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5.2.2.1 -4 Volt Regulator Unloading
Caution
Never turn on power with the -4V regulator unloaded
unless the correct jumpers are installed. Otherwise,
component damage to the 5424 or 5203 may result if
+6V is applied to the attachment board of these devices
(A-Bl and A-A3 boards) without -4V.
Danger
When the -4V regulator is unloaded the bulk supply
may go into oscillations. This may cause the resonant
capacitor in the bulk supply to explode. Limit power on
time with the regulator unloaded to 30 seconds, keep
the bulk supply cover on, and wear safety glasses.
To unload the -4V regulator
on the basic machine:
1.
Turn off power.
2.
Remove ac connectors 12 and J3 from base of CPU.
3.
Remove all cables from E3 and E 13.
4.
Install jumper from E3 to E13.
5.
Turn on power and make power checks.
To
unload the -4V regulator when the -4V
add-on regu-
lator
is installed:
1 .
Turn off power.
2.
Remove ac connectors 12 and J3 from base of CPU.
3.
Remove all cables from E3, E4, El2, El3, and El4.
4.
Remove all cables from E2 of -4V add-on regulator.
5.
Install jumpers:
E4 to E14
E3 to E13 (on both regulators)
E12 to El4
6.
Turn on power and make power checks.
Because the above procedure prevents the +6V and the
-30V supplies from sequencing up, the power check light is
on.
5.2.2.2 +6 Volt Regulator Unloading
Caution
Never turn on power with the +6V regulator cables re-
moved unless the correct jumpers are installed. Other-
wise, damage to the
CPU BSM
results if the BSM receives
-30V without +6V.
To unload the +6V regulator:
1.
Turn off power.
2.
Remove ac connectors
J2
and J3 from base of CPU.
3.
Remove E4, El 2, E14, and TBl-3 (-4V
lN
'ax drive'
line).
4.
Install jumpers:
E4 to E14
E12 to E14
5.
Turn on power and make power checks.
Because the above procedure prevents the -30V supply
from sequencing up, the power check light is on.
5.2.2.3 -30 Volt Regulator Unloading
To unload the -30V regulator:
1.
Turn off power.
2.
Remove ac connectors 12 and 13 from base of CPU.
3.
Remove all cables from E3.
4.
Remove cables from terminal position 8 on A gate
lower laminar bus (adjacent to A-B4).
5.
Install jumper from E3 to E13.
6.
Turn on power and make power checks.
Because the above procedure prevents the +60V supply
from sequencing up, the power check light is on.
5410 MM
5-3
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