viewsonic VA912b will not turn on.

[bigdoc675]

hello, I have a viewsonic 19 inch flat panel monitor VA912b, I have had it now for about 2 - 2 1/2 years give or take, it worked fine until just recently.

I have read alot of posts on here about this particular monitor but my problem is something I havent found in any other post yet so I decided to make a new topic for it.

Whenever the computer is shut off and the monitor goes to sleep mode, or the monitor is turned off , or anything resulting in no picture being displayed on the screen and the monitor going to sleep ( like a cable being unplugged ) it will not turn back on, I basically have to keep the monitor on all the time or risk it not being able to turn back on.

what it is doing is whenever I try and turn it on, no image comes up on the screen and it stays black, the green power LED located by the power switch blinks on and off and everytime it blinks it makes a peculiar popping noise, if I try and turn it on / off and plugged in / unplugged enough eventually it will turn on but only after about 30 minutes of blinking on and off and making a popping noise.

is this problem also indicative of the bad capacitors I have read about with this monitor? if so that would be good, because it doesn't look too terribly hard or expensive to fix, my other other question would be can any suggest what particular capacitors to use in fixing this monitor - if this is indeed the problem.

thanks in advance for any help

[Bobdee]

Re: viewsonic VA912b will not turn on.

You need to go in, take a look, post a picture of P/Supply
Your assumption that its caps is probably right

[bigdoc675]

Re: viewsonic VA912b will not turn on.

I got it open today and took a look at it, unfortunatlly I do not have a digital camera atm and can not a take a picture, but I can definatly verify that 6 of the caps are very much bulged, 5 of them are 470 25v and one is 470 10v.

my question is now what do i use to replace them? they are KF series, I plan to use 470uf 25v on the matching ones obviously, my question is can I use a 470 25v to replace the 470 10v?

I am planing on getting them from allelectronics.com radial electrolytic capacitors.

any help would e apreciated.

[PlainBill]

Re: viewsonic VA912b will not turn on.

I got it open today and took a look at it, unfortunatlly I do not have a digital camera atm and can not a take a picture, but I can definatly verify that 6 of the caps are very much bulged, 5 of them are 470 25v and one is 470 10v.

my question is now what do i use to replace them? they are KF series, I plan to use 470uf 25v on the matching ones obviously, my question is can I use a 470 25v to replace the 470 10v?

I am planing on getting them from allelectronics.com radial electrolytic capacitors.

any help would e apreciated.

Measure the dimensions of the caps. Yes, you can use a 470uF, 25Volt cap to replace a 470uF, 10 Volt provided it will fit.

I suggest using Panasonic FM or FC as replacements. You need low ESR, 105°C caps. It appears Allelectronics does not carry them. I suggest ordering from Digikey. This is my guide for picking the proper parts.

If you select Digikey's First Class shipping option it will cost about $2.00 for shipping.

PlainBill

[bigdoc675]

Re: viewsonic VA912b will not turn on.

so this will not even thought it is 470 25 volts? link below

https://www.allelectronics.com/index.php?page=item&id=470R25&extra=a:2:{i:0;s:40:"03823345592a403b2f4a37a59384e7ab28f02be1";i:1;s:0:"";}

[Krankshaft]

Re: viewsonic VA912b will not turn on.

All electronics is good for A/C adapters, and other specialty items also certain electronic components like semiconductors, resistors, etc.

But stay away from their cap lines I've seen them selling G-Luxons and other crap cap brands. Not to mention there is no telling how old some of the caps are since they do buy up alot of liquidation and discontinued stock.

Digikey, Mouser, and Newark buy direct from the manufacturer and they have decent turnover so you get fresh stock.

As for the cap at that link the brand and series is unknown (not even a picture) so it's a safe bet to say that it's a General Purpose cap which is what you DON'T need. You need low ESR.

Pansonic FCs or FMs from Digikey will do.

[bigdoc675]

Re: viewsonic VA912b will not turn on.

ok, I think i got it covered, Just got 1 more question, sorry for all the questions but this is my first time trying anything like this.

this is not MY board, but this is the exact same type , make, model, looks identical

https://www.badcaps.net/forum/attach...achmentid=9628

I have it narrowed down to either

http://search.digikey.com/scripts/Dk...name=P12389-ND

or

http://search.digikey.com/scripts/Dk...name=P12388-ND

these should work right? 1 is 8MM and one is 10MM i tried to measure my caps but I couldnt get a very clear measurement, does it really make a difference if i get 8mm or 10mm? does anyone happen to know which size they are going by the picture above?

[PlainBill]

Re: viewsonic VA912b will not turn on.

ok, I think i got it covered, Just got 1 more question, sorry for all the questions but this is my first time trying anything like this.

this is not MY board, but this is the exact same type , make, model, looks identical

https://www.badcaps.net/forum/attach...achmentid=9628

I have it narrowed down to either

http://search.digikey.com/scripts/Dk...name=P12389-ND

or

http://search.digikey.com/scripts/Dk...name=P12388-ND

these should work right? 1 is 8MM and one is 10MM i tried to measure my caps but I couldnt get a very clear measurement, does it really make a difference if i get 8mm or 10mm? does anyone happen to know which size they are going by the picture above?

Electrically, either will work. I suggest checking the length - measuring diameter is tricky unless you have calipers. Of course, if you have plenty of space around the cap diameter doesn't matter.

PlainBill

[Krankshaft]

Re: viewsonic VA912b will not turn on.

A cheap set of digital calipers does help alot especially since Panasonics datasheets list dimensions in mms but I personally like it that way you can get them for around 9-15 bucks at places like Harbor Freight or online.

If not then get a ruler with milimeters on it. Diameter as it was already said and height are the crucial measurements.

Based on the pics from the other post of the board the shorter stubbier cap will work fine. But you should measure and compare it to the caps size listed on the datasheet to double check.

[Krankshaft]

Re: viewsonic VA912b will not turn on.

Lets see:



The stubber cap EEUFM1E471 is 10mm in diameter by 16mm tall.

The taller cap EEUFM1E471L is 8mm in diameter by 20mm tall.

It's much easier to browse the datasheet for the caps to see if they're in the sizes you need then just copy and paste the Panasonic part number in the search bar on Digikey and it takes you right to them.

Always go by the datasheet for sizing the pics can sometimes be a representation of the series and not a pic of the actual cap.

[Toasty]

Re: viewsonic VA912b will not turn on.

Conversion chart I acquired from the web. It's in German, but you'll get the idea:

Inch to Millimeter Conversion Table

Toast

[Bobdee]

Re: viewsonic VA912b will not turn on.

ok, I think i got it covered, Just got 1 more question, sorry for all the questions but this is my first time trying anything like this.

this is not MY board, but this is the exact same type , make, model, looks identical

https://www.badcaps.net/forum/attach...achmentid=9628

I have it narrowed down to either

http://search.digikey.com/scripts/Dk...name=P12389-ND

or

http://search.digikey.com/scripts/Dk...name=P12388-ND

these should work right? 1 is 8MM and one is 10MM i tried to measure my caps but I couldnt get a very clear measurement, does it really make a difference if i get 8mm or 10mm? does anyone happen to know which size they are going by the picture above?

The lead spacings is the correct size for the 5 caps on the P12388-ND
The small cap by transformer, I suspect that there is not enough room for either, suggest you choose something closer to the original 470uf 10V
Also (are you sure that 10V is a 470uf and not a 47uf

[bigdoc675]

Re: viewsonic VA912b will not turn on.

here is a picture I labeled



Number 6 is the one that I am pretty sure is 470 10v, it looks like a 25v might just fit, but I will probably order a 10v as well just to be safe.

this here looks like the one I am going to get for #6 on that picture http://search.digikey.com/scripts/Dk...name=P12361-ND

[Bobdee]

Re: viewsonic VA912b will not turn on.

Hello bigdoc675
My mistake I missed a cap somewhere, I thought the cap left of the transformer (above No 4 cap) was the one you were refering to as 470uf 10V
bob

Just noticed that your first picture does not show the 470uf 10V, thats why the error
bob

[bigdoc675]

Re: viewsonic VA912b will not turn on.

yea, i figgured thats what it was, the one next to the transformer is actually fine and not bulged at all, and I am not going to replace since this is my first time I just wana tackle what is actually broken, maybe next time ill be a bit more brave

by the way , thanks to everyone who has replied, you all have been a HUGE help , i got the proper parts on the way and feel i can salvage my monitor

[kc8adu]

Re: viewsonic VA912b will not turn on.

yea, i figgured thats what it was, the one next to the transformer is actually fine and not bulged at all, and I am not going to replace since this is my first time I just wana tackle what is actually broken, maybe next time ill be a bit more brave

by the way , thanks to everyone who has replied, you all have been a HUGE help , i got the proper parts on the way and feel i can salvage my monitor

someone wants some extra practice tearing that thing down again in the near future.

[Toasty]

Re: viewsonic VA912b will not turn on.



I want him to come work for me!! He can look and tell what parts are good and bad! I can throw out all this test equipment! He's magic!

>>I have read alot of posts on here about this particular monitor... <<

...and evidently you're not going to pay attention to what they said.

Replace ALL the caps.

Toast

[PlainBill]

Re: viewsonic VA912b will not turn on.

Now, now guys, be nice. Not everyone learns in the same way.

A wise person learns from other people's mistakes.

A smart person learns from his mistakes.

A id10t doesn't learn from his mistakes.

PlainBill

p.s. Bigdoc, that capacitor is part of the VCC supply for the SMPS controller. It has been known to cause a 'will not start' problem in several different brands of monitors. The one that drove me nuts was a Gateway.

[bigdoc675]

Re: viewsonic VA912b will not turn on.

Ok, ill replace the little one to, I went ahead and ordered 2 of them anyway when i placed my order this morning just in case.

its this one here I do believe

http://search.digikey.com/scripts/Dk...name=P12927-ND

what I did not order was the really big one, I believe the 400v one? cause it was my understanding this one almost never fails and is ok to be left alone?

[PlainBill]

Re: viewsonic VA912b will not turn on.

Ok, ill replace the little one to, I went ahead and ordered 2 of them anyway when i placed my order this morning just in case.

its this one here I do believe

http://search.digikey.com/scripts/Dk...name=P12927-ND

what I did not order was the really big one, I believe the 400v one? cause it was my understanding this one almost never fails and is ok to be left alone?

That cap is most likely the correct one. Typically the Vcc cap has a value between 22 uF and 100 uF, depending on the SMPS controller.

The 400V cap rarely fails. It is handling 120 Hz AC ripple, the output caps are handling pulses at over 100 Khz.

PlainBill