Plotter nemesis defeated

I have a love-hate relationship (as do most folks in our office) with our HP 450C D-sheet plotter.  On the positive side of the ledger:  it prints out D-size sheets in color.  This proves valuable for schematics – having the entire circuit on one legible page makes understanding and troubleshooting designs much easier than having the schematic on a screen or paging through a bunch of 8 1/2” X 11 “ pieces of paper.  On the negative side:  it uses 12-year old ink-jet technology, so the ink pots dry out, unless a couple of full color pages are printed a week; loading a roll of paper, while theoretically easy, tends to become a half-hour adventure in “hoping the plotter accepts the paper this time”; sometimes it does not print certain symbols on the schematic; it is 12 years old, so it is obsolete and HP does not seem too keen on supporting it.  All that aside, the plotter is a workhorse in our company.  Because plotters are such a low volume item, the price of a new replacement is on the order of $2500 – pretty big pill to swallow when the plotter “mostly works”.

Unfortunately, last Thursday, the plotter gremlins decided to strike.  I was plotting a schematic for a new test circuit when the plotter made the most ungodly noise and stopped working altogether.  All three of the error indicators were blinking an ominous orange.  Upon further exploration, I was able to see that the main drive belt appeared shredded.  Much to my chagrin, there is no easy way to replace this.  Luckily I was able to find the actual service manual on line and disassemble the plotter.  Because of the way the plotter is assembled, this project would have been much more difficult without the manual.  There are a bunch of “hidden” screws and odd orders of operation.


After some teeth-gnashing and hair pulling, I removed the offending belt.  Obviously, there was no way to salvage it.  I think the belt was the original – so the 12 year old rubber was probably due to fail.


I ordered a new belt through Amazon.  It showed up the next day (amazing!).  I was able to get the plotter back together on Friday – it all looked good.  But I was unable to load the paper before I had to leave – my first try ended in heartache.  This morning I tried again and 20 minutes later, I had the plotter back up and running.  Now I should be able to get back to designing cool stuff, and the rest of the office can plot in peace.



  1. Nice page on repairs made. I have one of these plotters, most of the plastic shell and paper feed is gone,was going to scrap it out, save the electronics, part of the mechanical. Maybe I will place it on Ebay to see if someone needs it.

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