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Solectria Force Still Having Problem

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  • ECE Prof
    The saga continues: When we got our 1999 Solectria Force a few weeks ago, we thought it only needed new batteries and a charger. We replaced both, and on the
    Message 1 of 2 , Jun 13, 2011
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      The saga continues:

      When we got our 1999 Solectria Force a few weeks ago, we thought it only needed new batteries and a charger. We replaced both, and on the maiden voyage around the block it began making terrible noises and lost virtually all power. On jackstands the wheels go around, but at very low speed. We thought we tracked it down to the speed sensor, so we pulled it out and tried to track down the problem. We measured values all over, and replaced the optosensors, the transistors, and the op amp, but not the comparator.

      We put it back together, and it seemed to run better on the stands, but when we put it down it wouldn't move an inch. We put it back up on stands, and as we tired it a few more times we found that sometimes the wheels start turning backwards, and doesn't stop when you take your foot off the accelerator but keeps speeding up. You have to put your foot on the brake to stop the motor.

      I took some oscilloscope recordings of the A-, A+, B- and B+ signals out of the speed sensor, and posted them in the Photos section of this site. I see that the A- and A+ signals don't seem consistent. There are gaps and sections when the two are not oscillating correctly. The B- and B+ signals seem very good.

      The PTC temperature sensor for the motor is there, but the value is somewhat low. It is around 140 Ohms, when it is supposed to be 240 or so, as I recall.

      Any ideas of what I should check next?
    • Reed Bement
      Channel A seems to have a problem all right. I would work back from the comparator outputs comparing the two channels until you find the problem. One trick
      Message 2 of 2 , Jun 14, 2011
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        Channel A seems to have a problem all right. I would work back from the comparator outputs comparing the two channels until you find the problem. One trick that might help is to drive the board with an optical source on the bench while you are debugging. An IR remote control will work for this purpose, or you can drive an IR LED with a signal generator at a more realistic rate.

        Also while you have the car up on jacks you may want to test the rest of controller and transmission. You can tie the A-, A+, B- and B+ lines to a valid state with pull up resistors and grounding, then connect a 240 ohm resistor in place of the PTC. With this setup you should be able to spin the motor in forward and reverse without speed feedback. It should run smoothly with very little noise.

        -Reed


        On 2011-06-13, at 6:36 PM, ECE Prof wrote:

        > The saga continues:
        >
        > When we got our 1999 Solectria Force a few weeks ago, we thought it only needed new batteries and a charger. We replaced both, and on the maiden voyage around the block it began making terrible noises and lost virtually all power. On jackstands the wheels go around, but at very low speed. We thought we tracked it down to the speed sensor, so we pulled it out and tried to track down the problem. We measured values all over, and replaced the optosensors, the transistors, and the op amp, but not the comparator.
        >
        > We put it back together, and it seemed to run better on the stands, but when we put it down it wouldn't move an inch. We put it back up on stands, and as we tired it a few more times we found that sometimes the wheels start turning backwards, and doesn't stop when you take your foot off the accelerator but keeps speeding up. You have to put your foot on the brake to stop the motor.
        >
        > I took some oscilloscope recordings of the A-, A+, B- and B+ signals out of the speed sensor, and posted them in the Photos section of this site. I see that the A- and A+ signals don't seem consistent. There are gaps and sections when the two are not oscillating correctly. The B- and B+ signals seem very good.
        >
        > The PTC temperature sensor for the motor is there, but the value is somewhat low. It is around 140 Ohms, when it is supposed to be 240 or so, as I recall.
        >
        > Any ideas of what I should check next?
        >
        >



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