From: uhclemLOSE.sep06@nemesis.lonestar.org   
      
   Rick  wrote:   
   : This all begs the question: Does anyone know what this problem is with   
   : dot matrix printers as they age?   
   :   
   : I've seen if more than once on a well used printer where the head   
   : transport seems to just "jam" or stick, usually when traveling in a fast   
   : motion, creating all manner of illegible chaos when it recovers from   
   : getting hung up. I've had the problem with a Star Micronics NX-1000 and   
   : and old Epson that predated that one.   
   :   
   : On most of them disassembling the printer to see what type of bearings   
   : are moving across that carriage rail is very difficult. But it seems   
   : hard to believe the head transport is running on bearings that use no   
   : lubricant at all when shipped.   
      
   The most common problem with dot matrix (and some ink jet) printers acting   
   as you describe has nothing to do with the track bearings, but dust in   
   the optical interruptor disc, usually mounted on one end of the carriage   
   drive motor.  Dust in the unit causes the printer to mis-count its   
   position, and with sufficient error this cause the head assembly to   
   crash into either stop post and appear to be "jammed".  Wavy and   
   irregular vertical alignment of print output are the early warning signs   
   of dust in this assembly.   
      
   Typically higher speed operation (draft vs quality/graphics) print   
   settings cause the dust problem to show itself since the interruptor disc   
   is moving faster and so there is less time to interpret the "maybe"   
   optical state (instead of clear/opaque) caused by dust clogging one or   
   more of the slits or blanks in the disc.   
      
   Blow the interruptor assembly out fully and re-assemble.  Then see if   
   the printer starts acting less quirky.   
      
      
   Frank Durda IV - send mail to this address and remove the "LOSE":   
       http://nemesis.lonestar.org   
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