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1. Tecumseh Ignitions-Part 4, ESKA Outboard Twin Cylinder

(The ESKA twin ignition repair effort here is very much still in progress. I have yet to finish building my ESKA twin engine simulator for running these ignitions and have not personally repaired one yet. )
Most of what needs to be said about the ESKA Twin cylinder outboard has already under the ESKA Single so the discussion here is divided in two parts: Elements Common to the single and Elements unique ESKA Twin.
Common to the single:
Do's and Don'ts of testing
Basic circuit design and how it works
The dominant failure mode seems to be the usual main capacitor.
The repair is by replacing the main capacitor with a new one out from under the flywheel with the same replacement capacitor / diode kit as the single.
Elements unique ESKA Twin.
The twin has two cylinders and two ignition systems. The only thing common to the two ignitions is the single trigger magnet on a plastic spool under the flywheel on a mechanical centrifugal advance mechanism.
Since the two ignitions are the same, we only need to cover one of them.
Schematics for the ESKA Twin Cylinder Outboard
The schematic and images below was provided by Tom Scanlon who rebuilt his unit.

Figure 4-1

Figure 4-2

Figure 4-3

Figure 4-4

Figure 4-5

Testing the Main Capcitor
If you locate the terminal for the wire  that goes to the Pulse Transformer, PT, and label /disconnect the wire to it. Then make a cut to disconnect the diode and the main capacitor will be isolated from the rest of the circuit so you can do some meaningful tests on it. You will need an old fashion analog meter that has a meter on it, not a digital read out. As you measure the resistance of the capacitor, the Ohms circuit in the meter applies 1.5 Volts from its battery and charges up a good capacitor. The meter responds by jumping up scale and then drops back as the capacitor gets charged. If you reverse the leads, and re-test, the needle will jump twice as far. If you use a meter with a processor in it, it goes nuts because it is looking for a constant resistance, not changing voltages. If the capacitor is leaky, the needle will not return to the start position. If it has a short, it might read a constant low resistance on any meter.
Twin Ignition Repair
The repair approach I recommend here is minimally invasive in removing the epoxy to allow putting a jumper across the failed capacitor and disconnecting a diode. This allows the placing a new capacitor and diode out from under the flywheel where there is more room to work.



The modification looks like this on a circuit diagram.

Figure 4-7

Modifying the Electronic Module, EM
I don't think the Electronics Module, EM needs to be removed form the mounting plate and it is undesirable to do so.
Step1. Mark a line across the EM where the potting needs to be removed and have a damp rag handy.
Step 2. Make a cut, break line in the epoxy with a Dremal tool at the line.
Step 3. Heat the epoxy on the edge across from the Trigger and carve it off with a Stanley knife exposing the edge of the PCB.
Step 4. Simmerily, carve off the edge of the epoxy around the terminal that goes to the Pulse Transformer.
Step 5. Heat the top of the piece that need to be removed, stick the point of the knife under it and pop it off.
Step 6. Melt the solder around the terminal to the PT and brush it off. Also wipe the solder off with a damp rag.
Step7. Put the damp rag on the unit to cool it off.
Step 8. Solder a jumper wire across the old capacitor.
Step 9. Using a Dremel tool with a cut off disc, make a cut in the foil to disconnect the diode.
After successful testing, coat the PBB with silicone where you removed the epoxy.
Installing the New Capacitor and diode.
Doug Street has the best idea yet for a small package for the new capacitor and diode that can be mounted somewhere on the frame . See Figure 2-9, CapDiode.jpg

Figure 4-8

In final kit form, the assembly might have longer shrink wrap to accommodate the nylon cable clamps if they are needed. For the tractor wire harnesses that I have made, the various connectors are supplied loose, so the wires can be cut to fit the installation. The concept here is the same as that for the ESKA single. Wouldn’t it be nice if someone like Doug Street provided the kits already assembled and ready to mount and plug in.
I should note that the original capacitors had a voltage breakdown rating of 250 Volts which I consider too low which is why they are failing. I have used 600 Volt which may be over kill. A 400 Volt would likely be sufficient and would be smaller physical size so that is used here. The capacitance value is 1mf, micro farad. Not just any capacitor is suitable for this application because of the high peak current and high power constantly being moved into and out of the capacitor. A filter capacitor is not suitable. The capacitor are made of metalized polyester film and needs to be made for energy storage / discharge . The use of two .47 mf capacitors in parallel would cost about half as much.