Monitor displays breifly then goes to blank screen

Dear friend,

I just fixed my Viewsonic VA902b, here is how.

1/. Remove the LCD housing

2/. Remove e Main Power supply (label the 4 connectors for the 4 lamps before you unplug them)

3/. Locate the 1000uf-25v Cap (i think c806) check the top of the cap, if the top is buble up then replace it. I replaced my with 1000uf-35V 105 C, use the cap with long leads, solder it to the PCB and lay the cap down away from the heat sink (there should be plenty of room)

4/ check all solder joins, if it look like cold joins simply re-solder it

5/ when you are done, you can apply power to the board and check for the voltage at the cap, it should read about 14.7VDC

6/. Re-install every thing and it should be good to use again

Please pardon my english. Good luck to all

Before I started any of the above solutions, I called Acer Technical Support at 800-816-2237 and was given information on how to send the product in for service that is covered under the 3 year warranty. I have had two monitors that have the exact same problems, within about three weeks. I expect to have additional monitors to send back in the near future, since we use Acer primarily here at work.

Good luck all.

This is a tutorial with pictures to solve the problem specifically for the hp f1503 pavilion.
http://www.reddragonakai.com/Tutorial1Im...

Well my Acer AL1711 finally gave up in as much as the screen flashed briefly at switch-on then went blank, regardless of brilliance setting so I decided to take it apart and try to fix it. The good news is that IT WAS NOT THE LAMPS that I feared in my earlier post and was easier than I had ever dreamed! First allow a good period of time for the internal components to discharge before starting. Remove the plastic clip at the base hinge to expose 4 screws - remove all four to release the stand. Then remove the 4 black cross head screws that appear to hold the back on, they do but there is more to do. Carefully tease the silver surround away from the case, best to start in the centre of each side and finish at the corners. There are many plastic clips to release before the surround comes away. Now remove the four cross head screws holding the pushbutton switch circuit board. The whole assembly can now be removed from the case and reveal a metal cover held by 2 SHORT (remember that!) SHORT! threaded machine screws. These once removed will allow the case to be slid away from the holding tabs located down the edges of the cover and removed. Now unplug the connectors from the board that has the mains input connector attached to it. You will see a heatsink with 4 electrolytic caps above it. Silly ACER designers, have placed the capacitors so that they get all the heat from the heatsink! Yes folks, the capacitors are above the heatsink when the monitor is in its normal operating position! So all the convected heat dries them out, nice. So the fault is due to a silly design error!
Replace all 4 capacitors, two of them are 1000uF at 16V and the other two are 470uF at 16V, all radial types. Try and get capacitors with the highest operating temperature, at least 105 degree types and remember these are polarised, make sure you connect the capacitor + wire to + on the circuit board. You should have no problems with re-assembly but don't put the wrong screw where the short ones went or you are liable to see it come out of the screen LOL! Most important - - Don't forget the screw holding the earth tag to chassis. Good Luck, you will be amazed how much brighter the screen is now!

This problem is very often caused by dry electrolytic capacitors on the inverter board. If you have some skill with soldering you could try to change them. When buying new ones ask for LOW-ESR capacitors for switching mode power supplies (SMPS) and 105°C, they are a little bit more expensive than normal electrolytic capacitors, but are designed for this aplications so they lasts more. Normal el. caps will also works fine so when you cannot buy LOW-ESR for SMPS use normal ones.

This is a FIX ONLY for Rosewill R710E 17 inch Flat Panel LCD Monitor!

Symptoms: The LCD screes shows up for half second or more and turns black, but the LED light remains green and reflecting the light to the screen can be seen the screen working.

Changing the 1000uF condensator at 16V should make work your back lights like new. Usually when this problem occur you will see malformed (has to be flat at the top) at the top that peace of bad condensator. The board on work for this issue is the inverter located at the left side looking from the back. NOTE*** To prevent any accidental damage of other boards unscrew the inverter and work independently with it, specially the part with the soldering.

Hi scuball,


**PLEASE NOTE - This solution applies to ALL LCD's but NOT CRT's**


It's a very common problem with all LCD monitors

LCD's use four small Cold Compact Fluorescent bulbs to back light the display. (thats what gives the LCD it's brightness allowing you to see it)

The inverter board runs these lights and when they go bad they will typically show symptoms like you have or the monitor power light comes on and you have either no display or a very dim display.

If you ever have one that has no display but the power light is on you can check by shining a flashlight directly into the LCD from the front (right into the screen) if you can see an image then it's either the inverter board (most likely) or the CCFL bulbs have gone bad.

The inverter board and CCFL's are replaceable.

Good Luck,
El Duderino


**PLEASE NOTE - This solution applies to ALL LCD's but NOT CRT's**

I had same problem with my Sceptre X9S-Naga II 19", which I'd had to replace within a week of original purchase because of an apparently-identical problem at that time. Pissed me off that this second monitor had just 2 years' worth of use on it...I paid $500 in the day, now worth about $200 if new. I wonder if this lack of longevity is to be expected from LCDs, esp. considering the CRT I finally offed was 9 years old with never a problem.

In the end, it breaks out like this:
470uF/35VDC electrolytic capacitor from Radio Shack: $1.66
Hours here and there over the course of a week spent dissassembling, poking, prodding, and googling: incalculable
Satisfaction of resurrecting monitor: $200 plus landfill karma-credit

I had some assistance from a very public-spirited electronics repair website put up by a guy in Malaysia, without which I probably would have run the thing over with a truck by now. His pertinent web page is http://www.electronicrepairguide.com/lcd...
There is a /lot/ of info there--sift through the maze of pages and see what he's got to share from his tech experience.

Details: In my case, I had no fancy meter to check almost anything while in place, just an aging DVM. There was a chance that one of the lamps was bad (an easy but possbily expensive replacement) so I decided to pull them out of the pockets they slide into (like...fission control rods at your nearby nuke plant) so that I could directly see what they were doing during the brief power-on time. These are amazing ultramini fluorescent tubes, or at least closely resemble them in color, proportions, and wiring. They're powered by an inverter circuit that feeds them chopped high-voltage, I believe. When I reconnected them, now out of their wells, and powered up, they ALL came just partway on--not the full length of each tube, much like a fluorescent tube does when it is struggling to start--and just before my power-indicator would quit. I swapped around the lamp connectors to see if the performance would change, and it remained the same...so I knew it wasn't likely to be any lamp that was the problem.

The power supply was producing SOMETHING at some points on the board, but I had no idea what to expect or where. 80VDC at one point seemed wildly high, but turned out to be OK in the end.

On about day 67, brute force triumphed over lack of training and service data: I found the guilty cap by desoldering four of the 14 electrolytic caps on the board. I chose the caps I did to start with only because they were 'paired,' so I knew I'd be able to do crude side-by-side comparisons of resistance on them, in order to maybe-kinda-check if one was totally shorted or likely out of spec. The first pair checked out as approximately matching each other. The next pair...DIDN'T. It was ONLY then that I noticed that the cap with the substantially lower resistance (but not a full short) was, actually, BULGING a bit, as I'd hoped to notice from the outset, but it was very subtle. The bulge in the top was less pronounced than at the bottom, so it would never have jumped out at me without having desoldered them, so as to reveal them top and bottom.

A trip to Radio Shack netted me the $1.66 replacement. By this time, I was quite used to plugging and unplugging the AC power cord from the guts that were sprawled across my table, and I had laid out the board on a piece of insulating newspaper with the "cold-cathode" lamps splayed out haphazardly around it. During all testing, on powering up, the power light would come on in a blinking mode, apparently indicating the problem status. I'd hit the button to see if by chance it was going to stay lit solid for more than a few seconds, but every time it would resume the blinking status after a few seconds.

But now maybe it would be different...at last. Beads of perspiration built up on my forehead as I completed the resoldering of the caps I'd pulled. I restored the minimal external connections to the power-board and hit the power button...and was sorely dissapointed to see that it did ALMOST what it had done before. Now it looked like the lamps lit fully--but still would quit after the same brief duration. WTF? How much MORE time could I possibly spend on this?!

It's impossible to make this a long-story-short at this point, but believe it or not, I'm editing a bit of the pain here. The next day, after several more hours of messing with it and hating that the dissassembled stuff had polluted my kitchen table to the point where I was forced to eat elsewhere, I decided I could at least put parts of it back together, even if I WOULD end up running it over with a truck or throwing it out on the freeway. Also, I wanted to see how the lamps looked now, during their brief "on" duration, but when back in place, shining through the actual screen. So I powered it up again after this partial reassembly, and saw...nothing. It was getting WORSE? Where was the lamp-light?

I began to reassess my technique. What connectors had I maybe been too willing to assume didn't matter for testing this power-supply? I reconnected the chassis-ground wire. No difference. WAIT A MINUTE. I had dislodged a wide, fine connector from the back of the screen when I had been taking the lamps out a few days prior. But that shouldn't matter--I'm not sending the thing any data. Still, I'll reconnect it since I have to anyway. The excitement built, but no, STILL no difference. So this was getting weirder--why no lamps NOW? OK, just to be thorough, I reinstalled the video connector cable, to my laptop as before, though I had not needed this during the testing of the lamps while they were out of their ports...so why should it matter now?

Well, it did, though I can't say why. The bright white lamp light, I was thrilled to notice, was peeking through two small holes in the back of the frame, and...it WASN'T GOING OUT this time! So...the $1.66 cap really HAD cured the whole problem; the rest of the issues were artificial problems caused by my ignorance in testing and reassembly laziness.

Back to the basic bad-cap failure: I have NO idea what percentage of similar symptoms would be explained by this silly cap failure, but if I have this happen again, the first thing I will do is gat a bright light and a magnifying glass to inspect the caps for bulging. Even seeing nothing, I think I would remove the caps methodically, and either half-ass test them (as I did with less-than-optimal equipment) or simply replace them all. I'd guesstimate that you could buy all caps for about $20...though it would be a painful thing to do this and still not have a working monitor, I admit.

This applies to all CRT's:

Turn your monitor off, then turn it sideways or upside down.

Then turn it back on. If you get a picture when monitor is upside down or sideways, the problem is cold joint contact problem.

Solder the big transformer (the big black one with red cable) again and it's fixed.

It's high voltage transformer so remember to switch it off and verify that there is no dangerous voltage left before fixing it.

I had the same problem on my BENQ FP937 LCD Monitor.... After a lot of googling and looking and trying various solutions, I read one which said I may have a Dry Joint on on of the transformers on my Inverter Board. I grabbed the trusty soldering iron and reheated all the solder joints (particularly the coils/transformers)... Monitor has been working great ever since.... Thanks to whoever it was that suggested it to me......

My Acer AL1711 started to do this, the screen going to black at the first and maybe second switch-on but then it seemed to behave itself until the next time it was powered up. The brilliance was set at 80% so I tried lowering it down to around 50%. This eased the problem for a while but not for long. This to me suggests that the CCFL bulbs could be due for replacement rather than the inverter board as the latter will either normally fail when it gets hot over a long period of uninterupted use or it simply won't work at all.

I'm a monitor repairer, i have some of the lcd monitor information need to share with you. Most of the lcd monitor problem are power side(40%), inverter section(45%)and others problem are just 15%! When i repair the lcd monitor with no power, first, i will check the power adapter or power section and look at the electrolytic capacitor. If their no budged, then i will use the esr meter to check it. If there are no display or display come a while then shut off/no display, i will check the power secondary section capacitor, if capacitor ok, then check the inverter section. Before check the inverter section, please check their
solder point( most of the time, they have a lot of bad point or dry joint on that section affected lcd monitor display darkness, no display or display come about 1 second then display cut off. If all solder point ok, then you need to check the component inside the inverter section, especially the C5707 or C5706, these part are high damaged rate, so when you get one of that c5707 faulty, then you need change a pair! not only that faulty c5707.
Actually, when the lcd monitor before shut down, you can get some information on the screen. This information are use to help you know which part are defective! More info just try to www.fastrepairguide.com , you can get a lot of good lcd monitor repair tips!

Check your AC adapter. Mine did the same thing and was fine with a new adapter.

It has a lot of factors...maybe check the nearest or the dimpliest possible factors like the CPU case through the videocard check it if it has grounded. When the metal of the videocard and the casing attached closely they will posibly grounded. Its not a problem its just grounded.

ITS THE CAPACITORS!!!!!! READ THIS POST IM PUTTING IT UP ON ALL THE OTHER LT916S FORUMS I JUST FIX MINE THAT HAD THE EXACT SAME PROB!!!!!!OK PEOPLE I GOT THE SOLUTION TO THE MAG INNOVISION LT916S GOING BLACK AFTER ANY LENGTH OF TIME BEING ON!!! I JUST REPAIRED MINE TODAY! THE PROBLEM IS THE CAPACITOR BANK IN THE POWER SUPPLY PART THERE ARE 6 CAPACITORS I HAD A FEW LEAKY ONES "NOT GOOD" THE CAPACITOR SPECS ARE AS FOLLOWS 470UF 25V 105 DEGREES C MEANING 470 MICRO FARAD/25 VOLTS I HAD A VERY HARD TIME FINDING THE 25 VOLT ONES SO I WENT WITH 470UF/35V 85 DEGREES C THEY MIGHT NOT LAST AS LONG AS THE OTHERS DUE TO THE TEMP RATING HOWEVER, IM THINKING SINCE THEY CAN HANDLE UP TO 35 VOLTS IT SHOULD EVEN OUT AND HEY, ITS WORKING SO FAR SO GOOD!! THE CAPACITORS ARE FROM UNDER A DOLLAR A PIECE TO A COUPLE BUCKS EACH. THE CAPACITORS HAVE A BOLD LINE RUNNING UP ON ONE SIDE INDICATING THE POLARITY. BOLD LINE SIDE IS "-" SIDE WITHOUT BOLD LINE ITS "+" THE POWER SUPPLY BOARD HAS THE POLARITYS STAMPED ON THE BOARD ITSELF UNDER EACH CAPACITOR. EASY 30 MINUTE FIX IF YOU ARE LEARY ABOUT SOILDERING, FIND A FRIEND THAT KNOWS HOW TO. ITS REALLY NOT THAT HARD THOUGH AND YOULL HAVE SOME DECENT ROOM TO WORK WITH. I PROMISE WHEN YOU OPEN IT UP YOU WILL ALMOST CERTAINLY SEE AT LEAST 4 OF THE 6 CAPACITORS BULDGING AT THE TOPS MAYBE EVEN LEAKING BROWNISH STUFF. DO YOURSELF A FAVOR THOUGH AND REPLACE ALL OF THEM WHILE YOUR IN THERE "THE SIX BIGGER ONES ONLY" IF ANY OF YOU NEED FURTHER HELP OR ANY OTHER QUESTIONS ABOUT THIS PROJECT PLEASE FEEL FREE TO EMAIL ME AT BTLEE26@HOTMAIL I DAMN NEAR WENT CRAZY TRYING TO FIND A SOLUTION ON HOW TO FIX THIS THING SINCE I SPENT OVER 300 BUCKS FOR IT NEW. AND IM BY NO MEANS A EXPERT WHEN IT COMES TO THIS STUFF BUT I DO KNOW A FEW THINGS. AS IM SURE MOST OF YOU DO. TAKE CARE YOU ALL AND THANKS TO THE GY WHO MENTIONED SOMETHING ABOUT CAPACITORS BEING BAD IN HIS!

I have a viewsonic VA902b 19" that had this problem of displaying for a fraction of a second then going black when powered on. I followed the solution posted by "Tienlen" & it worked perfectly. There's only a single capacitor of significant size on the inverter board; 1000uf 25v 105c & it was bulged & leaking a bit. All others were very small none looked bad. Radioshack did not carry a suitable replacement that operates at 105c. Found a local shop that had 1000uf 35v* 105c caps(with long leads) for about $3.99 a piece. Removed the old & soldered the new one in place. The monitor works perfectly now. An easy, cheap & quick fix if you're not intimidated by pcb's & a screwdriver. All told, it was about a 45 minute project with new parts in hand.

Viewsonic warranty is fir 3 years on LCDs, get them to replace it!

Fixed my LCD exhibiting these problems. Repairer said dry joints on circuit board was fault.

no, i had the same problem,
you may have something in the usb port wen u turn your computer on,
take it out and try again,
this should work.

no, i had the same problem,
you may have something in the usb port wen u turn your computer on,
take it out and try again,
this should work.

go to menu, geomotry an h/v postion

The solution did work !!!!

I did replace the 4 electrolytic capacitors like mentioned by "The Boffin" and the TFT monitor is as new again.

 

I'm taliking about the ACER AL1711 monitor. After switching the power on the screen became black again after 3 seconds.

 

Regards, Peter Knol - The Netherlands

 

 

I have followed solution 3 and it worked perfect for me (except I have replaced only 2 capacitors, because I could see that only they were damaged. To help of understanding solution 3 a little better I have uploaded a picture of my opened Acer Al1711 monitor, hope it will help.
Link:
http://www.mediafire.com/imageview.php?q...

Regards,
Russian

unplug the monitor from the power supply completely. then plug it back in. i have the same monitor and it will not stay on when i reboot the PC unless it is totally disconnected from the power source.

@LuXOD

The page you directed me to, were backup caps, not the ones you want to put in as a replacement!

When you select replacements, you should match Capacitance, Voltage and temperature. Also, it's very important what current the caps are rated for.


I checked your link to see if they sold caps that matched the specs of the ones in your board now. The MV-WX series Electrolytes seem to be alright. They match Temp, Cap and Voltage. And have a slightly better max Ripple current.

And yes, it DOES matter how the legs are placed. These caps are polarized. Each cap has a "bar" going down on the casing with a Dash (minus) in it. This indicates the Negative pole of the Cap. Remember how the caps you take out are placed, and place the replacements just like this. You can always use the picture posted above for reference, should you forget.

It doesn't matter so much if the legs need to be bent a bit, in order to get them through the holes. Try to get them as short as possible though.

Goodluck!

@The Boffin or anyone else...


I have a Acer AL1711 which is broke, probaby the same problem as you had, the first 1-2 sec its fine picture, then so dark its almost completely dark.. I can se a little if the sun is shining... :D

So i'm about to place an order with
2 1000uF 16V
2 470uF 16V to replace the probably damaged ones...

Now to my question:

When I'm gonna solder the new ones.. Does it matter how the the "legs" are placed...


This is problably right?:
http://www.elfa.se/elfa-bin/setpage.pl?h...


I'd appreaciate some help..

BTW The site is Swedish, and so am I.. :D

Bad CCFL tubes are probably not the problem. The suggestion that the CCFL tubes are bad would mean that ALL of the tubes went bad at the same time. LCD monitors have at least 2-4 tubes each. This is an unlikely scenario. The real problem is most likely bad capacitors on the power supply board. It's easy to tell. Disassemble the monitor so the power supply board can be removed. The bad caps are easy to spot becasue they will be buldged up on the tops. This monitor typically has 6 caps that go bad. Under $10 and about an hour of labor will fix it.