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I'm so confused, this should be way obvious for anybody handling a multimeter, What are people expecting? It's like measuring the actual wind speed while driving in a car.

Hey, if that guy doesn't want his multimeter back I'll buy it and pay for shipping today. Just let me know if you send the information and the money. I kicked myself for not getting one when you first brought them out.

Auto sparky here, and yeah its always important to ensure all devices on the network were shut down before checking the network integrity

A common problem with measuring the terminator resistance in a vehicle is that the CAN bus can be live even when the vehicle is off. One fault that causes “parasitic draw” is that some module does not go to sleep at all after key off. You have to make sure the CAN bus is totally dead before doing the measurement. They make a breakout box with LEDs on it to help with this. Usually disconnecting the battery will kill the bus comms, but then it requires a drive cycle to prep it for a state inspection in the USA, so disconnecting the battery is sometimes not desired. The little oscilloscopes are very handy for many tasks, and chasing CAN bus problems is one of them.

It is absolutely pointless measuring resistance in a circuit with any source of power applied. As shown it gives meaningless results. Being that it is a serial bus as well, there is not much point taking the unit out as you would more than likely not have the 120 ohm resistors on that particular board. The suspect here is not the meter but the fault finding technique used.

I like those probes at 7:18.

Why have battery testers like RC3563 have no problem measuring the inner resistance of a battery? Would it work here correct? AFAIK they use AC current or do two measurements. ?

If any one wanna electronics book then comment me

I always thought multimeters go kabum if you measure resistance on active circuits.

CAN bus > CAN't bus

I think it is sad that you have to educate your customers about these elementary measuring techniques. That is the danger of selling advanced instruments to people who are not competent to operate them. You risk a bad reputation because of a rumor from people who don't know enough about what they are talking about.

That's why I invested in a DC capable clamp meter and never looked back. Measure current without breaking into the circuit. Problem came to light using a 12 volt system and an inverter drawing 10 amps. Multimeter shunt plus resistance of test leads was triggering inverter's low voltage alarm. Hopeless

Can buses often stay awake for ~20 minutes after the vehicle has been switched off.

Some semi's will power up if you apply miniscule voltages only to their GPIO pins, TI micros spring to mind.

Yeah, that customer should be extremely embarrassed.

You did it! Room temp superconductor 🎉

[chuckle] As soon as you said "I can't give it a thumbs up", RUclips played a rainbow animation on the thumbs up button for the video.

Sorry, had to turn off, irritating voice.

Beginners often make mistake by checking resistor value while resistor is in the circuit not counting on the rest of the circuit affecting the value. They find low value and replace good resistor that measures good once out side the circuit. This person could have known that there s nothing on the can bus affecting the resistance while bus is off. But measuring resistance while circuit is powered is just wrong. I remember the high school and back then teacher would check your multi meter and circuit before you measure. Schools multi meters were expensive. Actually there were no cheap multi meters period. All of them couldn’t survive applied voltage on resistance range. They were all analog btw. Voltage applied on resistance mode could burn parts or slam the needle so hard that it would mechanically break the instrument. Or it would do the both. So teachers instilled fear of breaking the expensive multi meters in us. That stays for ever. Well we are GenX we could take it. 😊 Now, disregarding who you are and how proficient you are, when you work a lot with stuff accidents can happen. Like you have a few multi meters on the table and you have complex circuit that you are working on. So you have one meter on the resistance and the other on the voltage mode. You want to measure some voltage but you grab probes from the wrong instrument. That can happen and I am glad that modern multi meters can take it. Actually I am sure BM235 can take few hundred volts DC. Don’t ask me how I know😂 It worked after it but back light was tripping. Sometimes it wouldn’t even go on. I have literary cleaned all internal contacts when I was inspecting it and that solved the issues with the backlight. I have found nothing wrong with it. After years of usage almost all looks like new inside. Rotary switch has its groove but it’s nothing you wouldn’t expect. I love Brymen products. I have 3 of their models and most probably next one will be Brymen as well. Good quality for normal price. Yeah I bought the BM235 because I saw some video of some RUclipsr 😂

Well d'uh. Try measuring the resistance of the mains power supply while it's supplying power...

-200 ohms? That's not resistance, it's insistance. Do we measure that in mOhs?

CAN bus superconductors??

When the CAM operates, it has a Digital signal above 0 volts with pulses Above or Below the no-signal line.

I always wished for a multimeter that would be able to measure volts and ohms simultaneously (series resistance to the voltage). So you could measure if a pin is active high or just has the pull-up resistor enabled, in that case voltage only measurement would measure the same in both cases.

But an old multimeter with a magnetic dial indicator in this case may be more useful in terms of accuracy and correctness of data readings.

Horses for courses as specialists meters will be set up to give readings you really want. This is why I have 4 multimeters in the van for different tasks. So have Automotive, electronics (accurate), industrial & high voltage as working on automation including lorry & industrial. So many people don't realise these issues as they buy the multimeter from the industrial wholesaler which only sells limited amounts or the company they work for supplying so they make sure it does not come back! So most people are totally ignorant but this will become an issue as these dedicated meters are expensive against buying online!

I work in the field of access control systems. And when checking multi-apartment intercom systems, without knowing the specifics of the system, you can measure a lot of different things with a multimeter. Especially when you are looking for a current leak or voltage coming from nowhere where it shouldn’t be. And only with experience do you understand that it is not enough to measure resistance, you need to carry out the entire cycle of measurements: voltage, voltage in LowZ mode, only then, making sure that there is no dangerous high voltage in the circuit, measure the voltage drop and measure at high resistance limits. And only then will it become clear whether the circuit is intact or not.

Ideally a multimeter should support multiple measuring algorithms.

At least Dave's traps aren't deadly, so that's something. I'll be worried the moment Dave goes and pulls out something akin to a "Death Star" in a future video, though!

Next up: Don't use circuits on antistatic foam...

There's a reason why many TV techs back in the day ground the Earth spade right off the mains plug of their CROs. I forget the exact reason, but I got a hand me down BWD scope like that, and saw mention of it elsewhere since.

Ohms for voltage measure 😅 what you doing .

New gadget for Sushi restaurant.

My Keysight has a function for measuring resistance in situ (1273A) but not in a life circuit (Although I never tried it, it's a bit pointless)

"If you get weird readings on passives, start suspecting actives."

Your audience expected more from you too apparently If even you can make mistakes then I feel a little less bad about mine

Awesome tutorial! thanks a lot 🙏

Actually when you are aware of this sometimes you can get away with in-circuit resistor measurement in a switched off circuit so that you roughly check as a ballpark figure, e.g. 10k resistor shows 120k - you know it's toast. It shows 3.2k - then you know nothing 😂

You can often get away with measuring resistors in circuit in vacuum tube circuits. When the filaments are cold, the tubes are open circuit. Just make sure the capacitors are discharged first.

Multimeter lesson 101

If the ohms reading is strange put it on DC and AC volts to see what that is, if its not zero don't trust the ohms reading.

😂 Sometimes even very basic knowledge is needed to be put out 😅

Proves that expensive meters aren't necessarily better than a cheapy. A 30 dollar meter more accurate than the $170 to $350 + meters.

-Ohms display is really handy! Then you instantly know something is wrong. I'd be upset to have a meter with zero reading in cases like this!

I always leave the film on

It is so simple. Do not try to measure resistance when the circuit is powered or signals are present, there might be voltage across the resistor that will affect the reading

Made in China

I can't tell you how many times during my career I have tried to measure resistance on a live circuit or had a charged capacitor after it was turned off. But trust my old battered Fluke multimemer.

I think the cheap multimeter put a high voltage on the datalines of the bus which caused the other components to disconnect themselves from the CAN bus for damage control. It is probably powered by a 9V battery. That way the cheap multimeter could measure the correct termination resistance. Good brand multimeters do ohms reading by supplying a much lower voltage, which does not shut down the other components on the CAN-bus (so they interfere with the measurement).

How did his old fluke get the reading correct? Surely the customer used the 2x meters under the same circumstances. He is unlikely to have measured with the Bryman with the bus powered up and then measure with the Fluke with the bus powered down. I can't imagine any meter getting the right result with the bus powered up.