today I will give a complete best tips
for repairing SMPS. Welcome to Haseeb Electronics Salaam o Alaikum friends in this
video I will discuss the major faults in between input and output there is ISOLATION, (transformer and opto-coupler) there is a transformer and optocoupler between input and output area input side is known as HOT SIDE, output section is named as COLD SIDE between input & output there is feedback circuit. we will see the faults and problems in HOT SIDE and COLD Side, and we will rectify them we will see how to troubleshoot input side, Short in input circuit (Fuse keeps blowing)- short circuit SMPS is dead SMPS output fluctuates some faults are common between input and output short circuit in output output not regulated, these are the most common faults in a SMPS sometimes these is excessive noise or hmmmm sound sometimes one output is good, other is making problem i uploaded a detailed video, how to remove short circuit today i will go in more detailed discussion when you want to eliminate the short circuit use a series lamp take Tingston lamp 100 or 200Watt, (100 Watt is best) cut anyone wire, and connect one end to one end of lamp holder and the second end to the second end of the lamp holder it will helpful to reduces the mistakes in repair process. so there will no more damage most of the time, MOV, voltage arrester get short circuit, if you find it short, remove it (for TEST ONLY), because if in parallel if there is one component short the complete circuit will show short circuit disconnected in parallel if any one
component is short, complete parallel circuit will not work we will ensure that the power supply is working, then i will inject faults set multimeter to DC VOLT mode i have 4.9 Volts in output suppose the MOV is short, i will remove it. and then we will see the response of power supply i will remove maximum components, and we will see, what are the minimum components to turn ON SMPS so you can remove short circuit very easily i removed this voltage arrester, set multimeter to OHMs, connect bothe leads across the component it should Open. if it multimeter shows continuity, then the MOV should be replaced i will apply power to PCB without MOV and will check the output then the most common failure item, these
capacitors, it is part of EMI filter electromagnetic induction filter these removes high frequency harmonics. if any one capacitor
is charged we will find we will get start in the input area so I will remove these capacitors also. IT IS TO PROVE THAT WE CAN TEST SMPS WITH MINIMUM COMPONENTS while working if we find short, we must remove shortage before installing the replacements how we can test this disaster put it to capacitor nanofarad first of all make short to both pins of thecapacitor short circuit between the two pins so
that there should no voltage in the capacitor it is 27 nanofarads, if it gives short, we have to replace it in case of shortage, we will find some resistance in OHMs, this time no OHMIc reading if the capacitor is short we will find a continuity tone now we will apply power without this capacitor voltage then if this capacitor is bad so
it will cause to fuse blowing up we removed voltage arrester, we removed EMI filter capacitor then we have second stage filter if you repair this power supply like
this it is okay when you connect in the assembly in the chassis, the chassis gives
short-circuit there is a phase present in the chases. in that case these
capacitors these ground capacitors may be short sometimes they become short if
this capacitor is charged then it will be installed in the chases the chases
will give a short shock electric shock so if indeed in that case you have to
remove these capacitors after that we have our bridge circuit now we will we
can check this main capacitor now we can find the short circuit. when
you remove capacitor, always take care of clear for the polarity. okay
now short the both leads set multimeter to homes and then capacitor and check the capacitance it is giving 47 micro
farad and we have 47 micro farad in the capacitor so that means this capacitor is good set meter to continuity, connected leads to capacitor points on the board if there is short circuit is input side, it will shown here now we are finding some resistance
forward resistance this is from the diode. okay some circuits have diode and some don't have diode if you find short circuit on capacitor terminals check the bridge rectifier, check MOSFET if we find continuity on main capacitor terminals, the problem in MOSFT, IC, SMPS controller, on capacitor terminal, it should open in one side and a diode forward reading by reversing the test probes if there is no diode, then the reading may some different other resistance. one side it will be resistant some other thruster terminals you have to check the
bridge rectifier and now we can check the short circuit here there is no short
circuit and if you want to check if you if you want to check whole input section set multimeter to diode connect one lead to one input terminal and second lead to one capacitor terminal you will find one diode reading, now move test lead to second input terminal you will find diode's resistance or forward junction voltage. because we are testing the bridge rectifier as well now our this circuit is okey now
positive lead one terminal and connect one lead here other read here could
actually adhere one lead at one terminal other lead at other terminal so you will
find the resistance if you find some if you find continuity on one input terminal or both input terminals, then the bridge may have problem now shift test lead to capacitor second terminal now you will not find any continuity. if you find reading in this way anyone diode of bridge circuit is bad now swap the test leads with each other connect the capacitor first terminal, where we got resistance earlier. it should show open move test lead to second terminal of capacitor. you will find resistance here you will find some success here that is one diode one diode so here we find one
diode continuity under continuity that means that's good and here we find one side that is protection diode for PFC it is best way to eliminate short in input section. just remove main capacitor and check the last step i will check another power supply, check in the same way today I will give
a complete best tips for repairing SMPS when there is short-circuit it is very
difficult to find short-circuit so after watching this video I am sure that you will be able to find the short circuit okay now here is input terminal connect one lead here we can see there is a problem. it should not be give continuity, some diode is short circuit here this diode is short. we can see it is good condition I remove the capacitor it is good condition. connect one lead to one terminal good circuit the condition of good circuit is here if you find like this. at main capacitor connect one lead here at input terminal if you find like this that means it's good and now I will show you this bad circuit. I will connect one lead here at input terminal I am finding short circuit I have short circuit in the input area. here I cannot find short circuit here I have short circuit so to
eliminate the short circuit what we will do we have to connect the input terminal. this is fuse. fuses burn out so connect one line here so I have one diode short circuit here this diode is also burn out we can see
this diode is burn out out this diode burn out this tire
burnout this we have completely satyr for my oats burn out in this these are a
good circuits these diodes are good so this power supply it have four diodes
burn out so far good testing remove capacitors and remove capacitor and
collect one lead here one lead here you will find one site resistance okay if
you have multimeter at Rohan's you will find some resistor 290 kilo ohm or 90
kilo ohm like this so best protect at diode Murat
continuity mod reverse leads connected on the same reads note no continuity
then move to the other pin serve these two points here and here adding AC input
terminals so if you are taking this condition our input section is good now
connect both leads at capacitors so I cannot find any shout circuit here and
if I connect to this power supply I am finding shop circuit this short circuit
may be from the input side are may be in the inverter section now with to check
input section the filter and that we have filter and EMI section we checked
during a short circuit in the bridge rectifier so you can find the
serviceability of the bridge rectifier like this now our input area emi filter
filter and protection circuit is okay now I will connect back the capacitor
when you are connecting always take care for the polarity never connect the
capacitor in reverse raise it is our first if we have bridge circuit short
circuit the bridges bridge rectifier is short the fuse will burn out if any
capacitor is short circuit the blow the food will forming out if
MOV the voltage wrestler is short circuit we will find the fuse burning
out so in this way we can check the power supply input section now we will
move forward if you find this capacitor chart you can remove for shortly and
then when it is sure that this capacitor is short you can replace it and never
bypass any safety because it is good for equipment for the testing you can remove
it but for the long term plan you cannot remove you can you should not bypass the
safety always safety must be the first priority we will check voltage
I have 115 volt input so I will check voltage of the capacitor here i have 160
world if you connected to 220 volt you will find 300 + volt here's the first
problem here chart an input we determined the short-circuit how we can
recombine and how we can remove short circuit and fuse blowing I discussed
what are the possible causes MOSFET is short fuse will burn out bridge circuit
is short Seussville Burman this name capacitor is short fuse will burn out
mov is short fuse will burn out if the capacitor is charged frequency to faster
filter Network then the fuse will keep blowing these are the main causes then
check voltage at me investor here i have 160 volt if you connect
because i have a fly here 115 volt if you have 220 volt you have to collect
220 and you will find because these are universal power supplies you will find
300 volts here 300 plus volt here 330 sometimes they go to 360 or okay now now
next there is a small capacitor besides the SMEs controller if we see from this negative and this negative and
is near directly here okay if we see positive and the positive and positive
voltage directly through one resistor there is directly connected to this
chemistry so this system is used to drop the voltage and we should find voltage
here and they should be stable this is 13 point 87 volt it should be stable it
should not fluctuate okay if this voltage are not present the power supply
will dead power supply will not work totally if this power supply if this
voltage are not stable if this voltage are not stable two reasons the first
reason maybe this cluster is burned check remove this capacitor main
character remove main capacitor and check if this capacitor is good then we
have problem in the inverter section in the outfit area if the voltage are
fluctuating here these voltage are not stable I will show you how I will make
no short circuit in the output area I have 157 volt now I will make short
circuits now I made short circuit between two leads and now we will check
the voltage we can see the voltage so this time we have short circuit in the
output area so I will remove the short and then we will see I remove the short
circuit and now the voltage are stable so how we can find now we have I have a
159 volt and if I make short circuit so I made short circuit I install it to
reserve we can see the condition of kilometer so we have problem and short
circuit so in this case we will not find the stable voltage here we can see the
multimeter this time I have short circuit in the output area so how we can
find where is the problem now go to step number 2 this time I have if I have no
output totally no output check this resistor check this resistor and then I
will show you what we will do if we don't have any output totally no output remove optocoupler by output area optocoupler pin number 3 and for
disconnect this is very the best technique which I use my own technique
and I I use this technique regularly but when you have using this technique you
must use I removed I disconnected a coupler this
is very smart technique okay now what I did we disconnected the opto coupler now our opto coupler is disconnected and
now we will check the results this opto coupler is bad we will find
the fluctuation in our pettalia and we will find full actuation in DC twister
main disc of Esther and we will find fluctuation in SMPS control of crystal
this VCC for SNPs this time this circuit is not finding any feedback so this time
we have problem we cannot find where is the problem is optocoupler is bad this
output area is there so remove power take diodes simple rectifier diode any
rectifier diode and we have removed opto coupler and connect the cathode side the
bar sides there is capacitive negative terminal this negative terminal the
negative terminal is connected to opto coupler so we will connect the negative
side of this diode this is very smart and very useful technique this is my own
technique I removed optocoupler collected negative
side cathode side to the negative terminal of the capacitor will his
canister this canister the negative side is collected here
okay now collected diode like this you will find 7.5 4 volt now I bypassed the
output section I bypassed the feedback feedback this time by using this
technique by using this technique I bypassed the feedback area and this time
our output area is stable it is 5 volt section fiber power supply and I am
getting 7.6 volt so in this way we can determine where is the problem
now it is very useful you can check tablet on the chart component will heat
up within few second just apply power connect lamp and series and you will
find the diode by touching a remove power after 2 3 seconds you will find
the hot component in this area if any components is short circuit you will
find very immediately so this is very very useful technique remove optocoupler
connect diode connected that gets hold the bar side to the negative side of the
capacitor and you will find the okay now then there is another technique now we
verified this section this portion is okay infra stage we tested the short
circuit in the input area if the power SMPS is dead
sometimes this optocoupler is short circuits if the scepter coupler Here I
am taking voltage if this applicable is short the snps will shaft
so check snps function use by removing up to coupler I removed opto coupler and
install the diode then install diode we will find some voltage after that okay
when you when we install this when we installed this diode and if the voltage
gets stable okay that time however this section is working properly
this area is working properly now how we can test how we can verify that
SNPs controller and MOSFET are working properly a set multimeter to AC volt
connect one line to ground the best of negative terminal and the product second
line this is main line capacitor capacitor and the second line is here I
should find this AC voltage I am finding 32 volt
this means the FE T MOSFET and SMPS circuit is working properly if I do not
find voltage here at this point that means that problem SMPS is not
functioning so to check the SMPS you have to first of all check this voltage
if you find this voltage then check feedback area to check feedback remove
up to coupler product this diode and if you find some voltage here then that's
okay if not fine to any voltage check as a PS controller and MOSFET now I will
remove this diode and we will connect October
these tips are very useful first of all I am NOT a professional youtuber maybe
someone can take benefit from my experience I am sharing my experience so
if this video is good please share this video for your friends maybe someone can
take benefit now I will connect apricot blossom so up until now we verified then
there is no short circuit in the input area we verified and we discussed how we
can remove short circuits then we checked the capacitor how we can test
the Wester and when we install diode we verified
however this portion is okey now I remove diode and if this power supply is
not stable first of first of all I will show you it is working now we collected
optocoupler and now DC voltage and I am getting for perm and when I removed
optocoupler and I connected this diode you remember will take seven point nine
volts now I am taking five volts now I will put some sharp circuit just one
circle so now I will connect another multimeter
to show you the response of the capacitors we will connect another
multimeter so that's it will very easy to understand now I have 160 volts at input area and
stable now if any components I have short circuit we can see fluctuating
voltage and here I have fluctuation if this capacitor is short the output
fluctuating input fluctuating if any component we can see we have fluctuation
in the output area and we there is short circuit and we have fluctuation if any
component is short circuited any such section is short circuit we can find
this voltage and we will find our song from the PFC transformer so it is very
easy so check the voltage reference here we have voltage reference in the central
pin and one side we can find a stable voltage in the central plain and right
side we will find stable multi and we will check the input of the opto coupler
okay if input of the upper coupler is varying here I have stable voltage input
is good that means the opto coupler is working good and if you get stable
voltage here and the output circuit is not working when we removed opto coupler
and diode was in style the output circuit was working and now when you
connect it the opto coupler and you have stable voltage into at the input and it
is not working then the the optocoupler is not good it replaces the possible
reasons in the our tips how to eliminate charge first half on locate the feedback
sent circuit where is feedback send circuit if we see this optocoupler one
line connected to this resistor and it is connected to this supply and if you
find this supply it is connected to this capacitor across this capacitor if we
see this supply it is connected here and for the same dr. it is going back to
these diodes this connector this capacitor is connected to an eight and L
8 is connected to these diodes these main diodes leave them and remove on
other diodes 1 and open all diodes one and one thing all diodes Raman remove
all diodes just keep these two diodes the main diodes rectified out remove the
leave them and remove other arm and check out books if you will not find
output in this area that means we have problem some of these components this
capacitor this inductor and after this inductor we have these diodes so check
these diodes after that install one diode turn on power
yes--the on other diode but non-and check power one by one then any diode
you install and you fail to find the power that diode of that circuit or that
semester is problematic you can find very easily I think this
video is good for you you can subscribe if you want in this section we discussed what we will do if we have
short-circuited what we will do if we have short in the area how to check snps
bet we discussed it and if we have fluctuation in the output we discussed
and we troubleshooted it how we can determine the fluctuation and the reason
of the fluctuation either this fluctuation from the input side from the
output side are from the feedback circuit when it start
we removed optocoupler and installed Iola and we test it and we can find the
problem and how to eliminate chartres in the output circuit we discussed
everything so if this video is good for you
you can subscribe if you want then if you want to watch my future videos you
can subscribe thanks for watching assalamu alaikum warahmatullahi
wabarakatuh
