Analog Card; Logic Cards; I Removal; Replacement - IBM 3279 2A Maintenance Information

3279 MIM
4.5.4 Analog Card
The analog card is located to the left of the CRT
when viewed from behind.
I. Switch power off and remove the mainline
power cord from the power outlet.
2. Disconnect the two ground wires from the
ground screw at the bottom of the card
assembly.
3. Remove the two screws at the top and bottom
of the analog card assembly and the center
clamp.
4. Withdraw the assembly toward the rear of the
machine taking care not to damage the cables
connected to the card.
5. Unplug P5, P6, P7. and P26 (see Figure 4-7)
from the analog card.
6. Unscrew the clamp that holds the red EHT
wire at the Line Output Transformer (LOPT)
connector, P21. Pull out the wire and discharge
it to the frame.
7. Remove the analog card.
8. To reinstall. first check that the jumper matches
the CRT.
Note: There are alternative positions for the
CRT jumper depending on the level of the
analog card, see Figure 4·7.
a. If the tube is manufactured by the
Matsushita Electronics Corporation (see label
on the bell of the CRT behind the analog
card). install the jumper in position L.
b. If the tube is manufactured by the
Mitsubishi Electric Corporation (see label on
the bell of the CRT behind the analog
card). install the jumper in position H.
9. Insert the EHT cable fully into the LOPT
socket. P21 and screw down the cable clamp.
10. Continue installation in reverse sequence.
Ensure that the card is correctly located in the
top and bottom guides.
It. Reconnect 2 ground wires and screw down.
DANGER
Verify that 1111 ground wires
liN!
ream_ted
sec"rely. Reier to Figllre 6-6 lor grounding
tkt;'i/s.
12. See Chapter 5 for adjustments.
Chapter 4. Removal and Replacement Procedures 4-4
4.6 Logic Cards
4.6.1 Removal
Switch power off. Remove any attached top card
connectors. Operate the levers in the directions
shown by the arrows in Figure 4-6 and withdraw
the card.
4.6.2 Replacement
Push the card firmly into its socket and then
operate the levers as shown in Figure 4-6. Replace
the top card connectors, see Figure 1-6.
CAUTION
Always use a card shroud when reinstalUng a card, to
prevent contact with adjacent cards.
For ECS and PS feature cards (E2. F2) see Figure
6-14 for details of switch settings and module and
jumper positions.
Note: 32 79s with the Video Output Facility have a
video output card instead of a line control card in
location C2. The video output card has two extra
modules. When this card is installed in location
C2, the resistance between each video output socket
and ground falls to less than 10 kilohms.