Condenser

[col_ken]

Is there a way to test a condenser to make sure it is good? I am trying to resolve the starting problems with my M38A1. Other than physical fit in the
distributor (original 24v waterproof type), are there different characteristics in condensers.?

[gmwillys]

Condensers are measured in micro-fahreds.
They can easily be tested with an ohm-meter. Place the leads on the base and terminal end of the condenser. The meter will go to zero end of the scale then smoothly climb to the other, infinity end of the scale (the battery inside the meter is charging the condenser). If you switch the leads the condenser will discharge then charge in the opposite direction. If the meter stays at zero the condenser is shorted. If it doesn't move it is open. If it stays in the middle of the scale, the condenser is leaky.

[LarrBeard]

Is there a way to test a condenser to make sure it is good? I am trying to resolve the starting problems with my M38A1. Other than physical fit in the distributor (original 24v waterproof type), are there different characteristics in condensers.?

Condensers (capacitors) vary in their electrical capacitance (microfarads) and voltage rating - and an almost infinite variety of physical characteristics!

Most condensers in 6 and 12-volt ignition systems are about 0.22 microfarads (often abbreviated uF), with a voltage rating of 450 or 600-volts.

The condenser is often described as keeping the points from sparking, but it in keeping the points from sparking, it really does a lot more than that. (There is a lot of physics happening in those three pieces of the ignition system).

When the points open, the energy in the primary of the coil discharges through the condenser, the current flow causing the high voltage spike in the secondary - and the spark across the gap of the plug. This causes a voltage to build up (charges the condenser) and then the condenser discharges back through the coil. This happens a number of times while the points are open, until the stored energy dissipates, giving the "ring" pattern seen on ignition analyzers. (Technically, a damped oscillatory waveform.) If the condenser is open, you get one chance at a weak spark. If the condenser, for some reason, has lost its capacity (say it has failed to a 0.10 uF condenser) you lose about half the spark energy. If the condenser has developed a high resistance leakage path, its efficiency is much lower.

I'll expand on gmwillys measurement technique a little, if I may. The results will vary depending on the meter you use. A Harbor Freight digital meter will check for an internal leakage resistance - it should read over a meg-ohm (>1000) on the 2000K scale. You may or may not see the charge current on a digital meter since there is no needle to wiggle.

An older analog meter does a bit better job of checking capacitors. A Simpson 260, like Pelago and I swear by, on the R x 10000 scale gives a definite "tic" to the meter, but only about a 5% upscale tic. Even if it tests OK on a meter, it might have an internal breakdown when it gets hit with the 300-volt or so pulse when the points open. Some garages have an old guy with a condenser checker in the bottom of his tool box.

I've not played with 24-volt ignitions, so I can't speak to what condenser the M38A1 might use. On 6 and 12-volt systems, it's generally better to just replace the stinkin' condenser than wonder if it's OK or not. KWAS has a rebuild kit for the M38A1 (cap, points, rotor and condenser). Mike might know more about the actual condenser, but in the picture they all look alike.

Good Luck - or maybe just "better luck".

[gmwillys]

LarrBeard is correct. He is our electrical resident genius!
To add a little more information for the 24 volt system, here is a link to a good read;
https://forums.g503.com/viewtopic.php?t=75409#p428991

[col_ken]

Thank you both! The electrical system was converted from 24 Volt to 12 Volt. I will test the current condenser and the older one I took out. I did purchase the KWAS rebuild kit mentioned and found the the new distributor cap is a lighter weight plastic. Since the original one is in good shape and not cracked, I am going to retain it for now.