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Method to Detect Power Supply and Motherboard Failures in an Inoperative PC System

IP.com Disclosure Number: IPCOM000019786D
Original Publication Date: 2003-Sep-29
Included in the Prior Art Database: 2003-Sep-29
Document File: 4 page(s) / 78K

Publishing Venue

IBM

Abstract

Today when a PC fails to "turn on" the servicer usually suspects the motherboard and power supply as the source of the failure. Unfortunately the power supply failure rate is much lower than the motherboard failure rate. This causes many servicers to replace good power supplies because they have no way of knowing whether the power supply is good or bad until the servicer changes it. Due to the low cost of the power supplies they are disposed of when they are replaced regardless of whether they are good or not. This costs IBM money needlessly. This method and associated low cost hardware allows the customer or servicer with a high degree of certainty to pinpoint the failure to either the power supply or the motherboard.

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  Method to Detect Power Supply and Motherboard Failures in an Inoperative PC System

   This method and associated hardware is used when the system performs no action when the power button is pushed. If the system has enough function to beep the beeper or show video then this method is not required. This is a hardware only method to detect a failed power supply or motherboard.

The method and hardware consists of the addition of the following LEDs on to the front of the PC or the power supply:

Power Button

Power and HDD LED

Hidden Diagnostic LEDs

These LEDs have the following functionality:

In d ic a t o r s :

1. LE D on +5V S B
2. LE D on P S O N #
3. LE D on O C Latch
4. LE D on +5V

 The O C Latch and +5V signals can be on one indicator: Both off = P/S Bad (LED O ff)
and the X O R of the them w ould be M obo B ad (LE D O n) The OC latch signal is brought over from the power supply. The table below shows the different conditions displayed and the actions taken to determine the state of the power supply or motherboard.

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C o n d itio n

O C _L atch


+5V S B

The table describes the following:
1. The first LED is the +5Vsb LED. If this is not on then the power supply is bad and the system cannot operate.
2. If the +5Vsb LED is on and the user presses the power button on the PC and the PS_on# signal does not go on then the motherboard is bad.
3. If the +5Vsb LED is on and the user presses the power button on the PC and the PS_on# signal goes on but the power supply does not supply +5V and does not latch up then the power supply is bad.
4. If the +5Vsb LED is on and the user presses the power button...