TOPIC: Designed to fail?

Didja ever wonder what was in that black brain box (CDI) that is the headache of older first gen OMCs?
I finally got around to reverse engineering one that I removed from my '67 100hp Johnson.
I knew what was inside them, combo of electronics, capacitors, resistors etc. but the way they are packaged makes me suspect failure of these units is due to heat more than anything else. Once assembled the whole unit is filled with a mix of a sandy rubber/silicone probably for vibration prevention and moisture incursion. The back is sealed with the rubbery stuff without the sandy stuff. The mixture sticks to everything and completely seals everything.
Cleaning the gunk was a pain, many hours with a dental pick. I was really looking for something that would jump out at me and tell what failed but no such luck.
Anyone have experience with these units as far as scoping them?

To think that failure of just one of those little buggers can leave you stranded out in the middle of the lake. Sure an glad I converted to a simple coil/point system.
I'm sure today's tech is better, at least I hope it is. As for me, a screwdriver and feeler gauge works

I think you answered your own question on this. Recall that these also use a proprietary HV transformer/coil, and those are notorious for failing. The problem with the packs had a lot to do with voltage spikes, and no protection against reverse polarity.

Scoping the board isn't the way to go about it at this point. You need to pull parts and check them with a DVM. Start will all of the semiconductors - check them for shorted / open junctions. They will need to be out of circuit to do this. The electrolytic capacitor at the upper left corner is likely dried out. Capacitors don't age well. The charge capacitor at the lower left is probably leaky and should be replaced as well. All of the capacitors should be checked, as well as all of the resistors. Don't over look all of the small signal transistors (looks like about 6 of them) populating the board. If it were mine - I'd grab a beer and a ball peen hammer and practice my nailing technique on it. I modified mine to use a Pertronix Ignitor, and it works fantastic.

We had a 1969 115 that ate them if the battery was low and you tried to start the motor.

After the motor got some age on it one time we had a Mec that said that he could put one on the outboard motor that would work; out of the Chevy Vegas.

Cost back then for the OMC part was near $300.

Part for the Vega was around $60 and he charged $60 to do the change over.

Dad was so sure that the Vega part would fail because of being around water so much that he had a new one in 2 baggies taped up and then a Tupperware container taped up stored in the boat with the tools to change it out.

We never changed it out again

Tex, Bruce, The nailing technique sounds perfect to me. My Navy background was in electronics in the '60's so doing those tests is doable but WHY? I was just curious to what the bugger looked like inside there and now we know. Cross that off the bucket list even though it was at the bottom
I think I would have carried a spare with me also but not being quite so paranoid about.
And...instead of the pertronix Ignitor I used the super high out MSD with a ballast, something like 46,000 output. Really don't want to be on the receiving end of that powerhouse. You were the one who steered me in that direction and helped through the changeover, and glad you did because it starts with a flick of the key, fires flawlessly and probably the only thing that didn't leave me stranded. An up side to all the snot is you can burn some pretty old gas/oil leftovers