Lexmark T65X -- Auto Size Sensing

The T65X series has much the same auto size sensing functionality as did the earlier Ts, but the associated hardware has been completely redesigned, and flaky sensing operation is not as easy to test for. Here's a view of the size setting 'fingers' at the left side of a T650's tray. They're set for letter size in the photo.


Lexmark hasn't broken out a service replacement part number for the fingers, or any other tray component, so discarded trays will be your only source of such items. To remove a finger, slide the tray's backstop all the way to the rear and flip the tray upside down. Each finger has a little claw in back that limits how far it can pivot outward. Press on a finger's claw with a small screwdriver blade to free it. Once swung out, a finger can be slipped off its pivot pin. Here's a view of a finger out of a tray, showing the claw I was referring to.


In the chassis of the printer, the lever array, and the PCA with little snap-action pushbutton switches have been done away with; the tray's fingers operate directly on a switch module. Here's a view of the switch module in a T650.

(Not shown in that photo is a rectangular cover that's been removed. The cover has a single claw at its rear end that holds it in place.) The switch module can be removed and replaced directly; no dismantling of the machine is required. The module has two claws on it that hold it in place. Here's a view of a module out of a printer.


Switch Module Replacement

The P/N is 40X4472; Lexmark calls it "switch (media size) assembly". To replace one, proceed as follows:

1) Toner Cartridge

2) Paper Tray (Tray 1)

3) Lay the printer on its left side.

4) Remove the rectangular cover (one claw).

5) Disconnect the cable.

6) Switch Module
- The lower claw is accessible; the upper one isn't. Get the lower claw dislodged, and then it's possible to worry the thing out of place. There's just barely enough clearance, but it does come out and go back in. Don't connect the cable until the module is in place.

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Testing
As in the earlier Ts, the Paper Size item in the Paper Menu reports the size setting being sensed, but it won't report changes made on the fly. You have to exit the Paper Size item and re-enter it to see a changed setting.

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I've looked at the internal construction of the switch module, and I think these switches may prove to be far more reliable than the old snap-action pushbuttons were; the contacts are smeared with an anti-oxidant grease. I suspect that contact oxidation was what made the snap-action switches become unreliable as they aged.

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