Dead Pixel Or Power Problem?

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b_jacobsen

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Joined 2003
#1
Hey,

Got my qa1650 today in the mail, ran over to radio shack and bought a 12v 1.5 amper power supply and i got it to power on and display the sharp logo. However it is very noticable that while i am watching anything on the panel 3 white lines come on and off horizontaly accross the screen. Originally i thought these must have been dead pixels but they are flashing so i am begining to think otherwise. The power rating for this panel is actually 12v 1.95 ampers. My question is has anyone had experience with flashing lines of these sorts accross the screen? Are they for sure dead pixels? If people think there is any hope that it is a power issue then i can obtain a 12v, 2a power supply today.

Please let me know if you have any suggestions/comments.

Thanks,
Brian
 
#3
so you think it is possible that it is just a power issue? Maybe this will help to descriminate. When i turn the contrast up i cant see these lines. It wouldnt be a big deal if it was one line because then i would just arrange the image in a 16:9 format so it wasnt visable. However this is not the case. Also i think my bulb on my ohp is getting a little burnt out. I am unfamiliar with the way these bulbs work. For example does the bulb keep its original brightness until burning out, or does it slowly decrease strength then burn out.

Any help would be appreciated,
Brian
 
#4
I'll answer what i know...

Halogens dont wear down they have same brightness till death..
if you have an MH (HMI) they it will most likely die down after 275 hrs(or more)

maybe the lcd is out of sync..or its a resolution problem..

my sharp panel said it will only work with special sharp psu, theres soemthing in the psu that the panels needs...this may be your problems as well...

i hope that helped.
 
#5
b_jacobsen said:
Hey,

Got my qa1650 today in the mail, ran over to radio shack and bought a 12v 1.5 amper power supply and i got it to power on and display the sharp logo. However it is very noticable that while i am watching anything on the panel 3 white lines come on and off horizontaly accross the screen. Originally i thought these must have been dead pixels but they are flashing so i am begining to think otherwise. The power rating for this panel is actually 12v 1.95 ampers. My question is has anyone had experience with flashing lines of these sorts accross the screen? Are they for sure dead pixels? If people think there is any hope that it is a power issue then i can obtain a 12v, 2a power supply today.

Please let me know if you have any suggestions/comments.

Thanks,
Brian
Click to expand...


Your panel will only draw as much current as it needs to operate. Your 1.5 amp supply isn't able to supply the 1.95 amps that your panel riquires. A 2 amp supply will be just fine. You could even use a higher current rating as long as you keep the voltage rating and the polarity the same. For example, if you were to use a 12V 15 amp supply, the panel would still only draw 1.95 amps.

Cheers,
Zach
 
#6
so you all think it will resolve my issue by getting a higher power, power supply? well i hope so but im not so sure because of this line issue. They seem to always appear in the same place 3 lines straight accross the screen.

Does anyone have any suggestions about how to get rid of dead pixels. I tried to massage them out but i didnt get any luck. I dont know how long to do it for, how hard to push ect. They are white lines, someone said that by leaving the lcd on a pure white screen you may be able to bring them back. Anybody have any other suggestions?

Thanks guys.
Brian
 
#7
what you have are not dead pixel, dead pixels means the pixel is completley burned they show no image at all , i doubt you have a line of dead pxels. also if you DO have dead pixel then you have em, there is no way to fix dead pix...maybe the manufacturer can.
 
#8
power supply

Run to Radio shack as fast as you can to return the ps.
Either buy a new one with ample amps it is to say 2 A or...... look in the garage for your old PC (an AT will do just fine)
Take the PSU out, look at the colored cables, they all have a different Voltage and or Amperage.... take the the wires you need and get that panel going!

Jean-Pierre

with that last option you get your money back from RS and with that you can buy yourselves the latest Matrix or Dreamcatcher.... not because they are good movies but just to impress your friends!


Logic RULES!
 
#9
like this....

other project, but the idea is recycling PSU's from pc's these psu's are extremely reliable, forgiving and CHEAP!

J-P

Logir RULES
 

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#11
so you all think it will resolve my issue by getting a higher power, power supply? well i hope so but im not so sure because of this line issue. They seem to always appear in the same place 3 lines straight accross the screen.

Does anyone have any suggestions about how to get rid of dead pixels. I tried to massage them out but i didnt get any luck. I dont know how long to do it for, how hard to push ect. They are white lines, someone said that by leaving the lcd on a pure white screen you may be able to bring them back. Anybody have any other suggestions?

Thanks guys.
Brian
 
#12
it might not be dead..just not enough power to light them up...try another bigger PSU before deciding to junk the LCD...if you got an extra PSU lying arund...the AT kind...just do as above...the yello wire for the +ve and the black for the -VE...should give you enough power to juice up ur LCD bright...
 
#15
I don't think that the power supply will cause the problem you are describing. The most likely cause is a defective panel. The pixels are not dead. They are not being driven properly. The problem is with the circuit board that drives the display.

Oh, don't use the 15 volt supply. ICs are very sensitive to voltage and this is a dangerious thing to do.

Later BZ:geezer:
 
#18
hey,

i got myself an extra pc psu and i am ready to build a psu for my panel. plese explain to me how to do it in more detail. the panel is a positive center. what color cable from the power supply do i solder to the positive center. And what color cable from the pc power supply do i solder to the outside negative. If anyone has some pictures of building a power supply for there sharp please post. I am not that great with soldering and electronics but i think i got the idea of what i need to do here.

I have one of those barrel ends for my rs power supply with two pins coming out of it. I would assume the easiest way would be to take that and solder the pc wires to it. Im not sure how i tell tho what pin is the center.

Also my pc power supply has many diff sets of cables, probably meant for all diff types of tasks (cdrom power , hd power , ect) does it matter from which set i choose to take power from?

I would like to thank everyone who has taken the time to post replies to help me out with this panel. I think we are almost there if you guys can help me out for a lil longer that would be great.

Thanks everybody,
Brian

r
 
#19
Okie doky...if you want +12V for your panle...grab those molex connectors...and cut the yellow and a black wire...the yello will be your +12V and the Ground will be your black wire...test with a voltmeter to be sure...I assume your PSU can power up without a load...if it doesn't...get a resistor and put it between the Red and Black lines..(+5V and GND) creates a load for the PSU to run properly...it will probably not be necessary for an AT PSU...
 
#20
hey,

well i tried using compulter power supply then i tried a 12v 3.3amper power supply and i still had the same problems. I am guessing its damages panel. I wish their was one set way with instructions on how to strip a good quality fairly cheap monitor. I wouldnt mind stripping an lcd but i would deff want 1. cheap, 2.good instructions.

I am prety sure this doesnt exist. O well i guess back to flee bay.
 
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