed on it and do a google search. Or try a dismantler like redbay cars.
     
  25. AndruL

    AndruL Karting

    Apr 4, 2018
    188
    Full Name:
    AndruL
    Good idea but probably not with WD40. Electrical contact cleaner will do better.
     

Share This Page