Lexmark T640dn: included wired duplex with a deeper body review

The duplex unit is included, and the body changes

The Lexmark T640dn is a monochrome network printer with a supplied duplex unit. Exact US part 20G0130 includes Fast Ethernet, USB computer connectivity and 350 sheets of input. It fits a wired office that needs automatic two-sided Letter, Legal or A4 documents within the maker's recommended 3,000–14,000-page monthly range.

The physical difference is substantial. The exact dn package is 25.1 inches deep and weighs 49.1 pounds, compared with the shallower, lighter base arrangement. Allow operating access beyond those body measurements. A base-model footprint or an image without the matching duplex unit is not an adequate space check for this package.

Set up a wired queue and protected release

The supplied network interface is 10/100BaseTX Ethernet. USB Type-B provides another computer arrangement, while parallel supports a separate legacy path. Wireless and gigabit interface options are not the included configuration. Confirm the offered hardware and compatible software on the systems that will actually print.

The original network instructions check connected status and IP settings before installing a print queue. For ordinary jobs, match paper source, size, type and side settings in the driver. The guide's historical Windows and Mac procedures do not guarantee support for every newer application or operating system.

Confidential printing has a specific submission and release routine. Compatible Windows software uses Print and Hold; the Mac procedure uses Job Routing and Confidential Print. Submit a user name and four-digit PIN using digits 0–9, then enter the matching code at the panel to release the selected job. The printed confidential job is removed from memory.

That memory-held process is separate from optional hard-disk encryption. Other held jobs, including Verify, Reserve and Repeat, have different behavior and do not all require a PIN. Choose the actual confidential routine when local protected release is essential.

Duplex capability does not add another drawer

The included matching 250-sheet duplex unit refers to the standard-tray configuration it fits. It is not an additional 250-sheet input source. Actual supplied paper input remains the 250-sheet drawer plus 100-sheet multipurpose feeder, totaling 350 at the stated 20-pound or 75-gsm basis.

Letter, Legal and A4 are positively supported by the ordinary inputs and duplex unit. Adjust guides, keep below load lines and select matching paper size/type. The guide's preprinted-paper loading directions change with duplex and finishing arrangements, so follow the illustration for the actual installed options rather than assuming one orientation fits every setup.

Suitable envelopes use the separate one-sided MPF routine, with up to ten under the documented conditions. Select Envelope and the exact size. Avoid stamps, windows, clasps, damaged stock and exposed adhesive. The optional 85-envelope feeder is different hardware, and envelopes do not inherit ordinary-paper duplex.

Front PDF access and expanded installations

The front USB Direct interface supports the documented PDF-printing routine from suitable FAT-formatted storage. NTFS, encrypted files and files without printing permission are excluded by the original guide. Leave the device connected until printing completes. This host interface is separate from the computer's Type-B connection.

Maximum input of 3,850 sheets, additional output devices and finishing need optional equipment. Base output holds 250 sheets. Inspect installed drawers and recognized driver options, and follow the support-furniture requirements for larger floor-mounted combinations. Paper-handling options do not add scanning, copying or fax to this print-only machine.

Use the proper speed mode and supply region

Lexmark declares up to 35 one-sided Letter pages per minute and separately 30 black Letter sides per minute in automatic duplex. Neither is a measured application result. The 200,000-page maximum duty rating does not replace the recommended regular monthly ceiling.

The original US supplied cartridge declares 6,000 pages. Americas replacements include 6,000- and 21,000-page choices under ISO/IEC 19752; the T644's 32,000-page option does not belong here. Inspect maintenance condition, specialized label components and the electrical label on this discontinued model. Compare another body or an MFP if space or original capture is the deciding requirement.