No Power In LCD Monitor Solved- Model: View Sonic VP720
A computer guy brought this to my shop and explained that it does not power up. While he was waiting in the shop, I powered it up myself and sure enough it was dead but I could see that the stand by light was on. I pushed the power button but there was no response.
It is an old machine. It dated back to November 2005 but even an old LCD computer monitor deserves a chance to be repaired. So, let the repair begins.
All these screws were taken off and the cover was lifted up. I exposed the main board and the power board. Take a look
I was expecting to see some bad capacitors but there was none. I have checked all the capacitors with my trusted ESR meter but all the capacitors were found in good working order.
Since there was a stand by light, that means the main board was sending the on and off single but for some reason, the LCD screen was not powering on.
All the powers to the main board were there and they were steady so my focus was on the main board.
The customer mentioned something about deserting the LCD computer monitor for a long time. It was sitting in this storage room for more than a year. I was looking for bad soldering joints and I found some but that did not solve the problem. I re heated the main board IC’s but that did not solve the problem either.
I almost gave up on this LCD computer monitor. So I let it sit on my repair table for a while. Took a break and I started working on something else.
I remembered in one of the LCD Monitor ebooks that MR Jestine Yong wrote if all voltages checked to be good and still no power then check the On/Off power switch. May be my case here is the same so I decided to check it out.
I was really shocked at myself because that did not cross my mind and it should have. I cannot explain it but it happened, after all I am still human. I used needle nose pliers to connect the two terminals of the power switch and I look what happened.
I replaced the main power switch and everything was restored perfectly. Mission Accomplished.
This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.
Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.
P.S- Do you know of any your friends who would benefit from this content that you are reading now? If so, forward this website to your friends or you can invite your friends to subscribe to my newsletter for free in this Link.
(153)Dislikes
(0)
37 Comments
Leave a Reply
Mark
July 9, 2014 at 9:02 am
Thanks Waleed,
I think we have all been there! Sometimes the fault that is staring us in the face is often the hardest to find as we overlook it, thinking it is too simple to be the fault.
It's great to be on a forum with others that aren't too embarrassed to share their triumphs and mistakes. Good on you.
We all learn a lot from one another if we share.
Waleed Rishmawi
July 10, 2014 at 2:27 pm
Mark: yes, we are not perfect and learning from mistakes is the way to grow in knowledge and experience.
Osman
September 3, 2014 at 3:11 am
U R Right
moshe
July 9, 2014 at 12:04 pm
now that must have been annoying...
thank you for sharing it and now i'll try and remember to look for that as well!!
Waleed Rishmawi
July 10, 2014 at 2:28 pm
Moshe: it was a little bit annoying but it is a process that we go through in learning and gaining experience.
Robert
July 9, 2014 at 12:20 pm
Good job Waleed. You must mean Mr. Yong's e-book, "10 True Repair
Case Histories of LCD Monitors Volume 3", page 15.
With Mr. Yong's e-books, good tools, equipment & components, some patience & carefulness, we can repair anything that can be fixed!
Waleed Rishmawi
July 10, 2014 at 2:29 pm
Robert: yes. thanks. yes that is what I meant. totally agree
yogesh panchal
July 9, 2014 at 2:55 pm
Waleed,
Good attempt,
Thanks for sharing.
Waleed Rishmawi
July 10, 2014 at 2:30 pm
yogesh: thank you and you are most welcome
Keith
July 9, 2014 at 4:59 pm
Yes those little push-buttons switches are very troublesome and its hard to get the contacts clean again. I sometimes drill a tiny hole in the side so that I can squirt in some cleaning fluid.
Robert
July 10, 2014 at 1:57 pm
The good thing is that they are cheap, plentiful, and easy to replace. I have a bunch of them from devices that I've salvaged.
Waleed Rishmawi
July 10, 2014 at 2:31 pm
Keith: it is always better to replace them with new ones but if new ones can not be found then, repairing them is my second option.
Dominic
July 9, 2014 at 6:21 pm
Yes....this is the repair technician's greatest headache....something so simple that it can easily be missed!
Waleed Rishmawi
July 10, 2014 at 2:33 pm
Dominic: yes very true.
Luciano
July 9, 2014 at 7:54 pm
Mr Waleed
Thanks for sharing your struggles and success stories! Indeed, Mission accomplished!
Waleed Rishmawi
July 10, 2014 at 2:33 pm
Luciano: you are most welcome. have a good day
Humberto
July 9, 2014 at 10:52 pm
Good repair Mr. Walee, keep up.
Waleed Rishmawi
July 10, 2014 at 2:34 pm
Humberto: thanks man.
bob
July 10, 2014 at 1:16 am
I used to work in a tv repair shop, seldom do these switches go bad. I probably would have given up on this repair, good job.
Waleed Rishmawi
July 10, 2014 at 2:35 pm
Bob: thanks. have a good day
Albert Hoekman
July 10, 2014 at 2:35 am
Mr. Waleed,
To comfort you, nobody is perfect not even the best electronic engineer (LOL).
This good article tells us to start at the beginning of the problem and not at the difficult side.
Keep on going, I like the articles here on jestineyong.com!
Albert
[Keyboard Failure, hit F1 to Continue]
Waleed Rishmawi
July 10, 2014 at 2:38 pm
Albert: oh, I am not bothered with it. mistakes is the process of learning and gaining more experience. I am glad you like article. have a good day
Atish Chand
July 10, 2014 at 2:40 pm
Hi. Waleed,
it was a brilliant repair news from you friend,
thanks a lot....
Waleed Rishmawi
July 10, 2014 at 8:34 pm
Atish: thank you my friend.
nahum baylon
July 10, 2014 at 7:20 pm
something confuses me because you mentioned that all voltages checked seemed to be good quoted from mr.jestine yong e-books for lcd monitors and yet still no power meaning something has been forgotten.if voltages can be found without switching the on/off button to on position then how can the voltage be available at the output side.in so doing that the on/off button or switch is the problem and by switching it to on position the monitor come to life again so be it ty
Waleed Rishmawi
July 10, 2014 at 8:39 pm
Nahum: i had so many repair cases from CRT TV to LCD screens to LCD TV set that all the voltages there but the pulse to turn it on is not there. it is a like a TV set and all the voltages there but you need a remote control to power it on or the channel buttons to power it on.
venu gopal
July 11, 2014 at 12:25 am
Yes those cheap micro switches fails quite often.
Thanks for the article.
Waleed Rishmawi
July 11, 2014 at 6:23 pm
Venu: yes they are . you are most welcome
Robert
July 13, 2014 at 1:54 am
Hi Venu, the good thing is that they are very inexpensive. You can get them on ebay: 100 switches for less than $10 US.
Whenever I salvage parts from a PCB, I always keep all of the switches that check to be good.
Alex Lee
July 11, 2014 at 11:51 am
Well, a mechanical microswitch button is easy to fix enough if found to be defective. What about those monitors that uses touch sensors (with no physical buttons)?
Waleed Rishmawi
July 11, 2014 at 6:24 pm
Alex: these are completely different. the digitizer on the screen has to be changed.
Alex Lee
July 12, 2014 at 11:00 pm
Not talking about touch screens. There are monitors which do not have any physical buttons for power and direct monitor control functions. Good examples would be Samsung SyncMaster 943BW+ and Samsung SyncMaster 943NWX. Those monitors mentioned uses touch sensors instead of buttons.
Francis
July 11, 2014 at 3:01 pm
I am still confused about the problem being the micro-switch. These micro switches are pulse switches they are not toggle switches.
Robert
July 12, 2014 at 2:35 pm
I highly recommend Mr. Yong's e-books. You will understand much better. His books are jam packed with very good information and plenty of pictures.
Waleed Rishmawi
July 12, 2014 at 3:33 pm
Francis: it was the micro switch. it was a simple as that.
Andre Gopee
July 11, 2014 at 11:47 pm
Great Article... I wish I was as good as you guys with computers but I will get there some day. Thanks for sharing.
Waleed Rishmawi
July 12, 2014 at 3:31 pm
Andre: thanks. give yourself time..it will happen before you know it. keep up the good work.