Quote:
Originally Posted by mshac
The chances of both those diodes failing at the same time is infinitesimal.
I suspect you have another problem.
Can you explain in more detail what exactly occurred leading to you posting this question?
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Hi Mark,
I doubt both diodes failed at the same time. I don't know for sure as I don't think the system has worked since I've owned the plane. The diodes are part of (and the resistor could also be part of) the problem.
The system is quite simple, here's the power flow:
Either, 2 D-Cell batteries (or 4 C-Cell batteries, if the SK337-46A Battery Pack Kit has been installed) supply the voltage ... I now have 4-Cell batteries installed);
The voltage from the batteries goes through a connector (which I haven't found, but must be good as I have voltage all the way to the alternators);
A resistor (12-ohm, 1-watt is located at the Alternator Restart Switch (the resistor is not open, because I have voltage at the alternators, ... and voltage is being reduced). I've not ohmed out the resistor yet as the cabin pressure instruments must be removed to check/replace it, so it "might" have the rated resistance value;
The power splits at the Alternator Restart Switch;
Then each line goes through its respective diode (F4 in the parts manual, superseded at Textron to 1N2070);
The power goes through another connector (which I haven't found, but must be good as I have voltage all the way to the alternators);
The power then reaches each alternator's field terminal.
I have about twice as much voltage at the rear alternator as I do at the front alternator (albeit both voltages must still be too low to excite the alternators). This voltage difference points to something downstream from the Alternator Restart Switch (ergo ... "The Diodes") as being, at least, part of the problem.
That's why I need to know where the diodes are located on the airframe.