Canon imagePRESS P400 Service Manual page 40

8. Grasp the CPU by its edges, lift it out of the socket, and then place the CPU in a safe place.
NOTE:
If you remove the CPU from the motherboard to install it on a new motherboard, unpack the new motherboard and remove the
protective plastic cover from the CPU socket.
Transfer the protective cover to the CPU socket of the old motherboard to protect the circuitry.
● To replace a CPU
1. Do one of the following:
• If you are installing a new CPU cooling assembly on an existing CPU, clean the contact surface of the CPU to remove
any old thermal compound residue. A thermal pad is preinstalled on the underside of the new CPU cooling assembly.
IMPORTANT:
Be sure to remove all thermal compound residue from the surface of the CPU. It may help to scrape all the residue
off the surface using the flat edge of a nonconductive tool. Then use a lint-free cloth moistened with alcohol to
clean the surface.
• If you are installing the existing CPU and CPU cooling assembly on a new motherboard, clean the contact surfaces of
the CPU and cooling assembly as described earlier. Then apply fresh thermal compound to the contact surface of the
CPU using the applicator provided with the new motherboard.
IMPORTANT:
To apply a fresh thermal compound, use ShinEtsu PCS-TC-11T-13 thermal pad.
2. Prepare the CPU socket by ensuring that:
• The socket lever is in the open position.
• The load plate is open.
3. Place the CPU in the socket (see
The CPU and the socket are keyed to ensure correct installation. The two notches on the edges of the CPU correspond with
the two small posts inside the socket. Align the two notches properly with the two small posts.
Align the yellow triangle on the CPU with the flat corner of the socket. Do not force the CPU.
4. Close the load plate.
5. Lower the socket lever and place it in the locked position under the retention post.
6. Prepare the CPU cooling assembly for installation.
• Make sure that the motherboard is placed on a padded, antistatic work surface.
• Apply the fresh thermal compound square, as described in step 1.
• Align the cooling assembly so that when it is installed, the fan cable easily reaches the CPU fan power connector CPU
FAN on the motherboard.
7. Place the cooling assembly on the CPU.
• Make sure that the thermal pad on the underside of the heatsink is positioned on top of the CPU.
CAUTION:
Be sure to remove any protective material that may be covering the surface of the thermal pad.
Otherwise, the CPU may overheat.
• Align the four screws with the four screw posts.
• Tighten the screws. Partially tighten all the screws before tightening any one screw all the way.
8. Connect the CPU fan cable to the motherboard connector CPU FAN.
The cable connector is keyed to fit only one way. Make sure that the connector on the cable is securely attached to connector
CPU FAN on the motherboard.
9. Install the motherboard in the chassis (see
"To remove a CPU" on page
"Replace the motherboard" on page
34
32).
28).
3. REPLACING PARTS