Viewsonic vx2235wm colors washed out after power board recapping

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Yes i did try monitor with other PC and same PC with other monitor and same problem persists with this monitor - all washed out.

Not sure what to look at next. There are 2 ribbon cables connecting the logic board to the TCon, I cleaned contacts on both sides, no improvement. I tried the monitor plugged in and pressed with a rubber stick along the connectors, no change.

Starting to get discouraged!

But hey, thanks for your input, its great to know that pros are looking a this and who know, might be able to point me in the right direction.

[momaka]

Re: Viewsonic vx2235wm colors washed out after power board recapping

I guess some of my questions in post #18 got overlooked as you posted shortly after me. But try the stuff I asked there and let us know. We don't always have answers and solutions for every problem here, but sometimes we piece together things little by little and eventually that may yield a solution.

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Hmmm.. If the menu colors are okay but only the image from the PC with distorted colors, then the problem likely isn't on the t-con board.

Does the monitor have more than one input? If yes, can you try testing it on the other inputs to see if the problem persists?

Also, what happens if you change the resolution and refresh rate in Windows?

Indeed it appears that the problem is related to a setting in the menu (though I doubt there is a setting to make the monitor this bright, so there may be something more). That said, have you tried a different monitor cable?

Lastly, there should be an "Auto" image-adjustment button on the monitor. Try pressing it to see if that alters the brightness while auto-adjusting and after it is done.

Hopefully all of these questions should help us narrow down the problem.

Hello Momaka,

I am so sorry for not having noticed your post. Ok, yes the menu colors are perfect and not washed out.

Yes the monitor has a VGA and DVI input, and I tried both inputs with same result.

Yes the same happens even if I change resolution and refresh rate in Windows. I have also tried another cable, both DVI and VGA, same result.

There is no auto adjustment button on the monitor, but there is an option in the menu, however it is grayed out...I cannot access it in the menu?? There is also in the menu an item called "Memory Recall" which they say in the manual is a return to factory settings. When I select this in the menu, the screen goes black and returns with colors washed out.

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Ok, I succeeded in selecting the Auto Adjust feature in the menu, the screen goes dark and it returns with the washed out display

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Does anyone think it could the that small capacitor on the logic board? I checked it on board and it seems to be fine, but you never know. Really don't know what to do now?

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

I decided to clean the cable connectors between the logic board and the TCon, when I noticed on the logic board there was a screw missing in the top left corner (see photo #4). So I installed a screw and tested it and bingo, everything was back to normal. So I put everything back to together and installed the monitor.

Everything was working fine for approx. 5 minutes, and then the screen started to fade and went back to washed out colors ???

And also, since Momaka had suggested I change those caps on the power board, I did and replaced them all with Rubycon caps.

When it went back to washed out colors, I fiddled around with it (factory reset), the first time it came back. Then it went washed out again, did another factory reset and this time it wouldn't come back. It is now stuck in washed out colors, all assembled and I am startled to know what could be causing this. Any ideas? Tks!

[momaka]

Re: Viewsonic vx2235wm colors washed out after power board recapping

I decided to clean the cable connectors between the logic board and the TCon, when I noticed on the logic board there was a screw missing in the top left corner (see photo #4). So I installed a screw and tested it and bingo, everything was back to normal. So I put everything back to together and installed the monitor.

Everything was working fine for approx. 5 minutes, and then the screen started to fade and went back to washed out colors ???

Hmm.....
That suggests the missing screw wasn't the problem. Most likely a coincidence. However, it does show that the monitor is capable of working normally. Thus, the problem indeed appears to be something "physical", like a bad solder joint, connection/cable, or similar. Install the missing screw must have moved or triggered the "right" component to make the monitor work again. So all hope is not lost yet.

And also, since Momaka had suggested I change those caps on the power board, I did and replaced them all with Rubycon caps.

When it went back to washed out colors, I fiddled around with it (factory reset), the first time it came back. Then it went washed out again, did another factory reset and this time it wouldn't come back.

Again, looks more like whatever symptoms appeared from the replaced cap were just a coincidence.

It's still a good thing that your replaced the Sprague with Rubycon (Sprague caps are very old and definitely not suitable for switching power supplies). Speaking of which, what series of Rubycon did you end up using? I'm pretty sure that's not the problem, but when I'm troubleshooting something and I haven't repaired/replaced something exactly 100% properly, that always leaves room for possible problems. So if you used a series of Rubycon that doesn't have enough low ESR for the PSU, that is a potential (even though unlikely) problem.

But before you do any more component replacements again, see what happens when you heat up the boards in the monitor with a hair dryer or a heat gun before turning it On (probably have to blow the hot air through the vents for a few minutes). If that doesn't do anything, try leaving the monitor in a really cold room. Anything changes in the symptoms?

Does anyone think it could the that small capacitor on the logic board? I checked it on board and it seems to be fine, but you never know.

Could be. Indeed you can never know until you either pull it from the board and measure it or just replace it. When you measure capacitors in circuit, there are often other components in parallel with it, and that can make your capacitor appear good when it isn't (or bad when it isn't). In your specific case, there is a ceramic cap right next to the cap you measured, so the ESR on your meter probably showed the ESR of that ceramic cap while also reading the combined capacitance of the electrolytic and the ceramic cap together.

So like I said earlier, this leaves room for another potential problem. That cap may or may not be bad.

Starting to get discouraged!

Don't be.
As long as you have the time to do this and you are enjoying yourself, you shouldn't quit. Hard problems like this are also an opportunity to learn and try something new.
And if you do get the problem solved, the sense of victory feels even more satisfying.

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Hello Momaka!

Thanks for your great reply!! And many thanks for your encouragement!

The Rubycons I got are the PX series.

This is getting weirder and weirder...I decided to reopen the monitor and while plugged in I just passed my finger along the logic board ribbon cable connector...the left one, and I could see the image change..from right to left, the image improved and from left to right it became washed out.

As if my body was creating some sort of ground. So I thought the cables and connectors needed cleaning ( i had already cleaned them) but this time I removed them and cleaned the cables with an eraser and alcohol, and the connectors with alcohol (99%). I reinstalled and shucks, the colors were washed out and I could not recreate what I did, even while applying some pressure on the connectors.

I decided to swap the cables, with same result - colors washed out and can't recreate the experiment.

Were back to square one, but it was amazing to see when I passed my finger along the connector, it was as if it was a volume for the sharpness of the colors! Any ideas?

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

As per Momaka suggestion, I tried heating up the board no change. Tried leaving it outside in the cold Canadian weather (-14 C) for a few hours, fired it up and still no change.

I repeated the experiment of passing my finger on the logic board connectors, but nothing changes, just washed out colors.

I saw on youtube a guy with weird colors on a monitor that says to solder the ground of the connectors. Not much space to solder there, and I would be afraid to damage the connector.

I took some close up photos of the connector I passed my finger along (the one on the left in the second photo) in case someone with professional eyes sees something.

I have a feeling there is something wrong with one of the cables (the left one). Where it is inserted, the connector has made a marking on the cable end. Looking with a magnifier, I can see a small aligned dent on each connection. Should I shave off (cut a 3mm edge) the end of the cable so that the connector would sit on a fresh piece of connections or is that a no no? They are 36 pin 125mm FFC cables that sell in China, but that would take weeks if not months to get new ones, and I'm not sure they would be the right quality. The original cables are sold on Viewsonic's website, but they are out of stock

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Well I checked those cables, pin by pin for continuity and they are fine. Problem is elsewhere...this a pretty tough one!!

Merry Christmas to everyone!

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

I got the service manual for this monitor and am attaching it. Hopefully someone knowledgeable like Momaka can take a look.

Many thanks,

Raymond

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Ok, I checked the test points on the logic board for the 3.3V, 5V and 12V voltages. Here's what I get, as soon as I touch the TP say for the 3.3V, I get 3.29 and then it goes to 3.304 V steady within about 1/2 a second. Same goes for the 5V, 4.99V on touch and after half a second 5.03 V steady. The 12V line, show 13.96 at start and goes up to 14.08 in the same fashion. The 12V is from the service manual, but on the board I can see it says 13.8V going through a fuse F1 and reads 13.96 at first and goes up to 14.08 stabilised.

I checked the voltage on that small Cap on the logic board (47uf) and when I touch the positive side, it gives me the same reading as the 5V test point..i.e. starts at 4.99V and stabilises at 5.03V.

Any ideas?

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Tested the little capacitor on the logic board - measured 48.3 uf, ESR 1.6, changed it for a capacitor that measures 47.3 uf, ESR .61, 25V rating - same result colors still washed out.

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Continued to do voltage checking on the 2 voltage regulators U7 and U6. (see photo 4, U7 is in the middle and U7 is on the top right.

U6 input is 5.05V and output is 3.38V. That looks good.

U7 input is 4.6V and output is 3.3V. I was wondering why I only had 4.6V on input so I traced it back to diode D20. On one side I have 4.6V and on the other side I have 5.03V. Is that normal?

Please help someone!

[R_J]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Yes it's normal, you are measuring the voltage drop of the diode.

[momaka]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Hi rddube,
sorry for the delay in response. I was away the last few days due to the Christmas holidays and will also be traveling a bit tomorrow.

But just a quick response to let you know I am still looking into this thread...

U6 input is 5.05V and output is 3.38V. That looks good.

U7 input is 4.6V and output is 3.3V.

Yes, those voltages are absolutely okay. Good that you checked them though. Same with the small cap. Slowly we are closing on all of the things that could be causing problems.

I was wondering why I only had 4.6V on input so I traced it back to diode D20. On one side I have 4.6V and on the other side I have 5.03V. Is that normal?

Yes, that's normal.
All diodes have a voltage drop when current flows from their Anode to Cathode. This voltage drop can be anywhere between 200 mV and 1.2 V (1200 mV) - it all depends on the type of diode. Schottky diodes usually have low voltage drop between 200-600 mV, and regular diodes between 400 mV to 1.2V.

So what you are seeing there is normal.

Ok, I checked the test points on the logic board for the 3.3V, 5V and 12V voltages. Here's what I get, as soon as I touch the TP say for the 3.3V, I get 3.29 and then it goes to 3.304 V steady within about 1/2 a second. Same goes for the 5V, 4.99V on touch and after half a second 5.03 V steady. The 12V line, show 13.96 at start and goes up to 14.08 in the same fashion. The 12V is from the service manual, but on the board I can see it says 13.8V going through a fuse F1 and reads 13.96 at first and goes up to 14.08 stabilised.

I checked the voltage on that small Cap on the logic board (47uf) and when I touch the positive side, it gives me the same reading as the 5V test point..i.e. starts at 4.99V and stabilises at 5.03V.

I don't see anything wrong with this either. The voltage going up looks like your multimeter "stabilizing" on the voltage reading more than anything else.

As per Momaka suggestion, I tried heating up the board no change. Tried leaving it outside in the cold Canadian weather (-14 C) for a few hours, fired it up and still no change.

I repeated the experiment of passing my finger on the logic board connectors, but nothing changes, just washed out colors.

That seems to eliminate bad solder joints.

I saw on youtube a guy with weird colors on a monitor that says to solder the ground of the connectors. Not much space to solder there, and I would be afraid to damage the connector.

Hmm, not sure about that. The T-con board is also grounded through the monitor's case, so that shouldn't be the problem either.

Whatever that "YouTube guy" is doing, if he doesn't have a good explanation of why the grounding the connectors fixes the problem and the video appears more like a random repair, then I would say his monitor "fixed" itself by coincidence. I've seen plenty of videos like that on YT.

Don't take anyone on there seriously unless they can offer a good solid description of why the problem is the way it is and not "this is the problem, this is how I fixed it".

I took some close up photos of the connector I passed my finger along (the one on the left in the second photo) in case someone with professional eyes sees something.

I have a feeling there is something wrong with one of the cables (the left one). Where it is inserted, the connector has made a marking on the cable end. Looking with a magnifier, I can see a small aligned dent on each connection. Should I shave off (cut a 3mm edge) the end of the cable so that the connector would sit on a fresh piece of connections or is that a no no?

Unfortunately, I don't see anything wrong with the connectors either.

You can verify connections between the two boards with the connector by using the continuity ("beep") or resistance setting on your multimeter.

That said, I am running out of ideas to test on this monitor to reveal the problem, but try this one more thing: with the monitor running, try putting pressure on the various logic/video boards chips as well as the t-con board chips. If the t-con is under a shield, remove the shield and hold it down with the screws that held its metal cover in place. This should keep it grounded and in one stop.

If that doesn't work, you can also gently press on the various t-con ribbon cables that go to the TFT panel.

Meanwhile, I'll see if I can think of something else to test. I am pretty much running out of ideas here, but you never know. Sometimes, it takes me time to sink all of the information and results I get from troubleshooting something before I realize what is going on.

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Hi Momaka,
Thank you for your reply. (Thanks to R_J too).

You can verify connections between the two boards with the connector by using the continuity ("beep") or resistance setting on your multimeter.

Did this, long task, but the connections are good.

That said, I am running out of ideas to test on this monitor to reveal the problem, but try this one more thing: with the monitor running, try putting pressure on the various logic/video boards chips as well as the t-con board chips. If the t-con is under a shield, remove the shield and hold it down with the screws that held its metal cover in place. This should keep it grounded and in one stop.

I did this all over the board, with an rubber eraser while watching the screen in a mirror. Nowhere I pressed did it reveal any change in the screen washed out.

If that doesn't work, you can also gently press on the various t-con ribbon cables that go to the TFT panel.

Ok, I tried this also and again, no change in the screen display.

Meanwhile, I'll see if I can think of something else to test. I am pretty much running out of ideas here, but you never know. Sometimes, it takes me time to sink all of the information and results I get from troubleshooting something before I realize what is going on.

This is a tough one. I tried recreating the experiment I had in a previous post, passing my finger along the logic board left connector, applying a bit of pressure, but nothing, it doesn't budge.

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

ok, here is quick update on recent things I tried. Trimmed the cables that connect the TCon to the main board and when I reinstalled them, the screen was white. I passed my finger on one of the connectors and boom, image came back, better but not perfect....

So I thought maybe the connectors or cables are dirty even though I cleaned them many times. Took it all apart, checked it again and cleaned with MG Chemicals Super Wash (as I don't see how I can clean inside those tiny connectors, so as to rub them to remove oxidation if any). Reinstalled the cables, white screen again. Passed my fingers this time no change white screen.

So I reseated (in fact pulled them out a very little from the socket and closed the latch) and image came back but still washed out, not as terrible as before, but not perfect.

Now I'm thinking maybe I should order some new cables? Or is it one of the connectors but I checked all 4 with a 10X loupe and could not see anything wrong with them. They still close tight (snap). So still seeking the answer!

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Hello Momaka, and Merry Christmas.

You won't believe this! I decided to reinstall the monitor. Reading through the service manual, I noticed a key combination to call up factory settings. Tried the key combination as per the manual, but it wouldn't work..it says to hold the power button, up arrow and down arrow simultaneously. Tried many times but did not work.

Then I decide to try other key combinations and at some point (I think I was holding the menu button and the up arrow), a factory screen came up! There were lots of adjustments but by luck I decided to fiddle around with a VCOM setting that was at 255. I lowered it and the screen improved...right around the 128 level was the peak best screem so I pressed menu again and the factory screen disappeared and the monitor was back to normal!

I've been trying to get back in this factory menu but can't, however the screen is beautiful, just like new! Any idea what went on, and how I can maybe recall this factory screen? I searched the web and saw some ideas but they don't work on my screen. There were a lot of choices on that screen but it seems that VCOM was the culprit. Anyways, now I have a fully recapped (with good caps thanks to you) and working beautifully! Just great!!

[rddube]

Re: Viewsonic vx2235wm colors washed out after power board recapping

Succeeded in calling up that factory menu again. Here's how:

5.3.5 Factory Mode Introduction

When input the signal, press "power key" to turn off the monitor. Press" [▼] +[▲] +[ ] "at the same time so as to enter factory mode. After power on, press ''Menu[1]'' key, you can see the Factory menu

Attached are photos of this secret factory mode for anyone who has the same problem I had. There is page 1 and page 2 - page 2 I took 2 photos so to show what the selection was.

You can see on the first menu Vcom is what I changed...initially it was at 255 and brought it down to 128 and bingo, that did it. Wonder what all those other settings are for?

Many thanks to all of you and especially Momaka for helping me out in this super adventure!