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andymeyer
Joined: 31 Mar 2015
Posts: 54
Location: SW MI
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 Posted: Sun Mar 14, 2021 5:27 pm Post subject: Strange voltage regulator issue... |
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I have a 1982 Long EZ... Prestolite alternator from back in the day, along with the original 3 wire voltage regulator with a big old cannon plug on it. From what I can tell - fairly stock Long-EZ configuration from the books...
A few flights ago - humming along no problem at 14.4 volts... (PC680 battery). Upped it a year ago when I replaced the RG25XC. Trim pot like this under a cap... https://www.amazon.com/uxcell-Through-Hole-Trimmer-Potentiometer/dp/B008LT4IGY
Last flight, noticed voltage up around 16 volts... shut the alternator down - voltage fell to the ~12V range and slowly fell (as expected)... Came back and landed...
Went out tonight to troubleshoot... Started up at idle and right up around 16 volts... Started spinning the screw back in the voltage regulator and it fell from 16.5 to around 15.8, then jumped down to 13.0. Turned screw back in, climbed to 13.7 or so, then jumped back up to 16.5 or so... Repeatable... Wierd!
Probably time to replace the voltage regulator - she's got ~40 years on her from what I can tell. Any other thoughts?
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user9253
Joined: 28 Mar 2008
Posts: 1920
Location: Riley TWP Michigan
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| Posted: Sun Mar 14, 2021 6:14 pm Post subject: Re: Strange voltage regulator issue... |
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Check all of the electrical connections in the charging system for tightness and corrosion. The alternator on-off switch is also suspect.
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Joe Gores |
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Ceengland
Joined: 11 Oct 2020
Posts: 386
Location: MS
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| Posted: Sun Mar 14, 2021 6:33 pm Post subject: Strange voltage regulator issue... |
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On 3/14/2021 8:27 PM, andymeyer wrote:
| Quote: |
I have a 1982 Long EZ... Prestolite alternator from back in the day, along with the original 3 wire voltage regulator with a big old cannon plug on it. From what I can tell - fairly stock Long-EZ configuration from the books...
A few flights ago - humming along no problem at 14.4 volts... (PC680 battery). Upped it a year ago when I replaced the RG25XC. Trim pot like this under a cap... https://www.amazon.com/uxcell-Through-Hole-Trimmer-Potentiometer/dp/B008LT4IGY
Last flight, noticed voltage up around 16 volts... shut the alternator down - voltage fell to the ~12V range and slowly fell (as expected)... Came back and landed...
Went out tonight to troubleshoot... Started up at idle and right up around 16 volts... Started spinning the screw back in the voltage regulator and it fell from 16.5 to around 15.8, then jumped down to 13.0. Turned screw back in, climbed to 13.7 or so, then jumped back up to 16.5 or so... Repeatable... Wierd!
Probably time to replace the voltage regulator - she's got ~40 years on her from what I can tell. Any other thoughts?
No experience with that particular product, but the symptom description
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sounds like what a potentiometer does when it gets a 'dead spot'. It
could just have some corrosion on that area in the resistance path
inside. *Might* be cleared with a few shots of tuner cleaner &
'exercising' the control a bit. Failing that, if you know the value of
the pot & have soldering equipment, you could just replace it.
Charlie
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Charlie |
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