I bought power supply kit on the aliexpress.
The day the item was arrived, then I assembled it, and did working test.
But it didn't work, so I tried to find the problem.
At firtst, I suspected that some componets are broke down.(transistor or op-amp)
However all components ware working nomally.
At the second, I focused on npn-transistor D1047.
this transistor is used for main component for keep doing constant voltage and output amper.
And I measured at base voltage, so I found out this voltage was 0.09V.
I thought something is wrong, because it is applied some volotage.
So I check the voltage on D822.(Darlington connection)
It is wrong too.
I measured voltage at R3 resistor(1k),it was 0.09V.
and I noticed OP1 was warm, this is caused by over current.
So finally, I checked transistor 9014.
While I applied voltage the circuit, I measured voltage between collector to emitter.
It was short, so I removed the transistor.
and I resupplied voltage.
As a result, the power supply was working completely.
this is schematic for TB-186840.
