"Entertainment page #9"
  June/July 2007 (10,007PH)
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Question to ponder on ?
A technician friend has put this to us :
"Why is it that the active pin on mains plugs is the one that always over heats if there is a bad connection ?

This applies even when no earth pin is present."

Click here for crossword No 3
(answers at bottom of this page)

Articles from "Rick's Workbench"

Tale of interest no.9
A tale of two printers :

Some time ago, a good friend of mine asked me if I was interested in an inkjet printer.
I was in need of an older style unit that would print in DOS, and he thought he had just the unit.
My favorite CAD programs were DOS based and would drive the older HP inkjet printers.
I said I’d be interested in any old HP printers that he may come across.
Eventually one had turned up.
A HP 870cxi professional series DeskJet…
Excellent, I thought,, and it had colour capabilities as well !

The printer was dispatched to me in the post along with other junk / treasures.
My friend couldn’t send the paper tray for it in the same package however, as it wouldn’t fit into the box.
He was going to send that separately in due course.
In the mean time I looked forward to receiving the package…
It’s always like Christmas when I receive one of my friend’s packages…
I never know what treasures lie within!

The printer was removed from the box and placed on the lounge room carpet whilst I drained the last of the packing paper and foam into a plastic bag.


The printer had leaked THICK, BLACK INK into the bottom of the box and it was also on the bottom of the printer.

I quickly removed the printer and then went about trying to clean the mess off the carpet.
I eventually got most of it off.
The printer had ink all through it.
I was going to have to strip it all down and clean the ink out of it.

I pulled it apart the next day and confirmed my worst fears…
Ink had gone everywhere inside it !
That was as far as I could go with it as urgent family matters intervened.
As it happened, I had to go to Adelaide for 3 weeks and I caught up with my friend at the same time.
He then gave me the missing part of the printer along with more junk he planned to send.

On my return to home, I tackled the printer again.
I stripped and cleaned every part of it.
I then reassembled it and was greeted by a flashing LED,,,  and that was it !
I knew this meant an error of some sort but I couldn’t determine what the error was.

I then fiddled around with it for some time and got nowhere.
In the meantime, I got part of the paper handling mechanism in the wrong position (I didn’t know this at the time) and it then made horrible clunking noises.
I put it aside for a while.

I found yet another HP printer at a local tip shop.
It was a HP 710C DeskJet and at the scandalous  price of $5.
I thought it might work.
It also used the same printer cartridges as the HP 870cxi, so it was purchased.
Upon trying it out, it did the same thing as the other one…
ie: Nothing,, apart from a blinking LED.

I then did what I should have done in the first place.
I looked up the printer on HP’s web site and looked up the error list for the 710C.
The printer cartridges were nominated as the cause !

Right, I thought.
I’ll buy a new (black) cartridge for it and see what happens.
Nothing changed until I tried a different colour cartridge then, lo and behold, the LED stopped flashing.
I then tried printing something from Windows,,  and it worked.
I then tried printing from DOS…                            Nothing…
I was sure this printer would work with DOS.
A check on the web site confirmed that it would.
I tried again, but even in Windows98 DOS mode it still wouldn’t work.

Oh well !   Back to my friend’s printer.

I sorted out the problem with the paper handling mechanism and, after a lot of fiddling about, got the printer up and running.
The cartridges were the problem after all, as HP cartridges are a little different to most other inkjet printers.
The cartridge itself contains the print head and it relies on lots of tiny contacts on the back of the cartridge to line up and (hopefully) make contact with mating pins on the cartridge carrier.
They are Gold plated, but it only takes the slightest bit of contamination to stuff it up, and the printer senses this and shuts down.

This printer works well with DOS or Windows, and I found a driver that works with my old favorite CAD software.
I still don’t know what’s wrong with the HP 710C…
I can’t even figure out how to get it apart to investigate any further !
I will tackle it again sometime but now at least, I have a good working printer.
The cartridges are large so they should last a long time.

I’ll now wash the ink off my hands and say bye !

Till next time.

All rights for this article belong to "Rick's Workbench" in Tasmania

 Disclaimer  :  We do not recommend attempting mains powered projects or repairs without qualified assistance.
                                                     The articles from "Rick's Workbench" are for entertaining reading only.

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