Using Eico Scope on car.

[meirman]

I have an Eico kit oscilloscope, that I bought used about 25 years
ago. (In NYC, from the store on the NE corner of the streets one block
south of Chambers and one block west of Broadway.)

I'd like to use it to check the the sparkplug waves on my 6-cylinder
car. Is there anything special I need to do? I would just try it,
but the scope is buried deep under uncompleted projects and other
stuff. .

Meirman

 

[NSM]

I have an Eico kit oscilloscope, that I bought used about 25 years
ago. (In NYC, from the store on the NE corner of the streets one block
south of Chambers and one block west of Broadway.)

I'd like to use it to check the the sparkplug waves on my 6-cylinder
car. Is there anything special I need to do? I would just try it,
but the scope is buried deep under uncompleted projects and other
stuff.

You probably need a capacitive probe for the plugs, and a magnetic probe to
sync with (off #1).

N

 

[CJT]

I have an Eico kit oscilloscope, that I bought used about 25 years
ago. (In NYC, from the store on the NE corner of the streets one block
south of Chambers and one block west of Broadway.)

I'd like to use it to check the the sparkplug waves on my 6-cylinder
car. Is there anything special I need to do? I would just try it,
but the scope is buried deep under uncompleted projects and other
stuff. .

Meirman

I assume that's just a normal 'scope, and not one intended for
monitoring spark plug voltages.

You need to limit the voltage the 'scope sees. Certainly _do not_
connect it directly to a plug. You can either use a HV probe
(probably worth more than the 'scope) or you might be able to rig
something up with inductive coupling and a neon bulb as a limiter.

 

[Art]

FYI: I had a similar setup back when the cars wee a bit more forgiving to
work on, actually had a hand wound coil that we would clip around each spark
wire and view the resulting waveform. Of course, sync was random since the
scope needed to capture it from the input signal. Worked fairly well to
diagnose shorted plugs or open wires. Of course I'm talking 66 Mustang, etc.
Yes, it was actually an EICO Scope, before we opted for the Heath-Kit
Automotive Diagnostic item that came out later. That way we did not need to
worry about over-loading the scope inputs, etc. Just remember, leave the
garage door open when running the flippin vehicle, Eh!! Good Luck

 

[Dan]

I was going to suggest something similar. I've had a bit of luck
connecting a standard scope up to the inductive pickup from my timing
light, which is then clamped around the plug wire in the usual manner.

Dan

 

[NSM]

I was going to suggest something similar. I've had a bit of luck
connecting a standard scope up to the inductive pickup from my timing
light, which is then clamped around the plug wire in the usual manner.

Better still, use that on plug #1 to sync the scope. Use a small clip from
the dollar store (bag closer type) with a couple of strips of metal in the
jaws to make a capacitive pickup for each spark lead and connect to vertical
in.

N

 

[James Sweet]

I have an Eico kit oscilloscope, that I bought used about 25 years
ago. (In NYC, from the store on the NE corner of the streets one block
south of Chambers and one block west of Broadway.)

I'd like to use it to check the the sparkplug waves on my 6-cylinder
car. Is there anything special I need to do? I would just try it,
but the scope is buried deep under uncompleted projects and other
stuff. .

Meirman

As others have said, you can't just connect the scope directly to the plug,
though you can connect it to the primary of the ignition coil to see what's
going on on that side of things. That's a vacuum tube scope I assume, so
it's quite forgiving to HV zaps unlike a modern solid state scope. Not very
useful for quantitive measurements, but adaquate to show you what's going
on.

 

[meirman]

In sci.electronics.repair on Sat, 22 Jan 2005 19:17:14 GMT "NSM"

Better still, use that on plug #1 to sync the scope. Use a small clip from
the dollar store (bag closer type) with a couple of strips of metal in the
jaws to make a capacitive pickup for each spark lead and connect to vertical
in.

Thanks to all of you for the advice.

As luck would have it, I just noticed in my wire drawer the wires from
a broken timing light, including the thing that clips around the #1
plug wire. I'll try to let you all know how it goes, once the weather
warms.

N

Meirman