ATX power supply maintenance methods

ATX Power Supply maintenance methods

A, the phenomenon of components have not blown, if the fuse has burned black, indicating that the primary circuit has a short circuit, focusing on checking the rectifier diode, standby power tube, half-bridge dual transistor, there is no breakdown.

ATX power supply

B, the phenomenon of components did not blow up, power on, use the table to measure the green line in the 20 pin, the purple line, there is no +5 V voltage, if not, we must check the standby circuit, focus on measuring the power-on resistance, the general power-on resistance to take the value of several hundred K, easy to appear resistance value becomes large, open-circuit phenomenon. Check with the standby power tube connected to the small triode has no short circuit, open circuit.
C, 20 pin in the green line, the purple line, there is +5V voltage, and then short-circuit the green line and black wire forced boot, see if it can boot, if not, look at the TL494 (7500B) power supply feet have no voltage (12 feet is the power supply), if not, check the line connected to the secondary of the standby circuit. TL494 (7500B) power supply feet have voltage, can not boot, to check the dead zone control feet ( 4) is 5V, or 0V, if 5V, is generally circuit protection, check the three double diode rectifier has no short circuit.