Indicator Leos; S Power Units; Fuse; Power Supply - IBM 3279 2A Maintenance Information

4.4.4 Indicator LEDs
Before removing the LED assembly. switch off
power and remove the mainline power cable from
the power socket. The indicator LEDs are
contained on a PCB as shown in Figure 4-S.
4"'.5 Secllrity Keylock
1. Remove the analog card (see section 4.SA).
2. Disconnect P9 and remove the retaining nut
(use wrench. IBM Part 4418787).
3. Withdraw the keylock assembly.
4. Replacement is the reverse of removal. but
ensure that the keylock is inserted the correct
way up
so
that the key can be turned without
hitting the side of the display unit.
Figure 4-5. Indicator LED Assembly
4.S Power Units
DANGER
IkfolY
/lily
po_ "nit repl_"t procedures are
perftmned, tM display mil$( be powered off aad tM
mainliM powe, Ctlble discolrneded at the powe,
socUf.
4.5.1 Fllse
DANGER
Switdt
powe, off aad
IYmaVf!
1M mai"liM powe,
Ctlble from tM po_
SOCUf
before c""ng;ng tM
f--
3279 MIM
The main supply fuse is located in the front
enclosure assembly below the bezel. Push the fuse
cover and turn it counterclockwise to release the
fuse.
4.5.2 Power SlIpply
The power supply is located to the right of the
CRT as viewed from behind.
DANGER
Compt>lfl!nls on t"is Ctlrd are
""t.
Before ""adUng
the card, allow
;t
to cool for 5 minutes with powr
""ned
off.
1. Switch power off and remove the mainline
power cable from the power socket.
2. Remove the rear cover (see section 4.3).
3. Unplug the A2 cable connector.
4. Remove the retaining clip that holds the cable
to the inside of the logic gate.
S. Pull the flat cable through the gap (it is easier if
the connector shroud is removed).
6. Remove the two screws and pul) out the poweT
supply card.
7. Reinstall in reverse sequence, ensuring that the
card is correctly located in the bottom guide and
both top guides.
8. See Chapter S for adjustments.
4.5.3 Prime Power Box
1. Switch power off and remove the mainline
power cable from the power socket.
2. Remove the power supply as described in
section 4.5.2.
3. Remove connectors P1 and P2 from the prime
power box assembly.
4. Disconnect the ground wires from the assembly.
5. Remove the two screws that secure the assembly
to the base of the enclosure.
6.
Remove the assembly from the display.
7. Reinstall in reverse sequence.
DANGER
EIWI,."
tIrot all grouad conned/om to, the prime
powe, assembly are
tw:rJnnected;·
Chapter '4. Removal and Replacement Procedures 4-3