HP LaserJet Enterprise M552 - Page 74

Figure 1-27 Three states of primary-transfer roller engagement and disengagement
Four colors are disengaged
Four colors are engaged
Only black is engaged
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M
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K
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K
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Fuser motor
FUSER MOTOR CONTROL
M4
SR5
The primary-transfer-roller disengagement motor rotates or reverses to place the primary-transfer-roller
disengagement cam into one of three positions. The cam causes the transfer-roller slide plate to move to the
right or left. This movement causes the primary-transfer rollers to move up to engage the ITB with the
photosensitive drum or down to disengage it.
The DC controller expects to receive a signal from the ITB home-position sensor when the primary-transfer
roller engages or disengages. If the DC controller does not receive this signal, but detects that the primary-
transfer-roller disengagement motor is rotating, the DC controller determines that the primary-transfer-
disengagement mechanism has failed, and noties the formatter.
46 Chapter 1 Theory of operation ENWW