Having had extensive (more than desired) troubleshooting experience with vintage car electrical systems, including the notorious Lucas electricals (Joseph Lucas, "Prince of Darkness"), I'd like to offer this advice.
Forget troubleshooting using the ammeter (load meter). Mr. Piper only put it there for us to monitor our charging system in the air. A voltmeter is the useful tool, particularly for working on the ground. If you can snag one, an older analog VOM is very handy for monitoring fluctuating voltages, but a digital one is better for finding small voltage drops across bad connections. Old cars used to have ammeters; in-fact it was the only instrument on the dash of Model Ts once they got batteries and generators. But they confused drivers so in the 60's car manufacturers switched to idiot lights, which were a crude form of voltmeter.
90% of the problems will be in the CONNECTIONS of the wiring, so use the voltmeter to probe for bad ones before your start replacing expensive components. The worst thing is to "shotgun" the problem by replacing stuff, have the problem go away (usually momentarily) because the connections were disturbed, only to reappear later. Look for bad connections first, then replace stuff. Sometimes the problem is in or near an AMP terminal. Also check for voltage drops across energized contactors and "closed" switches.
Don't forget that electrical systems are CIRCUITS, and the circuit consists of the "hot" side (connected to the positive pole of the battery thru various connections and devices), and the ground side, (connected to the negative of the battery thru various ground straps, jumpers, possibly corroded fasteners, and the airframe itself). You want to probe for bad connections across each connection, hot side and ground side.
For particularly tough problems, you might be better off going to an avionics shop, instead of having your AP do the troubleshooting. Better to pay an avionics tech, who knows electricals, $100 for an hour to find the problem, than an AP for $85 an hour for a couple of hours and still not finding the true cause of the problem.
Forget troubleshooting using the ammeter (load meter). Mr. Piper only put it there for us to monitor our charging system in the air. A voltmeter is the useful tool, particularly for working on the ground. If you can snag one, an older analog VOM is very handy for monitoring fluctuating voltages, but a digital one is better for finding small voltage drops across bad connections. Old cars used to have ammeters; in-fact it was the only instrument on the dash of Model Ts once they got batteries and generators. But they confused drivers so in the 60's car manufacturers switched to idiot lights, which were a crude form of voltmeter.
90% of the problems will be in the CONNECTIONS of the wiring, so use the voltmeter to probe for bad ones before your start replacing expensive components. The worst thing is to "shotgun" the problem by replacing stuff, have the problem go away (usually momentarily) because the connections were disturbed, only to reappear later. Look for bad connections first, then replace stuff. Sometimes the problem is in or near an AMP terminal. Also check for voltage drops across energized contactors and "closed" switches.
Don't forget that electrical systems are CIRCUITS, and the circuit consists of the "hot" side (connected to the positive pole of the battery thru various connections and devices), and the ground side, (connected to the negative of the battery thru various ground straps, jumpers, possibly corroded fasteners, and the airframe itself). You want to probe for bad connections across each connection, hot side and ground side.
For particularly tough problems, you might be better off going to an avionics shop, instead of having your AP do the troubleshooting. Better to pay an avionics tech, who knows electricals, $100 for an hour to find the problem, than an AP for $85 an hour for a couple of hours and still not finding the true cause of the problem.
