Viewsonic VX2035wm stays on for hours

[Uranium-235]

all caps are good, well, they're Hermei's, which is somewhat of an oxymoron I know, what I mean is they're unbloated, but I know that can mean crap too. I've seen a bunch of pictures from this model with bloated capXon's, but ran into a wall when trying to figure out the common problems with Hermei's. there just might not be many posts on the internet with this model failing with these

anyways, here is the problem. it says on for about 3 hours, then, the pictures goes away. Though if I look close I can see this single little line randomly flash every few seconds. the lamps are still on though. OSD will not come on. maybe cap on the video board? (which errg is also hermei). Then I can turn it right off with the power button, and back on, and it comes up no problem, but then does the same thing within much less time, so this might be heat related.

I've never ran into this problem before with a flatscreen. could it be one cap value is slightly bad/offspec and it could be just like, locking up the video signal processor? Maybe a cap on the power board is dropping power just low enough to the video board?

[PlainBill]

Re: Viewsonic VX2035wm stays on for hours

all caps are good, well, they're Hermei's, which is somewhat of an oxymoron I know, what I mean is they're unbloated, but I know that can mean crap too. I've seen a bunch of pictures from this model with bloated capXon's, but ran into a wall when trying to figure out the common problems with Hermei's. there just might not be many posts on the internet with this model failing with these

anyways, here is the problem. it says on for about 3 hours, then, the pictures goes away. Though if I look close I can see this single little line randomly flash every few seconds. the lamps are still on though. OSD will not come on. maybe cap on the video board? (which errg is also hermei). Then I can turn it right off with the power button, and back on, and it comes up no problem, but then does the same thing within much less time, so this might be heat related.

I've never ran into this problem before with a flatscreen. could it be one cap value is slightly bad/offspec and it could be just like, locking up the video signal processor? Maybe a cap on the power board is dropping power just low enough to the video board?

OK, let me explain this in simple terms.

Hermei caps are known garbage. You have Hermei caps in the power supply. You have Hermei caps on the signal (video) board. You have a problem that could be either bad caps or a failing voltage regulator. I suggest a two step process.

1. Let the monitor run until it loses the display, then measure the output of the voltage regulators on the signal card.

2. Replace every Hermei cap on the power supply, every Hermei cap on the signal board, and every questionable regulator on the signal board.

PlainBill

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

yeah I know the're garbage. but why would it work for 3 hours, the one hour? that screams a heat issue. can it be normal when its cool and bad when it heats up? I've never expirenced such a thing in my...eh few years of re-capping

the power output from the supply to the card, or the mosfet on the video board itself?

[smason]

Re: Viewsonic VX2035wm stays on for hours

Marginal caps can get worse with heat, or a component being fed dirty power from crap caps can handle it, until it heats up, could be a lot of things.

Recap first, ask questions later.

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

now if someone only would of said that when when the BP oil rig first blew *rimshot*

I don't have to re-cap the 10uf 16v tiny caps on the video board, do I?

[smason]

Re: Viewsonic VX2035wm stays on for hours

I'd wait on those, they're (generally speaking) not under the same stresses that the power supply/inverter caps are.

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

I have some 16v 1200 rubys to replace the 16v 1000, but, I think I have a height limitation issue. ontop of the heatsinks for these two mosfets, there is a screwed in plate, i'm guessing it would be a worse heat issue if I were to take that off. probably overheat and blow the rubys

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

well, I replaced them on the video board, and all the 16v 1000's in the power board. they were slightly too tall and this single metal plate that screws into the top of the mosfet heatsinks dosen't fully screw down, and dosen't conduct much heat, which caused the two mosfet heatsinks to heat up much more, and it caused the monitor to black out only after about half an hour

[alexanna]

Re: Viewsonic VX2035wm stays on for hours

I have some 16v 1200 rubys to replace the 16v 1000, but, I think I have a height limitation issue. ontop of the heatsinks for these two mosfets, there is a screwed in plate, i'm guessing it would be a worse heat issue if I were to take that off. probably overheat and blow the rubys

You may have just invented a way to stress test the monitor!
You probably know this but The capacitors are right at the high end of 20% tolerance on the capacitors, May or may not aggravate your problem I don't know.
Have you tried monitoring the output voltages of the voltage regulators as PlainBill suggested?
I have seen voltage regulators cause some really strange problems.

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

where do I put the test leads? on the regs or the output wires from the power to the video board?

[PlainBill]

Re: Viewsonic VX2035wm stays on for hours

where do I put the test leads? on the regs or the output wires from the power to the video board?

You put the black lead on a convenient ground point. You measure the voltage at each pin of each regulator. You report the voltages and the part number of each regulator. I'll explain if each voltage is good or bad, and why.

PlainBill

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

so I can touch the ground lead to anywhere on the chassis?

soo on the subject, what are the replacement specs for regulators? tolorences? requirments? I've never much messed with mosfets, though i'm hopeing to start

[PlainBill]

Re: Viewsonic VX2035wm stays on for hours

so I can touch the ground lead to anywhere on the chassis?

soo on the subject, what are the replacement specs for regulators? tolorences? requirments? I've never much messed with mosfets, though i'm hopeing to start

You can use any point that is at ground potential. I'd point out a few possibilities, but without a picture, it's rather difficult.

PlainBill

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

ok. I only really got a reading on the middle pin other ones were like 0.005... one time I accidently shorted the middle one one of the sides and sparked, but did not seem to effect the screen. scared the piss out of me though. one read ~13.4 other other read ~5.1. after the video goes black, its the same

[retiredcaps]

Re: Viewsonic VX2035wm stays on for hours

Go back and reread post #11 and then repost the results as PlainBill requests.

And we are still waiting for pictures (use manage attachments and please do not post inline).

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

ok here we go. well, I can't find the usb cable for my phone, and my crappy old sony cam ran out of batteries, which I have no replacements for right now, so here is a picture of the board from another website. This board looks clean, and with the exception of a few cap brand differences (mine had all hermei caps, and this picture has mostly hermei). I already replaced them around those twin mosfets

here is mine with the voltage readings on each mosfet. the ones on the twin caps seem stable, and also the other mosfet, except for the middle pin

actually, when I try to test that one, something wierd happens. not only is the voltage never the same, but every time I test it, the reading on my meter (LCD screen, meter is fluke 8010m) gets really dark and bold, and goes back to normal when I take the leads off

oh yeah, last time I tested it when it went blank, the twin mosfets were the same. I have been unable to really test it when it goes blank is cause it has yet today to do it

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

well this just gets more and more fascinating by the second

so its been just fine...I decided to change the resolution on it up to the monitors naitive (1920x1080). the second I did, and the screen did it

and now the volts are really strange, on all of them

[Uranium-235]

Re: Viewsonic VX2035wm stays on for hours

ok I posted a pic and the voltages, why is no one replying?

[tehtronics]

Re: Viewsonic VX2035wm stays on for hours

Same defect has my monitor ... You have found damaged component ?

[tehtronics]

Re: Viewsonic VX2035wm stays on for hours

I repaired the monitor...
I found the capacitors C106, C122 and C126 (10uF/16V) with high ESR(manufactured by HERMEI) on the signal board.
I replaced with RUBYCON caps and my monitor works perfectly ...