Bar-Code Printer / Thermal Printer General Troubleshooting Guide

The following guide is not specific to any model of thermal printer but should be used as a general guide to troubleshoot and correct problem for barcode and thermal printers. This guide will be updated as various symptoms and solutions are added. You can use the guide above to jump directly to a specific topic or you can read it here or save it in adobe format.

Nearly all problems fall into or overlap three categories: 1) Print Quality Issues, 2) Set-up and Configuration Issues, 3) Poor Operation Issues.

Print Quality issues are the most common type problem encountered with this general class of printer. Most of them are corrected by simply cleaning the printer. Others can be corrected by making minor adjustments to compensate for general wear of the printhead and drive rollers. Some of these adjustment are mentioned in your operator’s guide. Other adjustments are best left to the trained service technician. Like most people, I like working on my car and motorcycle to keep them operating at their best and preventing catastrophes. But other times, the trained service technician are recommended to do the level of work beyond my garage training. Having a service technician available to you will also help to sort out many of the causes of symptoms listed here since cause and effect many times overlap.

Light print is generally caused by an inadequate darkness setting. It is generally corrected by increasing the darkness setting. But beware of increasing the darkness setting because doing so increases the time it takes printhead to transfer an image to the label. Too much can burn and cause ribbon or label material to build up on the printhead resulting in premature printhead failure. It can also cause the print to blur or smear. Many times, users increase print darkness to compensate for light printing when the fault is really due to a line in the image due to dust or an incompatibility between the ribbon and label material being used or incorrect printhead adjustment. Before increasing the darkness setting correct what may be causing any of the above to happen. There are many types of label and ribbon combinations that can be used depending on the application. For instance, a resin ribbon will not transfer properly when used with plain paper stock. Alternately, wax or wax resin ribbons may look OK on a poly film label but will smear or even rub right off. Correcting printhead adjustment, regardless of the model, needs to be done in an organized fashion or else the print quality will deteriorate.

Smearing print and blurred print may also be caused by poor mechanical adjustment of the printer or printhead. Too much or too little printhead pressure, ribbon supply tension, or ribbon take-up tension will cause ribbons to perform poorly. Many common adjustment for these assemblies are listed on the operators’ manual but often they’ll need maintenance and small parts replaced.

Dark print is most commonly caused by too high of a darkness setting or thermal vs direct thermal setting, and can be corrected quickly through front panel operation, but often times we see poor quality ribbons in use. Such ribbons may not meet or exceed OEM standards and eventually cause premature printhead failure. Some things to look for are “fast wax ribbons” or “low temp ribbons”. Check with your vendor to make sure the quality of your ribbons meet or exceed OEM standards and that the ribbon type is matched up properly with the type of label being used. Dark print can also be the result of too much build up of ribbon or label material on the printhead. This build up retains heat and can cause excess transfer and can reduce the life of the printhead. It can also cause vertical dark lines to appear in the print direction of the label. This build up creates ridges on the printhead or the printhead’s ribbon strip plate which etches the ribbon material onto the label itself, creating a false image. Check your operator’s manual for the proper frequency the printhead should be cleaned.

When a printhead is worn and past it’s useful life, it will cause vertical white lines to appear. These “voids” can cause barcodes to misread. Generally they cannot be brought back to life, the printhead needs to be replaced. Be sure of the proper procedure to replacing a printhead. Printheads that are not installed properly are doomed to fail prematurely and most vendors or distributors will not warranty printheads if they are not properly installed and adjusted Improperly adjusted printheads can also cause diagonal lines, crows feet,ribbon wrinkling, faded print from left to right or right to left and darker print on either side or the middle. Many time these same phenomena are caused by a worn drive roller. But in any case they are cause by the interaction of the printhead’s uneven pressure in relation to the drive roller and all are most noticeable when the printer is used with ribbon. Service technicians are trained to get these settings back to the way they were set at the factory. If you have a service technician that visits you regularly, they’ll probably know just how to set your printer up for the type of printing you do.

“No printing at all” is a common occurrence when a printhead is completely shot, but it is most often a result of incorrect printer configuration to either the type of label printed, incorrectly loaded ribbon or paper (backwards or upside-down). In these cases it is best to unload the printer of media and ribbon observe the side in which label are loaded to the liner, and observe whether the ribbon you have is “coated side in” or “coated side out”, then load both accordingly. Sometimes vendors get it wrong and ship you the incorrect material.

Set up problems , data communication issues, incorrect printer drivers and cabling problems will cause garbage printing, paper out errors, ribbon out errors, and missing labels. With all these possibilities, troubleshooting is best handled by first reviewing the setup parameters, then separating the host computer from the printer or substituting the printer with another to see if the problem follows the printer or stays with the computer. A good technician will be able to point out the cause and fix it if it is a printer issue, but don’t count on them fixing your computer issues, driver problems, or network communications unless you are ready to accept a hefty bill for their troubleshooting and their work. Most technicians I know will probably walk away at this point and tell you that it is an IT problem. Others, like myself, will pinpoint the problem but leave it up to you to fix it unless you’re willing to pay for the extra time needed to correct the problem entirely.

The last set of problems falls into the poor operation / no operation category. Most of these problems will require a service technician to be called, simply because their experience and training allow them to quickly identify the problem and correct it.

If your printer does not power up properly or not at all, doesn’t feed labels when the “feed “button is pressed. There is not sense fooling with the printer except to try a clean power supply and restarting the printer. Call a service technician immediately since the printer is most likely a safety hazard at this point.

If it doesn’t operate properly, such as squeaking, skipping labels, elicits ribbon out and paper out errors, incorrectly feeds labels, misses every other label, prints garbage, or peels up labels, check the setup of the printer, recheck proper loading of ribbon and paper, assure the proper label format is correct for the type of label printed and the driver. These problems, many times occur right after a new ribbon is loaded or a new roll of paper is installed. Just reinstalling these, many time corrects the problem. Other times, checking to see if sensors may have been bumped and brought out of alignment may reveal the cause of the problem. Cleaning the printer and keeping it clean goes a long way in preventing problems. Otherwise, calling in a technician who has a respectable response time will save you many hours of pain and misery and well as wasted stock and ribbon. Most technicians worth their salt will clean and inspect the printer and this will save future service calls.

There are many other problems that should be left to a trained eye can sort out, identify and remedy:

• Cant remove ribbon or slips on spindle
• Can’t remove paper or slips on supply
• Labels peal off in printer
• Chattering / Grinding noises
• Squeaking noises
• Paper doesn’t feed out completely
• Paper walks left or right
• Breaking ribbons
• Tearing paper

If you are experiencing any or a combination of these problems, it is time to go over the printer with general maintenance. Each brand and type of printer has its own set of maintenance checklist so it cannot be covered here, but in general, drive rollers, belts, gears, internal printer cabling, printhead adjustments should all be inspected and adjusted as well a thorough general cleaning which focuses on the drive mechanism itself. Your technician should know this checklist for the type of printer you have. A periodic maintenance check such as what you have on your car or motorcycle will go a long way in preventing emergency calls and unproductive downtime.

If you would like specific information regarding your printer, please contact us and we'll be glad to get you on your way to resolving you problem.

--Bill Marks, Thunderbird Technical Services, Inc.

Send mail to info@thunderbirdservice.com with questions or comments about this web site.

Last modified: December 4, 2004

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