Snap on MT3000 Counselor II ?

[TJP]

Does any one have, use or familiar with a older Snap on MT3000 Counselor II diagnostic machine?

My question specifically relates to the Ignition SECONDARY Inductive Pickup clamp. Mine has a ground lead attached that knocks the measured voltage from 30kv + to 10kv or less when the ground is connected.
You will also get a reasonable "BUZZ" off the ground lead if touched while not grounded.

In looking at the clamp it appears as though someone added a decent sized ceramic disc capacitor on the inside of the handle not sure why ?
Thanks

 

[richfinn]

Does any one have, use or familiar with a older Snap on MT3000 Counselor II diagnostic machine?

My question specifically relates to the Ignition SECONDARY Inductive Pickup clamp. Mine has a ground lead attached that knocks the measured voltage from 30kv + to 10kv or less when the ground is connected.
You will also get a reasonable "BUZZ" off the ground lead if touched while not grounded.

In looking at the clamp it appears as though someone added a decent sized ceramic disc capacitor on the inside of the handle not sure why ?
Thanks

Secondary ignition pick-ups are capacitive, maybe it's been repaired or modified for some reason

 

[TJP]

Secondary ignition pick-ups are capacitive, maybe it's been repaired or modified for some reason

Thanks for your reply, Capacitors are where my "use it or lose it" comes into play I'm not understanding why it's knocking the reading down so far. Unless the cap is breaking down and partially shorting ? Which might also explain the "shocking experience with the ground clamp? Electronics 101A was about 45 years ago

 

[Ditchdigger]

The counselor II here has the ceramic disc cap as well.

 

[2ndGearRubber]

While I do not have any mt3000 experiences, I do have experience with secondary ignition leads.


The secondary lead "ground" is more so a safety device for the scope itself. You can still see a secondary pattern of value even without the ground attached. If a wire is damaged, and a spark event gets sent into the scope, that channel at a minimum will be destroyed. The ground connection on the pickup is to give that errant spark a better ground path than through the scope. If you are getting shocked from the ground clip, ie: hit with a secondary spark event, you have leaking insulation on what you are measuring.

 

[vpd66]

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Contact Aeswave.com. They deal in Automotive oscilloscopes and parts. They can make up custom leads and they know a lot about the MT3000a scopes. They should be able to help you and are very decent to deal with.

 

[TJP]

While I do not have any mt3000 experiences, I do have experience with secondary ignition leads.


The secondary lead "ground" is more so a safety device for the scope itself. You can still see a secondary pattern of value even without the ground attached. If a wire is damaged, and a spark event gets sent into the scope, that channel at a minimum will be destroyed. The ground connection on the pickup is to give that errant spark a better ground path than through the scope. If you are getting shocked from the ground clip, ie: hit with a secondary spark event, you have leaking insulation on what you are measuring.

Thank you for responding. You appear to know more about this than I so i will provide a bit more info
The probe in question measures the Coil wire itself. The MT 3000 has two inductive pickup leads. One for number 1 cylinder and the other for the coil wire itself. I did make a new coil wire the same results. I could try a 3rd if you think that would be worthwhile. It was a resistive type wire not solid core. However it is pretty short.
I wonder if it is possible that the pickup plates themselves are leaking or possibly the capacitor itself. Your analysis makes sense as the Kv readings drop by 60-70% when the ground is hooked up

 

[TJP]

The counselor II here has the ceramic disc cap as well.

Thank you very much for posting the pic and I apologize to all for my delayed response.

 

[TJP]

/

Contact Aeswave.com. They deal in Automotive oscilloscopes and parts. They can make up custom leads and they know a lot about the MT3000a scopes. They should be able to help you and are very decent to deal with.

Thank you and I will call them to see what they have to offer. I have to say thogh, it does go against my nature to not at least attempt to screw it up myself first though LOL

 

[2ndGearRubber]

If you just need a trigger, even holding a basic lead near/on the plug wire will produce a suitable pattern. Not sure how the leads connect on your machine, but if it were my problem child I would try to find another way to trigger.

FWIW idle Kv around 10kv isn't wildly out of the ordinary, but kv in the 39 at idle would get my attention for a potential problem. Your first picture shows all the kv lines even, the second picture they're more varied as I would expect. You'll also notice on the 39kv capture the burn lines are starting at 15kv +. That might be an issue of resolution on the screen though, making things look worse. My point is I think the second capture with a 15kv range represents closer to reality than the setup producing 39kv.

As I said, if you're getting shocked on the ground , you have another issue. That pickup isn't measuring Kv directly, no high voltage is traveling through it. If high voltage IS traveling through that lead, it's leaking out of the secondary ignition components and into your test equipment. Most secondary leads I've used produce voltage at 1000/1. So 1 volt being sent into the scope means 1000v on the secondary system, 1Kv. Some of my pico leads are 10000/1 IIRC. Anyways, with 39Kv being displayed, on my leads I'd expect 39volts. 39volts on a scope lead with no effective current to speak of obviously isn't shocking anybody.

 

[American Locomotive]

FWIW: I don't think it's really possible to accurately measure voltage in a "contactless" manner. I'm pretty sure the displayed voltage is basically just a wild guess based on the measured secondary current, estimated spark plug gap and plug wire impedance.

I wouldn't worry too much about the displayed voltage, and pay more attention to the actual waveform shape.

 

[jimzilla]

HI, I had read elsewhere at this site that schematics and repair manuals are available. Please let me know if anyone has them stll for the 1665. I have one with no 12 V internal. Thanks in advance Jim