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May 20, 2018 17:57:14 GMT
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Is anyone familiar with alternator outputs as shown on a Crpyton 'scope? My car seemed to not be charging very well according to the voltmeter today, but when I put it on the machine it was generally showing 14.4v on the meter and the gauge seemed a bit better. The trace on the scope looked like this, the shape of each "blip" seemed to be about what the manual shows for "good", but I wondered if anyone had any ideas on why it isn't in a straight line as the manual shows?  (Given that I had to turn the flash off, there's a chance this is more than one "refresh", but it's the varying position vertically that I'm wondering about). |
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Last Edit: May 20, 2018 17:58:03 GMT by droopsnoot
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Phil H
Posted a lot
Posts: 1,448
Club RR Member Number: 133
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Alternator Crypton tracePhil H
@philhoward
Club Retro Rides Member 133
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Alternators are a 3-phase generator (alternating current - hence “alternator”) with a diode pack to try and smooth it out and with the battery acting as a smoothing function to a degree. Looks like a 3-phase rectified waveform to me? If you were missing a peak, then you’ve got a diode down by the way. Strictly speaking, they are in packs of 6 but they should look like a continuous waveform like that does.
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OK, so you're saying that doesn't look "wrong" to you? If that's the case, then all good. I'm not used to what these things should look like, so I only have the Crypton book to go from, and that just shows the same shape but all in a straight line on the vertical scale.
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Phil H
Posted a lot
Posts: 1,448
Club RR Member Number: 133
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Alternator Crypton tracePhil H
@philhoward
Club Retro Rides Member 133
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Depends if it’s AC coupled - without a vertical scale for reference I couldn’t say for sure. I’m pretty sure it’s not running at 0-20kV!
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May 21, 2018 16:50:46 GMT
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No, I'm not sure that the actual reading on the scope is related to the printed scale. I was just wondering about the way it varies up and down, rather than the specific reading.
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May 21, 2018 22:51:52 GMT
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Hi, The shape of the waveform is full wave rectification so the diode pack is doing its job. The voltage drifting up and down, ignoring the voltage scale for now, suggests that the regulator is not controlling it properly. So changing that for what it costs would be a start.
Colin
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OK, thanks for that, I will look into that.
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