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Showing posts with label digital multimeter notes. Show all posts
Showing posts with label digital multimeter notes. Show all posts

Digital Multimeter Step by Step Guide

23 May 2018
hi, I am sure all of my blog reader understand that in the field of mobile phone repairing multimeter is a very the important tool without a multimeter you will not be able to measure anything in the field of the cell phone repairing so come let we try and understand how we can use the digital multimeter to measure AC current and DC voltage and how we can check basic electronic components

Digital Multimeter Function

the device you can see in the picture is a digital multimeter. the reason why we call this a digital multimeter is that of its measures and gives you the results in the form of digits as you can see in the picture
digital multimeter measures gives results in digits is more accurate measure current
introduction definition
the digits are very clearly displayed on the picture and that is one of the reasons why this is called a digital multimeter because digits will help you understand the results of whatever you are checking very easily
digits clearly displayed help you understand the results
accurate reading in digits

Multimeter Probes
two probes specific positions in the digital multimeter to placed at a point written ohms and Com
probes place diagram
now, first of all, you need to understand what probes are as you can see there are two probes which are commonly used with analog and digital multimeters the first one is a black colored one the second one is a red colored one 
two probes commonly used with analog and digital multimeters black colored red colored
red black probes
and these two probes have very specific positions where you need to place them on the multimeter now the first one is a black probe now the black probe has to be placed at a point where it is written as Com which basically signifies a common range so the black probe has to be placed only in the common range 
place it there and press it will fit in tightly there see a symbol written voltage ampere ohms
measure electronic components
place it there and press it and it will fit in tightly there right above that  you will see a symbol where it is written as voltage-ampere M a this is where you take readings of voltage-ampere etc and you place the red probe here press it tightly so it can fit in right above that is another point where you can check higher values of electricity with the meter however commonly in a multimeter we normally use the red and black probes and that is more than enough to measure a lot of the electronic components. Right now let us try and understand what are these other readings that are displayed on the multimeter

Direct Current and Alternating Current Voltage Checking

now on the left-hand side top, you will see something written as V followed by a dash and a few dots there now this is the symbol for DC so on the left-hand side basically when you turn the Range Switch to the left you will be able to check the DC voltage somewhere ranges in the where
left-hand side top written as V by a dash dots the symbol of DC Range Switch
check DC voltage here
the range is between 20 volts two thousand words so you can check DC voltage by placing the Range Switch at the respective voltage point if you have a smaller voltage to be checked like cell phone battery you can place it at 20 volts

DC Current Measuring

now let's try and understand how we can check DC we are going to be using a battery booster to test this so we switched on the 12 volts DC adopter with Ampare 
digital multimeter how to use testing voltage on 12 volts DC adopter with Ampare
for repair cell phone battery
this is a device that is used to boost cell phone batteries and we are going to connect the output wire of this to the probes and we are going
boost cell phone batteries connect the adopter output wire to the battery terminal
boost mobile phone battery
to be testing the voltage of the output now we connect the two output wires of the booster to the two probes of the multimeter make sure that you connect it to the right and so the black and the
how you do your measurements of  DC voltage on mobile phone battery
three point eight volts
black red in the red and you can see this is around three point eight (3.8)volts so this is the DC voltage that we have measured and you can measure DC voltage by placing it at the Range Switch at the right position on the DC voltage set so whenever this is typically how you do your measurements of AC and DC voltage
switch off multimeter battery inside gives the power to display the digits on the reading scale
meter digital
whenever you are done with using the multimeter please switch it off because typically all these multimeters have a battery inside them so the battery is what gives the power to the multimeter to display the digits on the reading scale so if you beep it switched on the battery can drain off very easily and you may not be able to use it when you need it on the right-hand side, you see something like a V followed by an ampersand sign now this is where on the right-hand side, you check the AC voltage requires 200 volts or less requires the Range Switch to be placed at the 200 volts points higher value equipment can be measured using the 750-volt point so these are the two most important ways of measuring AC and DC voltage using a multimeter the range is between 200 volts to 750 volts
how ac voltage is measured check ac voltage with a digital multimeter
range switch of ac
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AC Current Measuring

now let's try checking at home typically the voltage that we have is between 120 or 230 volts we will turn the range switch now and place it at the 750 volt AC point and we will connect this to the main power plug to check the voltage now in many of the houses is between 220 volts voltage is usually available at the circuit boards electricity at your house and whenever you want to check whether you are getting the right voltage or not you use the multimeter place it place the Range Switch at the 750 volt position and we try and place the two probes in two points on the plug point you can see
use a multimeter to test voltage of live wires measure voltage at home
measure ac voltage with a multimeter
the wires are being plugged in into two points on your plug point and this is exactly where you get 120 to 230 volts once the probes are placed there and as you can see we can see the reading here it shows 120 now going further down you will see a few more micro readings on the right-hand side which is for smaller readings that can be measured using the multimeter, however, let us focus on those readings that are very important that we commonly use using a multimeter so let us go ahead and try and understand a few more checking cell phone components checking cell phone basic electronic components at multimeter ohms now right below the DC voltage you will see a few ohm reading is given there
Range Switch to check the value of resistance when you check cell phone basic electronic components
understanding ohm readings
this is where you place the Range Switch to check the value of resistance when you check cell phone basic electronic components (resistance) which ranges from 200 ohms to 2000 kilo ohms and that is how you turn the Range Switch there you can place it at the respective point and check the resistance value

what is SMD polar capacitor and How to check Non-Polar Capacitor with the digital multimeter click here

How Do You Check Continuity Beep on Cell Phone PCB

this point is called the buzzer or continuity testing in digital multimeter
test continuity
the next one that we will understand is where we the continuity or beep testing comes now this is a very essential component when you do when it is an essential test when you are doing tracing or testing of cell phone PCBs or laptop motherboard for that matter this reading or this point is called the buzzer or continuity testing
how to use digital multimeter for mobile repairing the probes together you will hear a beep sound
multimeter red & black probes
when you place it here and that's the probes together you will hear a beep sound now the beep sound is very distinct here but let us try and understand what is the reason behind this beep sound
Q: why do we use this continuity test now the reason why we do this beep testing?
A: when we are checking a wire and we want to check whether the wire is broken in between typically broken wires are called open wires so if you want to check whether the wire is broken from inside now you will not be able to find it out looking at it from the outside so in order to check the continuity we use the beep or continuity testing

which means you touch the two ends of the probe using the two ends of the wire using the black and red probe and if you hear a beep sound which means that the circuit is not open the wire is proper but if you don't hear a beep that means that the circuit is broken somewhere and you need to fix it
this is also used while doing tracing on a cell phone printed circuit board to check whether two points are connected properly

How Do You Test and Trace Prints on a Cell Phone PCB

how to test or trace a Prints on a cell phone circuit system using multimeter
testing power supply in prints
Now we will try and understand how we can test or trace a Prints on a cell phone PCB circuit system testing or tracing in a PCBs essentially is to find out whether the power supply is properly reaching different parts or components of a cell phone and as you all know we will be using the digital multimeter to try and test this whole process so once we switch on the multimeter we place it in the beep or continuity testing position and we will touch the probes to check it up if we here the beep which means the continuity testing position is working perfectly and the probes are in proper condition using these probes we will be able to test the circuitry in a cell phone PCB

The Ground Line in Cell Phone PCB (GND)

so, first of all, we will check the negative line in a cell phone PCB as you all know a power comes with a positive and a negative line, a negative line is what is also called a ground line or the baseline and this is signified by the yellow strip that you see all across the phone PCB
the negative line in a cell phone PCB also called a ground baseline signified by the yellow strip that you see all across the phone circuit
GND in mobile circuit
so this entire yellow strip that you see in the picture right now brightly colored strip is what signifies the negative line on the cell phone

How to Measure Ground Resistance with a Digital Multimeter

How much resistance should a ground wire have to Measure Ground Resistance
testing ground resistance with multimeter
in order to test this negative line, you can place the probes tips in the multiple points across this entire circuit and check whether the continuity is intactor not so let's try and first check the probes and try and start off with the tracing of the negative line in all Phone PCB so every board typically will have a very prominent line like this the negative line or the grounding line as we call it in order to test if you place the probe on any 2 on the grounding line and you can hear the beep so when we do this testing you'll be able to check whether the circuit is broken at any point in time if it's a closed circuit which means it's perfectly all right all the points are connected very well and the negative line is intact if it's an open circuit you will not hear a beep sound when you place the probe at the respective point.



so as you can see in this deep article on Top Multifunctional Digital Multimeter we tried understanding what a digital multimeter is how the probes work where the probes need to be placed how we can measure AC current and DC voltage, live wire testing and continuity testing check Ground accurately on cell phone circuit board going forward we will collect a lot more information about how we use this tool in different streams including iPhone repairing electronics thank you very much for reading

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