"Entertainment
page #18"
July/August 2010 (10,010PH)
BEST
VIEWED IN 1024 x 768
|
Questions to ponder on : |
|
Click here for crossword No 8 |
Click here if you have your own cartoon you
wish to
see displayed.
Articles from
"Rick's Workbench"
Tale
of interest No.17
Fountain follies
|
What
can go wrong with a desk-top water feature?
The
phone rang one evening … It was the set-top box man at the other
end. I
had visions of more drama with his T.V. set, etc. She had
this little water fountain would only run for a day on a pair
of dry cells. I
was not really surprised when told that it used AA cells. I
was also not surprised that it only ran 1 day on these puny batteries! I
thought that it would be an easy job to permanently hook it up to a
small plug pack instead As
per usual with any small repair job or the like … They snowball
into major dramas… This
turned out to be no different! I
have a habit of hanging onto virtually all the junk I inherit. I
knew that one of the old mobile phone chargers I had hoarded would come
in
handy one day! The
DC output could easily be adapted. The
fountain was delivered to me the next day for me to “have a look at”. The
owner wasn’t in a hurry for it … Just as
well as it turns out! I
removed the exhausted pair of cells from it and hooked it up to a pair
of D
cells via clip leads. It
wouldn’t go. Puzzled,
I turned the unit upside down and examined the pump impeller. It
wasn’t spinning … And for a good reason. It
was clogged up with lint. I
couldn’t see any way of disassembling the unit. The
whole lot was sealed in. I
had to use a fine needle to carefully pick all the junk out of it. The
only access being a 3mm hole which was the water inlet! After
about half an hour it was ready for a test. The impeller was now spinning. I
measured the current it drew … Around
100mA at this stage. I
then set it up to pump some water. It
now happily gurgled away and drew about 200mA when pumping. I
was pleased to see it working at last and could now make up a lead for
it to
connect to the plug pack. A
suitable resistor was found to drop the voltage to the correct figure. The
glued in battery holder took up all of the back of the unit and hence
there was
no room to install a power socket. I
installed a flying lead with a socket on it to match the plug on the
plug pack. I then
noticed that a plug and socket assembly was used between the pump and
the
battery holder. The
plug wasn’t water-proof and the contacts were badly corroded when I
unplugged it. I removed
the old wiring .. Another
fault bypassed! I
contented myself that it was now running well on the plug pack. I
planned to run it all the next day just to be sure everything was O.K. In
the meantime, the owner rang to check on progress. I
told them it was going but I said I’d run it for a day …
They agreed to my plans. I
first thought that the plug pack had failed. I
measured the output voltage and found it to be fine. This
meant that something was wrong with the fountain. I
measured the resistance of the pump motor and found it to be open
circuit! I
removed the pump and started to phone around for a replacement. I
had no success in locating a suitable replacement. The
internet didn’t help in this regard either! I
had a feeling that water had got inside the motor and corroded the
connections
to it. I
tried every solvent I had at my disposal to dissolve the glue that
bonded the
lid onto the rest of the pump. As
I had nothing to lose, I ended up cutting right around the lid to
remove it. Water
came flooding out. I
managed to separate the motor from the impeller. I
was curious to see what had gone wrong with the motor, so I
disassembled it. More
water came out! All
was revealed! One
brush was completely missing and there wasn't much left of the other. The
whole rotor was also badly corroded. I presume that the brushes
wore
and or
corroded away. This
motor looked familiar somehow and then I remembered! I was sure
Jaycar sold a very similar motor! I
looked it up in their catalog and sure enough, there was one. I
purchased one a couple of days later. In
the meantime, I kept the owner informed of the unfolding drama. When
I got home I compared the new motor to the old one. Absolutely
identical … They both came out of the
same factory! There
was only one slight problem however, the shaft on the new one was
shorter than
the original. This
was a very frustrating development! The
shaft needed to be longer so it would join up with the impeller. The
only solution was to use the original rotor. I
cleaned it up and it looked surprisingly good after all the corrosion
was
removed. The
water was getting in where the motor shaft emerged from the motor
housing, but there was nothing I could do about that. I
set the fountain up and got it running. I
discovered that it didn’t need a lot of water to operate. I
originally fell into the trap of putting too much water in the fountain
… As had the owner! I instructed them on the correct amount of
water to fill it with when they came to collect it.
No,
not really.
|
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. |
Click here if you have your own article you
wish to
see displayed.