Fujitsu DL6400 -- Jam Lever Alarm

The subject alarm can be falsely caused by a flaky sensing switch. Here's an explanation of the alarm, and the jam lever's operation.

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The DL6400's front tractor has a curious feature associated with it -- the tractor and the pinch roller set directly above it can be unlatched from their normal operating position, and opened up somewhat to facilitate clearing a jam. There's a green tab and a lower black tab at either side of the front tractor cavity. You press the green tabs down to open the mechanism; press the black tabs up to close and latch it. Here's a view of that in its normal operating position.

And here it is opened up for clearing a jam. (The difference is subtle -- the position of the green lever is the key to seeing it.)

The paper path above the tractor is opened up slightly, the tractors are lowered and disengaged from the drive train, and a switch at the left side of the chassis (the 'OC switch unit') has been opened. The switch is the sensor for open/closed status of the front tractor.

The printer's controller considers the open state to be a fatal error condition, and displays a "Jam Lever Alarm" indication if you unlatch the tractor while powered on, or if you power on with the tractor unlatched. The alarm looks like this.

'PAPER OUT' is flashing, 'COUR 10' and 'Time PS' are lit. (The 'MENU 1' LED has no relevance to this.) The printer is inoperative. To recover from the alarm, latch the tractor back in its normal operating position and power off and back on.

The sensing switch, the 'OC switch unit', is on the left side vertical chassis member. Prop the chassis up in its service access position to get at the switch. Here's a view of the switch.

Note the disengaged gear that's below and to the right of the switch; that's the tractor drive gear. It's normally in mesh with the gear above it when the tractor is latched up in place.

And here's the switch free of the chassis. (Just pinch its claws to remove it.)

A switch that develops high contact resistance with age will give false Jam Lever Alarms. A service replacement switch is P/N CA02464-F365. The switch's two-conductor cable plugs into connector 'CNMUOC' on the Connector PCA.

WD-40 is sometimes helpful for a flaky switch. Apply it around the switch's plunger and work the plunger many times. Check the switch's closed resistance with an ohmmeter; it might be restored to normal.

In a pinch, you could cut the switch's cable and short the wire ends together to get a printer going.

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