Wow, super fast with many broken parts but how did you get 12V if the PS wasnt turned on yet? What did i miss? I have to use a tester to get the green and grey pins to be on and a small load.
Hello friend Thanks for being here in my channel. ATX power supplies are designed to output a constant 5V standby (5VSB) on the purple wire when connected to mains power, even without shorting the green wire to ground. While Some other power supplies may also partially power the 12V rail in standby mode for testing or minimal load purposes. However, this 12V output is typically low current and may not be sufficient for operating high-power components. In our case the power supply has no dedicated stand-by wire. So it partially starts the 12v rail to work as a stand-by rail and provides the necessary voltages for the motherboard to start running and and then the power supply is fully activated.
Hello friend Thanks for being here in my channel. Its (PFC) Power Factor Correction. Its a circuit that improves the efficiency of power supplies by reducing the phase difference between voltage and current, thus increasing the power factor closer to 1. It ensures that the power drawn from the AC mains is used more effectively. PFC circuits are commonly found in modern computer power supplies. There are two types of PFC circuits: 1. Active PFC: Uses electronic components (boost converters) inductor, a MOSFET, and a diode. The Mosfet is controlled by a PWM (Pulse Width Modulation) signal to adjust the input current waveform to match the input voltage, minimizing the phase difference between them to shape the input current waveform to match the voltage waveform. 2. Passive PFC: Uses inductors and capacitors to improve power factor but is less effective than active PFC. The purpose of the PFC circuits is to reduces wasted energy, minimizes heat, lowers electricity costs, and reduces stress on the electrical grid.
Hi, have simple repair question if you can help. I have a 12V 500ma input working Electronic Keyboard and when i push in the Power button, there a load pop from the speakers and maybe the main CHIP ect are getting hit hard too?. Its cheap chinese but i like it SO....... i was thinking of like a 240V inrush limiter sort of thing, Is there a way of delaying that 12V just a little when i push the on/off hard switch? I was thinking of a CAP in series that would charge up in a few seconds? or a inductor in series but that is for killing AC so probably wont do much for the DC?
The loud pop sound in the speaker when the device is powered on is likely caused by a power-on transient or voltage spike propagating through the audio circuit. To eliminate this issue, you can implement a soft-start circuit as in the link here ( i.sstatic.net/h65JZ.png ). This circuit will cause the voltage to ramp up from 0 to 12v linearly. If the Keyboard you have gets 220v then it convert it to 12v for its electronics then you may Add an inrush current limiter thermistor like (NTC) to the 220V input to reduce the sudden current spike when the rocker switch is turned on.
@@FixTronics To keep this simple, would one of those green 240V inrush varistors do anything or do they make 12V ones? All the repairs i have done, i never faced a situation when i want to delay turn on except to use a 555 timer circuit but thats not for power as such.
Yes an NTC can be used in 12v circuit but you need to choose an NTC with a current rating higher than the maximum operating current of your 12V circuit. The NTC is to be connected in series with the load.
@@FixTronics Thanks. Rating for the keyboard is 500ma and the Varistors on say a computer PSU has to put out approx 500Watts , So they would be rated at least 2 amps? so would on from that PSU be ok?
Resp Sir! Very Nice Sir..... 🙏🏻.... -- ChinnaRao Paderu Andhrapradesh
Thank you so much brother
A very well shown repair. I would still put it on electronic load for a while.
Thanks for being here brother
Excelents🎉🎉🎉
hello nice repair keep it up
ps can you share the the protection circuit box schematics its very useful for repairing powersupply's
Wow, super fast with many broken parts but how did you get 12V if the PS wasnt turned on yet? What did i miss? I have to use a tester to get the green and grey pins to be on and a small load.
Hello friend
Thanks for being here in my channel.
ATX power supplies are designed to output a constant 5V standby (5VSB) on the purple wire when connected to mains power, even without shorting the green wire to ground. While Some other power supplies may also partially power the 12V rail in standby mode for testing or minimal load purposes. However, this 12V output is typically low current and may not be sufficient for operating high-power components.
In our case the power supply has no dedicated stand-by wire. So it partially starts the 12v rail to work as a stand-by rail and provides the necessary voltages for the motherboard to start running and and then the power supply is fully activated.
Good 👍
Thanks brother
What is the function of the circuit you mentioned 'BFC'?
Hello friend
Thanks for being here in my channel.
Its (PFC) Power Factor Correction.
Its a circuit that improves the efficiency of power supplies by reducing the phase difference between voltage and current, thus increasing the power factor closer to 1.
It ensures that the power drawn from the AC mains is used more effectively. PFC circuits are commonly found in modern computer power supplies.
There are two types of PFC circuits:
1. Active PFC: Uses electronic components (boost converters) inductor, a MOSFET, and a diode.
The Mosfet is controlled by a PWM (Pulse Width Modulation) signal to adjust the input current waveform to match the input voltage, minimizing the phase difference between them to shape the input current waveform to match the voltage waveform.
2. Passive PFC: Uses inductors and capacitors to improve power factor but is less effective than active PFC.
The purpose of the PFC circuits is to reduces wasted energy, minimizes heat, lowers electricity costs, and reduces stress on the electrical grid.
@@FixTronics Thank you
nice fixed
Thanks brother
Hi, have simple repair question if you can help. I have a 12V 500ma input working Electronic Keyboard and when i push in the Power button, there a load pop from the speakers and maybe the main CHIP ect are getting hit hard too?. Its cheap chinese but i like it SO....... i was thinking of like a 240V inrush limiter sort of thing, Is there a way of delaying that 12V just a little when i push the on/off hard switch? I was thinking of a CAP in series that would charge up in a few seconds? or a inductor in series but that is for killing AC so probably wont do much for the DC?
The loud pop sound in the speaker when the device is powered on is likely caused by a power-on transient or voltage spike propagating through the audio circuit. To eliminate this issue, you can implement a soft-start circuit as in the link here ( i.sstatic.net/h65JZ.png ). This circuit will cause the voltage to ramp up from 0 to 12v linearly.
If the Keyboard you have gets 220v then it convert it to 12v for its electronics then you may Add an inrush current limiter thermistor like (NTC) to the 220V input to reduce the sudden current spike when the rocker switch is turned on.
@@FixTronics To keep this simple, would one of those green 240V inrush varistors do anything or do they make 12V ones? All the repairs i have done, i never faced a situation when i want to delay turn on except to use a 555 timer circuit but thats not for power as such.
Yes an NTC can be used in 12v circuit but you need to choose an NTC with a current rating higher than the maximum operating current of your 12V circuit.
The NTC is to be connected in series with the load.
@@FixTronics Thanks. Rating for the keyboard is 500ma and the Varistors on say a computer PSU has to put out approx 500Watts , So they would be rated at least 2 amps? so would on from that PSU be ok?