Information Systems:Zebra Thermal printers

Configuration

Each picking station in the warehouse has two Zebra label printers. One label printer is for printing price tickets and the other is for printing shipping labels. Most of the Zebra label printers have model numbers of 2746E or S4M and need to have a firmware level of E50.13.5.

At the picking station there is an HP print server with three LPT ports. Port 1 is always used for the invoice laser printer (Lexmark), port 2 is always used for the shipping label printer and port 3 is always used for the price ticket printer. This arrangement is determined by the setup of the print queue on the System i.

The Zebra label printers at the picking stations are 'direct thermal'. Thus, they do not use ink/toner, nor do they need ribbons. Essentially, the paper acts as the ink and the heat from the printhead exposes the print.

Other notes

• The thermal rolls (print media) required for these printers are managed (including sourcing them) by Gerald/DC.
• Rolls are loaded into the printer differently according to their type. DC staff are familiar with how to load price tickets vs. box labels. Instructions are also imprinted on the inside wall of the printer.

Administration and troubleshooting

Administration is done through the panel on the device (e.g. the S4M cannot be remotely administered through a web GUI). When using the panel, there are two admin levels beyond the basic settings that you can enter with the following passwords:

Admin level 1 password: 0000
Admin level 2 password: 1234

The Zebra S4M printers are very stable. They can operate for years without issue, needing only basic cleaning every so often. Problems are rare, but given the age of our fleet of printers (~8-9 years), a myriad of issues have been observed (although few and far between). Since the mechanical design of these printers is quite simple, diagnosis is not difficult and it is usually visibly clear what the problem is and whether the problem/part is serviceable, or if the printer is considered irreparably broken (e.g. not feasible to repair). Most problems fit one of the following:

Bad flash

Symptoms: 'BBLOCK' messages on LCD, delayed printout with constant 'Defrag' messages on the LCD.

The printer has a small amount of memory (most likely some flash card). Over time, flash memory eventually degrades, and this manifests as warnings on the printer (Bad block), or through the printer attempting to self-correct flash errors by defragging the filesystem. The latter causes noticeable delays in print output, while the former is just a constant error display on the printer LED. However, print quality is unaffected. Use your own discretion when deciding whether to replace printers degraded by bad flash. If the printer is constantly defragging, there is an admin function in the settings to initialize memory that should be tried (it may help).

Cracked platen roller

Symptoms: Faded print areas, gaps in printing

The white, dense, rubber platen roller is one of the few parts that can feasibly (in terms of cost of the part and degree of difficulty of installation) be replaced by a user. This roller is critical to the function of the printer, as not only does it help feed the media, it is responsible for pressing the media onto the printhead. Gaps in contact lead to gaps in the printing.

Broken head motor

Symptoms: Media not feeding, misaligned feed, loud whirring

This part can also be purchased but probably requires the expertise of a printer technician to install.

Degraded printhead

Symptoms: Print appears faded.

Over time, we have seen printheads become degraded. When this happens, the prints no longer come out dark, as if the printer were 'running out of ink'. A possible theory is that the head can no longer reach a sufficient temperature to heat the print media. The printhead is probably the most expensive part and it is not feasible to replace.

Obstructed gap sensor

Symptoms: Printer feeds endlessly after a printout or after a single press of the 'Feed' button. There is a laser/light that acts as sensor to tell the printer when to stop feeding. Essentially, it senses the gap between two labels and positions the feed so the label can be torn off. Sometimes, bits of labels or other pieces of dirt can obstruct this sensor. This sensor is visible as a red dot shining up onto the left side of the thermal printhead.

Future Upgrade

It would not be logical to replace all printers with newer devices in one batch; that kind of hardware life cycle or upgrade routine just does not suit this class of product. Rather, it was decided to purchase a new printer when the number of available spares reaches 3. Buying printers in 2s should be proposed, as then a picking station can be converted from print-server connectivity to direct, ethernet connectivity.