View Full Version : CQ Bizhub 750 light prints duplex only. Thoroughly Stumped.

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07-12-2012, 01:34 AM
I have a 750 at a shop with 4.4 million copies on it. Intermittent, irregular patterned light copies seems to be on the duplexed side only. I have a lot of thoughts and questions running through my head on this so I am going to record them here. Toner control board, Drum, Transfer Charge Assembly have all been replaced. Dipswitch 27-2 is set to off so toner is being added during operation, atleast software wise. I have only seen the machine once and that was to replace clutches and gears on the front of the ADU. It appears that every other copy is fine. I should see if simplex copies appear normal one after the other. I bet they print fine. Perhaps a height adjustment on duplex angle is possible? Need to check TCR and life remaining on developer unit and developer powder. Toner recycler gear and clutch look old. Replaced 2 of those in other machines but that issue was noise only, no image deformation. Not sure how likely that is. Way to check if toner motor spins bottle? Perhaps an HVB is going bad? Why duplex only though?

Any other possibilities guys n gals?

07-12-2012, 04:38 AM
The control board needs to be replaced, it controls the transfer separation for the second side.

07-12-2012, 06:02 AM
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07-12-2012, 06:52 PM
Which control board?

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