"zirath" wrote in message
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Arfa Daily wrote:
"Arfa Daily" wrote in message
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"zirath" wrote in message
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Tim wrote:
In article xTkLj.3775$bQ1.832@trndny09, says...
Arfa Daily wrote:
"zirath" wrote in message
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We recently got a gateway fpd1520 (15" lcd flatscreen) monitor from
ebay. It didn't have a power cord. It says it's a 12v dc 2.5a but
it doesn't give the polarity. A person from gateway said he thought
it wouldn't hurt the monitor if it got plugged in backwards but I'd
rather not try it.

Would appreciate any help.
If it has got any external metal parts such as RCA (phono) connector
outers, BNC connector outers, 'D' connector surround etc, or
possibly screws for a stand, as these often go right through the
plastic case, and into the internal chassis, then try measuring from
any such metal to each of the DC power input connector's terminals
in turn, using an ohm meter. Chances are you'll find a direct
connection, and that will be your DC ground ( "-" ) connection. The
other will then be the "+". Assuming that it's a 'standard' co-axial
DC connector, on most modern equipment, 'pin' is "+" and side
contact is "-" although that's not cast in stone. Be aware when you
are obtaining a replacement PSU, that the plug is often a slightly
abnormal size, being a little larger than those you typically find
on 'general' power supplies. Also, make sure that you get one well
rated for the job, as these monitors do draw quite a lot of current,
and may well surge up close to the quoted 2.5 amps at startup, as
the LCD backlights first fire up before settling to their run
current.

As to whether it would be safe to reverse connect it, I wouldn't
like to say. Some equipment is perfectly well protected against such
'consumer antics', but it is by no means guaranteed, and if it is
not adequately protected, the result is often an item that's fried
beyond repair, for no other reason than unobtainable power supply
devices, as many previous posts on this subject over the years, will
attest ...

Arfa

The ohm meter showed something like a capacitor on the center pin (it
went to 0 and then back towards the center). The side showed no
resistance.

The monitor went on briefly and then went black when plugged into the
power. Seems like it's a dud. Not sure if it's worth trying to repair
it or just return it.

Is there no little pic of the connector around where it give the info
about power? Usually there is a universal icon used that indicates
polarity, kinda like a big C around a dot. Most, but not all, coaxial
power connectors have the minus side on the outside, that way if it
touches a grounded side, it will not destroy the adapter. If the
adaptor cannot start the monitor because it is not powerful enough, it
will sometimes just flash the backlight then go off.

- Tim -
The adapter symbol shows center + and side -. It is labeled 12vdc 4a.
The monitor is 12vdc 2.5a so the adapter should have enough power.
Before condemning the monitor, I would feel inclined to just try a
different power supply (bearing in mind that the one you are using now
is not an 'original'). The reason that I say this is that there can be
quite a high initial pulse of current demand, as the backlights strike,
and it just might be that the power supply sags a little when hit with
this, even though it *says* that it is rated for 4A ...

Arfa

Thinking about it again, were you trying it with a signal going in ? LCD
monitors, like their CRT counterparts in many cases, don't just 'idle'
when there is no signal. They do just like you say - that is power up
long enough to check if they can detect an input signal, and if they
can't, go back to an inert condition.

Arfa

I tried it in a few different conditions: with the monitor on 1st and then
the computer - it showed the computer booting for a few seconds and then
went black - then it came on again after the boot was finished for a few
seconds and then went black again; with the computer on and then the
monitor; with the monitor disconnected from the computer (the manual says
it's supposed to bring up a diagnostic screen in this condition but it
didn't). The screen stayed black the whole time in subsequent attempts.

The power led would go from yellow to green when the computer started
booting but the screen stayed black.

I also noticed that the screen was not completely flush in the housing -
like someone had tried to, or did, open it and didn't close it completely.

The fact that the light stays green, is a good sign. What you next need to
do, is to shine a strong desklamp or hand flashlamp at the screen at an
angle, after it has gone back to black. If you can then see an image on the
screen, that indicates that the backlamp tubes are not staying alight. This
could well be because either the inverter is faulty, or that a worn tube is
making the inverter shut down. Either is quite a common fault condition.

Arfa