Electrical trouble shooting Tools

[ThomasC]

There are a lot of threads about electrical problems. They can be one of the most frustrating things that anyone can run into. I got quite good at solving them during my career as a mechanic. 12 volt DC systems no problem but AC I can be a little fuzzy on sometimes.

While there is no substitute for a decent volt meter, DVM, I wanted to mention the best tool that I have found in the past 50 years. It really changed the way I look for electrical problems now. It is called a Power Probe and the basic one sells for $40 Please note this is for low voltage DC systems.

https://www.amazon.com/Power-Probe-P...%2C240&sr=8-42

I have had mine for a long time and of course they have lots of new things that you can spend a lot of money on. I originally bought mine to help me get through trailer wiring problems quickly. The key to it is the long cord that has clips to connect to the battery or an adapter to plug into a cigarette lighter.

Once connected to the battery you simply probe anything for power or ground. There are two different leds one for power and one for ground. It also has two tones one for power and one for ground. There is also a switch to send power or ground out of the probe so you can complete circuits to see if a bulb or whatever is working or not.

There are a lot of YouTube videos on their use. The one I have has a nice plastic box and I got an extra 20 feet of cable so I could get around the entire truck and trailer. Mine lives in the front overhead of my BigFoot along with spare parts and screws that I carry all the time.

https://www.powerprobetek.com/

[gordon2]

Originally Posted by ThomasC

...
While there is no substitute for a decent volt meter, DVM, ...

I thought DVM meant Digital Volt Meter... but you make a good point.. get a decent one. Perhaps a DDVM

And to confuse people further, pretty much all of DVMs read more than volts.. Resistance in Ohms, so they are sometimes called VOMs (Volt Ohm meters), or DVOMs. Or just multimeters (DMM if digital), or multi-testers , or Volt Ohm Milliamp (or amp) meter (VOM or VOMM)....

Your probe looks handy but I'm OK with my VOM (DVOM, DMM, etc) and a long piece of wire with alligator clips.

[mary and bob]

Does it have a sharp point that can be used to poke through the insulation on a wire ? If so, keep in mind that anywhere wire insulation is penetrated now becomes a point where moisture can enter resulting in corrosion.

[Mary Ann in NC]

If you have to penetrate the insulation on your DC wiring, this is what you need. I used it on our boat for 18 years. There is no moisture on the RV that can rival the bilge on a sailboat.

https://www.homedepot.com/p/Gardner-...-400/100119178

[ThomasC]

Originally Posted by Mary Ann in NC

If you have to penetrate the insulation on your DC wiring, this is what you need. I used it on our boat for 18 years. There is no moisture on the RV that can rival the bilge on a sailboat.

https://www.homedepot.com/p/Gardner-...-400/100119178

Yes I have that it is so much better than tape.

[ThomasC]

Originally Posted by mary and bob

Does it have a sharp point that can be used to poke through the insulation on a wire ? If so, keep in mind that anywhere wire insulation is penetrated now becomes a point where moisture can enter resulting in corrosion.

If it is inside I wouldn't worry about it.

[ThomasC]

Originally Posted by gordon2

I thought DVM meant Digital Volt Meter... but you make a good point.. get a decent one. Perhaps a DDVM

And to confuse people further, pretty much all of DVMs read more than volts.. Resistance in Ohms, so they are sometimes called VOMs (Volt Ohm meters), or DVOMs. Or just multimeters (DMM if digital), or multi-testers , or Volt Ohm Milliamp (or amp) meter (VOM or VOMM)....

Your probe looks handy but I'm OK with my VOM (DVOM, DMM, etc) and a long piece of wire with alligator clips.

I actually thought about the letters a bit but I was to lazy to look it up. Quite a few years ago when I worked on Mercedes they wanted all of the techs to buy a Fluke scope meter which was new at the time and $1500 25 years ago. All of the techs told them to stick it.

[Darwin Maring]

Now on a good day you can get a digital multimeter at Harbor Freight for free or for little of nothing.

[CarlD]

I really like my fluke 325. It aint cheap but the capability to measure DC current with a clamp on was a must have for me.

[Air Doug]

I just got a Power Probe 3 for my birthday. Yay!

[Raz]

Originally Posted by gordon2

I thought DVM meant Digital Volt Meter... but you make a good point.. get a decent one. Perhaps a DDVM

And to confuse people further, pretty much all of DVMs read more than volts.. Resistance in Ohms, so they are sometimes called VOMs (Volt Ohm meters), or DVOMs. Or just multimeters (DMM if digital), or multi-testers , or Volt Ohm Milliamp (or amp) meter (VOM or VOMM)....

Your probe looks handy but I'm OK with my VOM (DVOM, DMM, etc) and a long piece of wire with alligator clips.

VOM's (volt-ohm-milliammeter) have been pretty much obsolete since the 70's. Back then the VTVM (vacuum tube voltmeter) was considered superior because of it's high input impedance when measuring voltage. The benefit of the VOM was portablility. It was battery powered but only on the resistance scale. On voltage and current scales the meter used passive (resistor) networks. As such, VOM's required consideration of the ohms-per-volt rating. Twenty thousand ohms-per-volt was common. What that means is that the meter behaves like a resistor when making a measurement and as such, can effect the measurement you are trying to take. For example, a meter with a 20k ohms-per-volt rating on the 2 volt scale would behave like a 40k ohm resistor when placed in a circuit. The effect is often referred to as loading.

DVM (digital volt meter) or DMM (digital multimeter), one in the same, replaced the VTVM as the prefered meter. Unlike the VOM, the DVM input impedance is hugh, typically well over a gigohm, making loading, effecting the circuit you are trying to measure, no longer an issue. It's rare to see a VOM for sale today but you do see them on occasion, recognized by the analog or needle meter. You are far better off with the $20 DVM hanging next to it. And in most cases spending more yields little benefit to the average user.

[Darwin Maring]

Have used VT M and all the others while doing electronics for over 60 years and now, the only meter I use is the one they sometimes give away at Harbor Freight. The only problem I have with it is forgetting to turn it off then it depletes the battery.

[John in Santa Cruz]

There *are* places where the lower impedance of a VOM is preferable, the very high impedance DMM (and VTVM) meters can read float voltages that wouldn't be present in a real circuit under load, and the significantly lower imedance of a classic VOM provides a place for those float voltages to dissipate. also for fluctuating voltages, a mechanical needle is easier to read than a digital readout, which can be quite random on voltages that are changing.

I kinda wish I'd snagged a 260 when a friend was purging his shop...

[Darwin Maring]

Simpson Use to be I. The absolute Best category.
TS352 Army great one, big and heavy.

[Byron Kinnaman]

I rmember when we switched from the Simpson 260 to DMMs. It was a problem for the field techs, when the notation on a schematic indicated 24 volts they would call say something like I read 23.7 volts and the schematic says 24 volts. Another issue is the modern DMM is digital. Any digital instrument id always ±1 LSD. Which means if your meter read xxx.L than L is always ±1. If you read the specifications that will be said. It's not an issue if know it's there.

Example of problems caused. Measuring a battery charge level such as 12.5 volts Withe a DMM that could be anywhere between12.4 to 12.6 volts.

[Raz]

Originally Posted by John in Santa Cruz

There *are* places where the lower impedance of a VOM is preferable, the very high impedance DMM (and VTVM) meters can read float voltages that wouldn't be present in a real circuit under load, and the significantly lower imedance of a classic VOM provides a place for those float voltages to dissipate. also for fluctuating voltages, a mechanical needle is easier to read than a digital readout, which can be quite random on voltages that are changing.

I kinda wish I'd snagged a 260 when a friend was purging his shop...

I am really not sure what you mean by "dissipating float voltages", but if you want a low impedance voltmeter simply put a resistor in parallel with your DVM.

Simpson 260 VOM's can be had for $50 on ebay, cheaper at a hamfest. I had a Heathkit VOM. Sold it years ago. As far as time varying voltages, that's what an oscilloscope is for.

[Mary Ann in NC]

I am not sure what you guys have to measure on your rigs, but this one was on our boat for years and will be moving onto our Escape 19 in February. I never know how to measure anything this dude couldn't measure.

[Darwin Maring]

I work in a pawn shop and can have any meter I want and I still use that free one Harboe Freight gives away. We have all the expensive ones come through the doors and I can see where field repair people need them especially dur to their ruggedness. Recently we had one designed for someone that knows nothing about how to use it. Just connect it and it starts telling you what to do. Stay safe my friends, the COVID numbers are going up.

[minke]

Originally Posted by Byron Kinnaman

I rmember when we switched from the Simpson 260 to DMMs. It was a problem for the field techs, when the notation on a schematic indicated 24 volts they would call say something like I read 23.7 volts and the schematic says 24 volts. Another issue is the modern DMM is digital. Any digital instrument id always ±1 LSD. Which means if your meter read xxx.L than L is always ±1. If you read the specifications that will be said. It's not an issue if know it's there.

Example of problems caused. Measuring a battery charge level such as 12.5 volts Withe a DMM that could be anywhere between12.4 to 12.6 volts.

I think you meant that 12.45 thru 12.54 will read as 12.5.

Meters like the Simpson 260 damped the measurement making it easier to read which of course was both good and bad. Some DMMs (e.g. the Fluke 115) improve on that by having a min/max function to determine range. If that isn't enough you need a 'scope.

[Byron Kinnaman]

Originally Posted by minke

I think you meant that 12.45 thru 12.54 will read as 12.5.

Meters like the Simpson 260 damped the measurement making it easier to read which of course was both good and bad. Some DMMs (e.g. the Fluke 115) improve on that by having a min/max function to determine range. If that isn't enough you need a 'scope.

I think I meant what I said ±1 not ±.5