Free Computer Repair Service

1. Requirements:
(1) Have a certain hardness, can withstand a certain load without deformation.
(2) Reasonable internal structure, easy to install equipment and expand.
(3) Has a good thermal performance, electromagnetic screen to prevent external electromagnetic interference.
(5) Panel switch, indicator layout is reasonable, clearly marked.
(6) Appearance

2. Classification
(1) Power supply: AT, ATX
(2) Exterior: Vertical, horizontal
(3) Use: specific, standard general-purpose

3. Chassis Power Supply: AT, ATX
(1) ATX power supply output voltage specifications, 20-pin connection, “D”-shaped, in general could not get into the wrong direction
(2) AT Power Supply Connection: (1) K with two black lines.
(3) Power AT200W, 220W, 250W, 300W (with the corresponding device of microcomputer).
(4) POWER GOOD (PG) signal: is done by the DC output voltage detection signal and communication input, voltage fault signal phase “and” generated, it is compatible with the TTL high level, power supply is normal, low means power supply failure. PG power supply from open to output is effective, about 100 ~ 500MS delay, whose role is to stabilize the power output and then notify the host system start, and when the city electricity outage, PG signals will respond before the DC output disappear, makes the hard drive have enough time to reset the head, to prevent the drive from accidental damage. Abnormal PG signal often cause system can not boot.