Practical - 82 :- To test a faulty CPU power switch by shorting motherboard pins and to safely remove the CMOS battery for BIOS troubleshooting or replacement.

 1. Objectives

At the end of this practical, you will be able to:

• Test a CPU power switch by jumping motherboard pins.

• Safely remove and replace a CMOS battery from the motherboard.

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2. Tools & Equipment Required

No.	Item Description	Quantity
1	System Unit (CPU) / Motherboard	1 No.
2	Flat-head Screwdriver (Insulated)	1 No.
3	ESD Tweezers / Small non-conductive tool	1 No.
4	Cotton Cloth / Cleaning Brush	1 No.

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3. Procedure A: Testing the Power Switch 

Use this method if the computer is not powering ON to check if the physical button is defective.

1. Preparation: Unplug the power cable from the wall outlet and open the PC case.

2. Locate Front Panel Pins: Find the Front Panel Header on the motherboard (usually labeled JFP1 or PANEL).

3. Identify Power Pins: Locate the two pins specifically for the Power Switch (PWR_SW). In standard layouts, these are typically pins 6 and 8.

4. Disconnect: Unplug the power switch connector cable from the motherboard.

5. The Jump Test: * Connect the power cable back to the wall outlet.

   • Take a flat-head screwdriver and touch the tip to both pins 6 and 8 simultaneously for 1–2 seconds.

6. Observation: If the PC starts up, the motherboard is healthy, but the case power button is faulty.

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4. Procedure B: Removing the CMOS Battery

Perform this to reset BIOS settings or replace a drained battery (CR2032).

1. Power Down: Turn off the computer and unplug it. Press the power button once to discharge any remaining electricity.

2. Locate Battery: Find the silver coin-shaped battery on the motherboard.

3. Release the Clip: * Using an ESD tweezer or your finger, locate the small metal retainer clip on the side of the battery socket.

   • Gently push the clip outward. The battery should pop up slightly.

4. Extraction: Lift the battery out of the socket. Avoid using excessive force to prevent damaging the plastic housing.

5. Reinstallation: To put it back, slide one edge in and press down until the clip clicks into place. Note: The "+" side (flat side with text) must face UP.

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5. Safety Precautions

• Static Electricity: Always touch the metal frame of the PC case before touching internal parts to discharge static from your body.

• Short Circuit Risk: When jumping pins with a screwdriver, ensure you only touch the two designated power pins.

• Battery Handling: Do not use metal pliers to grip the battery; use ESD-safe tools or your fingers.