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68 Turbo with electrical problem
I've owned a 68 Turbo for over 13yrs and it has been a reliable and sound aircraft. Recently though, on a trip back from the Bahamas, I noticed a low voltage indication on my digital volt/amp meter. The system could not handle any load other than a radio without the voltage dropping down to batt voltage or below with a heavy load and just slightly above batt voltage with most accessories turned off. I cut the trip short and landed in JAX due to hard IFR up ahead. While in flight I trouble shot some and on either relay 1 or 2 I got the same low voltage problem. While on the ground, at lower rpms, the system discharges. With the alt switches OFF, the discharge isn't as bad but still is in a low voltage condition. Turning the alt switches on causes a higher amp draw in the negative range. At higher rpm I get some charging, but only enough to keep the batt topped off and run one radio. I flew the plane back on a clear day with one radio and transponder running and was able to keep the voltage just above 24v. Turning on even a landing light causes voltage to drop down to around 23v.
I have read several excellent threads on 337 charging issues and will start with my wiring, checking for poor connections and corrosion. I was primarily looking for someone with knowledge of the 68 system to help me on where exactly to start. A lesson on how the system and lights truly work would help as well. I fly larger jets for a living and do have plenty of piston time, but can't completely understand the dual alt, dual regulator relationship.
Thanks, Mike
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