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Old 06-11-2011, 04:59 AM   #21
alexanna
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

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Originally Posted by Welchs101 View Post
Had a little time this morning. THought i would try the last suggestion about replacing bulbs. Then i started to think about what it was i was doing and well i am not sure why i am doing.

I already tested the bulbs of the broken MOnitor. To see how i did this see enclosed picture. "Test already done"

It is proposed that i switchout the bulbs one at a time from the bad monitor to a good bulb/monitor. From what i read, i included a pic of what this test is to do as well. See enclosed pic "Test to do".

What i dont understand is what I will learn from this new test. Seems like i am just testing the "bulb". If this is the case then didnt i already do this.

Just trying to understand this "test to do" a little more because from what i know (which is obviously not much) it seems that i am testing the integrity of the bulbs in both cases.
I dont know how else to explain it, but what you know now is that there is no problem with any of the circuitry in your test monitor, and it is able to light the CCFLs from your BAD monitor.
When you install a good test CCFL into the bad monitor you will at the least know if each of the inverter transformers is capable of at least lighting a CCFL.
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Old 06-11-2011, 05:15 AM   #22
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

thanks alexanna for the reply.

After sending the last post i began looking at some of the caps as you and other suggested because i had the time. I decided to replace one of the caps (470uf/25V)......just to see what would happen. THe ESR meter did not indicate a problem (fluctuated between 0.2 and 1 out of circuit) but i went ahead and replaced it. I chose this one to replace because i figured the problem was somewhere in the inverter part of the circuit because after the bulbs go out i can still see a faint image on the screen.

I then tested the monitor with this new cap......and it stayed on. So you and the others were right from the begining....change out the caps.

To see which cap i replaced see enclosed pic. I am a little surprised that the monitor works now given that the cap i replaced did not seem that bad using the blue esr meter. Live and learn i guess.

thanks. After i replace a ll the caps i will send a post indicating what caps i replaced and the status of the monitor.

thanks.
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Old 06-11-2011, 07:04 AM   #23
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Quote:
Originally Posted by Welchs101 View Post
thanks alexanna for the reply.

After sending the last post i began looking at some of the caps as you and other suggested because i had the time. I decided to replace one of the caps (470uf/25V)......just to see what would happen. THe ESR meter did not indicate a problem (fluctuated between 0.2 and 1 out of circuit) but i went ahead and replaced it. I chose this one to replace because i figured the problem was somewhere in the inverter part of the circuit because after the bulbs go out i can still see a faint image on the screen.

I then tested the monitor with this new cap......and it stayed on. So you and the others were right from the begining....change out the caps.

To see which cap i replaced see enclosed pic. I am a little surprised that the monitor works now given that the cap i replaced did not seem that bad using the blue esr meter. Live and learn i guess.

thanks. After i replace a ll the caps i will send a post indicating what caps i replaced and the status of the monitor.

thanks.
A reading of .2 and higher on a 470F 25V low ESR cap indicates it is bad!!! A good cap of that value should have a reading of less than .07.

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Old 06-11-2011, 07:05 AM   #24
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

I recently,had a unit where the ESR looked fine,However on measuring the Capacitance,the 1000uf one read under 500uF,and the 680uF under 220uf, replacing them cured the problem.The location of the one you changed near to the Inverter Transformers,seems to a be favourite place for them to fail in a lot of Monitors.
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Old 06-11-2011, 08:19 AM   #25
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Is there a listing of the esr values for given cap value/voltage which determines if its good or bad. On the front of my friends blue esr meter i read that the value must be "below" 0.8 for a 470uf/25V cap. But i always took this value as should be "about" 0.8.


thanks for the info.
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Old 06-11-2011, 10:50 AM   #26
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

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Originally Posted by Welchs101 View Post
Is there a listing of the esr values for given cap value/voltage which determines if its good or bad. On the front of my friends blue esr meter i read that the value must be "below" 0.8 for a 470uf/25V cap. But i always took this value as should be "about" 0.8.


thanks for the info.
ESR is a 'better than' (lower than) parameter. As a reality check, I use the published ESR values for name brand low ESR caps. 0.07 is the ESR spec for a 470F, 25 Volt Panasonic FC cap. I usually routinely replace all electrolytic caps if any show signs of failure or if they are suspect brands (Capxon, Elite, Lelon, etc). When testing the ESR of caps, I would replace any that have a reading even close to the published spec. Recall that a new Panasonic FC would have an ESR of well below .07, probably .01 or .02.

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Old 06-11-2011, 11:16 AM   #27
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

thanks.
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Old 06-16-2011, 02:32 PM   #28
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Update: I replaced all the caps on the power supply/inverter board except for a few small ones (see enclosed pic).

Problem: When the monitor has been on for a while and I have not "touched" it for a while...ie...i think monitor goes to sleep........I have a hard time getting monitor to "wake up". I can turn monitor on / off and it works fine but moving mouse or hitting space bar does nothing.

The strange thing is i can connect this same monitor to my wifes older laptop and when it goes to sleep i can revive it. But i cant seem to revive/wake it up when i connect it to the two desktop machines that ihave.

Any ideas? The monitor seems to be working it just seems to be dependent on what machine i connect it too.......very strange.
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Old 06-16-2011, 03:21 PM   #29
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Is that picture before-recapping?
What are the red/brown Panasonics? A new variant of FR?
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Old 06-16-2011, 04:26 PM   #30
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

yes, its before recapping. I forgot to take a new picture after i put the new ones in. I replaced all of the caps except the two that i have arrows drawn to .


also, i tried something onthe monitor setttings...........i reset the monitor to its "default" settings and things seem to be working well now. Now when the monitor sleeps the windows xp logo comes up on the screen and moves around the screen. before the screen would just go blank and i would have to turn it off and then back on to get the image to come back..........but it seems to be working fine now.

thanks.
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Old 07-05-2011, 05:06 AM   #31
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

ok, so things are not totally fixed with this monitor yet.

Here is the strange thing.
I change the OnscreenDisplay from 15min to 60min and this "seems" to fix the problem on computer #1. However, when i gave the monitor back to my neighbor and again changed OSD to 60min............it DID NOT fix the problem. Computer #1 is newer than my neighbors computer and both are running xp-pro.

I am at a loss at this point. I brought my neighbors computer over and have been trying different settings but after about 10min the monitor goes to sleep and i cant seem to wake it up unless i turn on and off and even when i do this it only stays on for about 15 sec.

I foudn the service manual........and i am enclosing it here as well. ok fil eis to larage to post here so i am going to post web address where i found it.

http://ftpkuban.com/FTP/Manual/ViewS...035wm-1_sm.pdf
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Old 07-06-2011, 06:30 PM   #32
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

ok, i have some additional info.

When i boot my computer up in safe mode the monitor stays on .......with no problems. THis seems to suggest to me its a driver or some sort of conflict. But i have no idea what.

Any ideas?
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Old 07-06-2011, 06:36 PM   #33
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

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Originally Posted by Welchs101 View Post
ok, i have some additional info.

When i boot my computer up in safe mode the monitor stays on .......with no problems. THis seems to suggest to me its a driver or some sort of conflict. But i have no idea what.

Any ideas?
This is grasping at straws, but the only thing I can think of is that the video signal is going to some not fully supported resolution. When operating the monitor can display it, but when in standby it doesn't recognize it.

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Old 07-06-2011, 07:42 PM   #34
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Do you think it could be hardware related like maybe a bad cap on the logic board?
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Old 07-06-2011, 07:59 PM   #35
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Make sure the computer is set to the native resolution of the monitor, 1680x1050 at 60 Hz.
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Old 07-06-2011, 08:52 PM   #36
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

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Originally Posted by Welchs101 View Post
Do you think it could be hardware related like maybe a bad cap on the logic board?
It COULD be, but I'd think a resolution / refresh rate incompatibility would be more likely. It also has the advantage of being readily testable. Note jsog's suggestion.

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Old 07-07-2011, 04:31 AM   #37
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Per your suggestions: I went into the display settings (advanced tab) and changed the monitor refresh rate FROM 75Hz .....TO 60Hz.

This seemed to fix the problem. Monitor does NOT go blank after a few min. But i will keep testing for an entire day and I will try the same thing on my neighbors computer. ONce i have done this if it still works then I will say its truely fixed. I will let you know the out come in a day or so.

THANKS!!!!!!!!!!!!!
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Old 07-20-2011, 06:45 PM   #38
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

ok. i finally got my neighbors computer to try out the monitor.

Bad news. I set the native resolution to 1680x1050 and made sure the refresh rate is ste to 60hz. After about 5min it shuts off. Really weird. I am now going to boot up in safe mode and see if it works there.......my guess is it will since ALL computers i have booted up in safe mode with works with this monitor...........not sure what to try if it works in safe mode.

i did not replace any of the caps onthe logic board...........think i should have?
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Old 07-20-2011, 07:17 PM   #39
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Five minutes could be power save. Check the screen saver or power settings.
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Old 07-21-2011, 04:49 AM   #40
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Default Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

i checked power save and screen saver options........all seem fine. now just doing google searches........i will keep you guys updated if i find anything out.
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