Perhaps, if it is set to read AC at a low voltage -- there is 60Hz (or 50Hz) EMF (and other forms of RF) that is picked up by the probes (acting as antennas).
Try shorting the probes together and see if the reading settles down at or near 0.00[00...]. If not, there might be something wrong with the meter.
What is your meter set to? Or, on what setting(s) do you see this effect?
There is a vast amount of electrical energy (electromagnetic radiation) in the air, from radio station and mobile phone transmissions, and radiated energy from all the mains cables and electrical devices in your house.
The multimeter leads act like a radio aerial, picking up this energy and producing a reading on the meter. You will see this effect even more clearly with an oscilloscope.
Rarely seen now, there are simple radio receivers, called "crystal radios", that are powered purely by the radio signal transmitted from the station But they only work on AM signals, which are all being switched off in this digital age.
As Steve says, this effect should normally only be seen on low AC voltage ranges, and touching the probes together shorts out this energy by putting the two terminals at the same electrical potential, so an absolute zero reading would then be normal.
It's set to read DC voltage V. But the numbers go up and down very unstable reading until I probe some voltage.
But even with the atmospheric noise around and with the high internal impedance of the meter, it should be stable at least showing something close to 0 value.
You sound like someone who, like me, was first exposed to analog meters. I have one meter that annoys me as it is difficult to see what range you are actually measuring in. It is very easy to misinterpret as the range indicator is only a series of dots that are very difficult to see and almost impossible if you are in direct sunlight. It makes it very easy to misinterpret 2 volts for 20 volts. If you want to really want to see it jump around move a magnet within a foot or two of the leads. I have even seen stray indications with the leads touching. If you see that, then try twisting the leads gently together and touching them. That should cancel out most stray voltage indications. You may have a source of EMI in your area you are unaware of and you must remember that your meter is sensitive to one millionth of a volt. Personally I would like to see a range switch that could lock the meter in a one tenth volt range. Reading one tenth volt is accurate enough for 95% of the measurements I take. I know others will disagree but they might like the ability lock the range in another scale. There may be a meter out there that is already capable of this but none of the four I own do.
Actually it's. How bad we feel when we pay a lot for something that's supposed to be close to perfection or at least bug free, and then realize it's just over-hyped and lied about. The problem with the support we got which sucks, the printed manual that comes with this super expensive bastard is low quality, no colors, very thin, and printed in Asia!
If your meter is a moving coil type (not indicated) then the problem is RF from a nearby source being picked up by the meter leads and rectified by the meter reverse protection diode. Otherwise on a digital meter, if your leads are floating your meter could be reading the static buildup on the leads. I have done experiments to prove this by holding on to one meter probe metal tip and swing the other rapidly in the air so you can hear the wind from it. You will see on the display tens of millivolts.. The other explanations I have seen here are equally valid i.e meter turned of RF in the semiconductors in the meter etc.
The floating unstable reading goes from +-mV to a +-1/10 V. When the pobes are shorted on DC voltage it shows 0, and on AC it still shows 6 to 7 mV. When it's set to current A, and shorted or not, it shows ~1/10 mA and depends on how I move the probes it reads 0.
It's in a closed room with wireless modem and a computer. I'm not sure how much close is considered close in this situation. But it's within the room space, 6 - 10 feet.
Winner Winner, Chicken Dinner! Try turning the wireless modem and computer off and see if it helps :~) I bet it does. Especially the modem (transmitter)!
The fact that your meter is reading something other than 0 may be a tribute to how good it is. It's sensitive enough to pick up the stay voltages. Readings in the mv range are typical, and as long as it goes away when the probes are shorted no prob. The readings on the AC scale with the probes shorted might be due to RF and the probes behaving like a loop antenna. Try bringing the wires together (while shorting the probes together) so they are parallel to each other and in close proximity (and even try twisting them together loosely and see if that reduces the reading.
Readinga on the *ma* scale with the probes open is a bit puzzling, but might be explained by standing quarter waves on the probes. At the meter end of the probe would be the high-current section of the antenna [but, the meter would have to be able to read fairly high frequencies for this to be the case]. Again, try twisting the probes together, but NOT shorting them and see if that goes away. Also, try removing the probes and see it that makes a difference. [but if it's on the _DC_ ma scale, then quarter-wave antenna effect is probably not the answer]
If the DC ma readings persist during all of the above experiments, then perhaps the meter is not adequately shielded.
BTW: All of my meters indicate voltage on the AC range. My cheaper meters go as high as 1 volt and even 2 volts. My more expensive Protek meter shows around 10-20mv. All go to zero when the probes are shorted.
So if it's not adequately shielded would it be a problem in the design of this specific multimeter model, or due to a defect/damaged equipment that I should take back to the store?
So its a DVM OLED "organic light emmiting diodes "
FP meaning floating point , IEEE standards Floating point math’s springs to mind here especially when dealing with micro's for measurement
This might help further in understanding how FP or floating point numbers are represented in digital micro controllers also on early mobile phones example the Sony Erickson T610 upwards before smart phones arrived which required extra libraries and classes to be written so that we could use J2ME for scientific calculators
Link as follows
Should help you understand a lot more about DVM “Digital Volt meter”
If you want more information on what OLEDS are here a DIY how to make your own Oled "Interesting article this because it will change the way that glass windows might be manufactured in the future to incorperate OLED technology " Example the future of shop signs
Terrible I agree wait till you see some of the schematics which you cant even read without so much as component marking or what it is never mind readability
That’s another subject all on its own if your luckey to even get such informations out of them which is normally diabolical
✨ The Agilent U1253B digital multimeter exhibits floating voltage readings of small fractions of volts when its probes are open and not connected to any circuit. This behavior is normal due to the high input impedance and floating input of the meter, which causes the probes to act as antennas picking up ambient electromagnetic interference (EMI) such as 50/60 Hz mains hum, radio frequency (RF) signals, and other electromagnetic radiation present in the environment. These stray voltages result in unstable, low-level AC or DC voltage readings that fluctuate. Shorting the probes together typically stabilizes the reading near zero volts by equalizing the potential and canceling out the interference. The effect is more pronounced on low AC voltage ranges and can also be influenced by nearby sources like wireless modems, computers, transformers, or other EMF emitters. Some users note that even on DC voltage settings, the readings can be unstable but should settle when probes are shorted. The meter’s sensitivity to microvolt levels and the high internal impedance contribute to this phenomenon. Twisting the leads together or moving them closer can reduce the interference. The presence of small current readings on the milliamp scale with open or shorted probes may be due to standing waves or RF pickup on the leads. The issue is generally not a defect but inherent to sensitive digital multimeters with floating inputs. Some users express dissatisfaction with the meter’s documentation and support quality. Additional technical references discuss floating point representation in digital voltmeters and the challenges of shielding and EMI rejection in handheld meters.
TL;DR: Yes—open DMM leads “float,” so you may see noise, often around 10–20 mV, and even up to 1–2 V on cheap meters. “All of my meters indicate voltage on the AC range.” [Elektroda, Steve Lawson, post #21666312]
Why it matters: Knowing this prevents you from misdiagnosing a good meter as faulty and shows how to reduce false readings.
Is it normal for a DMM to show voltage with open probes on DC or AC?
Yes. With open probes the input floats and the leads pick up ambient fields, so the reading drifts. This behavior is expected on sensitive digital multimeters. Shorting the probes should bring the reading near zero if the meter is healthy. [Elektroda, Steve Spence, post #21666296]
Why do readings jump more on the AC range?
On AC, the meter is designed to detect alternating signals. Your leads behave like antennas and pick up mains hum and RF. Shorting the probes forces both inputs to the same potential, collapsing the pickup and stabilizing the reading. [Elektroda, Frank Bushnell, post #21666298]
What quick test confirms my meter isn’t faulty?
Short the probes together. A good meter will settle at or near 0 on DC, and to a very small value on AC. If it does not, suspect a setup or hardware issue. “Try shorting the probes together.” [Elektroda, Steve Lawson, post #21666297]
What numbers should I expect with shorted leads on AC?
Quality meters often show about 10–20 mV with shorted leads, while cheaper units can indicate 1–2 V. Both go to zero with ideal shielding, but small residuals are common in normal environments. [Elektroda, Steve Lawson, post #21666312]
My Agilent U1253B shows ±mV to ±0.1 V open-circuit. Is that within reason?
Yes. Users have observed ±mV up to ±0.1 V when the probes float. The value depends on ambient interference and lead geometry. Shorting typically stabilizes near zero, which indicates normal operation. [Elektroda, Joseph Sam, post #21666307]
How do I reduce the wandering reading without special gear?
Use this 3-step fix: 1. Short the probes tip-to-tip. 2. Keep the leads parallel and twist them loosely. 3. Separate the setup from EM sources like transformers. These steps cut loop area and RF pickup. [Elektroda, Steve Lawson, post #21666311]
Can Wi‑Fi routers or PCs in the room cause false readings?
Yes. A nearby wireless modem or computer can couple RF into the leads. Powering them down often reduces or eliminates the apparent voltage. This is a quick diagnostic to try first. [Elektroda, Chuck Sydlo, post #21666310]
Why does the meter show a few millivolts even when probes are shorted on AC?
Small residuals occur from internal noise and residual coupling. Readings like 6–7 mV AC with shorted leads have been observed and are not unusual in typical rooms. [Elektroda, Joseph Sam, post #21666307]
My DC mA range shows ~0.1 mA with open leads. Is that a defect?
Not necessarily. RF can induce currents in the lead loop, especially with quarter‑wave effects. Twist the leads, keep them close, and test again; remove the leads to compare. Persistent DC mA offset may indicate shielding issues. [Elektroda, Steve Lawson, post #21666311]
When should I suspect a real meter fault?
If shorted DC voltage does not settle near 0, or AC readings remain high after twisting and isolating from EM sources, investigate further. That behavior suggests a setup error or a defective meter. [Elektroda, Steve Lawson, post #21666297]
What does “floating input” actually mean on a DMM?
It means the meter’s high-impedance input is not referenced to a defined potential. With open probes, tiny fields move the input, so readings drift until you reference it by shorting or connecting. [Elektroda, Steve Spence, post #21666296]
Could input impedance design affect these symptoms on the U1253B?
Yes. Discussions note input-impedance behavior can influence apparent readings. Reviewing known notes and tests on this model helps separate normal floating behavior from design-specific quirks. [Elektroda, Mark Harrington, post #21666301]
Do analog (moving‑coil) meters behave differently from digital meters here?
Analog meters can rectify RF through protection diodes and show deflection due to nearby RF sources. Digital meters manifest drifting digits instead. Both are reacting to energy picked up by the leads. [Elektroda, Rodney Green, post #21666305]
Can a nearby magnet make the reading jump?
Yes. A strong magnet moved near the leads can induce signals and make readings jump, especially on sensitive ranges. This demonstrates how easily fields couple into open or looped leads. [Elektroda, Chuck Sydlo, post #21666300]
What is a DVM/DMM, and what’s special about the U1253B display?
DVM stands for Digital Volt Meter; DMM measures several quantities. The Agilent U1253B features an OLED display, which is bright and high-contrast compared with LCDs. [Elektroda, Mark Harrington, post #21666314]
