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AEAD 200-le idle control board repair

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  • #16
    Duaneb55. I know this is an old post but I’ve got AEAD200 LE with the same problem. SN JA385443 with an idle board number 049443. I’ve changed the 2 scrs plus numerous diodes that looked bad(corroded) and the zener diode. Still same results. Will not idle down after welding. When I turn the idle switch off and on it will idle down. Any chance of getting the troubleshooting guide for this board? Thanks
    Bob

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    • #17
      I remember reading how owners of certain machines are not to jump start their machine off a vehicle, I don't know if it was the LEAD though, but it might be something to check into.

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      • #18
        Thxs but don’t think that is the issue. Welds and generates fine just doesn’t idle down. Maybe another capacitor or diode on the board or a diode on the rectifier. Just trying to find the troubleshooting guide to steer me in the right direction

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        • #19
          According to the parts list for that board in the manual, it contains three tantalum capacitors, C51, 52, & 53.. Tantalum caps do not age well, and I've found a bundle of bad ones in equipment I've repaired. They are especially prone to failure if running at or near their rated voltage--a couple of volts over and they are often toast. If you have a circuit running at 20 volts, I would automatically use a 35 or 50v tantalum for insurance. When tants came out, they were the answer to every engineer's dreams--incredibly small for the amount of capacitance, very stable, and supposedly highly reliable....but, it was learned much later, only if you really pay attention to any possibility of them experiencing a voltage higher than their rating due to some glitch..Their usual failure mode is to become a dead short, usually taking out something else along the way just for company, but they also fail open. Anything I open up that's more than 15-20 years old automatically gets them all replaced.. They even make them in surface mount style, but those tend to leak corrosive gunk and destroy surrounding components on the board. Sometimes they're really easy to find if you happen to be nearby when they fail shorted--one of their failure modes--sounds like a small firecracker going off. I don't work on equipment that contains them unless wearing safety glasses. Not saying they all fail, or that they are causing your problem, but they're very suspect, especially with the common failure symptoms among several owners.

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          • #20
            Aeronca41. Really appreciate the info. I’ll get some ordered and give them a try. Already replaced both scrs and every diode which were all corroded out. Really cool airplane by the way. Cheers

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            • #21
              No guarantees, but definitely a good lead. Tantalums are a type of electrolytic capacitor, and you can generally replace electrolytics with a higher-microfarad value without a lot of effect. However, I think the value here has to do with the timing on the idle control, so I would try to get the same mfd. values. I would raise the 20 volt ones to 35 or 50 volts, and the 15 volt one to whatever you can find in the 20-35 volt range. I assume you know to order from an electronics house, not a welder supply place. TEDSS, Mouser, Allied, Digi-key all good places.

              That's a pretty simple board; if I had my electronics bench re-established, I'd offer to run some tests on it for you so you wouldn't have to shotgun parts. But, I sold off most of my (very antiquated) test equipment when I became the caregiver for my wife for about 25 years, and have just begun to buy replacements since her passing on to heaven.

              The airplane is an Aeronca O58-B from WWII; used as an artillery spotter and for general liaison duties. They were also called L-3s. "O" was for "observation" and "L" was for liaison. I've got a good number of hours in it in my younger days. It's in my garage in pieces; my dad was in the middle of a restoration project when he died, and mom just wanted it out of the garage so she could get her car in. Maybe someday I'll get to finish it if I don't get too old first!

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              • #22
                Got a few hours in an L3 back in the early 80’s from a buddy who had one. . Fun aeromachine. Sounds like a cool project. Will get some tantalums ordered and let you know how it turns out. Thanks for the info.

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                • #23
                  I have a 1990 aead 200le that surges continuously. Won’t throttle up. Put 12 volts to throttle solenoid and it will throttle and weld. Where do I start looking and any recommendations? Thanks. No ac power to middle outlets ever.

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                  • #24
                    I have the wiring diagram and schematic of this board.
                    Attached Files

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                    • #25
                      I've found broken traces on these boards, bad diodes, SCR's and capacitors mostly from them getting wet, mosture build up and corrosion. I've been able to repair every board that came in on a welder unit like these, must be about 10 in all. Also bought new components for these boards from Mouser electronics, digikey got crazy stupid with their pricing.
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