Hello guys,
I have a TV box power supply adapter, 5V, 2A that's not working correctly. Input is AC 230V 50 Hz.
I would like to use this as a learning example.
First of all, when adapter is connected to AC power, there is 5 V DC at its output (4.95V) when no load is connected.
If a small light bulb is connected (5V, 0.3A), the output voltage drops to 0.85V and there is a weak light on the bulb.
Attached is a picture of PCB. There are two black IC s on the board. The smaller one 4 legs is probably a voltage feedback chip. On it is written something like: PC817C 1452, and I cannot see that anything is written on larger 8 legs chip.
So when load is connected voltage drops and even green LED light becomes weak. Even after I remove the adapter from the AC power, its DC output remains 0.85V for a long time.
What could be the problem in such cases, i.e. when there is output voltage with no load connected?
Thank you.
I have a TV box power supply adapter, 5V, 2A that's not working correctly. Input is AC 230V 50 Hz.
I would like to use this as a learning example.
First of all, when adapter is connected to AC power, there is 5 V DC at its output (4.95V) when no load is connected.
If a small light bulb is connected (5V, 0.3A), the output voltage drops to 0.85V and there is a weak light on the bulb.
Attached is a picture of PCB. There are two black IC s on the board. The smaller one 4 legs is probably a voltage feedback chip. On it is written something like: PC817C 1452, and I cannot see that anything is written on larger 8 legs chip.
So when load is connected voltage drops and even green LED light becomes weak. Even after I remove the adapter from the AC power, its DC output remains 0.85V for a long time.
What could be the problem in such cases, i.e. when there is output voltage with no load connected?
Thank you.
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