Solucion de fuente de pc con fallo de Power Good

PC source solution with Power Good failure
More PC source solutions:
https://www.youtube.com/watch?v=xhRveJWlwKQ&t
https://www.youtube.com/watch?v=IMMGgujs7k4&t
https://www.youtube.com/watch?v=levCOSc9mRk&t
Continuing a bit with the issue of PC source repairs, this time I bring you how to repair a PC power source, when it turns on, it gives all its voltages except Power Good.
The problem with this power source is that it is detecting some abnormality, and for protection it places zero volts in the Power Good signal. To solve this problem, the first thing to do is to trace the configuration of this signal to the source. By checking its configuration it was possible to determine that this signal is controlled by the SG6105 chip, it is the supervisor of the power supply, pwm and regulator. This integrated allows to monitor, the output voltages, such as the source of 12, 3.3, 5, and -12 volts, and the low voltage of the alternating signal, in case one of these signals has a fault, the source it is protected, I put in under the signal of power good, otherwise I would place a stop. The main failure that was occurring in this source was that it activated the UVAC protection (low voltage detection of the AC signal), since this signal was less than 0.7 V. This is the reason why the comparator is activated internal, and this saturated the transistor, to get a low on the power good signal (PG). Making a deep revision, it was found that the AC signal in the secondary stage was saturated and therefore did not generate a voltage greater than 0.7 volts. The failure occurred because the source did not generate the 320 VDC; when checking the selector, it was observed that it was at 110 VAC, but this selector was open and consequently the source was working as if it was selected at 220 VAC. To perform a small test run, a bypass was done on the selector wires, allowing to obtain a satisfactory result. The attractiveness of the repairs of the PC power source, is that each day you learn interesting things, but having clear concepts and consulting the technical specifications of the chip, it facilitates the diagnosis of failures. Many times we can present the same fault but with different solution, however the technique of detecting the fault is the same. I hope this video is very useful.
In this channel you will find all kinds of repair from the simplest to the most complex, but the most important thing is that you learn how to repair your electronic equipment, so the invitations to subscribe, activate the bell to be pending notifications, so be alert when upload a new video.
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