14-03-2014, 03:36 PM
Computer power supplies tend to start and run up to full voltage as soon is there is enough mains at the input and will not run below that.
These PSUs also have a standby wire that connects to the power button that will need to be connected to start it up.
They also monitor the 5 volt wire for regulation and if this does not have a load on it the output will all be poor or may even pulse on and off.
I would still put a pair of wires on the points where the missing resistor came from and connect a volt meter to them.
Then just dab a resistor across them and watch the volts. 220 ohms at 10W should be fine as a start.
We can work out the currant from the voltage reading. The resistor will get warm so keep them off anything that will get burned including your hands.
The unit has been powered up with the resistor burned out so no further damage will happen if power is applied again without the resistor.
If you have got a Variac then it can be run up that way with the test resistor in place.
These PSUs also have a standby wire that connects to the power button that will need to be connected to start it up.
They also monitor the 5 volt wire for regulation and if this does not have a load on it the output will all be poor or may even pulse on and off.
I would still put a pair of wires on the points where the missing resistor came from and connect a volt meter to them.
Then just dab a resistor across them and watch the volts. 220 ohms at 10W should be fine as a start.
We can work out the currant from the voltage reading. The resistor will get warm so keep them off anything that will get burned including your hands.
The unit has been powered up with the resistor burned out so no further damage will happen if power is applied again without the resistor.
If you have got a Variac then it can be run up that way with the test resistor in place.
