IBM iSeries 270 Service Manual page 138

5. Install an L3 module.
6. Press the Rocker switch forward to the MCM/L3 Pwr/GND position. This checks the L3s for power to
ground shorts. It also checks the MCM for power to ground shorts. Note the following:
v The green L3 LED must be lit for a pass condition. If the amber L3 is lit, there may be a short
between one of the two L3 voltages and GND, which is a fail state, or the combination of memory
books, I/O books, and L3 in parallel are creating a low resistance. Perform the following:
a. Disengage memory books followed by I/O books one at a time.
b. Repeat this test after each is removed until either the L3 test passes, or all memory and I/O are
disengaged and the L3 test remains in a fail state.
c. If after disengaging all memory and I/Os, the L3 LED remains lit, remove the L3 and inspect the
interposer for shorts.
d. Reinstall the L3 once and repeat the test. If the fail persists, replace the L3.
v The green MCM LED must be lit for a pass condition. If the amber MCM Led is lit, there is a
short across the MCM voltage and GND. Perform the MCM/passthru test and correct the short
condition before powering on.
7. Press the Rocker switch backward to the L3 PWR/PWR position. Both the green and amber MCM
LED will be off. Power is removed from these circuits when the switch is in this position. Note the
following:
The green L3 LED must be lit for a pass condition. If the amber L3 LED is lit, there is a short
between the two L3 power domains.
Perform the following:
a. Remove the L3 and inspect the interposer for shorts.
b. Reinstall the L3 once and repeat the test. If the fail persists, replace the L3.
8. Repeat steps 5 (See page 126), 6 (See page 126), and 7 (See page 126) until all required L3s are
installed.
This ends the procedure.
Test method 2: Testing MCM and passthru modules for a short circuit using a multimeter and capacitor
book: There are two procedures that are covered in this topic:
v Testing MCM and passthru modules for a short circuit (See page 126)
v Testing L3 cache modules for a short circuit (See page 128)
Test method 2: Testing MCM and passthru modules for a short circuit
Perform this test to ensure that a short circuit was not created when installing an MCM or passthru
module. You can use one of the following two options during the MCM replacement:
v Install and use a multimeter and new capacitor book (part 44P2471)
v Install and use a multimeter, the original capacitor book, and MCM/L3 module short-circuit test tool
(part 44P0209)
Note: This procedure should only be performed by trained personnel. Ensure the UEPO switch is in the
Off position before performing this procedure.
MCM installation shorts test, procedure 1
1. Power down the system. See Power on/off the system and logical partitions.
2. Ensure the UEPO is off.
3. Disengage all DCAs from the planar.
4. Choose from the following options:
v If you are using the new capacitor book option: Install the Capacitor book in CAP
base location (M33), with no meter attached.
126
Hardware (Remove and Replace; Part Locations and Listings)