C9148-90909 5 Theory of operation 59
Copy processor board LEDs
The CPB has four light-emitting diodes (LEDs) that can be viewed when you face the back of the
MFP (callout 1). These LEDs illuminate in specific patterns depending on the CPB status during
initialization (initialization occurs when power to the MFP is turned on). After initialization, the
LEDs can be used to troubleshoot the CPB (see “Troubleshooting with the copy processor board”
on page 124).The table in this section describes the LED pattern sequences during the first and
second stage of CPB initialization.
Hint The LEDs can be difficult to see through the holes provided in the CPB faceplate (callout 1) in a
high-light environment. It might be necessary to turn off some lights or remove the faceplate to
see the LEDs.
The LED patterns an HP LaserJet 4100/4101mfp displays are the opposite of those on the
HP LaserJet 9000mfp because of how the CPBs are mounted. The CPB is mounted upside down
in the HP LaserJet 9000mfp.
Figure 22. Copy processor board LEDs
11
Table 9. Copy processor board LEDs (initialization sequence)
LED pattern CPB status
First stage of CPB initialization
ON* ON* ON ON
*LEDs might flash
before coming to a solid
illuminated state
● CPB flash DIMM detected
● CPB RAM DIMM detected
● CPB processor is working
● CPB has communication with the ASIC
Note If CPB initialization stops and the LEDs stay in the continuously illuminated
state, a CPB failure has occurred (for example, a memory DIMM is not
present or fully seated). To troubleshoot a CPB failure, see “Troubleshooting
with the copy processor board” on page 124.
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