Technical > Home Improvement > Need help reading a analog multimeter.

Need help reading a analog multimeter.

Multimeter reading

Looks like 43VAC to me. Looks to me like the red AC scale goes along more or less with the black DC scale that goes from 0-5. If you had the switch set at 50VAC, then the scale would go from 0-50. Adapter should put out 19 Volts ?

reply to Jackorama
Doesn't the power adapter have a nameplate on it that lists the output specs? Or at least a model number that can be looked up?

Most laptop power adapters that I have seen convert to DC, so you may have selected the wrong scale on your meter...

reply to Jackorama
Looking at my Lenovo power supply 'brick' it does not say if the 20V output is AC or DC. It does however show that the center of the plug to the laptop is +. You only have + and - if the output is DC.
Can you post a pic of the label on the adapter ?

reply to Jackorama
Another thing worth pointing out: If you have it set to AC, and are looking at an unloaded DC supply output from a supply such as for a laptop PC, you are going to see ripple on the DC output. With it being unloaded, the ripple will be fairly high, so the 43VAC you are seeing is not a surprise.

More than likely, the power supply is supposed to be 19 VDC supply, a lot of laptop manufactures are going to that as a standard. Newer Dell and HP/Compaq supplies are virtually interchangeable.

What does it read when you set the switch one of the DC settings?
--
Shine on you crazy diamond...

reply to lew_b

Adapter

reply to rockotman

reply to Jackorama

reply to Jackorama
Ahh, you kids these days with your silly digital toys! But I can't laugh too much, because I have at least three analog and maybe four digital multimeters myself, scattered around here and there.

A few helpful hints:

1. Google "micronta 22-201u manual" and you will probably find an actual copy of the owner's manual for this unit, even if it is quite old.

2. Your meter doesn't appear to be zeroed out properly. See the little round clear doohickey on the meter itself, just above the words "OHMS ADJUST"? Turn that slightly counter-clockwise until the needle sits precisely on zero. (The red "OHMS ADJUST" thumbwheel itself is for making another type of adjustment.)

3. See the mirrored surface on the meter? That is there in order to prevent what are called "parallax errors". In order to take a proper reading, in addition to having the meter switches set to the correct type and scale, you also have to line up the needle with its reflection. If you are taking a reading and you can see both the needle and its reflection at the same time, then you need to adjust the angle at which you are looking at the meter slightly until the reflection disappears behind the needle, then read the meter again.

4. Avoiding "pegging" the meter whenever you can. That is, don't drive the needle all the way to the left or right until it hits its internal stop. When dealing with an unknown range, always set the meter to its highest value first, then work your way down into a more appropriate range.

Items 2, 3, and 4 (and plenty of others) typically don't apply to digital meters, which is why so many people love them. But it turns out that there are some things you can do with an analog meter that you simply can't do with a digital meter, which is why most people still keep a cheap little analog one around.

reply to Jackorama
Ah yes... the infamous "not charging" power supply problem.

Usually it's due to a bad connection, or the circuitry on the motherboard that communicates with the power supply to determine the type is defective.

Manufacturers have been putting such circuitry into power supplies and laptops because there are far too many people who aren't very smart and just grab any random power supply they can find that physically fits, without bothering to read the ratings on the laptop and power supply to make sure they match.

reply to Jackorama

reply to Jackorama

reply to Jackorama
Meter won't help you, you could have a "psu" that can put out 19v @ 0 load... you need a load to really test it (resistor and led example).

Also the brick is not going to "say" "dc" it will have the DC symbol.

reply to scross

reply to Jackorama
BTW, if it is a problem with the connection, and it is one of the Dells with the center "data" pin in the connector from the laptop, you can try to following - it worked on my daughter's Dell that had the same problem I am having on this laptop...

With the supply unplugged, and drained (i.e., the LED on the power supply itself goes out), take a small, thin, flat blade screwdriver, and ever so slightly (and I do mean slightly, like maybe 1/2 millimeter), bend the center pin to the side. I can not overstress how slightly. If the loose connection is due to wear in the connector on the laptop, this will generally correct the problem.

Caution. If you bend the pin too much, you may not be able to plug the supply into the laptop. Also, if you do bend it too much, and then try to bend it back it could break off, and you would then be in the market for a new supply.
--
Shine on you crazy diamond...

reply to rockotman

DCV reading

reply to scross
I took the picture of the meter standing up. When doing the readings the meter was laying flat and the needle was lined up with the zeros.

Thanks for the helpful info.

reply to tschmidt
The battery slowly drops in percentage over time, but never charges up. When I unplug it and plug it back in I get "plugged in and charging", but it never charges. After about 5 or 6 hours it switches to "plugged in, not charging". Right now the battery is at 74% and I have made sure that it is not on the Samsung battery saver of 80%.

reply to Jackorama
Ah - I see you added while I was typing my last reply. What you have added changes everything.

1-1/2 years is usually around the time that OEM batteries will start taking less and less charge, and not have a charge last as long. It sounds like you may have reached the end of life for your battery.

Does your battery have a test switch and some lights on it. The switch may just be a flat spot that says something like "press here to test".

If you don't use the laptop too often, and usually use it with it plugged in, I wouldn't worry about it. If you need it to be able to run for an extended time on battery only, you may want to consider buying another battery.

Also, check to see if you may have one of the batteries that were recalled by some manufacturers a few years back. I got mine replaced for free when it failed to take a good charge after only 13 months of service.

He gets plugged in and charging at the beginning. Sounds to me like his battery is toast as he doesn't use it much. A bad battery in a laptop will never charge up and it will have limited capacity.