Newbie with Viewsonic VX2835WM Problem

[Lumberjack777]

Re: Newbie with Viewsonic VX2835WM Problem

Ok. Just so you know, the one I fixed did have bad caps. So cap replacement will probably fix this problem.
If there is no plastic cover in the middle back (with screws under it) then you have to pry those sides apart. The very same seam you have on the top and bottom continues on the sides. Try using 2 butter knives. With the first one you pry the plastic apart a little. Then you slide the 2nd butter knife in and pry further and slide it up the side. It WILL eventually pop apart. There's no severe damage even if an inner plastic clip breaks off. But you have to get those sides unsnapped from the inner clips! Don't use one thin screwdriver. Use 2 butter knives. It'll work!

[Supramantt]

Re: Newbie with Viewsonic VX2835WM Problem

I just verified and there are no screws under the sticker. There is a dimple though. This monitor has been dying on me for almost 2 years. I added a surge protector to it so i could easily "unplug" it but this last week it was really tough to get it on and it was actually causing my computer to blue screen. Very strange. It would try to come on and so the computer kept thinking the hdmi connection was there and then disconnected, sometimes 10-20x in 20 seconds. It would cause a blue screen any time this occurred. So i finally gave up and started taking it apart. I bought this in 2007 when it came out. It has been a great monitor.

[Supramantt]

Re: Newbie with Viewsonic VX2835WM Problem

It's been awhile since I disassembled one of those. Don't remember having any problems with it. Where exactly is it stuck?

I can give you a few tips that will generally disassemble most lcd monitors.

1. Remove the stand, and all screws with it.
2. Remove the back outer cover screws. Check and remove inner screws.
3. Pry the back cover from the front using 2 butter knives.

Sometimes there are hidden screws (on the back) that are covered with a removable plastic cover. Also, hidden screws can be buried behind stickers. You have to run your finger across the stickers and feel for the impression of a screw or a divot.

The bottom and top are prying just fine, but i was rolling a thin screwdriver down the sides and it was not "popping" apart. I could not understand because I spent over an hour searching online for help on this and it seems like I am the only one with the problem. I disassemble electronics regularly, so I am really stumped.

[Lumberjack777]

Re: Newbie with Viewsonic VX2835WM Problem

I am having the exact same issue as most people. My issues is I cannot get it disassembled. I have removed all of the screws. I have now sort of destroyed the casing trying to separate it.
I even have found the factory manual and still I cannot figure out how it is held together.
someone please share their trick?

It's been awhile since I disassembled one of those. Don't remember having any problems with it. Where exactly is it stuck?

I can give you a few tips that will generally disassemble most lcd monitors.

1. Remove the stand, and all screws with it.
2. Remove the back outer cover screws. Check and remove inner screws.
3. Pry the back cover from the front using 2 butter knives.

Sometimes there are hidden screws (on the back) that are covered with a removable plastic cover. Also, hidden screws can be buried behind stickers. You have to run your finger across the stickers and feel for the impression of a screw or a divot.

[Supramantt]

Re: Newbie with Viewsonic VX2835WM Problem

I am having the exact same issue as most people. My issues is I cannot get it disassembled. I have removed all of the screws. I have now sort of destroyed the casing trying to separate it.
I even have found the factory manual and still I cannot figure out how it is held together.
someone please share their trick?

[selldoor]

Re: Newbie with Viewsonic VX2835WM Problem

Does the screen flash at all? can you post good clear pictures of your boards
front and back?

[pratul.chandra]

Re: Newbie with Viewsonic VX2835WM Problem

Issue with my ViewSonic VX2835 too - The blue light comes on and then turns yellow with the screen remaining black with no image.
I have already replaced all capacitors across the power board and the video board. Advice please.

[Lumberjack777]

Re: Newbie with Viewsonic VX2835WM Problem

hi all, i had the same problem with my viewsonic vx2835wm, and replaced 3 capacitors on the power board, it worked for more than two years, now i have a problem with white screen.,I have power but i only have a white screen, no picture. Please help, sorry for the English

Your english is just fine. And welcome to badcaps

With a white screen the first thing to check is to see if the cable that goes to the lcd panel is plugged in securely. I have seen them wiggle loose all on their own.
The next thing to check is the main board. If you could post some pictures it would help a lot.
Hopefully its just that cable wiggled loose.

[darraman]

Re: Newbie with Viewsonic VX2835WM Problem

hi all, i had the same problem with my viewsonic vx2835wm, and replaced 3 capacitors on the power board, it worked for more than two years, now i have a problem with white screen.,I have power but i only have a white screen, no picture. Please help, sorry for the English

[Lumberjack777]

Re: Newbie with Viewsonic VX2835WM Problem

The best place to buy caps in the USA is from DigiKey. For price, fast shipping and low shipping cost; they can't be beat. Good quality caps are the Panasonic's. Most people in this forum recommend them the most. But I'll also use Rubycon, or Nichicon if the Panasonic cap is not available. Did you catch the temperature rating on the radio shack caps? Was it 85c? You want good low ESR caps (Panasonic,Rubycon,Nichicon) that are rated at ----> 105c <---- That's what'd I'd definitely use in the future.

[Kennewb]

Re: Newbie with Viewsonic VX2835WM Problem

That could be but this is my first time replacing caps. It went well and if I have to do it again then at least I know I can without a problem. Time will tell if they last and I do have a backup monitor on hand if it goes bad again. What would be the best caps to buy and have on hand just in case? Thanks for your input... They are 470uf 16V but I used 470uf 35V.

[selldoor]

Re: Newbie with Viewsonic VX2835WM Problem

If you have used readioshack caps you could be back in weeks not years.

[Kennewb]

Re: Newbie with Viewsonic VX2835WM Problem

I had the same problem that Scotstrenght had and my monitor went out completly. The C124 and C126 were both bad so I decided to replace them. 1.5 hours later after tear down and assembly again it came back up just like new. Screen was brighter than it's been for a long time it's like new again. So my problem was just the two caps. I've never replaced caps before but I'm a handy guy so it was already not working so said give it a go. Was so easy at least for me, I took my time on the board to make sure I didn't get it too hot or damage it. Went to Radio Shack to get the caps figured since the ones on the board only lasted for 5+ years that if I get a couple more years out of the fix it was worth the test. Replace with 470uf 35V caps since RS this not have the 16V on hand. Works like a charm so if I have to go back in a couple of years from now it's worth the cost.

[scotstrength]

Re: Newbie with Viewsonic VX2835WM Problem

Hi Guys,
Thanks for all your advice and tips so far and no i haven't blown myself up yet!
To be honest the past week or so i have been reading over various articles and looking at youtube clips on testing boards and i have to say i am still pretty clueless about the mechanics of it all.
How exactly do you set the dam thing up to test with your multimeter?
Please i know this may seem like a dumb question but i am really an electrical novice.
I have both the power board and main board out of the case and if i want to test various points how am i supposed to position the boards? The power board is normally grounded into the cover plate of the boards and i am little lost as to what surfaces i should be placing them on and where exactly i should placing my probes? So my questions are thus:
Should i be suspending both boards on top of little pieces of wood perhaps and have no part of the soldered joints on the bottom touching anything else?
Should i only be testing the voltage regulators that are around the capacitors - and is this to help me see whether it is the capacitors that are bad, where the voltage is being disrupted or something else i have missed completely?
As for placing the ground probe if/how/when i have the boards suspended/set up am i still grounding it on one of the corner rings or should i use something else?
I know the above may seem rudimentary but i failed to find out this basic info from the forums or youtube.
Yes i could i probably just replace all the caps and see what happens but seeing as i did buy the multimeter i would at least like to give it a go.

In addition what is the opinion of Hitano caps? I can pick these up easily enough at my local shop where as the Panasonic ones would have to be an internet order from Germany - no biggie but if Hitano will pass i could get these quicker.

Thanks again guys

[Lumberjack777]

Re: Newbie with Viewsonic VX2835WM Problem

I thought I recognized that board! That's the same one used in the Hanns-G 28". Due to the heat, that board tends to dry out the smaller capacitors in the middle. Try this: replace the 3 caps circled in red. And I would also replace the 5 circled in blue. See if that doesn't bring it back to life ~L-J-7~

[mariushm]

Re: Newbie with Viewsonic VX2835WM Problem

Just be careful not to accidentally touch the HOT side (the high voltage area) and kill yourself..

Always keep the power supply isolated, some heatsinks may be live (high voltage) so you don't want to just flip it over and have it stand on the metal frame or the panel - I tend to use a cardboard or several sheets of A4 paper sheets covering the surface I work... both are insulators

Even after you pull the power cable out, don't grab the power supply in your hands, the large capacitor will still hold a charge... so you really don't want to touch both its pins on the back side of the board with your palm or fingers. The capacitor will discharge to safe levels (usually, not a rule! measure dc voltage across it, should be safe when it's below about 20v DC) in about 3-5 minutes.

When measuring voltage on the hot side, put the black probe on the GROUND on that HOT side (for example one of those rings for the screws which hold the PCB in the metal frame)

When measuring voltages on the secondary, use the ground from that side... ex the ground on the connector going to the display board which is usually a black wire... or the negative side of a capacitor on the secondary ...

Select a value higher than the value you think it's gonna be in the circuit... the power supply says on it that it outputs 24v, 12v and 5v so set it to 200v and if it's below 20, switch to 20v for better accuracy.

[scotstrength]

Re: Newbie with Viewsonic VX2835WM Problem

Thanks for the tips Mariushm,
I didn't see your post before i went shopping but ended up buying the second one you recommended so i guess great minds think alike!
This is a slow work in progress as you can tell with my infrequent posting but i hope to be able to get some testing done this week.
After another careful look at the board and some additional capacitor reading i noticed i have at least 4 caps with mushroomed tops which will need to be replaced on the main board and possibly one on the power board. Of course testing should tell me more.
If i am having problems i know where to come and i will report back in once i have some results.
Quick question though,
What are the main things i should be careful of when testing the main board to make sure i don't do more damage to the circuitry?

Thanks again.

[mariushm]

Re: Newbie with Viewsonic VX2835WM Problem

For basic tests, any multimeter would work.

A good and cheap one from that page would be this one: http://www.ges.cz/en/digitalni-multi...S07313196.html

A slightly better one would be this: http://www.ges.cz/en/digitalni-multi...S07313190.html

It adds measuring capacity but in real world, that's not very useful, as capacitors often go bad without capacity value changing enough to tell you anything. So the first meter would be enough for you.

Even if you don't fix this monitor, a multimeter is always good to have around the house, so you won't feel sorry.

How you do measurements with a tool like this...

It comes with two probes. You plug the black one in the COM (short for common, as it's common probe for all measurements) and the red one in one of the jacks, depending what you want to measure.

For example, if you want to measure DC voltage - that's DC with a line and dots, AC voltage is the wiggly line with AC by it - you plug the red probe in the jack marked V omega Hz C . As you can probably tell, this jack is also for measuring resistance (omega sign) , frequency (Hz) or temperature (C)

Now you have the probes plugged in and you want to measure... in our case, you expect the voltages to be 12v, 5v, 3.3v, small values.
So with the probes away from the boards, you turn around that switch until it's positioned on DC voltage section (the one marked with DC and line and dots under it) and a value that's above what you expect to be there. If you expect 12v, you select 20v.

If it turns out to be more than 20v, the meter will show OL (from overload) or not show anything, and you should remove the probes in a few seconds otherwise it may not like it and if it's a bad meter it may damage itself. You just have to switch to a bigger value in that case.

[scotstrength]

Re: Newbie with Viewsonic VX2835WM Problem

Hi Guys,
Thanks for taking the time to look at my pics, i can't believe you think it could be a candidate for saving, i really thought it was done.
I am off to buy a multimeter today so i can test the board and some test circuit boards to practice my soldering.
I have to admit i have never tested anything electrical so i am a complete novice as far as how i go about it.
If anyone gets the chance i have included two links below of multimeters that are at my local electrical shop - note the ones which have the letters PR highlighted in green are in stock at my local shop - and i was hoping someone could have a look and give me a rough idea of what is required for testing boards and let me know which one would be suitable.

http://www.ges.cz/en/measuring-instr...ing/SEA2G.html

http://www.ges.cz/en/measuring-instr...ing/SEA2H.html

Additionally are there any stickies on 'testing' within the forum? A sort of idiots guide on not getting blown up or making matters worse!
I had a look on the various threads but couldn't find anything for the novice.

Thanks again

[mariushm]

Re: Newbie with Viewsonic VX2835WM Problem

The power board looks OK, yes, it's a bit dark but that's in places expected to be hotter, like the transformers.

The capacitors are a good brand and a good series, so I don't think they're a problem.. though it wouldn't hurt to check them if you have some way to do it.

The video board on the other hand... it looks to me that at least the two capacitors by the linear voltage regulator are looking swollen.

I'm thinking of C124 and C126 ... that chip between them is a linear voltage regulator.

Its purpose is probably to convert whatever comes from the power board from to 5v , or it converts 5v from the power supply down to 3.3v

If you have a multimeter, put it on Voltage DC.
With all the boards connected and monitor turned on, put the black probe on the ground (one of the rings on the corners) and then put the red probe on the pins and the tab.

Measure the voltages on all those pins and see if the output is 5v, 3.3v or 1.8v

There's another capacitor that looks bad, c198.

You might also want to check C176 , near another linear regulator U33 - check the voltage on the pins of that regulator, it's probably for 1.8v

There's another linear regulator U41 ... check the capacitors around it and the voltages on the regulator.