Viewsonic VX2235wm random black screen

[jsquail]

Hello all,

I have been reading threads here on the forum containing information about the Viewsonic monitor I have in an effort to correct the random black screen issue it has. I have replaced the suggested capacitors on the power board but the problem still persists. To define "suggested caps" i went to ebay and located a capacitor kit that replaces several of the on board caps. If the list is need i can supply it. I did not get the caps from ebay, instead i purchased them from Digikey after reading a post on the forum here.

I am hoping that someone has seen or has had this issue and can point me in a good direction to go.

For information purposes, the monitor black screens when ever is feels the need. If you wiggle the mouse sometimes you can get a horizontal line flash across the bottom of the screen. its a quick flash, nothing discernible. The other thing is that power cycling the monitor brings it back to normal working conditions. by power cycle i mean off-on with no wait.

Any help of where to look next would be appreciated.


thank you.

[retiredcaps]

Re: Viewsonic VX2235wm random black screen

Any help of where to look next would be appreciated.

1) Post clear focused pictures AFTER reading

https://www.badcaps.net/forum/showthread.php?t=1868

2) Please do not post pictures inline as they slow down the loading of pages.

3) For best picture quality and clarity take your boards to a window on a sunny day, turn flash off, and use macro mode. Take a top down view of all your boards (front and back). Make sure the photo is legible so that we can read the PCB printing clearly. A shutter speed of 1/125 or faster will produce nice clear focused pictures. Try to get a photo that is 2000x2000 resolution or as close as possible.

4) Here is an example of the pictures we want.

https://www.badcaps.net/forum/showpo...94&postcount=1

[EGuevarae]

Re: Viewsonic VX2235wm random black screen

Hello all,

I have been reading threads here on the forum containing information about the Viewsonic monitor I have in an effort to correct the random black screen issue it has. I have replaced the suggested capacitors on the power board but the problem still persists. To define "suggested caps" i went to ebay and located a capacitor kit that replaces several of the on board caps. If the list is need i can supply it. I did not get the caps from ebay, instead i purchased them from Digikey after reading a post on the forum here.

I am hoping that someone has seen or has had this issue and can point me in a good direction to go.

For information purposes, the monitor black screens when ever is feels the need. If you wiggle the mouse sometimes you can get a horizontal line flash across the bottom of the screen. its a quick flash, nothing discernible. The other thing is that power cycling the monitor brings it back to normal working conditions. by power cycle i mean off-on with no wait.

Any help of where to look next would be appreciated.


thank you.

I saw that on a laptop not too much ago. It worked (the panel/screen), then suddenly it went blank (black in this case...).If you switched to external screen and then back on to internal (or simultaneous display,which had the same effect of turning off the screen and then back on for testing purposes) it worked.It was random and you could see the screen in the back when it did that, so only the backlight was off (you did not mention that in your post).A line (most a flash than a line) could be seen on the bottom sometimes. Believe it or not, i did this via a Web cam.I then asked the guy in the other side (Alaska, go figure ...) if he could perceive a sound when the black screen issue appeared.He said that he could listen to a hiss.In the end, the lamp on the bottom was arcing (so there is the hiss cause) and he replaced the bottom lamp,and problem solved.
.Do you hear something?

[jsquail]

Re: Viewsonic VX2235wm random black screen

1) Post clear focused pictures AFTER reading

https://www.badcaps.net/forum/showthread.php?t=1868

2) Please do not post pictures inline as they slow down the loading of pages.

3) For best picture quality and clarity take your boards to a window on a sunny day, turn flash off, and use macro mode. Take a top down view of all your boards (front and back). Make sure the photo is legible so that we can read the PCB printing clearly. A shutter speed of 1/125 or faster will produce nice clear focused pictures. Try to get a photo that is 2000x2000 resolution or as close as possible.

4) Here is an example of the pictures we want.

https://www.badcaps.net/forum/showpo...94&postcount=1

I will get some pictures uploaded ASAP and outline my post better.

[jsquail]

Re: Viewsonic VX2235wm random black screen

I saw that on a laptop not too much ago. It worked (the panel/screen), then suddenly it went blank (black in this case...).If you switched to external screen and then back on to internal (or simultaneous display,which had the same effect of turning off the screen and then back on for testing purposes) it worked.It was random and you could see the screen in the back when it did that, so only the backlight was off (you did not mention that in your post).A line (most a flash than a line) could be seen on the bottom sometimes. Believe it or not, i did this via a Web cam.I then asked the guy in the other side (Alaska, go figure ...) if he could perceive a sound when the black screen issue appeared.He said that he could listen to a hiss.In the end, the lamp on the bottom was arcing (so there is the hiss cause) and he replaced the bottom lamp,and problem solved.
.Do you hear something?

No sounds of any kind. The screen just goes black. It does appear the back light is still on, but i will look for that the next time it blacks out.

[jsquail]

Re: Viewsonic VX2235wm random black screen

pictures of my power and logic boards.

[retiredcaps]

Re: Viewsonic VX2235wm random black screen

1) Those are excellent pictures.

2) Are those Panasonic FR caps?

3) When the screen goes black, does it stay black until you power off/on?

4) The next time the screen goes black, try shining a flashlight on it and see if you can see the display image.

5) When the screen goes black, do you mean the backlight goes off?

6) Do you have a multimeter?

[jsquail]

Re: Viewsonic VX2235wm random black screen

1) Those are excellent pictures.

Thank you.

2) Are those Panasonic FR caps?

They are panasonic caps. I just put them in. Dont remember if they are FR

3) When the screen goes black, does it stay black until you power off/on?

Yes

4) The next time the screen goes black, try shining a flashlight on it and see if you can see the display image.

ok will do.

5) When the screen goes black, do you mean the backlight goes off?

I dont believe the backlight goes off. I will check this the next time it goes black

6) Do you have a multimeter?

yes.

[retiredcaps]

Re: Viewsonic VX2235wm random black screen

1) With power off and lcd unplugged, wait 2 minutes and then measure the resistance (set your multimeter to 2000 ohms if manual) between the 2 red dots. Do the same for the yellow dots. These are the secondary inverter transformer pins. Report both measurements. They should be within 3% of each other.

2) With power on and lcd plugged in, please measure the DC voltage on the 10 pin connector between the power board and logic board. Use a ground screw for your black probe. List voltages for all pins. This will be your "base" voltages.

3) If there is a legend on the connectors, please provide a photo of it.

4) Can you run this lcd with the back cover off? If yes, wait for it to go black. When it goes black, remeasure the same 10 voltage pins. This might give us a clue as to why the lcd goes black?

[retiredcaps]

Re: Viewsonic VX2235wm random black screen

On the logic board, I101 and I102 are voltage regulators.

5) With power on and lcd plugged in, measure the DC voltage on each pin (not the big tab). Also list the part number of each.

6) When the screen goes black, remeasure these same voltage regulators.

[jsquail]

Re: Viewsonic VX2235wm random black screen

1) yellow 390 Ohm, red 387 Ohm. Within 3%

2) 10 pin connector
red - 0
blue - 5.1
black - 0
Orange - 0
Yellow - 5.1
green - 5.1
White - 3
Black - 0.3
Brown - 0

3) No legend that I can find

4) Measured it black then measured it live. No change in voltage. When the screen was black I unplugged the 10 pin and plugged it back in the monitor returned to normal state(no black screen)

5) for I101

large pin 3.2v
Small pins Left to right
5.1v, 3.2v, 0v

for 102
Large pin 1.6v
Small pins from left to right
3.2v, 1.6v, 0v



At this point the monitor seems to be displaying wavy lines, but not distorting the picture. Best way for me to describe it would be like when you put a CRT below a fluorescent light. when i started typing this reply the lines were there, now they are gone.

I will remeasure the VR's once the monitor goes black again and pot them results.

[jsquail]

Re: Viewsonic VX2235wm random black screen

Tried the flashlight thing. no image seen.

It does appear that the backlight is still in when the screen goes blank.

[retiredcaps]

Re: Viewsonic VX2235wm random black screen

5) for I101

large pin 3.2v
Small pins Left to right
5.1v, 3.2v, 0v

for 102
Large pin 1.6v
Small pins from left to right
3.2v, 1.6v, 0v

I will remeasure the VR's once the monitor goes black again and pot them results.

1) If the part number on I102 is something like AS1117-18, the suffix 18, denotes output voltage of 1.8V DC. Voltage regulators should be with 1% of spec. 1.6V DC is below spec. This could cause the logic board to stop displaying an image (i.e. it goes black).

2) The same can be said for the I101. It should be 3.3V DC.

3) Now your multimeter could be low on batteries (which affects the accuracy) or your leads could be dying? Set your multimeter on 200 ohms. Touch the 2 leads together. What is the ohms reading?

4) What make and model if your multimeter? If you have a pic of the multimeter, please post it.

[jsquail]

Re: Viewsonic VX2235wm random black screen

ok got tit o black screen again. It seems to happen faster when i play quake live at fullscreen.
so i measured the VR's again. for 101 the voltage is unchanged. for 102 the voltage went on the 1.6 legs went up to 1.7 volts.

Part numbers:

101:
6F5L
17-33L

102:
6H3L
17-18L

I have 2 multimeters. One is a no name brand the other is a sperry clamp ammeter. I checked everything with both meters and received the same results. i just put a new 9v battery in the no name last week when trouble shooting my icemaker.

[retiredcaps]

Re: Viewsonic VX2235wm random black screen

for 102 the voltage went on the 1.6 legs went up to 1.7 volts.

Part numbers:

102:
6H3L
17-18L

1% of 1.8V implies

.99 x 1.8 = 1.782
1.01 x 1.8 = 1.818

If you are getting 1.70V or 1.60V DC, I would say this voltage regulator is suspect. These parts are "jellybean" parts and can be found on video cards, boards, etc. If you have "junk" boards laying around, try finding one that has the 18 suffix and maybe swap it out?

[retiredcaps]

Re: Viewsonic VX2235wm random black screen

I should also point out that I101 could be bad as well. It is not uncommon to have 2 regulators being bad or out of spec.

But, try changing out I102 first since it seems to be "most" out of spec.

[jsquail]

Re: Viewsonic VX2235wm random black screen

Thanks. I will get them on order and let you know the outcome later this week. I will replace both of them.

[jsquail]

Re: Viewsonic VX2235wm random black screen

OK. so i went looking for them on Digikeys website. what exactly am I looking for so i can order them? Im kinda electronic part dumb.

[retiredcaps]

Re: Viewsonic VX2235wm random black screen

OK. so i went looking for them on Digikeys website. what exactly am I looking for so i can order them? Im kinda electronic part dumb.

I *think* these are the correct parts for your board based on your photos.

3.3V regulator

http://search.digikey.com/scripts/Dk...Y33G-13DICT-ND

1.8V regulator

http://search.digikey.com/scripts/Dk...Y18G-13DICT-ND

The part that I'm not 100% sure is the TO-243 (3 Leads + Tab) packaging if that is what you have or not.

[jsquail]

Re: Viewsonic VX2235wm random black screen

Thanks. i will give those 2 a try and see what I get. a couple of bucks isnt gonna break me.