Originally Posted by 250 Coupe

I’m not sure when Mercedes started using the electronic amplifier with points. My ‘68 250/8 had it. The problem was that since the points were switching low voltage and current, they lost some of the “self cleaning” action that just a bit of sparking provides. They required an occasional cleaning with a business card to keep the ignition in top shape.

I went optoelectronic in the 250C and either the 280C or 450SEL. I may have done it partly due to marketing but did like the results. The 250C started instantly and seemed to run better right after the install where idle had been a bit rough before.

I think the original amplifier was in an aluminum housing, you mention a black box with a red light. That sounds like an aftermarket unit. Do you still have points? It might be a points driven CD ignition or an ignition amplifier. If you have a shutter and optical pickup, it’s probable either a Crane or Pertronix.

Michael