Anyone got a faulty viewsonic VX912 that I could have for the psu??

I havent been using my faulty monitor very much these last few days, cos with it set up as my secondry screen It only gets used when I need refer from it and a odd bit of tv. Ive noticed it doesnt take as long to stay on from cold now, takes about 3-4 attemps to come on, before staying on. Before when I was using iit a good 12hrs a day it took a good 15-20 attempts to come on before staying on.

strange hey guys?
 
Phil2008 said:
Ive just taken my 19" apart to see how easy it would be to change the powersupply, and it looks quite easy. The prob is it doesnt like turning on from cold, screen and power led flashes on and off for a good 30sec or so before staying on. It looks easy to replace wouldn't you say guys??

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Hi Phil
New to this.
I know this is an old discussion but hope for your indulgence.
I have Viewsonic VX912 which has died.
Poverty requires I fix this myself.
I have undone the 4 screws in back but can't see how to take it off without breaking plastic.
Please could you tell me how you got the cover off and whether/how you got the bolts out that the stand is attached to?
 
guys, just to let you know, a backlight inverter for a CCFL backlight kicks off at over 1000v at high frequency... Enough to kill.

If you don't know what you're doing, Be careful is all I'm going to say! (without trying too much like a nagging parent! ;P)
 
PJE said:
Hi Phil
New to this.
I know this is an old discussion but hope for your indulgence.
I have Viewsonic VX912 which has died.
Poverty requires I fix this myself.
I have undone the 4 screws in back but can't see how to take it off without breaking plastic.
Please could you tell me how you got the cover off and whether/how you got the bolts out that the stand is attached to?
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Just lie it face down undo the 4screws and the back should just come off, the stand is attached to the back aswell, so cover and stand will come off in 1 bit.. Yours may be a diff rev/version then mine tho..

My faulty screen is still working after a year from creating this thread and the fault hasnt goten any worse, but it gets used not much now as its my secoundry screen,, cos got another vx912 in perfect condition off ebay for £5.50.

Ive figgered out, if I use the screen say 45mins seesion or longer, it has trouble comming on, next time I turn it on from cold, but If I use it say a 10min session, the next time I turn it on from cold, it comes on without any probs....... Its like its got a memory.....Spooky... Also if I get a lot of white on the screen when I switch it on, that helps the screen to stay on qucker too.

But guys If anyone has a fulty vx912 I still would like the psu out if it.
 
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I have a similar problem with my VX912 when i press the power button the screen comes on for a second or two then turns black, ive just in the last half hour taken it apart to have a look at the internals then got to this forum and stopped, is it true that there can still be deadly amounts of power buzzing around even though the monitor isnt connected in any way to a power supply? i should count myself lucky if it is - Adam
 
My VX922 did something very similar, literally a week after the warranty ran out. Haven't thrown it away yet but I was going to. Might get my electrical buddy at work to have a look at it now after reading this.
 
ecat said:
I'm all for curiosity and have had my fair share of electric shocks as a result. One of the absolute worst ways to learn electronics is to go poking around switch mode power supplies, doubly so the supplies in LCD monitors.

Consider every part of the yellow pcb in the picture to be potentially lethal. The input is at a very unhealthy 240 volts and in common with most switch mode power supplies you can expect to find twice that voltage running around the board - even after the power has been disconnected! Please note the heatsinks, large bits of metal sticking up from the board, are probably live and dangerous. As the board supplies the backlight, the connectors on the left could be carrying around 2,000 volts (yes, two thousand).

Still interested? One of the best places I've found to learn about electronics is here:

http://sound.westhost.com/index.html

I am in no way connected with Rod Elliott or his site. He is well respected, experienced and always considers safety first.
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This guy is pretty much spot on, the yellow PCB is the power supply and very likely the cause of your cold start problem. The issue is probably electrolytic cap ageing, the electrolyte in the cap drys out over time and reduces the effective capacitance. The power supply is definitely a switch mode, which means there will be high ish volts (400v+) on it in operation. The big black/dark blue cylindrical lump lying on its side in the middle of the picture is a capacitor and when removing the PCB even after power down is your enemy. But of course this is connected to many other parts of the PCB so handle with caution. The PCB will almost definitely have a plastic cover on the back so you won't be able to touch anything dangerous that side. From the looks of it the top right hand side of the PCB above the aluminium partition is the DC part, ie the low voltage not dangerous part.
One thing you don't need to worry about is the inverter. Although in operation the voltages are very high, when the monitor is off the inverter will not be running. Also looking at it the inverter is not built onto that yellow PCB, true it probably is connected to it from one of the left hand connectors but the supply to the inverter will be very low (12v DC).

Anyway, an age old adage holds true here "a little knowledge is a dangerous thing". I think this may be one of those times when its best not to proceed. Of course you don't have to listen to anyone here, but it'll be interesting to see if you're still posting in a few weeks LOL.
 
thebandit said:
This guy is pretty much spot on, the yellow PCB is the power supply and very likely the cause of your cold start problem. The issue is probably electrolytic cap ageing, the electrolyte in the cap drys out over time and reduces the effective capacitance. The power supply is definitely a switch mode, which means there will be high ish volts (400v+) on it in operation. The big black/dark blue cylindrical lump lying on its side in the middle of the picture is a capacitor and when removing the PCB even after power down is your enemy. But of course this is connected to many other parts of the PCB so handle with caution. The PCB will almost definitely have a plastic cover on the back so you won't be able to touch anything dangerous that side. From the looks of it the top right hand side of the PCB above the aluminium partition is the DC part, ie the low voltage not dangerous part.
One thing you don't need to worry about is the inverter. Although in operation the voltages are very high, when the monitor is off the inverter will not be running. Also looking at it the inverter is not built onto that yellow PCB, true it probably is connected to it from one of the left hand connectors but the supply to the inverter will be very low (12v DC).

Anyway, an age old adage holds true here "a little knowledge is a dangerous thing". I think this may be one of those times when its best not to proceed. Of course you don't have to listen to anyone here, but it'll be interesting to see if you're still posting in a few weeks LOL.
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Intresting, and I think I will leave it to the pros if I get mine fixed. But I think I'll carry on using it untill it goes bang,, cos hopefully next year I'll be buying a 27" monitor at some point, so I'll prob bin the faulty vx912 and sell the good vx912.
 
Thanks Phil2008. I have managed to get back off my dead VX912.
Bought mine in 2005 (about) with 3 year warrenty.
It died a year to 18 months later and was fixed under warranty.
As I remember it was not fully dead that time - green LED was on but no display.
From look of things now (ie dull solder joints) 2 Capacitors at top and possibly large capacitor in middle were replaced.
Incidentally yours look as if they are on the way out plus possibly one on the controller board.
This time unit dead and it looks as thought the bridge rectifier is dead.
Was going to leave this post until I had tried new, hoping it would be more useful to you all, but ****** didn't have spare so will not be resolved for a little while but will let you know how I get on.
With regards to attempting fix youself - I agree with Persil and Leeser3.
Main reason I thought I would post before sucessful fix is that, if we do find solution before Adam182 throws his away we'll all get that warm glow from helping fellow traveller and saving the planet from a little landfill.
 
From a cold start my VX912 flashes on and off for five minutes before it is usable. I have had it since 1st December 2004 :)
 
Thanks to this thread I fixed my VX922. Took it apart and found the offending capacitors on the power supply board had their tops bulged. Mate at work tested them and they had all completely failed, e.g. the 470uF ones were reading like 6uF, no wonder it wasn't working. Bought replacement caps and fitted them and it now works perfectly. Cost £9, £6 of which was postage. Chuffed, got a spare monitor now.

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In a switch mode power supply, which is what that circuit is essentially, they act smooth out the rectified AC voltage into a stable DC voltage. Well you did ask ;) Basically they charge up, then discharge when needed, a sort of "voltage" buffer.
 
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