|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
02-19-2024, 07:26 PM | #1 |
Senior Member
Join Date: Aug 2012
Location: Central NJ
Posts: 238
|
What the heck just happened ? (electrical)
So I’ve always been interested in test equipment, especially simple things like test lights but never went to the trouble of buying one. Anyhow I’m on Amazon and see a cheapo test light that has a built in readout that shows voltage so I buy it. It arrives and I’m eager to try it (even though nothing is currently broken). I pop open the drivers side hood and connect the ground to a head bolt and then the probe to the starter terminal. It lights up and reads 6.5v, nice. I then think, hmm what else can I try…. So I stick the probe on the cutout output terminal. Instantly it sparks, welds itself to the terminal nut and I’ve blown my 30a starter fuse….
What the heck? Any idea why this happened?
__________________
1931 Slant Windshield fordor |
02-19-2024, 07:51 PM | #2 |
Senior Member
Join Date: May 2010
Location: Oregon
Posts: 5,993
|
Re: What the heck just happened ? (electrical)
You bought a welder? Is your car + to ground?
|
Sponsored Links (Register now to hide all advertisements) |
|
02-19-2024, 07:56 PM | #3 |
Senior Member
Join Date: Aug 2012
Location: Central NJ
Posts: 238
|
Re: What the heck just happened ? (electrical)
Yes sir, positive ground. What i dont understand is why it happened on the cutout output terminal, but everything was fine when i hooked up the main starter terminal. Just wondering if that spot is a general no-no for some reason.
__________________
1931 Slant Windshield fordor |
02-19-2024, 08:16 PM | #4 | |
Senior Member
Join Date: Jul 2012
Location: California
Posts: 1,726
|
Re: What the heck just happened ? (electrical)
Quote:
Is it possible your test light has a "amps" or "current" setting and it accidentally got switched to that?
__________________
2024 MAFCA Technical Director |
|
02-19-2024, 08:33 PM | #5 |
Senior Member
Join Date: Aug 2012
Location: Central NJ
Posts: 238
|
Re: What the heck just happened ? (electrical)
Thank you for the response, your hypothesis could certainly be true. I've had my A for 12 years now and I've probably used my fluke at the cutout terminal dozens of times without issue. I'm guessing this 20 dollar amazon test light must be junk, after the incident the unit is totally dead. Swapped out the fuse and the car is happy as can be. Letting you all know to avoid this item:
"Heavy Duty 3-65V Backlit Digital LCD Circuit Tester, Test Light with 140 Inch Extended Spring Wire, Car Truck Low Voltage & Light Tester with Stainless Probe"
__________________
1931 Slant Windshield fordor |
02-19-2024, 08:49 PM | #6 |
Senior Member
Join Date: May 2010
Location: Mansfield, Ohio
Posts: 420
|
Re: What the heck just happened ? (electrical)
Sponsored Links (Register now to hide all advertisements)
|
02-19-2024, 09:09 PM | #7 |
Senior Member
Join Date: Aug 2011
Location: Eagle Bend, MN
Posts: 2,027
|
Re: What the heck just happened ? (electrical)
The other thing that may be a possibility, could you have touched both the terminal AND the case of the cutout?
__________________
"There are some that can destroy an anvil with a teaspoon and shouldn't be allowed to touch anything resembling a tool." |
02-19-2024, 09:09 PM | #8 |
Senior Member
Join Date: May 2010
Location: So Cal
Posts: 8,782
|
Re: What the heck just happened ? (electrical)
Strange. It says you can hook the alligator clip to either POS or NEG.
|
02-20-2024, 08:08 AM | #9 |
Senior Member
Join Date: Jan 2012
Location: Western North Carolina
Posts: 3,991
|
Re: What the heck just happened ? (electrical)
Either you accidentally touched ground while probing the cutout terminal or there is a short in the circuit tester. Does the circuit tester still work? You could test for resistance of the circuit using the ohm setting on your Fluke. If very little resistance, it is shorted. That way you don't have to chance another welding experience.
__________________
A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
02-20-2024, 08:56 AM | #10 |
Senior Member
Join Date: May 2010
Location: Long Island, NY
Posts: 3,498
|
Re: What the heck just happened ? (electrical)
It appears that the probe provided a connection of the battery to the generator, so the generator acting like a stalled motor, drew a large current to it.
__________________
Bob Bidonde |
02-20-2024, 10:11 AM | #11 |
Senior Member
Join Date: May 2010
Location: Pine, AZ
Posts: 797
|
Re: What the heck just happened ? (electrical)
I think eagle hit the answer. You could test the test light by using a battery like a 9V or AA and see if it works. The bulb and circuitry inside the tester would not allow that much current to flow and allow the welding of the probe.
|
02-20-2024, 12:50 PM | #12 | |
Senior Member
Join Date: May 2010
Location: Young Harris, GA
Posts: 1,830
|
Re: What the heck just happened ? (electrical)
Quote:
(Cheap Chinese Crap) Although $20 is not so cheap.
__________________
Jim Cannon Former MAFCA Technical Director "Have a Model A day!" |
|
02-20-2024, 05:15 PM | #13 |
Senior Member
Join Date: Aug 2012
Location: Central NJ
Posts: 238
|
Re: What the heck just happened ? (electrical)
Unfortunately the unit is totally dead, no further testing on it possible. I'll probably stick with the tried and true units that have just a bulb in them.
__________________
1931 Slant Windshield fordor |
02-20-2024, 05:38 PM | #14 |
Senior Member
Join Date: May 2010
Location: Young Harris, GA
Posts: 1,830
|
Re: What the heck just happened ? (electrical)
I'd send it back to Amazon for a refund as defective.
__________________
Jim Cannon Former MAFCA Technical Director "Have a Model A day!" |
02-20-2024, 07:39 PM | #15 |
Senior Member
Join Date: May 2016
Location: Scottsdale, Arizona
Posts: 618
|
Re: What the heck just happened ? (electrical)
Amen! Ernie in Arizona
|
02-22-2024, 09:51 AM | #16 |
Senior Member
Join Date: Sep 2022
Location: Canton, Michigan
Posts: 127
|
Re: What the heck just happened ? (electrical)
"CCC" Probably came from Ali-Baba over in the nether-regions!
__________________
--------------------------------------- 1929 Model A Tudor "Stay away from negative people, they have a problem for every solution" Model A Ford Club of America Model A Restorers Club Motor City A's Club |
02-22-2024, 10:31 AM | #17 |
Senior Member
Join Date: Jul 2012
Location: California
Posts: 1,726
|
Re: What the heck just happened ? (electrical)
Why does it seem like everything made in China has QC problems?
__________________
2024 MAFCA Technical Director |
02-22-2024, 11:21 AM | #18 |
Senior Member
Join Date: May 2010
Location: Southern Maine
Posts: 1,502
|
Re: What the heck just happened ? (electrical)
I agree. Not to pile on here but if the car is positive ground your first connection of ground clamp to head bolt was reverse polarity and electronics usually if not always turn up their toes on that one.
|
|
|
Sponsored Links (Register now to hide all advertisements) |
|