As you've found, most used a strobe of some kind. These usually didn't display the points open time using the light since they only flashed once for each cylinder. Some LED conversions work like that and some show the dwell as the unlit section. Some conversions are switchable. The dwell doesn't really need to be seen like this as what you are looking for is that all four firing points are 90 degrees apart. If these are even, the dwell will be too. It does help to display the dwell though as it is clearer than looking at an analog dwell meter and never will need calibration due to how it works.
Many people change to LED simply because they find the strobe dim, this depends on the machine as some are better than others.
I'd suggest reading the manuals of a few different machines.
Here's two which are both the single strobe type, not LED
https://www.starchak.../sun manual.pdf
https://archive.org/...raph-410-manual
I have a page on an LED type which I can scan later.
There is no question here I just learned how the machine measure and displays the Dwell angle
My numbers (0-50 and 51-90) are only theoretical, not actual numbers. My 0º equal 130º in your machine, where the contacts open, my 50º is your 93º where the contact closes and so on
I studied the operation of that french machine, I've found forums about it. Common practice that they replace the original 400V strobe tube for 12V LED's
Next I have to learn how it light up a LED with an open circuit. I bet there is a simple solution
My machine is one of the last "old" distributor machines made so uses an LED to display the points open time (dwell being the unlit section).
My machine has a 15v transformer which is rectified to about 20VDC. To power the strobe circuit and simulate a load for the resistance test, this goes to the points thru a resistor. The strobe supply is fed from the points wire. When the points are closed it's at 0v, when they open it's at 20VDC. It's just like an ignition system but a resistor instead of a coil. I haven't pulled my machine that far apart but I'm told on the disc it has the led and a transistor which are powered inductively.
I have the schematics for a couple of strobe type machines, no LED ones. They all use parts which are hard to get so it's probably best to design a new board and for an LED.
Edited by 68+86auto, 21 November 2024 - 01:13 AM.