DIYbanter - View Single Post

Michael Black[_2_]

On Thu, 26 Feb 2015, wrote:

I have a flat screen LCD computer monitor which needs a transformer for
power. I dont have this transformer. I can get one on ebay for around
$15, but before I spend the money, I want to make sure the monitor
works. It needs 24 volts at 1.2 Amps DC. I have one from an old Laptop
computer that has an output of 16 volts 3.6 Amps DC. The amperage is
fine, but the voltage is 8 volts low. The power plug (to monitor) is
the same as needed.

I just want to be sure the monitor powers up and operate it for a
minute. Is there any chance of damaging the monitor or transformer of I
connect it to the monitor? Or will it even power it up?

It probably needs the 24volts. There's no reason to specify a high
voltage if it's not needed.

There is no expectation that the voltage might come from a variety of
sources, in this case the power supply is external either because it was
easier to get UL approval with the external supply, or perhaps because the
supply might fail and it's easier to change the power supply if it's
external. So they picked the needed voltage in the first place.

Keep looking. Ever since the move to switching supplies rather than 60Hz
transformer based power supplies, the world is alive with no longer needed
external power supplies, and they all have good current rating, and offer
a wide selection of voltages. If the first one you find isn't the right
voltage, keep looking, chances are good you'll find one in the garbage or
at a friend's place, they no longer needing it. I'm sure I've pulled
24vdc supplies out of tossed out inkjet printers (they tend to need a
higher voltage) so that's another place to look.

The big issue is to make sure you wire it properly so the polarity is
right for the monitor.

Michael