viewsonic VX800 LCD

[divx dude]

i got these two monitors VX800 nice looking 18" LCD desktop monitors
that use an external power brick.
my research sez the brick is 12vdc at 5A.
my plan was to makeshift something, i found a 3mm?
plug to fit the power jack and wired it to the 12v drive molex line on
an old AT power supply form the 486 days pre-ATX.
the 12v rail is rated at 8A.
the grren light on the moniotor comes on but flashes display text the
POST screen on the PC flashes it only for a second.

i can repeat that 1 second by cycling the power button but thats all i
can get from it. i tried a 12v rated lass than 2A
same responce. i tried the drive molex line from the ATX supply on the
PC i'm using tot test it but no green light. i measured the volts on
that line and its like 13.5vdc or so..
there was another brick i tried also but no green light and slightly
more than 13vdc.
so the monitor is picky and refuses 13v+

i havent tried the other monitor yet. im expecting someone already
knows these are buggy and bet it probably has the same issue.

requesting any assistance u smart people can provide.

 

[Meat Plow]

On Sat, 14 Aug 2010 10:57:07 -0700, divx dude wrote:

i got these two monitors VX800 nice looking 18" LCD desktop monitors
that use an external power brick.
my research sez the brick is 12vdc at 5A. my plan was to makeshift
something, i found a 3mm? plug to fit the power jack and wired it to the
12v drive molex line on an old AT power supply form the 486 days
pre-ATX. the 12v rail is rated at 8A.
the grren light on the moniotor comes on but flashes display text the
POST screen on the PC flashes it only for a second.

i can repeat that 1 second by cycling the power button but thats all i
can get from it. i tried a 12v rated lass than 2A same responce. i tried
the drive molex line from the ATX supply on the PC i'm using tot test it
but no green light. i measured the volts on that line and its like
13.5vdc or so.. there was another brick i tried also but no green light
and slightly more than 13vdc.
so the monitor is picky and refuses 13v+

i havent tried the other monitor yet. im expecting someone already knows
these are buggy and bet it probably has the same issue.

requesting any assistance u smart people can provide.

I was given a Sanyo VIZON 15" LCD TV without its PSU. The 4 pin
proprietary jack said 12 volts @ 2.5 amps. I managed to install a common
jack and thought I would use an old ATX supply. The ATX supply puts out
12 volts at 10 amps. When measured it was slightly higher at 12.2 volts.
I said cool and applied power to the Sanyo. All was well for a few
minutes then the backlight started to flicker. Slow at first then
faster until it reached about 2 flashes per second. I thought well the
inverter is shot. Hooked up 13.8 volts @ 1.5 amps (actually a variable
supply) and the flashing stopped at 13.3 volts.

So yes your situation could be similar. Borrow a 0 - 15 vdc supply and
see if you can dial in a voltage where the monitor will work.



--
Live Fast, Die Young and Leave a Pretty Corpse

 

[divx dude]

Hooked up 13.8 volts @ 1.5 amps (actually a variable
supply) and the flashing stopped at 13.3 volts.

So yes your situation could be similar. Borrow a 0 - 15 vdc supply and
see if you can dial in a voltage where the monitor will work.

think i can maybe use a POT on a 13.8v supply ?
what value pot?

if put it in series after a fixed resistor 2x its value doesnt that
focus the variable to the upper 1/3 of the voltage range?
in other words would make like 9 - 13.8 vdc variable supply instead
of
0 -13.8.

 

[Meat Plow]

On Sat, 14 Aug 2010 11:49:44 -0700, divx dude wrote:

Hooked up 13.8 volts @ 1.5 amps (actually a variable supply) and the
flashing stopped at 13.3 volts.

So yes your situation could be similar. Borrow a 0 - 15 vdc supply and
see if you can dial in a voltage where the monitor will work.


think i can maybe use a POT on a 13.8v supply ? what value pot?

if put it in series after a fixed resistor 2x its value doesnt that
focus the variable to the upper 1/3 of the voltage range? in other words
would make like 9 - 13.8 vdc variable supply instead of
0 -13.8.

Look up Ohm's Law and calculate the values yourself.

I=V/R or V=IR or R=V/I V-voltage I-current R-resistance.



--
Live Fast, Die Young and Leave a Pretty Corpse

 

[divx dude]

On Aug 14, 3:08 pm, Meat Plow <mhyw...@yahoo.com> wrote:

On Sat, 14 Aug 2010 11:49:44 -0700, divx dude wrote:
Hooked up 13.8 volts @ 1.5 amps (actually a variable supply) and the
flashing stopped at 13.3 volts.

So yes your situation could be similar. Borrow a 0 - 15 vdc supply and
see if you can dial in a voltage where the monitor will work.

think i can maybe use a POT on a 13.8v supply ? what value pot?

if put it in series after a fixed resistor 2x its value doesnt that
focus the variable to the upper 1/3 of the voltage range? in other words
would make like 9 - 13.8 vdc  variable supply instead of
0 -13.8.

Look up Ohm's Law and calculate the values yourself.

I=V/R or V=IR or R=V/I   V-voltage I-current R-resistance.

i guess the pot would need to be 5-10 watt , a 5k pot after 4 5k fixed
Rs would make approx 11v- 13.8v adjustable.
let me know if that sounds right, i'm shaky in this area.

i dont understand something tho.
theres a ton of generic viewsonic external DC supplies on fleebay
and non of then discuss a specific voltage other than 12v.theres
almost a differnet model for every viewsonic but the only differences
are the amp rating and the plug tips.

could it be theres a knowm magice voltage number like your 13.3vdc
that they all use that isnt widely known to the users?

almost all are around $10 shipped except mine is about $50.
it seems that is due to the unusual size of the 3mm plug tip.
i'm wondering if i just buy the $10 12v/5a supply for the different
viewsonic and hack the end off and wire a 3mm tip (have one)
if that wouldnt make it happy.

problem is i only have a 4day period to return this montior.

 

[divx dude]

ummm...



this is not a supply issue.
as discussed in other LCD brands a inverter problem is detected by
pressing a flashlight onto the screen to detect display text etc.

i did and i did.

omg..
its full of werds
theres werds in there.

 

[Meat Plow]

On Sun, 15 Aug 2010 01:32:24 -0700, divx dude wrote:

ummm...



this is not a supply issue.
as discussed in other LCD brands a inverter problem is detected by
pressing a flashlight onto the screen to detect display text etc.

i did and i did.

omg..
its full of werds
theres werds in there.

That was the problem with giving the Sanyo VIZON less than 13.3 volts
even though the input voltage printed above the DC jack said 12v.
If you have an inverter problem more often than not it will prevent the
monitor from operating without backlight.

I'd guess that these VX800's have a common inverter malfunction if you
got two of them with the same symptoms. As far as my Sanyo goes, flashing
backlight at anything between 12 - 13 vdc the work around was to give it
13.8 volts. I don't have the original PSU nor the actual voltage specs.
But one would think that if it called for 12 that's what it needed, not
13.8.



--
Live Fast, Die Young and Leave a Pretty Corpse

 

On Sat, 14 Aug 2010 10:57:07 -0700 (PDT), divx dude
<divx.dude@gmail.com> wrote:

i got these two monitors VX800 nice looking 18" LCD desktop monitors
that use an external power brick.
my research sez the brick is 12vdc at 5A.
my plan was to makeshift something, i found a 3mm?
plug to fit the power jack and wired it to the 12v drive molex line on
an old AT power supply form the 486 days pre-ATX.
the 12v rail is rated at 8A.
the grren light on the moniotor comes on but flashes display text the
POST screen on the PC flashes it only for a second.

i can repeat that 1 second by cycling the power button but thats all i
can get from it. i tried a 12v rated lass than 2A
same responce. i tried the drive molex line from the ATX supply on the
PC i'm using tot test it but no green light. i measured the volts on
that line and its like 13.5vdc or so..
there was another brick i tried also but no green light and slightly
more than 13vdc.
so the monitor is picky and refuses 13v+

i havent tried the other monitor yet. im expecting someone already
knows these are buggy and bet it probably has the same issue.

requesting any assistance u smart people can provide.
Other than the substitute power supply, this is the classic 'two

seconds to black' scenario. A backlight inverter is essentially a
constant-current AC source with protection features to detect an open
lamp or excessive current. The protection is disabled for about two
seconds when the backlights are activated to allow the system to reach
a steady state. Thus, a persistant fault results in 'two seconds to
black.

Possible faults include bad electrolytic caps on the inverter, one or
more bad CCFLs, a bad solder joint on the CCFLs, a bad inverter
transformer, a shorted transistor, or the real fun possibility, a
defective component in the protection circuitry. In theory, slightly
high or low voltage should not cause the problem, but it shouldn't be
ignored.

The first step is to open the monitors up and look for obvious
problems, especially bulging caps. Then you try arranging the
monitors in such a manner that you can hook one or more of the CCFLs
from monitor A to the inverter in monitor B. If one of the CCFLs in
monitor A will result in monitor B working normally you have
identified a problem.

PlainBill

 

[divx dude]

On Aug 15, 4:55 pm, PlainBil...@yawho.com wrote:

On Sat, 14 Aug 2010 10:57:07 -0700 (PDT), divx dude



divx.d...@gmail.com> wrote:
i got these two monitors VX800 nice looking 18" LCD desktop monitors
that use an external power brick.
my research sez the brick is 12vdc at 5A.
my plan was to makeshift something, i found a 3mm?
plug to fit the power jack and wired it to the 12v drive molex line on
an old AT power supply form the 486 days pre-ATX.
the 12v rail is rated at 8A.
the grren light on the moniotor comes on but flashes display text the
POST screen on the PC flashes it only for a second.

i can repeat that 1 second by cycling the power button but thats all i
can get from it. i tried a 12v rated lass than 2A
same responce. i tried the drive molex line from the ATX supply on the
PC i'm using tot test it but no green light. i measured the volts on
that line and its like 13.5vdc or so..
there was another brick i tried also but no green light  and slightly
more than 13vdc.
so the monitor is picky and refuses 13v+

i havent tried the other monitor yet. im expecting someone already
knows these are buggy and bet it probably has the same issue.

requesting any assistance u smart people can provide.

Other than the substitute power supply, this is the classic 'two
seconds to black' scenario.  A backlight inverter is essentially a
constant-current AC source with protection features to detect an open
lamp or excessive current.  The protection is disabled for about two
seconds when the backlights are activated to allow the system to reach
a steady state.  Thus, a persistant fault results in 'two seconds to
black.

Possible faults include bad electrolytic caps on the inverter, one or
more bad CCFLs, a bad solder joint on the CCFLs, a bad inverter
transformer, a shorted transistor, or the real fun possibility, a
defective component in the protection circuitry.  In theory, slightly
high or low voltage should not cause the problem, but it shouldn't be
ignored.  

The first step is to open the monitors up and look for obvious
problems, especially bulging caps.  Then you try arranging the
monitors in such a manner that you can hook one or more of the CCFLs
from monitor A to the inverter in monitor B.  If one of the CCFLs in
monitor A will result in monitor B working normally you have
identified a problem.

PlainBill

thanks for the input guys.
i decided to return the monitors to the guy that sold them.
amazing how "losing" the power supplies can entice a moron
like me into thinking hes getting an easy deal..
not worth the effort.

i do appreciate the tips tho...im sure i will
need to fix one sooner or later..