As mentioned in previous blogs in this series "Replacing Drive Belts in Thermal Transfer Printers" and Platen Rollers Part 1: Replacing Platen Rollers on Zebra Performance Industrial Printers," all configurations of Thermal Transfer Printers have rubberized, dual-purpose rollers.For more details and photos, please reference those entries.Because Platen Rollers are vital for producing high quality thermal transfer print and the rubber coating is subject to various forms of degradation - they must be replaced on a regular basis. What's An Economy Industrial Zebra? Well, it's not a striped horse willing to work for peanuts. Models Z4000, Z6000, Z4M, Z6M, Z4M+, Z6M+, ZM400, ZM600 and the S4M make up most of the Economy Industrial Tabletops from the past and present. Fortunately, this whole set of Zebras has Platen Rollers that are removed and installed in the same way. Grooves, Scratches, Cuts, Divots and Wraparounds Do they sound suspiciously like the dance moves of a Platen Weasel?No, they're reasons for removing a Platen Roller.If the rubber coating is flawed in any way it will sooner or later fail its vital function of providing consistent back pressure for the labels to be printed with acceptable resolution. The results will be random, open areas that may make text unreadable or barcodes incapable of being scanned. These should be replaced as soon as possible. If the rubber coating is still in good condition but has a label wrapped around it - it will fail its other vital function of pushing labels forward. These must be cleaned of all adhesive and debris before being fully operational.When considering those candidates for cleaning, the idea is to take a removed platen roller and soak it in isopropyl alcohol or citrus degreaser, then peel or rub away all of the adhesive and label debris with paper towels without harming the rubber coating. Avoid any tools although a soft toothbrush may help. This is easier to do with paper labels because they allow the solvent to penetrate into the adhesive. Synthetic labels prevent this but with patience and repeated applications these will also eventually fall away. For more detailed photo and text procedures on cleaning platen rollers please visit future entries in this series. And Away It Goes - The Sequel First, release the latch that holds the Printhead down and lift the entire assembly into the UP position and onto the left-side magnetic contact. Unlike most Zebra printer models this set has printhead assemblies hinged to the left - Gull Wing style. Pry away the front plastic trim with a screw driver and remove the Peel Tear Plate along with its pair of Hex Key Screws using a 5/64" or M2 Allen Wrench. Over to the electronics side loosen (one turn is plenty) the M3 (metric Allen wrench) Hex Key Screw that holds the Stepper Motor onto a curved, steel slider. This slackens the Main Drive Belt which is connected to the steel pulley gear on the Stepper Motor's turning rod facing the inside of the printer.Then loosen the pair of 5/64" Hex Key set screws that fix the plastic pulley gear to the inside steel rod of the Platen Roller which would be the left side rod when facing the printer's front. This gear is usually double-tracked depending on the Dots Per Inch rating so be sure to make note of which one that the Main Drive Belt is being removed from.Push the Stepper Motor forward on its slider and remove the belt from both pulley gears. Slide the Plastic Pulley Gear away from the left side rod of the Platen Roller. The Platen Assembly from left to right includes a left-side U-shaped steel clip, a brass bearing, the platen roller in the middle, a curved washer, another brass bearing, and the right-side U-shaped steel clip. The steel clips are interesting because they have a barb on each leg designed to prevent any lateral or upward movement. This tight tolerance is very effective while in operation but it makes removing them quite the wrestling match. Here's How.Starting with the right-side when facing the front of the printer, take two flat-tip screw drivers and press both barbs of the right-side U-shaped steel clip inward and up at the same time.This may take several tries but eventually the clip will loosen enough that it can be pried upward its curved section and removed. Repeat for the left-side clip but leave it in place because the space is too cramped for full removal.Lift the right side of the Platen Assembly and pull the left-side rod out of its brass bearing. Be sure to remove the curved washer and right-side bearing from the Platen's right-side rod. All that remains is the left-side bearing and clip.Gently pull the left brass bearing out with pliers if necessary. Then pull the left-side U-shaped steel clip up and to the right to avoid catching on the Printhead Assembly. For the Economy Industrial Zebra printers this is what an empty platen housing looks like.Whether you have cleaned a Platen Roller or will install a new one altogether, be sure to give the rubber section one last cleaning with an isopropyl alcohol soaked paper towel before installing. To install, repeat the entire procedure in reverse and use this opportunity to replace the Main Drive Belt before it starts to slip. Once the Platen Assembly is in place, slide the Plastic Pulley Gear onto the Platen's left side rod but not so far that it grinds against the wall and then tighten the pair of 5/64" set screws. Push the Stepper Motor forward and place the belt over its metal pulley and the Platen's Plastic Pulley Gear. Be sure that the belt is on the correct track of the platen pulley. Slide the Stepper Motor back while allowing the belt a small amount of wiggle room. Tighten the M4 screw. Test by gently pulling the entire assembly forward to make sure that there are no odd noises and that the Main Drive Belt is on track. There, it is done and with only minimal intervention by a disco Platen Weasel. Mike previously provided Tech Tips for Replacing Platen Rollers for Zebra Thermal Transfer Industrial Printers. He followsup that highly successful blog with the companion Replacing Platen Rollers for Zebra Thermal Transfer Economy Printers. Please click on the button to ASK MIKE any questions you have.
