The CDI whines?

[gbhumphrey]

So Ive had my 1971 911e for a while and I never recall it “whining” .
Is this really a thing?
Ive seen a video of it here whining and I have never noticed it making a noise, maybe I just missed it. Anyway, its definitely not whining now, and I get no voltage on the coil when turning the key on.
Seems like its suddenly dead. Ran when parked.

[brp914]

Originally Posted by gbhumphrey

So Ive had my 1971 911e for a while and I never recall it “whining” .
Is this really a thing?
Ive seen a video of it here whining and I have never noticed it making a noise, maybe I just missed it. Anyway, its definitely not whining now, and I get no voltage on the coil when turning the key on.
Seems like its suddenly dead. Ran when parked.

I could hear it in my 914-6...until the cdi blew out leaving me on the side of the road. The rebuilt cdi was silent. I preferred it to whine.

[Funracer]

My 83 whines however I have never heard it. I cannot hear anything in that frequency range do to a lifetime of working around loud machinery. My wife says it whines quite obviously.

Do you have someone else around that can listen to it?

[Bob Ashlock]

Depends... some original Bosch units are louder than others due to variations in the internal transformer construction. And if the ferrite cores are actually damaged/cracked or just a tad loose they can be downright noisy. If the unit has been rebuilt with newer electronics replacing the original Bosch design they typically are not audible due to operating at much higher frequency or different design approach.

[gbhumphrey]

Ive removed it, and on the back it has a date it of 2009, so, that's likely it when it was last restored. My issue is, I get 12v at the center plug for the CDI, but NO voltage at the coil and no sound from the CDI. When i say no voltage at the coil, I hook + multimeter to the wires that attach to the + coil , then - multimeter to the gound, bypassing the coil altogether. So, that's why I was wondering if ithe CDI was working.
Anything else I should check?

[PeteKz]

If you are using a digital multimeter, you probably can't measure the voltage at the + terminal of the coil. The CDI box dumps a very short sharp pulse of current to the coil (on the order of a millisecond). Digital meters may not register that pulse. You usually need an O-scope to see that max voltage and duration.