Samsung 931BW 19” LCD Monitor-Display Shutdown In One Second Solved!
Monitor came in with the complaint of display shutting down after 1 second. You could hardly see any display/logo because it happens so fast. Most of the LCD Monitors that have display shutting problem will shut down after few seconds and not in one second.
Once the cover was removed I could see a bulged e-cap. I thought by replacing the e-cap the Monitor will come back alive again but I was wrong. It seems the problem still the same. The only thing I could suspect was the bad backlight and bad high voltage transformer. I did not suspect the Inverter IC because it is usually very robust.
Fortunately customer brought in two similar LCD monitors and I could swap the boards to see which board is causing the problem. Although I have the spare backlight, I still prefer to use the same model parts for comparison purpose. The first thing I do was to swap the working LCD panel that has 4 good backlights. The outcome stills the same-shut down after 1 second.
Next, I swapped the Inverter/Power board (I/P board) to really make sure is indeed this board is the problem and not the mainboard. It is confirmed that the Inverter/Power board was the problem.
My next move was to swap the high voltage transformer. Although the high voltage transformer checked to be good, I still have to replace it. The reason for it is because some high voltage transformers could breakdown when under load. Even after the replacement of the high voltage transformer, the problem still has not resolved it yet.
The only choice I left is to either direct replace the Inverter IC (SEM2005) or to check on the ballast capacitors. For your information if one of the ballast capacitors have problem the display could go into shutdown mode after powered it On.
I did not check on the ballast caps and instead I opted to replace the inverter IC first. I took out the inverter IC from the working unit and soldered it on the bad power/inverter board. Guess what is the result? The LCD Monitor worked superb!
Now, obviously the IC that I took out should be bad because the bad Monitor already working with a new inverter IC. So I soldered the bad Inverter IC onto the working Monitor power/inverter board and expected that it will shut down in 1 second. I was stunned when the LCD Monitor also worked perfectly!
My conclusion was that I made a mistake that I did not resolder the suspected inverter IC first. I should have resolder the IC before putting in a working IC. It was a cold solder joint problem. No worries about this because you can learn from my mistake. My mistake is your gain.
In the future if you see any LCD Monitor that the display shutdown in 1 second and not in few seconds, then head on to the Inverter IC section. You can:
· Resolder the IC first and if the problem stills the same you can….
· Direct replace the Inverter IC and if the problem stills the same you can….
· Check all the corresponding components related to the Inverter IC
Of course before you do the above tests make sure there are no bad or bulged e-caps. There is no harm trying to swap the backlights or the high voltage transformer first. The choice is yours. After all troubleshooting should be fun.
Note: Please do not attempt to perform the repair work if you do not know about electrical safety.
If you have any interesting repair article that you want to share to others please do email me.
I encourage you to leave your comments on the post, as well as share the post with anyone you feel may benefit from it using the social media buttons below-thanks.
Click here to learn the 10 True Repair Case Histories Of LCD Monitor Volume 1
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Victor von Grueter
November 20, 2012 at 9:38 am
Hi there. I read your repair article. I repaired thousands of old (CRT) and mabe 100's of LCD Screens in the last few years. To check if I get a signal on the output of the "switch-mode-IC", I go to the internet to look for the pinouts of the IC, (print the pinouts/read through the specs.) Then I check with First: a multimeter for the correct voltages and/or check with an oscilloscope the signals. The clock is normally crystal controlled (check frequency on X-tal pins) then check for squarewave or sawtooth or pulse-wave at the output .... into the FET (often 8 pin SMD) .... and output on FET .... to the HV transformer. This cuts out the guessing and a lot of probing around. Logically all caps are tested before with an SER/cap meter. Sometimes they still look OK, but the values changed too much to work properly. Hope this will help.......... Essential instruments: Variable power supply (home-built) 40 Mhz Scope, Multimeter (with perhaps a frequency meter), "normal tools", 2 or 4 good working loose Backlights with plugs on the ends. These I use for testing if the backlights in the unit whether they are at fault or the circuit that is defect..
Jestine Yong
November 20, 2012 at 10:23 am
HI Victor,
That was a good one!Thanks
Jestine
Christopher Simbeye
June 16, 2016 at 2:48 pm
That was quiet great Victor, now we need such more details so that we are simplify our troubleshooting techniques. Honestly I would love to be a quick troubleshooting technician. You need to highlight more on the best tools to be used on all levels. You mentioned about the 100's repaired CRT TV's,how did you summarize your troubleshooting.
Aden
November 20, 2012 at 9:40 am
thanks for your amazing feedback from your work. congraturation. its real interesting. i wish one day i will be Jestine Yong. Thanks my teacher and i will never stop to be the follower of your articles. wishing you long life.
Jestine Yong
November 20, 2012 at 10:32 am
Hi Aden,
Thanks and you are welcome!
Jestine
bob lou
November 20, 2012 at 10:17 am
Jestine could you tell us the part number on that invertor chip?
Jestine Yong
November 20, 2012 at 10:26 am
Hi Bob,
The inverter chip is SEM2005 and can be downloaded from this link:
http://www.eserviceinfo.com/downloadsm/55805/SEM2005_INVERTER.html
Jestine
Edward Dunaj
November 20, 2012 at 12:12 pm
I sure appreiate all the repair tips you offer Jestine.
Keith Bosenberg
November 20, 2012 at 12:49 pm
I have a Samsung Syncmaster 226BW. A fri\end gave it to me and said that I could have it if i could fix it - it was shutting off as soon as I switched it on. I remembered a previous article of Jestine. I opened it up and spotted a bubbled cap. I purchased a Hitano 1000microF 25V cap and soldered it it - Perfect (months already) - and I'm using it at the moment to type this comment. Thanks Jestine.
Jestine Yong
November 20, 2012 at 7:44 pm
Hi Keith,
That was a very good experience!
Jestine
Waleed Rishmawi
November 20, 2012 at 1:12 pm
Very interesting article. Thanks for sharing
Abimael
November 20, 2012 at 1:33 pm
Good trobleshooting still. thanks!
Luis Estrada
November 20, 2012 at 2:03 pm
Jestine,
Thanks for a great article and sharing your knowledge. I second what Aden said and thanks to Victor for his insights; any chance of getting more details on his home built variable power supply?
Jestine Yong
November 20, 2012 at 10:53 pm
Hi Luis,
Getting more details on his home built variable power supply? Could you elaborate?
Jestine
moshe
November 20, 2012 at 3:10 pm
Hi Jestine
Thanks for sharing that.
Its instructive to see how you went about the resolution to the problem!
Your articles are always great.
Jonathan
November 20, 2012 at 3:11 pm
Very interesting, . Would it be possible to reliably check for cold solder joint with a sensitive ohm
meter or by injecting and recieving some sort of ac signal?
A wise man once observed that an expert is someone who has made, and learned, from every concievable mistake in his chosen field!
Thanks for sharing.
Jonathan
Yusuf
November 20, 2012 at 6:21 pm
Hi Jestine, Congrats for your good work.We are learning alot from you.Keep it up.Maybe you can also cover about troubleshooting satellite decoders.Some of us have interest in that aspect.
Thanks.
william
November 20, 2012 at 8:51 pm
Thanks for the great steps.
If I am in your position after swapping the IC, I might just simply replace with new IC on the other monitor.
But you continue to solder back the suspect faulty IC and found it was due to cold soldering.
Great tips!!!
Octavio Ramírez
November 20, 2012 at 10:20 pm
Hola Jestine: Gracias por tus informes de las reparaciones, excelente informcación para todos los que nos dedicamos a esto. Felicitaciones
chaminda
November 20, 2012 at 10:24 pm
why do you not have the more difficult repairing
Jestine Yong
November 20, 2012 at 10:51 pm
Hi Chaminda,
Could you define more difficult repairing?
Jestine
Ghris
November 20, 2012 at 10:44 pm
Every encounter i read from your articles gets so interesting and nice. Please, Mr Yong i would like to understand more about the flow and separation of signals in form of a block diagram- thats is like signal that finally comes into picture and that of sound and the components responsible for the same respectively.
Jestine Yong
November 20, 2012 at 10:52 pm
Hi Ghris,
Wish I have the time for it.
Jestine
Khalid Ahmed Sheikh
November 20, 2012 at 11:11 pm
Hi Jestine Yong,
Day by day i am becoming experts with your emails providing alot information about resolving LCD MONITORS etc.
Thank you
Jan Coetzer
November 21, 2012 at 12:56 am
Hi Jestine, thanks for the article and tips on the 19" Samsung though I would like to mention I have had a similar problem on an LG TV mod 32LC2R, also to find that the fault is caused by the inverter board on one of the high voltage transformers (internal short) and shutdown fault message is evident. Unfortunately these boards are obsolete and I could only repair it by stripping another transformer from a spare broken board I had. Never throw your old broken boards away you always salvage something from them. Best regards.
Jestine Yong
November 21, 2012 at 12:58 am
Hi Jan,
You are right, never throw away those broken boards.
Jestine
Peter
November 21, 2012 at 1:06 am
Great post, its helpful. But I had a similar problem on a CRT monitor, do you know how to go about it.
Jestine Yong
November 21, 2012 at 2:10 am
Hi Peter,
Have you checked the output voltage from power supply? What is the B+ supply voltage?
Jestine
mustabz
November 21, 2012 at 1:09 am
Thanks jestine for that lovely article. I can imagine we've all taken giant leaps to get over small puddles. it will do alot to knowing where to start.
thanks again.
mustabz
Roderick Serrano
November 21, 2012 at 1:20 am
Hello Mr jestine, thank you for sharing your knowledge how to be a good repairer. it is a good opportunity to me to gain all tips that you shared. have a nice day and more power..
Mustapha
November 21, 2012 at 2:38 am
will this also repair Samsung B2030 with no power
Jestine Yong
November 21, 2012 at 5:08 am
Hi Mustapha,
No power would be different way of troubleshooting and not in the inverter board. You have to concentrate on the primary side and make sure no shorted diode in the secondary side.
Jestine
Abdoulie Bah
November 21, 2012 at 4:09 am
Thanks well done master, you really great to help people like me to get experience on this technology world, wish you well and the family.
Nimal
November 21, 2012 at 4:22 am
Hi, Mr Jestine. Your tips and tricks are very valuable. Thanks for sharing with us.
Nimal
Bela
November 21, 2012 at 8:26 am
Hi Jestine Yong.
This is a very nice artycle. This is nice tip for avrywone.
Thanks.
antonio Diaz
November 21, 2012 at 9:25 am
hola hermano pueden enviarme el contenido pero en español no entiendo nada,Dios los bendiga
Jestine Yong
November 22, 2012 at 6:24 am
HI ANTONIO,
You can use Google translation to translate the web content.
Jestine
Dharmesh
November 21, 2012 at 9:43 am
nice article
abdulazeez
November 21, 2012 at 10:29 am
hay,sir Very interesting article. Thanks for sharing
carlos
November 21, 2012 at 12:58 pm
great¡¡¡, hi jestine, nice article. thanks
arniel
November 21, 2012 at 9:35 pm
thanks sir, i always reading your article that's highly relevent to my job. As of now my focus is on repairing hp centralized printer a 3 in 1 printer, with its features of printing, copying, scan to email or network folder and fax.
I appreciate you so much for sharing your knowledge.
Crispin
November 21, 2012 at 11:04 pm
Jetine,
Very subscribing... I've learned a lot from you. Keep up the good work. God bless you and your family.
mosbad
November 22, 2012 at 2:05 am
Jestine,
Always interesting articles from you, in fact refreshing the brain and knowledge
of the veteran techs as well, pls keep it up, more grease to your elbow.
Del Corso A.
November 22, 2012 at 12:26 pm
Thank you,Jestine ! Another very interesting article.We continue to learn!
henry nyeche
November 23, 2012 at 12:51 am
well jestine, that mistake is really a leason, i have been away for sometime, but am back now
henrynyeche
Daniel
November 23, 2012 at 4:55 am
Hi Jestine very good update on the samsung also the backlights just by resoldering it solved lots off shut down problems.I repaired lots off it recently all are working well now.Thanks to you for all the knowledge that you shared with me . From the time i purchased *how to repair lcd monitors* to this date i repaired over 100 all thanks to .Well done keep up the good work Jestine.
Jestine Yong
November 24, 2012 at 9:46 am
HI Daniel,
Thanks for the support and keep up the good work!
Jestine
Victor almendarez
November 23, 2012 at 6:18 am
Thanks Justin for sharing his knowledge to those who want to learn more
Henry Thomas
November 24, 2012 at 12:30 am
hi jestine i just donw load the copy of your book 10 repair cases of lcd monitor repair its a good material. this i will use to repair monitor problems. i will be buying your course lcd and plasma tv repair shortly.thanks Henry Thomas from belize.
Jestine Yong
November 24, 2012 at 9:45 am
HI Henry,
Thanks for the support!
Jestine
Ripon
November 24, 2012 at 12:56 pm
Sir,
I am Ripon From Bangladesh. I can't repair lcd monitor white display problem and on the screen line(vartical).please help me.
Jestine Yong
November 25, 2012 at 7:52 am
HI Ripon,
Vertical lines and white display are the common faults of bad lcd panel and usually it can't be repaired. This means if the lcd panel controller board is getting the supply voltage this means the lcd panel is bad.
Jestine
Romeo
November 27, 2012 at 6:28 am
Hi Jestine,
I just want to ask you what program or software did you use when you take picture of circuits from their board because I see they are very clear on the screen.
Romeo
Jestine Yong
November 27, 2012 at 6:30 am
HI Romeo,
I just use my normal digital camera and edit the photo using Paint provided free by microsoft. By the way the camera has the macro mode where it can take picture on close range.
Jestine
John
November 28, 2012 at 4:55 am
Dear Jestine,
In your repair procedure listed above you said the problem was a cold solder joint.
I was always taught to call it a DRY JOINT. Just thought you would like to know that.
Jestine Yong
November 28, 2012 at 6:28 am
Hi John,
Yes sometimes I will use the word dry joints too in my other articles.
Thanks.
Jestine
bhavin
December 2, 2012 at 8:26 am
i have 17'' samsung monitor dfx 763 and eht not working good like out fouces i replace it but still 4 corner show is double sheds. so what is the problem..
Jestine Yong
December 2, 2012 at 8:36 am
HI Bhavin,
It could be the crt tube or the crt socket problem.
Jestine
Davip
December 3, 2012 at 8:57 am
I have a question for Jestine: the big e-caps in inverter sections serves as a power reserve for ccfl startup?
To John : i don't understtand neither "cold solder" nor "dry" joint, for "cold" i think it means that a joint is made with no enough melting temperature, for this article is probably the case, then a factory defective job or maybe a too few solder joint, in some cases when in other monitors we find cracks in high voltage / high frequency / high current pins, is maybe right "crackd joint" or "poor joint" due to low quality/quantity of solder, for "dry": there's no liquid at ambient temp. so it could means too long melted solder where the flux part has gone away and it doesn't melt more well, but this is not the case 'cause more probably it was a factory soldering. In the end, i don't think is productive to select for one word or another, the meaning is clear to all.
Jestine Yong
December 3, 2012 at 11:58 pm
Hi Davip,
The big ecaps are the filer caps to remove ripple in the dc output lines and one of the lines is going to the inverter section.
Jestine
rajesh
December 4, 2012 at 3:41 am
Hi Jestine yong,
always great please regard THanks.how can you winding inverter transformer any calculation .fault back light of instantly .can you open return pulse to protection circuit for temparaly on backlight.
Jestine Yong
December 4, 2012 at 7:05 am
Hi Rajesh,
It can't be rewind because the wire is just too thin.
Jestine
onen
December 5, 2012 at 11:22 am
hi, mr. yong,thanks alot with your wonderful knowledge you are feeding us with. i would like to know if you can help me about how to repair my personal 14 inch monitor/computer which disturbs me to power on andyet when i try to check it shows power is flowing inside but no powering, thanks .while i look forward for your ebooks .strictly jestine first then the rest later, ok .not for bad. kindly awaits for your reply. onen
Jestine Yong
December 10, 2012 at 4:16 am
HI Onen,
If there is no output voltages that the problem could be in the primary side. You may have to check all the components or by using voltage testing to make sure the vcc supply to power ic is good. Sometimes a shorted secondary diode also could cause no power symptom.
Jestine
Vaibhav (onelove1984)
December 6, 2012 at 11:44 am
Model: Samsung 933SW.
Symptom: Colour problem.
Hi Jestine,
I get this monitor from my customer for repairing. There are Red, Blue, Green & White displaying on the screen. It keep changing from one color to another. Like a disco light LOL. I opened the back panel and checked the mainboard and the power supply. Everything is looking fine from above. I am suspecting the mainboard display chip SE717M - LF.
Jestine Yong
December 10, 2012 at 4:19 am
Hi Vaibhav,
Before you change the mainboard make sure no bad/leaky components in the VGA connector especially the h/v lines.
Jestine
suhaimy
December 6, 2012 at 6:35 pm
Dear Justine
How do you know the inverter IC or how to recognize inverter Ic.
I do have a panasonic tV that could not lit-up the back light. The only i can get the clicked sound.
I feelthat i have I have the same problem.
Jestine Yong
December 10, 2012 at 4:04 am
Hi Suhaimy,
Inverter ic is the ic located in the inverter board. Bigger tv have few inverter ics while small tv/monitor only have 1 inverter ic.
Jestine
Nimal
December 14, 2012 at 3:57 am
Dear Mr Jestine.
Your repair tips are very informative. Thanks and best regards.
victor 4rm lagos
December 25, 2012 at 2:21 pm
u a the best of this moment; young thanks alot. happy xmass & new year n advance
Jestine Yong
December 25, 2012 at 7:26 pm
HI Victor,
Thanks.
Jestine
DENNIS
January 10, 2013 at 5:52 pm
i have two different units that previously played both cd and dvd but now only plays dvd.
can you help mr?
Jestine Yong
January 10, 2013 at 9:06 pm
Hi Dennis,
Try check or replace the spindle motor. A slower speed motor will cause such problem.
Jestine
Ronald
January 13, 2013 at 9:50 am
Dear Jestine,
You are the best,i learn something in your repiar guide and thank for sharing your skills,experience in repairing lcd tv and knowledge to us.Hope you have more..more..more..repairing tips we got from you.
Din
September 25, 2013 at 1:33 pm
Same monitor I guest.. My problem is the IC blown... Now I dont have any idea what type of IC. That IC is located with the heatsink.
Jestine Yong
September 26, 2013 at 9:43 pm
HI Din,
The monitor is not with me now thus I would not know what is the exact part number-sorry.
Jestine
Zahid
September 19, 2014 at 11:52 am
Dear jestine yong,
Im having problem with my Lenovo 2251 pwd 22 inch monitor.
first lies and pixels problem on booting (some resolution moods) but it used to get fine when wondows logon screen came.
Now on this resolution mood (Windows logon screen _1280x1024)this problem appeared.Cables is OK also replaced but problem is with Diplay.
I like u to help me.
Thanks in advance,
Regards,
ZAHID
Jestine Yong
September 19, 2014 at 9:36 pm
HI Zahid,
If related to resolution problem it is usually due to OSD menu setting or programs problem in the MCU/FLASH ROM IC.
Jestine