Question about ViewSonic Optiquest Q19wb LCD Monitor

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I have the same problem -- monitor goes blank after 2 secs. I found C815 on the PSU board. 1000uF, 25V cap, lilon brand. I measured the voltage while PSU was plugged in (very dangerous!), and found it to be holding 14.3V with lcd attached, 13.9V with lcd panel disconnected. Cap still held charge once plug was yanked. Should I still try to replace the cap? I didn't see any caps which had any signs of burn/bulging. LCD is made by InnoLux in China.

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Considering the slow discharge of the cap, it is probably good and without an RCL meter with loss capabilities, it would be tough to condemn it.
In most cases I've seen, the larger filter caps are not at fault but rather caps in the range of 4.7-100uFd that are used in the feedback path. The voltage ratings are seldom over 50VDC. These are exposed to high frequencies and if a standard electrolytic is used (they are cheaper) they will eventually fail due to the decay of the chemicals in them.
You might check for a radio amateur club in your area since one of the members might well have an RCL bridge/meter with DF capabilities. If you find one with more than one frequency range, a bad cap will show a major decrease in capacitance and increased losses at the higher frequency.
Good luck-

Posted on Oct 06, 2010

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Posted on Jan 02, 2017

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Hi I need to replace 3 x blown capacitors for my LCD monitor. They are 820uf 25v. Do they have to be an exact match ie ceremic/tolorences?


They can be 1000uf 25v (20% higher value is OK), higher voltage is also OK but it may not fit the board. The temperature rating must be 105c and Low ESR type which is very important for switching power supply. You should replace them in a set.
You can get the PANASONIC FM or FC series from DIGIKEY, or from Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.

http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
Failed TV and Monitors: http://s807.photobucket.com/home/budm/allalbums

Oct 03, 2010 | Samsung SyncMaster 940N Flat panel Monitor

3 Answers

ViewSonic Optiquest Q19wb LCD Monitor goes blank after 2 secs. A couple of posts say replace the 1000uf 16v Cap, My problem is i can't find them on the pcb (where are they?)


sgcb1971, There are lots of pics on web for you to view and then you will know what to look for. Electrolytic filter capacitors are not to hard to spot on a "switch-mode-power-supply"/"ccfl inverter supply" combo board. Why don't you visit YOUTUBE for some video clips of "lcd monitor disassembly" and "lcd monitor repair" . Also try www.ccl-la.com/badcaps.htm for more clues as to just what to look for. Ya know , you need a soldering iron to replace them if they are bad!!! It's not like changing batteries in a flashlight 12fixlouie

Mar 28, 2010 | ViewSonic Optiquest Q19wb LCD Monitor

1 Answer

I own a XG-91D monitor that the screen goes black after about 5 seconds. I found 2-470uF 25V capacitors on the power supply board that were leaky - replaced them but the problem still persists. There...


Hello,

Replace thee 1000uf caps too. A capacitor meter will not test the ESR ( equivalent series resistance ) of the caps the cap meter will show them to be good but an ESR meter will show then to be bad. Also be sure to use low ESR caps. If you use general purpose aps like from Radio Shack it can damage the board board because of the ESR rating. The temp rating needs to be 105c or the new caps will blow out within a month because of the heat in the monitor case ( No fans ).

I hope this helps, if so please rate our solution.

Buddy
Corporate Computer
www.ccl-la.com

Mar 17, 2010 | Xerox XG-91D 19" LCD Monitor

1 Answer

Power light blinking on and off


You will need to replace the below failed caps.
2 - 1000uF @ 10V
3 - 470uF @ 25V
1 - 470uF @ 10V


May 18, 2009 | ViewSonic VX910 19" LCD Monitor

1 Answer

931B tries to come on but shuts back off


Problem solved by changing 3 capacitors (C112, C113, C316).

Replace the 470uF 25V with a good quality low ESR type and the two 820uF 25V with 1000uF 25V low ESR types.

The 1000uF caps should be 10x20 in size, however I managed to get 13x20 caps in, but it was a bit tight.

Apr 03, 2009 | Samsung SyncMaster 931B 19" LCD Monitor

2 Answers

Optiquest q20wb Screen goes blank after powering off


I had the exact same problem. The screen went black and the green light flashed. I went ahead and took the monitor apart (scary) and took a look at the power supply circuitry. I saw 6 suspicious electrolytic caps on the board. Three 470uF 25V 105 degree C caps, two 1000uF 10V 105 degree C caps, and one 470uF 10V 105 degree cap. They all appeared to be slightly bulging and one even had a small hole in the top. I decided to replace all of them. The parts cost a little more than 5 bucks. I couldn't find a 470uF 10V cap at my local store so I bought a 16 V version instead, which is fine. Anyway, after replacing all 6 caps, the monitor works as good as new.

Mar 02, 2009 | ViewSonic Optiquest Q7b Flat panel TFT 17"...

2 Answers

Samsung 940BX LCD monitor 9 mos. old, Problem with monitor not staying on. You turn it on, it will come on for about 3 secs w/picture then goes off, but blue light stays on, black screen. Press power...


The IPboard part no. BN44-0012A is bad. We had to replace 5 monitors with the same problem. If under warranty call 1-800-Samsung for repair or exchange.

Korhan Balimtas

May 19, 2008 | Computers & Internet

5 Answers

Can changing 3 capacitors on motherboard solve my problem?


We had a power surge and my VL2018W LCD monitor stopped working... blank screen and flashing blue light.

I carefully opened up the back and found the power board (the one the AC plug goes into). There were about 5 electrolytic capacitors that were bulging (but not ruptured). There were 3 with the values listed by the original poster (470uF @ 25V) and 2 with 1000uF @ 10V.

I scrounged a couple of 2200uF@10V caps for the last two and bought 3 470uF @ 35V caps from Radio Shack (P/N 272-1030).

Luckily, the monitor came right back up and seems to be OK. It was out of warranty, so there wasn't a big risk.

Just increasing the working voltage won't do that much for you. If any caps are bad, just replacing them with the same value is good enough, but a higher working voltage won't hurt (usually means a bigger cap).

Good luck.

Rich

May 04, 2008 | Princeton Digital VL2018W Monitor

1 Answer

Nec LCD1720M


Replace the bulging caps:
C 701; 1000UF @ 35V
C 704; 1000UF @ 16V
other caps that may test weak and should be replaced are:
C727; 47UF @ 25V
C613; 10UF @ 50V

Jan 13, 2008 | BenQ FP737S-D 17" LCD Monitor

3 Answers

Picture problem


Having the same problem, storm the night before? Mabye lighting

Jan 09, 2008 | ViewSonic VA902b 19" Monitor

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