Re: Measuring voltage output of stator and trigger coils with analog meter
I'm a Merc guy now but here's a couple of things that might interest you.
The DVA is a sample and hold circuit used to read fast pulses with long rest periods. It uses a recitfier diode to fill up a capacitor which stores the charge. You read across the capacitor and after say 30 secconds the cap has charged up to the peak of the trigger/voltage spikes and allows an analog or digital conventional multimeter to read the peak output on the proper voltage scale. So you would want the 500 to 1kv scale to read these voltages. Then there is a bleeder resistor across the cap to bleed off the charge on the cap over time so you don't get shocked when accidentally touching both cap leads.
The anode of the diode connects to the circuit under test, the top of the cap and the bleeder connect to the cathode of the diode as does your meter hot lead. The ground of the meter, cap, and resistor is the engine block or suitable battery return point. Voltage will be positive and should be relatively steady.
Since the max number is 400 a 1k PIV diode and a 600v mylar or ceramic capacitor of .47 uf will work. Bleeder of 1/2 watt 1 meg will work. Values not real critical here. The smaller the bleeder the larger the cap. Mylar and especially ceramic caps can follow the fast rising pulses very well. Radio shack should be able to fix you up.
Just think of the circuit as a capacitor input 1/2 wave rectifier circuit.
On the 0 ohms, reverse your meter leads and see if it remains. If not you apparently have an inverse diode on the output circuit protecting it from any negative reflections form the load which is ok. Different ohm meters have the battery installed differently and sometimes the + lead will forward bias a diode and other times it takes the - lead. Reversing the leads solves the confusion. If it remains, you aren't going to be able to develop any voltage at the output and I would say that whatever you are measuring is defective.
HTH,
Mark
