1971 110 Phase Maker spark issue

[IkeOBH]

I have a 1971 110/9.8 hp mercury that I picked up for $100. (the infamous phase maker ignition)
I suspect a bad stator but wanted to make sure before I spend $400+ on a new one.
I changed the insulator blocks which were badly cracked and I get some spark at low RPMs. However the spark is intermittent and sometimes stops entirely at higher RPMS. (I cranked with drill.)
I put an Oscilloscope on the + terminal of one of the coils and see the attached ("with points") image
It looks like something is shorting when the voltage gets to about 200V (I assume there is a Cap in the ignition that would just charge and stay high until points close)
To rule out the points I disconnected the green stator wire and hooked it up to the Scope
I then saw the attached (Open) image.
with the green wire floating I would have expected it to charge and then just hold the voltage but again something is shorting.
Any ideas?
Thanks for the help

 

[IkeOBH]

Well I can't seem to attach the images but I will try to explain
with the points attached the voltage rises quickly to about 200 volts then jumps back down to about 50 and back up to 200.
I suspect something arcing as the voltage does not always go all the way to 0 before charging againg.
This cycles a few times before I clearly see the points close and voltage goes to 0.

When I have the Scope on the open green wire I see the voltage do a similar thin just lots more charge/discharge cycles with peaks up to about 400 volts but the average volateg probably only around 100 the 400 volts never holds more than about 10ms before discharging.

 

[fitz73222]

Did you check the high speed coil and the large capacitor?

 

[IkeOBH]

How do I check them?

 

[IkeOBH]

How do I check them? The capacitor is in the stator and I'm not sure which coil is the high speed one

 

[IkeOBH]

I managed to put the pictures on this msg board if it helps.

Thread '1971 Mercury 110 Phase Maker spark issue' https://forums.iboats.com/threads/1971-mercury-110-phase-maker-spark-issue.770385/

 

[fitz73222]

PM me your phone number and I'll text you the images from the factory service manual for this ignition system.

 

[faztbullet]

Go here and read and test..

1971 Mercury 7.5 Phase Maker Learnings

I thought it would be useful to post a few of my learnings on the 1971 Mercury 7.5 Thunderbolt ignition system --known as the phase maker. I've learned a ton from this site over the years and am hopeful some info I gathered might be useful to others. Background: A few of years ago I bought a...

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