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This is how we repaired a SSI Ignition module that was not sparking. This has been a common problem with these modules dying after many years of use. We have successfully found a way to repair these units.

This repair will require basic soldering/desoldering skills as well as some electronic testing tools

DISCLAIMER: We have just recently began repairing these units and they have not had any long term testing to compare the longevity of the originals. Below is a video of a 12HP Tecumseh HH120 running on one of our repaired units:

https://youtu.be/uWyH5mavRec

This article will contain 3 "sections" on repairing these modules. It will be divided into:

1.) Accessing the Printed Circuit Board

2.) Testing the Components Within the Module

3.) Replacing the SCR Transistor which we have found to be the problem


Note: In the write up there are 3 different modules used for pictures and reference. All of these we have found slight differences in production however the problem was all the same

SECTION 1

Here is one unit before disassembly




After researching the epoxy that seals the unit we learned that it is heat oriented. With that principle we figured heat should soften it enough to cut into it and remove it from the aluminum casing.

We used an old electric frying pan (no, don't steal the wife's) that we use for bearings and other non food grade applications. We then added cooking oil with the pan itself tipped toward one side. We then set the module in the oil making sure the level DID NOT touch the magnetic trigger coil. Also, be sure to wire the spark plug boot to the coil so it does not enter the oil



We set the electric frying pan to 250 degrees F and used a infra-red heat gun to measure the center of the epoxy's temperature. When it reached 170 degrees F we carefully removed it (using a pair of gloves) from the oil and began slowly scraping away thin layers of the epoxy using a dull flat screw driver. Depending on where the scraping begins as well as the amount of pressure applied varying amounts of material will be removed. CAUTION must be taken to not damage the board, trigger coil or other components (a completely cleaned box is shown below to reference the general location of these components).




The module on the right is a fully exposed example of what is inside, taking note of the position of the primary coil and trigger coil as to not damage them. The module on the left shows how wide of an area to remove material from to do the repair shown later in the article.

Once the material is removed from the board area (it does not have to be spotless but you have to be able to see the solder joints) you begin to de-solder the components. The spots to de-solder are shown on the picture below



Once de-soldered remove the grounding screw (it can be either hex or a torx headed screw) and then reheat the module and carefully pry the board side to side to detach it from the remaining epoxy. This must be done very carefully and can be time consuming. Patience is needed so the board does not break. (If it does break we repaired one with crazy glue and it still works). Once the board is removed you will be left with:




After removing the board the imprint of some of the components will be in the epoxy (as shown in the photo above). These impressions will have to be removed to allow the board to be reassembled since it will be impossible to line up all of the components into there original locations. This must be done by reheating the module and removing the epoxy that outlines these impressions. An example of this is shown below



Section 2
Now that the board is removed first checked for any physically broken or burned components.

We used some information found on the website linked below that explains ways to check the components as well as values for these parts


Engines&Magnets

For the other components of the module instructions on their testing can be found on the internet. Since there are many ways to test components depending on the tools you have we do not want to limit how they can be tested. There are many tutorials on these subjects using various tools on the internet for you to use. Our main goal is to repair these modules as cheaply as possible so we are trying to avoid added costs for the repair.

Section 3

In the 3 modules we have repaired we have found that 2 failed due to the SCR and the other one was a shorted diode. Once you have verified that the other components are good the SCR may be the likely problem which we have found replacements for.

New SCR's that we have found that will work in these modules are part numbers ECG5410 or ECG5427 or equivalent. The bad diode we found had the number 1N4006.

After testing the unit and making sure it works we plan to use silicon to cover the components.

That brings our article to a close. If anyone has any further questions feel free to contact me through the site. If we find any new information on repairing these we will be sure to update the article

Happy repairing :trink39:
 
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