Mobility Scooter Power Supply Repair.

Discussion in 'General Electronics Chat' started by studiot, Jul 26, 2008.

  1. Wendy

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    I can't help much, but I'm following this thread with interest.
     
  2. R!f@@

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    Apr 2, 2009
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    Hey.
    I'm sorry, I got caught up with star delta starter that is burnt up in a fuel barge here
    they need it repaired ASAP. You know I was up day before yesterday and this is Friday, worked on dismantling the whole thing. since Fridays a holiday for us, nothing could be bought from the hard ware stores, seems like I'll be at it tomorrow.
    I just followed up the tread. Do what others are telling, it's all good and I'll let you know if all fails after a thorough study.
    Don't loose hope, as a member said before, if an error is shown by the led, PIC is functional, so the rest is 100% replaceable. I'll get back to you
    Cheers
     
    Last edited: May 29, 2009
  3. eblc1388

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    Nov 28, 2008
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    Hi Studiot,

    Can you also post back the resistance value from the color band markings of five BLUE 1% resistors as I can't quite make out their color bands from the image.

    1. the one nearest to PIC pin 15
    2. the one adjacent to this
    3. the one between PIC and U2, next to the marking "C18"
    4. the one between PIC and U2, next to 10K
    5. the one next to the marking "R15"

    Also the value of two resistors partially blocked by a white wire in the image. The two resistors are on the side of U3 pin 8, adjacent to 100K.

    Thanks
     
    Last edited: May 29, 2009
  4. R!f@@

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    Studiot, I envy you. :p
    That PCB Pic you have posted, I have been wanting to do that for like ages.
    I want to keep my research documented and needed to do what you did, and I donno how to go abt . Awesome
    :D will u teach me
    Anyways I'm reviewing you fault. I'll get back to you
     
  5. studiot

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    Here are the resistor values. It is not easy to see them even in strong light. The 1% ones are all from the E96 range. In the same order you asked

    1 green brown black brown 5100 (5.06k)

    2 red green green brown 2550 (2.51k)

    3 brown black black brown 1k (690)

    4 red red blue brown 2260 (690)

    5 orange black black orange 300k (224k)


    6 red red orange 22k (21.5k)

    7 brown black green 1M (135k) .. closest to board edge.

    Measurements in brackets taken with a low impressed voltage LCR meter, both the functioning board and the faulty (without some semiconductors or TX connections) one gave pretty similar readings.

    Of note
    3 and 4 have the same value, although different resistors

    7 must have a very low shunt.
     
    Last edited: May 29, 2009
  6. R!f@@

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    The more I study it the more confused I get.....was it working?
    when try to draw the schematic. it does not make sense. Prove me wrong but, do you see the two electrolytic caps near 10-0-10 connector and full wave diodes, isn't the cap connected in reverse.
     
  7. studiot

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    What exactly did you want to know?

    Most of the pics were taken with an elderly Minolta Dimage S404 4Mpixel digital camera with which I have been very pleased.

    They were taken in closeup mode using the camera autofocus/ autoexposure both with and without flash. It is often difficult to avoid glare or reflections from flash.

    Most of the pictures were taken in 1600 x 1200 size which I find adequate for most purposes and the camera is normally set to. The whole board was taken 2272 x 1704 size.

    All the pictures were cropped/resized in Paint Shop Pro, prior to posting and I think I adjusted the gamma on one.

    The scale ruler comes form a child's shop and I have used these for many years to add a scale to pictures.
     
  8. studiot

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    I am doing this for my wife's parents who have 2 identical mobility scooters (1 each), complete with chargers.

    One of the chargers stopped charging the scooter so they have been using the other working one for both.
     
  9. R!f@@

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    my bad!! :p sorry my mistake. still figuring out what to do.
     
  10. R!f@@

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    Studiot....see the png

    the black tracing is the gnd of the Control circuit. with reference to this GND, I need the voltage levels of the points that is marked by white circles.
    U have to give power to the circuit. remove the load.
    and give me the results and mark them on this png
     
    Last edited: May 29, 2009
  11. Wendy

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  12. R!f@@

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    Bill :confused:
    What's with that picture
     
  13. loosewire

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    Apr 25, 2008
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    You have to have a regulated battery charger that will shut off when battery
    Is charged.so you have one working charger,you have not supplyed the voltage out put used to charge the batteries.The parts removed for testing where did they come from
    the charger or chair curcuit.So the good charger needs to stay in good condition. Go back to charger that is not working,and what It needs a transformer diodes capacitors and parts to regulate and turn off when battery is charged, What happen
    to process that stop It from charging. Id for the guys where you removed the
    parts,charger or chair curcuit, you need a good multimeter to read base,emitter
    .6 and other critcal measurement that will help the guys guide you thru testing parts
    short curcuit that you don't do more damage.The battery voltage in the leads
    of a poor multimeter can damage good parts removed to test.You need slow help
    from the guys,get the simple proper tools like heat sinks and proper heat. You have been getting helped from members that is under stress to get there work done.A lot
    of guys are monitoring this post,you know them all,the scooter company may violate
    your warranty If you ask for parts Take this for from Its worth,I yield to the guys
    that are not under stress.multimeter 200,000 per volt About $100.00 you need a good digital meter
    also with diode tester ,in curcuit cap tester.
     
    Last edited: May 30, 2009
  14. R!f@@

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    :confused::confused::confused::confused::confused::confused:
     
  15. studiot

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    Nov 9, 2007
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    Thank you for you concern, loosewire, about the health and safety of myself and my equipment. However read on.

    I can now report that this most modern of PIC controlled power supplies suffered an old fashioned fault because after I had reinserted and resoldered the semiconductors the voltages and waveforms matched those in the working model. So I tried it with a scooter and it now functions correctly. I will give it a day or so to make sure.


    Thanks in particular to elbc for working out the circuit and showing me where to put the probes. My measured ramp was rather less (1.7 volts) than your calculated one (3.4 volts) however.

    Thanks to others who also offered support, including our new recruit from divers paradise.

    It has been a most instructive exercise.
     
  16. R!f@@

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    Most welcome buddy.. I guess the PIC needs resetting. Sometimes it happens, though.

    Rifaa
     
  17. studiot

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    By 'old fashioned fault' I meant dry joint (not reefers without water cooling).

    Resoldering is often the most successful repair technique.
     
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