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12-17-2022, 09:35 AM | #1 |
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Snap-On MT640 Coil Tester
I just acquired one of these - no user directions came with it, other than what’s printed on the unit itself.
It looks like it’s designed to test a coil installed in the car…. I would appreciate any guidance on how to hook this thing up. Many thanks - Jim |
12-17-2022, 09:55 AM | #2 |
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Re: Snap-On MT640 Coil Tester
I did a video on it:
https://youtu.be/2X6LPS2zgUw |
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12-17-2022, 01:44 PM | #3 | |
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Re: Snap-On MT640 Coil Tester
Quote:
Jim |
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12-17-2022, 01:46 PM | #4 | |
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Re: Snap-On MT640 Coil Tester
Quote:
Jim |
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12-17-2022, 03:15 PM | #5 |
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Re: Snap-On MT640 Coil Tester
I am guessing that they no longer make these.
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12-17-2022, 03:39 PM | #6 |
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Re: Snap-On MT640 Coil Tester
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12-17-2022, 03:54 PM | #7 |
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Re: Snap-On MT640 Coil Tester
The one I bought on eBay is missing the little neon(?) tube between the electrodes. Does anyone know what that thing is called or where I might find a replacement?
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12-17-2022, 04:49 PM | #8 |
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Re: Snap-On MT640 Coil Tester
Those tubes are called Geissler tubes. No one makes them anymore, but if you search online for "discharge ampoule," you can find some tubes filled with chlorine, bromine, or iodine gas that are pretty similar and might fit the MT-640.
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12-17-2022, 07:10 PM | #9 | |
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Re: Snap-On MT640 Coil Tester
Quote:
Thanks! Sent from my iPhone using Tapatalk |
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12-20-2022, 01:32 PM | #10 |
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Re: Snap-On MT640 Coil Tester
Will a neon bulb work there?
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12-20-2022, 02:34 PM | #11 |
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Re: Snap-On MT640 Coil Tester
Probably. The tester works just fine with the tube missing. It comes into play when you have a really bad coil or condenser; the tube should light up when you switch the tester on to show that current is flowing, even though the coil is not able to create sufficient voltage to arc across the air gap. So really you could hook up anything there, an analog voltmeter, whatever. I think most folks are wanting to recreate the original look.
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12-21-2022, 12:31 PM | #12 | |
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Re: Snap-On MT640 Coil Tester
Quote:
Methinks I have some, PM me and I'll send you one.
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12-21-2022, 12:41 PM | #13 |
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Re: Snap-On MT640 Coil Tester
A self-contained bulb like the NE-51 won't help much, you would need a bulb with wire leads. The neon tube sits between two opposing springs, as seen in the attached image.
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12-21-2022, 12:41 PM | #14 |
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Re: Snap-On MT640 Coil Tester
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12-21-2022, 12:59 PM | #15 |
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Re: Snap-On MT640 Coil Tester
I have some like this, I could send, it's worth a try. Just protect your eyes in case the bulb "pops". Might need a resistor in series.
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If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn! Last edited by katy; 12-21-2022 at 01:00 PM. Reason: Addition |
12-22-2022, 12:26 PM | #16 |
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Re: Snap-On MT640 Coil Tester
Here's a picture of an NE51, with wires soldered on, connected across the output of a Model T coil. If using one I would put something like a 47K Ω resistor in series with it. The output of the coil was measured at just over 20,000 volts.
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If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn! Last edited by katy; 12-24-2022 at 10:48 AM. Reason: Addition |
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