Video Components; Amplifier Card; Video Card; Crt And Coil Assembly - IBM 3279 2A Maintenance Information

4.8 Video Components
4.8.1 Amplifier Cllrd
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1. Switch power off and remove the mainline
power cable from the power socket.
2. Remove the four push-in multi-wire connectors
PI7A, P17B, P18 and P19 from the amplifier
card (see Figure 6-10).
3. Remove the screws that secure the safety cover
and remove the cover.
4. Pull the amplifier card off its four locating lUgs.
S. Reinstall the amplifier card in reverse sequence.
The multi-wire connectors cannot be mixed up
because they are different sizes. Do not finally
tighten the safety
cov~r
securing screws until
these connectors have been reconnected.
6. See Chapter 5 for adjustments.
4.8.2 Video Card
\. Switch power off and remove the mainline
power cable from the power socket.
2. Remove the analog card (see section 4.5.4, steps
I through 4 only).
3. Unplug P5 and P26 from the analog card (see
Figure 4-7).
4. Disconnect the three ground wires from the
video card. Note the connection points and
routing of the wires (see Figure 6-9).
5. Pull the video card off the CRT base.
6. Disconnect P14, PI5 and Pl6 from the video
card (see Figure 1-4).
7. Reinstall in reverse sequence.
8. See Chapter 5 for adjustments.
4.8.1 CRT lind Coil AS1embly
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4.8.3.1 Removal
CAUTION
Support tbe logic gate to prevent tbe display from
falling backward wben tbe CRT aDd coil assembly is
removed.
\. Remove the mainline power cable from the
power socket.
2. Position the display as described in section 4.1,
with logic gate open.
3. Remove the bezel (see section 4.4) and place it
face down in front of the display. Release the
internal power cable from the rubber clamp near
the ON/OFF switch.
4. Remove:
• The power supply (see section 4.5.2)
The analog card (see section 4.5.4)
• The amplifier card (see section 4.8.1)
The EHT bleed assembly (see section 4.8.4,
but do not remove the bleed assembly from
the bracket)
5. Pull the video card from the CRT base and
place it on the table.
6. Loosen the clamp and pull the convergence coil
assembly from the CRT neck.
7. Disconnect P27 (front left of the CRT screen -
see Figure 1-2).
8. Disconnect the ground braid clamp and its
jumper link (Figure 6-9). Ensure that the braid
can move forward freely.
CAUTION
The following steps free the CRT from its
mounting. The CRT weighs approximately 7.5
kg;
support it aDd protect it from excessive
pressure tbat could damage It or other units.
Handle the CRT by the bell only, NOT by the
neck.
9. Remove the four hexagonal nuts and washers
from the comers of the CRT face.
10. Check that the logic gate is supported.
Chapter 4. Removal and Replacement Procedures 4-7