IBM pSeries 670, Service Manual

Page: 838 / 1032

3. Install an MCM or pass through module.
4. Press the toggle switch on the LGA-ST forward to the MCM/L3 PWR/GND position. This action will test
the MCM or pass through modules for power-to-ground shorts. Observe the lit LEDs on the LGA-ST
and take the corresponding following actions:
Green MCM LED is lit
This is a pass state. No further action is required.
Amber MCM LED is lit
This is a fail state. There might be a short across the MCM or pass through voltage and
ground. Complete the following steps to correct this condition:
a. Remove the MCM or pass through module and inspect the interposer for shorts.
b. Replace the MCM or pass through module and repeat step 4. If the fail state persists,
replace the MCM or pass through.
Green L3 LED is lit
This is a pass state. No further action is required.
Amber L3 LED is lit
This is a fail state. There might be a short between one of the two L3 voltages and ground,
which is a failing condition, or the combination of memory books, I/O books, and L3 cache
modules in parallel might be creating a low resistance. To ensure that no shorts are present on
the L3 modules before power the system on, perform “Method 3. Testing L3 Cache Modules
for a Short Circuit” on page 835.
5. Install another MCM or pass through module and repeat step 4 until all required MCMs are installed.
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pSeries 670 Service Guide