Viewsonic VX2035WM Turns on for a few seconds then goes black

[seanc]

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?

[Welchs101]

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.

[Welchs101]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

thanks.

[PlainBill]

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.

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 470uF, 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.

PlainBill

[Welchs101]

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.

[Rtech]

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.

[PlainBill]

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.

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

PlainBill

[Welchs101]

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.

[alexanna]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

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 don't 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.

[Welchs101]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

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.

[alexanna]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

If you look at the end of the CCFL conector, where it plugs in to the inverter you will notice a square slot and on the top of it is a rectangular slot.
Push the lead of a small capacitor into the rectangular slot, this will release a tab on the metal connector and allow you to remove the wiring pigtail from the plastic connector. You can then install the wiring pig tail into the plastic connector your monitor is using. Just remember the orientation of the Hot and Return wires.

[Welchs101]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

In trying to hook up external bulb to monitor i am tyring to fix:
1) Recall that for this monitor there are 4 connectors. Two of the connectors look like what i would call the "two" wire standard connection. The other two are more "non-standard". For the standard two wire connections i can plug my other bulb into the non-working monitor. However, for the "non-standard" connector..........not sure how to handle these.

today i am going to a friends to borrow their esr meter so i can check the caps.

[Welchs101]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

i do have some extra "bulbs" and i think i went through this exercise before but i need to find the "jig" i made. i have been very busy lately so i dont have a lot of time. this monitor is my neighbor's and i am trying to fix it for him.

thanks for the reply.

[alexanna]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

^
Don't you have an LCD with a damaged or broken screen? You do enough monitors, they will come in really helpful in the future, Just remove the bulbs

[Welchs101]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

i am posting a mag pic of the cap sabre504 thought was bulging. I think it was just the bad lighting. I am enclosing another pic........looks ok to me.

alexanna, i like your idea but i will have to create a "jig" that goes from the LCD i am trying to repair to an LCD bulb i know is good. may take a while as i am really busy these days but i will try.

[Welchs101]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

i have not tried any of the suggestion yet........i just realized i did not put the picture in my post this morning. so i am posting it now.

[alexanna]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Transformers seem ok (couldnt see your pic)

Caps would be the next thing

Welchs, I don’t know where you are with your monitor, but it sounds like 2 sec to black.
I think I would also replace the capacitors to take one more thing out of the equation. Also
If you haven’t done this, try it.
Find a good CCFL from a 17” monitor, Hook up all but ONE of the CCFLs from your monitor.
Place the 17” in the remaining connector, power on the monitor dose the test bulb light or do the CCFLs stay on?
Repeat this on all of the other CCFL connectors.
This is going to try to identify a particular circuit that may not be working

[sabre504]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Could be the angle or trick of the light but the cap i have ringed seems slighty bulged .
Are there any under the heatsink plate ?

[sabre504]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

Transformers seem ok (couldnt see your pic)

Caps would be the next thing

[Welchs101]

Re: Viewsonic VX2035WM Turns on for a few seconds then goes black

I finally got around to posting the measurements on the transformers. They ALL measured the same so either they are ALL bad or ALL good........i think.

See enclosed pic to see pin identifications.

For all transformers (T1 - T6):
Pin1 to Pin2: Open
Pin2 to Pin1: Open
Pin1 to Pin3: 1.1Kohm
Pin3 to Pin1: 1.1Kohm
Pin1 to Pin4: 2.7Megohm
Pin4 to Pin1: 2.7Megohm
Pin1 to Pin5: 2.7Megohm
Pin5 to Pin1: 2.7Megohm
Pin1 to Pin6: 2.7Megohm
Pin6 to Pin1: 2.7Megohm
Pin1 to Pin7: 2.7Megohm
Pin7 to Pin1: 2.7Megohm

Pin2 to Pin3,Pin4,Pin5,Pin6,Pin7: Open