Subscribe Forever Tech Youtube channel to get every latest video updates Assalam-O-Alakium Friends i am Nadeem robin and you are watching your own channel forever tech so friends today we will repair it before this video i made its part 1 so in that video we totally checked its high side so there was no such fault but today we will check its SMPS but the advantage in todays video is that i will also explain you its schematic because some of my friend complains me that you don't explain with schematic but today i will try to make its schematic and show it to you and how system is made in it and which thing is attached with other thing and why it is attached so today i will give you full explanation first we will understand its schematic after that we will test it and after testing we will on it that it will on or not so friends here we will use different techniques so friends in off the camera i will make the diagrams step by step and than step by step i will explain you and like this you can save your time as you can see i have made IC here which is IC number IC50 this is switching IC which is installed here and as you can see IC50 is written here so i will also show it to you here IC50 is written this is chopper and in chopper it is written T60 as you can see T60 is written here so i have made both of them now i will change its marking and explain it to you today in this video i will tell you techniques that how you can recognize schematic diagram how you can read it to read it as you can see if anywhere anykind of lines are drawn as you can see they are far from each other and they are parallel but if lines are crossing each other than how you can know that which wire is joined to other as you can see if they are crossing eachother like this so it means they are jumping each other none of the wire are linking each other but if any any point you get this circles so it means that this wires are joined to each other so you can read it like this so now i have made circuit DC input of 320 volts goes directly towards the chopper as you can see as you can see it is directly going towards chopper after that its drain comes from switching IC it comes from here and goes to chopper when switching IC is on than circuit is completed and chopper gets on but here the circuit i have made this is safety circuit after getting on if some spikes cross it so what will happen after crossing that from here it will move towards it through this diode and after passing through diode capacitor will open and after opening they both will get shortcircuit and fuse will get burst thats why safety circuit is installed here here i have made another circuit but let me explain you one thing that its switching IC we have draw 7 pins here but here they are 11 pins 6 are on this side and 5 are on other side so totall are 11 pins so do not get confused in it because usable are like this so thats why do not get confused in it so now lets talk about the drawn diagram what is this as you can see 470 kilo -ohms resistance is attached here here three resistance are installed which is of 510 k when voltages come from here so it is made very less so that very less voltages can come on pin number 1 here M is written so it means here monitor voltages will come switching IC also monitor the input voltages if any fluctuation occur and if here are high volts so it will also cross high volts on the pin so than it will close the system thats why here presetted system is made so that monitoring voltages can be checked here here 320 volts as you can see we have give chopper directly its positive side but its negative side so it will go from here to its switching IC source point here sorce pins are 2, 3, 8 and 7 they all are its source pins so when switching IC will on it so from drain circuit will be completed so high side is completed so now lets talk about low side so in the low side that the chopper 10 number pin we should get 15 volts in it and the ground for low side that is taken from chopper and as you can see it comes here and one capacitor is installed with it so that 15 volts can be made here now we will talk about chopper pin number 9 so here we get one diode diode is for safety so return voltages can not be stay and chopper can de safe here we should get 12 volts and as capacitor is installed with it so that we can receive voltages but here 10 kilo-ohms resistance is also used that if voltages are high than 12 volts so they can be discharge by 10 kilo-ohms resistance so than we can get fix 12 volts here now we will talk about pin number 7 and 8 as you can see in pin number 7 it is directly grounded as in pin number 8 we should get 8 volts on the other side of diode and if here will be 8 volts it move towards the voltage regulator which is of 5 volts voltage regulator so 8 volts will appear on pin number 1 and pin number 2 will be grounded and we should get 5 volts on pin number 3 and as you can see capacitors are installed with it now we will talk about pin number 6 as you can see we should get 12 volts on pin number 6 where capacitor is installed and is grounded towards its positive side and on its negative side we should get -12 volts so here i have explain you SMPS schematic on its high side as well as its low side but how it works until its feedback will not come it will not become stable so mostly it occurs that when we give it 320 volts and voltages appear and here switching IC for few seconds means for mini seconds it directly on it what happens when we directly on it chopper also get on and voltages are also produced but which voltages we need that in our pin number 4 which is control pin and some voltages should be appear on it and from where it will come as you can see this 15 volts are producing here will come on this side and with it one diode is installed and here a zener diode is also installed but in many systems reference IC is used but here instead of reference IC zener diode is used and zener diode also works like a voltage regulator when 15 volts will come here as it is of 8.2 volts zener diode if it was less than 8.2 volts than it can not cross it but when 15 volts will appear here and 15 volts will be converted on its another side here it will start flowing in the form of 8.2 volts and 8.2 volts will appear here and with it two inductors are installed and these inductors are used to filter them if there are any kind of spike so they will be filtered after this it will go to diode diode is also installed for safety and here capacitors are used for spikes so from here 8.2 volts will go to its control pin which is 4 number pin when these voltages will come here this system will become stable and SMPS, microcontroller and other things will be oned and thus this system will start working so as i have explained you its SMPS schematic overall you have understand it but what happened in this PCB now i will explain it to you you have not to do this mistake thats what happened…..that when this PCB was on that its fan motor connector it has opened and when it is opened so it is tried to install it in on PCB you can take it out but when you will try it to install it again so SMPS can become short beside it the print of high side on the PCB board it is also faded and here its 15 volts are also finished beside it as you can see here is a resistance which is of zero resistance it is also faded beside here diode number 60 (D60) D60 is also responsible for 15 volts it is also faded beside it here we have D63 it is also faded so i will now test it and show it to you as we have D60 if i bring camera a bit forward i will show it to you as you can see here is D60 so i will check it so when i check it or test it as you can see when we check D60 here it is showing 0.00 now we will change its polarity after changing polarity again we will check it as you can see again it will come 0.00 as it has again come 0.00 so it means they are damaged and here someone have changed resistance we will put SMD on it because someone has dipped it and on the backside when we check its D63 so it is also showing 0.00 as you can see after changing its polarity again it is showing 0.00 so we will change both of them and thus the PCB will become fine and i hope that you can also test PCB and hope that you have understand the schematic that i told you so we will meet in our next informative video ……………
Keep watching Forever tech.
