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10 True Repair Case Histories of LCD Monitors Volume 3

Brought to you by Jestine Yong http://www.LCDMonitorCaseHistories.com 1

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You cannot give this E-book away for free. You do not have the rights to redistribute this E-book. Copyright@ All Rights Reserved Warning! This is a copyrighted material; no part of this guide may be reproduced or transmitted in any form whatsoever, electronic, or mechanical, including photocopying, printing, recording, or transmitting by any informational storage or retrieval system without expressed written, dated and signed permission from the author. You cannot alter, change, or repackage this document in any manner.

Jestine Yong reserves the right to use the full force of the law in the protection of his intellectual property including the contents, ideas, and expressions contained herein. Be aware that eBay actively cooperates in closing the account of copyright violators and assisting in the legal pursuit of violations. DISCLAIMER AND/OR LEGAL NOTICES

The reader is expressly warned to consider and adopt all safety precaution that might be indicated by the activities herein and to avoid all potential hazards. This E-book is for informational purposes only and the author do not accept any responsibilities or liabilities resulting from the use of this information. While every attempt has been made to verify the information provided here, the author cannot assume any responsibility for any loss, injury, errors, inaccuracies, omissions or inconvenience sustained by anyone resulting from this information. Most of the tips and secrets given should only be carried out by suitably qualified electronics engineers/technicians. Please be careful as all electrical equipment is potentially dangerous when dismantled. Any perceived slights of policy, specific people or organizations are unintentional.

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Limit of Liability / Disclaimer of Warranty: The authors and publisher of this book and the accompanying materials have used their best efforts in preparing this program. The authors and publisher make no representation or warranties with respect to the accuracy, applicability, fitness, or completeness of the contents of this program. They disclaim any warranties (expressed or implied), merchantability, or fitness for any particular purpose. The reader is expressly warned to consider and adapt all safety precautions that might be indicated by the activities here in and to avoid all potential hazards. By following the instructions contained herein, the reader willingly assumes all risks in connection with such instructions. The authors and publisher shall in no event be held liable for any loss or other damages, including but not limited to special, incidental, consequential, or other damages. As always, the advice of a competent legal, tax, accounting or other professional should be sought. This manual contains material protected under International and Federal Copyright Laws and Treaties. No parts of this manual shall be reproduced or transmitted by any means, electronic, mechanical, photocopying, printing and recording or otherwise. Any unauthorized use of this material is prohibited. All product illustration, product names and logo are trademark of their respective manufacturers.

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Content 1

No Power In LCD Samsung 17” 713n

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Intermittent Power Problem In Benq LCD E2200 HD 22”

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No Power In Benq T705 17” LCD Monitor

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Display Shutdown After Few Seconds In Hp LCD 19” HPW19e

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No Power In DELL LCD 20” E2010HC

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No Power But Good Output Voltages In LCD Samsung 931

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Display Shutdown After Few Seconds In LCD Acer AL1715

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Burnt Power Supply In LCD ACER AL1717 (Modification Of External Power Supply Method)

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Display Shutdown In Samsung LED 20” SA300

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10 Dim Display In LG Flatron M197WAM (Converting LCD Backlight to LED Backlight)

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11 Bonus X (1)- Display Image Problem In Samsung 152s Solved 12 Bonus X (2)- Shutting Down LED Monitor Repaired. Model: Sense M989C 13 Conclusion 14 Recommended Electronics Repairing Related Information

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86 90 91

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Samsung 713n No Power Once the internal metal cover was removed I could clearly see a dark patch in front of the power IC. This means the power IC could have blown. The main fuse was open circuited. This lead me to check on all the components in the primary side since the power IC was burnt.

When I checked on the transformer primary winding with my blue ring tester there was no light. By right it should have about 7 to 8 LEDs light up. This suggests that either the transformer primary winding or one of the secondary diodes have shorted. Please see the photo in the next page:

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Since a shorted secondary diode can be easily checked with analogue meter using X1 Ohm thus I focused on these diodes first. There were two dual Schottky diodes and I found one of the dual Schottky diodes already shorted.

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I used another similar part without metal casing as replacement as seen from the photo.

After installing the diode and recheck with the Blue ring tester I found that all the 8 LEDS lighted up.

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Further checking found a 15 volt and a 1N4148 diode shorted. This means there were 5 components replaced.

After the replacement I did not turn On the monitor instead I placed a 100 watt bulb across the place where the fuse is located. The reason for it, just in case if there is any more short circuit the bulb will take in all the current thus preventing the replacement parts from blowing again. I found that the bulb did not light which indicates good sign. I further confirm if the power supply is good or not by measuring the output voltages as seen from the photos in the next page:

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5.05 Volt-Good

12.95 Volt-Good 9

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If you get good voltages this means you can remove the bulb and place in the fuse and power up the Monitor without worrying the replacement parts will blow again. Finally after everything was fixed back, the monitor came back to life again.

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Benq E2200HD 22” LCD MONITORIntermittent Power problem

The complaint was after running for about half and hours and if you power it off and on again there will be power blink. You have to let it cool down for about 10 to 15 minutes then only you can power it on. I thought the symptom was cause by bulged filter capacitor but found all to be in good condition.

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When the monitor is running, all the voltages are good 27volt and 5 volt but when you turn off the power and turn on again the power will blink. The symptom was quite weird so I began to use the hair dryer and freezer to detect such problem. I began to spray the semiconductors especially the power IC, Optoisolator IC and TL431 IC.

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The moment I sprayed on the Optoisolator IC the power suddenly came back to life. To confirm if the Optoisolator IC really is the problem I used hair dryer to blow on it and the symptom immediately appeared (blinking again). I took out the Optoisolator IC and check with my analog meter and found it to be good. So I direct replaced the Optoisolator IC and the Monitor worked superb with no more power blinking problem. The part number was PC817B and it was easy to get from any electronics shop.

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I concluded that the Optoisolator IC broke down when it was hot.

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No Power In Benq t705

The complaint was no power and the solution is to replace the 8 filter capacitors at the secondary output side.

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I thought after replacing the filter caps it will be ok but I was wrong. The Monitor stills no power. I decided to check on the mainboard especially the voltage regulator IC. If there is no output or improper voltage output there will be no power. Surprisingly there was 2.5 volt output.

This means it is either the MCU, Flash Rom or EEprom data could have corrupted or the On/Off button have problem.

Since the On/Off Micro switch is easy to check thus I checked this component first. Guess what, it was open circuit. You can use a long nose plier to touch on the pins to trigger the power supply to turn On.

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After replacement, the Monitor now can be turned On and Off. For your information I do not have the original type of Micro switch in my spare part compartment thus I have to modify another type as seen from the photo below:

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Assuming if the Micro switch is good then I may have to reprogram the EEprom IC or even the MCU IC provided if I have the programs. This is why copying out the MCU/Flash Rom/EEprom programs is so important because you do not know when you will need it.

Conclusion- No power does not mean the power section will have problem. Always check on the output supply voltages from the power supply. If the supply is ok you move on to check output voltage/s from the voltage regulator IC in the mainboard. If still ok then you check on the On/Off switch or reprogram the memory ICs.

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Simple Modification To Solve Display Shutdown After Few Seconds in HP 19” LCD Monitor HPW19e

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Display shutdown after few seconds was the complaint by my customer. The first thought in my mind would be one of the backlights have problem, bulged electrolytic capacitors in power supply secondary side, bad high voltage transformer or dry joints. After opening up the cover, I did not see any bulged e-caps thus my focus was on the backlights. Comparing the backlights with known good backlights can easily know which backlight is having problem. From the test I found the bottom backlight have problem. You left only two choices either to replace with a new backlight or do a simple modification. I have chosen the modification method so that you have the chance to learn from it. I have done this repair tricks many times and usually it will work. I did mention this trick also in the LCD Monitor Case Histories Volume 2. Let’s begin. First we need to pull out the bottom backlight connector and put in a capacitor to test to see if it will shut down or not. If shut down, then you may need to test few more other capacitor values. I usually have a bunch of different value of capacitors with me as this will save my time in picking the most suitable one to act as backlight.

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Note: The capacitors must have at least 2 KV and above. The first one that I picked was 821 2kv (820 nanofarad 2000 volt) and the display no longer shut down. If it shutdown then I will try on another value like 472 2KV 471 2KV and etc until I found the right one. What you need to do now is to solder the capacitor (behind the board) as seen from the photo in the next page and increase the brightness so that the display won’t look so dim.

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There you are, a simple modification could bring the LCD Monitor back to work again without much cost.

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No Power in E2010HC DELL 20” LCD Monitor This monitor came in with no power symptom. It was brought in by one of my customers and he had tried to repair it but unsuccessful. The reason I said this was because I could see some soldering mark on certain components in the power supply especially the bridge rectifier, power FET and secondary diode.

Since my customer was not a professional electronic repairer thus he did not really know how to perform troubleshooting work. I took out the power FET and checked and it was good. The fuse, big filter capacitor, Optoisolator IC, transformer primary winding and secondary side filter capacitors all were tested good.

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The only component I did not check was the power IC LD7576GS. From experience, this IC was the biggest suspect since all other major components were tested good. I don’t have this IC with me thus I ordered it from my favorite online store http://www.iccfl.com and the IC reached my office in just 4 working days.

I actually can try to perform the voltage and signal test on this power IC but judging from many case histories, SMD power IC have a high failure rate if all other components were tested good.

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After I’ve got the IC and replacement was done, the Monitor worked perfectly fine. The power supply produced 5 and 13 volt as seen from the photo below and next page.

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Samsung 931 No Power but all output voltages are good The first complaint was no power and the common fault for this model was to replace the three 820uf 25 volt capacitors. You can replace with 1000uf 25 volt capacitors. I thought after replaced the capacitor it will work fine but this time the power refused to come on. When I checked on the output voltages they were fine.

Since power supply output voltages were good so I focused on the mainboard. For your information the power LED signal came from the Microcontroller Unit (MCU) and if there is no supply voltage to this IC the power LED will not light up. A corrupted flash rom also could cause such problem. After checking on the supply voltage I found that there was supply indeed going to the MCU IC and also EEPROM/FLASH Rom IC. Since I have the Flash Rom original bin file thus I programmed it using the EZP2010 programmer that I bought from www.iccfl.com.

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You will not believe me, after loading in the original data taken from my computer hard disk and programmed into the Flash Rom, the power LED lighted up and the display appeared!

Note: From this experience we know that bulged e-caps could cause either Flash Rom or EEPROM data corrupted.

In the future, assuming if you came across a LCD monitor with the complaint of no power but have good output voltages from the power supply and good supply voltage to MCU/Flash Rom/EEprom IC then chances is high the Flash Rom data already corrupted and need to be reprogrammed. The function of EEprom IC is usually to take control of the OSD display and to save current setting and will not affect on no power symptom unless the IC is shorted. One word of advice-No matter what type of electronic equipment you are repairing and if you could not locate any fail hardware/components then there is a possibility the memory IC/s could have corrupted. Always keep/save the program of good memory ICs if possible. You wouldn’t know when you going to use it. 29

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Display Shutdown After Few Seconds In Acer AL1715 LCD Monitor Solved

The moment I powered up the Monitor I could see the Acer logo and then came the display. Just after 1 or 2 seconds seeing the display it shut down and the power LED light was green. This indicates there was problem either in the inverter board or one of the backlights have problem.

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The moment the metal cover was removed I could see there was a burnt mark in one of the push pull transistors. The part number was D1805 which also means 2SD1805. You can Google it for the datasheet. Since the component has burnt mark thus I have to check and make sure the surrounding components are in good condition.

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The secondary winding of the high voltage transformer was checked with the Blue Ring Tester and the result was good showing about 5 to 6 LEDs lighted up.

The small PowerTrench drive IC (built in FET) located beside the burnt transistor was good. How do I test the IC? Simple, just compare with the good one at the other side as seen from the photo in the next page:

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Use the Ohms range to compare between the two ICs pins. Any differences in the Ohms reading means one of them already have problem. Always check the Ohms reading of the good IC pins first for reference before you test on the suspected IC.

I also checked the non-polar capacitor located in between the D1805 transistors. Please see the photos in the next page. If the non-polar capacitor ESR value is out most likely the replacement transistor would not last long and will burn again eventually.

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Note: Having a good non-polar capacitor value does not mean it is good unless you have checked it with ESR meter. I have seen many non-polar capacitor tested good with Digital Capacitance Meter but failed when tested it with Blue ESR meter.

Blue ESR meter could check non-polar capacitor value from . 1uf and above. Lower value then that it will not be able to test it.

After checking the corresponding components, I concluded that only two transistors shorted and both have to be replaced. 36

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There was one problem-I do not have the original part number with me. From experience, many LCD monitors inverter designs were using the famous C5707 transistor. So I compared both the transistors specification (D1805 and C5707) and found that C5707 has a higher specification in term of Volt and the Ampere. Of course there are other specifications that we need to take into consideration. Sometimes a higher Voltage and Ampere does not guarantee it can work. The only way to find out if C5707 can be used as substitution is to test the set and monitor the temperature with an Infrared Thermometer as seen from the photo in the next page.

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Turn on the set and start to take the temperature measurement by pointing the Infrared Thermometer to the transistor you have just replaced (C5707) and the original transistor (D1805). It is normal for a transistor temperature to increase proportion to time in the beginning but it has to reach a level where the temperature has to be at the maximum point and would not rise again. This means if the temperature continues to increase then the replacement transistor is not suitable for substitution or there could be some other bad component that have not detected it yet. In my case the temperature stops rising after about 15 minutes in operation. This is a good sign that I can use the transistor (C5707) as replacement. If it continues to rise then the replacement transistor is not suitable to use. You can always compare the temperature with the original transistor (D1805) for reference purpose. There should be some difference in 38

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temperature value between the replacement and original transistor. Note: You can use this technique on other type of electronics equipment especially when you have replaced semiconductor components. The Infrared Thermometer brand that I’m using was Victor model 303B. It is also called as Non-contact IR Digital Temperature Gun. You can buy it from Ebay.com

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Acer AL1717 LCD Monitor Burnt Power Supply Solved

The complaint was no power and the moment I opened the cover I could see the power IC already blown, the main filter cap and the secondary side filter capacitors bulged also.

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The fuse also was open circuited. It seems that it is not worth to repair the power supply. Here are the reasons: 1)

2)

3)

4)

No information of the blown power IC. Finding the original part number may take time. You may need to find the schematic diagram, visit forum, call/email your repair friends and etc. The main and secondary side filter capacitors already bulged and replacing all the caps could increase the cost of repair There could be more bad components besides the blown IC, fuse and the bad e-caps. It will take more of your troubleshooting time. The power supply may not work even after you have replaced the necessary components.

All the above will take lots of your time to troubleshoot and repair and there is no guarantee that the power supply will work again. Why not we use a better way to solve the problem? The method that I’m going to share with you is to modify an external power supply. It is fast and easy to fix and the best part is it can guarantee to work. 43

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Here are the steps: First you need the external power supply that can produce two output voltages (5volt and 12volt) and the ampere should be about 4 to 5 ampere output. You can get this small switch mode power supply from http://www.iccfl.com

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Next, identify the two secondary output voltages of the burnt power supply. Usually the outputs would be from two Schottky diodes. Look at the center pin of the Schottky diodes. The one that go to the inverter section is usually 12 volt and the one that go to the Mainboard is usually 5 volt.

Now, connect 3 wires from the external power supply to the burnt power supply. One wire goes to the 5 volt section, one wire to the 12 volt and the last wire to cold ground as seen from the photo in the next page.

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Power up the external power supply and see if there is display in the LCD Monitor. If there is good display this means you can start to modify it. If there is no display you may have to find out why. Perhaps the 12 volt from the external power supply is not high enough to power up the inverter section. Or perhaps you have connected wrongly and etc. Note: Not all LCD Monitor power supply will have output 12 volt but many will have the 5 volt output. If the power supply produces 16, 18 or even 20 Vdc instead of 12 volt then you have to use a DC to DC converter (boost circuit) to convert 12 volt into 18 volt. You can see the small circuit board photos in next page.

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Note: If the original board is using 13 or 14 volt then the external power supply of 12 volt can used. There must have some tolerance in inverter board. This means if the inverter section is taking in 12 volt to function, a 10 or 11 volt DC

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supply voltage should not affect the performance of the inverter section. If you have confirmed everything is working fine with the new external power supply connected, it is the time now to remove all the components in the power primary and secondary side. The reason to remove the components is to be able to put in the external power supply onto the circuit board as seen from the below photo.

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Note: If the LCD Monitor that you want to modify have lots of space then it is not necessary to have the components removed in the power section. Just install it externally and jump few wires to the original board is good enough. In my case, the original power supply is compact and this is why I have to remove the components and fix the external power supply so that it could fit into the casing. Once done removing all the components, you can place the external power supply onto the power section. In order to secure the power supply, one has to drill few holes (if necessary) onto the external power supply and the original power supply circuit board. Cable ties will do a nice job in securing the power supply.

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Remember, just before you use the cable tie; make sure the 3 wires from the external power supply are soldered onto the original board. You can see the photo in the next page:

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There you are a simple modification could bring the LCD Monitor back to life again. You no longer have to return a dead set/burnt power supply to your customer because you are now able to modify and make the Monitor to work again. Your repair rate will increase thus making you more money.

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Samsung 20” LED Syncmaster SA300 With Display Shutdown Problem Repaired

Monitor came in with the complaint of display shutdown the moment you connect the VGA cable. After shutting down, the power Blue LED was still On. If the VGA cable is not connected you would see the “Check Signal Cable” message appear in the OSD menu as seen from the photo below.

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For your information this is a LED Monitor thus the internal circuit will not have inverter board. The power source is coming from an AC adapter.

It has a LED driver board which already integrated with the Mainboard as seen from the photo in the next page.

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There was no inverter board in LED Monitor

Since without connecting the VGA cable and could see the OSD error message “Check Signal Cable”, this clearly indicates that 55

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the LED driver circuit and the LED backlight were good. I have checked the input signal lines Red, Green, Blue, Horizontal and Vertical from the VGA connector to the MCU IC and found all components to be good. In fact by doing a simple Ohm test reading on the components one could roughly know if the circuit is working or not.

One thing good about checking these lines is that you can compare the ohm reading with other lines. You can compare the ohm reading between the R,G,B components. Similarly you can compare the Horizontal and Vertical components. If there is a different in Ohms reading then you can start to troubleshoot on this particular area.

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Since the input VGA components area was tested good I focused on the memory ICs. There are two main memory ICs i.e the 24C08 EEprom and the Flash Rom 25x40 as seen from the photo below.

First I removed the EEprom IC and save the data by using my EZP2010 programmer. After saving the original data I erased all the files and left it blank. I then solder the IC back and turn the Monitor On. The problem was still the same. The reason for doing this is because in certain Monitors one can erase the EEprom file and the MCU IC will copy the original data back to EEprom and the Monitor will work again. 57

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www.facebook.com/casalaptopguide I left only the Flash Rom IC but I do not have the original file with me. I contacted Kent and he had one. He sent to me the file (is a .Bin file) and I was able to reprogram the Flash Rom IC and upon turning On the Monitor, immediately I saw the full display except that the OSD menu was in other language. I played with the setting and able to change the language back to English.

Conclusion- Other information that I’d got was that the Samsung LED Monitor series ranging from the size of 20” up to 24” have this common fault. This means that if you have a working Samsung LED monitor then try saves the Flash and EEprom IC data. Who knows one day you will use it. Just imagine if Kent did not have the Flash Rom file I will not be able to repair the Monitor. If you need this Flash Rom file I can email you.

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LG Flatron M197WAM LCD MONITOR/TV 19” Dim Display Problem Solved By Converting the CCFL Backlight to LED Backlight.

The complaint was no display and the power LED light was Blue. When I tried to use a bright torch light to shine at the LCD screen I could see faint picture which indicates the problem in the Inverter section and not the mainboard.

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If you could not see any picture then there is a chance the mainboard having problem. For your information dim display problem and display appear for few seconds and becomes dim (shutdown) are two different problems. Dim display problem means there was no AC supply to the backlight. Display appears for few seconds and then becomes dim means there was AC supply to the backlight. The AC supply later was cut off due to problem in the Inverter section or one of the backlights have problem. So what causes dim display in LCD Monitor the moment you power it up? 1.

2.

3.

4.

5.

6.

Missing DC supply voltage to Inverter IC (probably the Pico fuse open circuit Bad Inverter IC (no output to drive IC to energize the high voltage transformer) Bad high voltage transformer (shorted or open primary and secondary winding) Shorted driver transistor/IC to drive the high voltage transformer Both backlights are bad (very rare case and I’ve not seen two backlights turn bad at the same time). Bad components surrounding the Inverter IC causing Inverter IC not producing output.

After opening up the cover I could see there was a burnt mark in the inverter driver. The circuit board also burnt as seen from the photos in the next page:

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The high voltage transformer winding checked to be good. When I connected the backlights to a working set I found that the bottom backlight does not light up. This indicates there were two problems- bad IC and a bad backlight. I decided to convert the CCFL backlight to LED backlight as I believe the set could last longer. If I replaced only one backlight and the IC I’m afraid the top backlight may give problem in the future. 61

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Converting CCFL backlight to LED backlight is not tough. If you have the parts with you, the conversion can be done in less than 40 minutes.

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This is the procedure: 1)

Identify the VCC, GND, ON/OFF and ADJ (ADJUST) pins in the LED driver board.

Note: GND=ground, ADJ=adjust, N/F=On/Off and VCC=DC supply voltage

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2)

Identify the VCC, GND, ON/OFF and DIM pins in the inverter board.

Note: Adj pin means Dim also and the function is to adjust the brightness. These four pins configuration is the most important one and others are not so important and one can ignore it.

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3)

Solder LED driver board DIM and ADJ pins accordingly to the inverter board pins as seen from the photo below:

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4)

Now remove the DC supply pin to the high voltage transformer as seen from the picture below.

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The supply that I have removed was 15 VDC. For other Monitors model it can be 12 volt, 14 volt, 16 volt or even 19 volt. Note: Since the inverter section (high voltage transformer and the inverter IC and corresponding components) is no longer using DC 15 volt, I prefers to cut it off for safety purpose. 5)

Connect the LED backlight and do a testing first to check if the LED will light up or not. If it lights up mean you can fully fix the set into the LCD Monitor.

Next step is to remove the top and bottom backlights from the casing. You must be very gentle in pulling out the backlights without breaking the TAB bonding. If the TAB bonding have 67

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problem then there is no point for you to continue to do the modification as there is no way to repair the TAB bonding.

Gently pull out the backlights and replace with LED backlights as seen from the photos below and in the next page:

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Once done you can use the aluminum foil tape to cover the bend metal are as it will look nicer.

Note: Usually I prefer to bend the side soft metal to remove the backlights as I do not want to dismantle the LCD panel into

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pieces as there will be a chance the TAB bonding or the TCP package could tear. 6)

Your next task is to remove the high voltage transformer and other related components like the ballast capacitors, drive IC and backlight sockets since they no longer serve any purpose.

Now place in the LED driver board and adjust it so that you can fix the LED board onto the inverter board. If necessary you can drill holes to secure the board with cable ties.

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In my case I drilled another small hole on the inverter board (make sure you don’t drill a hole that can break the circuit lines at the back of the board) so that the wires from the LED driver board can go through it and make connection at the desire solder joints in the back circuit.

Once the LED backlights cable is connected to the LED driver board you can power up the Monitor and make a test.

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Make sure you test the brightness control that it can be adjusted.

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Assuming if the Inverter board does not have the marking for the 4 important pins/points i.e. VCC, DIM, On/Off and Ground then you have to test those pins with your voltmeter. 1.

2.

3.

4.

VCC pin- It is easy to test. The highest dc voltage usually is the VCC pin. Please don’t choose the 5 volt pin because it is for mainboard and not inverter board. On/Off- Simply place your Voltmeter red probe to one of the pins. If the Monitor is in standby mode (without VGA cable connected) there will be no voltage at the pin. The moment you plug in the VGA cable and you could see few volts (and the display appear) then that pin is the On/Off pin. Ground- This is the easiest pin to find. If your meter have continuity reading when checking the pin and cold ground then that pin is the Ground pin. DIM- Once you have located the 3 pins then the last pins would be the DIM pins. 75

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Let say you still not sure if that pin is DIM pin, what you can do is you power up the unit (with the 3 pins connected) without connecting the ADJ pin in LED driver board to the inverter board. After powered up you will surely see the display. Now select the brightness from the OSD menu and set it to maximum and minimum value. While you are setting the brightness, place your meter red probe to the pin and see if there is any changes in dc volt or not. If there is changes then that pin is the DIM pin in inverter board. Conclusion. If you know how to convert one LCD Monitor backlight to LED backlight this means you can convert others. In the future if you see any LCD Monitors that has burnt high voltage transformer, bad or weak backlights or you simply just can’t repair the inverter board, the fast way is to convert it into using LED backlights. With this repair trick, now your repair rate can be increased. Just have the parts ready and you are set to convert any LCD Monitor to use LED backlights. The parts can be bought from http://www.iccfl.com Additional note: If a LCD Monitor had a bad/burnt inverter board and if you choose not to convert the CCFL backlight to LED backlight, you can always just use an external inverter board to solve the problem.

All the procedure is just the same as when you convert CCFL backlight to LED backlight. Instead of using the LED driver 76

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board you use an external inverter board as seen from the photo below:

The pins in the external inverter board is the same as LED driver board which have the supply voltage (vcc), On/Off (Ena), Ground (Gnd) and Adj (adjust).

Just follow the exact procedure I have mentioned when converting CCFL backlight to LED backlight and you will be

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able to disabled the original inverter and use the external inverter board. Note: If you use external inverter board this means you have to use back the existing LCD Monitor CCFL backlight and not LED backlight. Once you already know how to add in an external inverter board this means you can use this information to replace bad/burnt Laptop inverter board to a universal inverter board.

The reason why you are able to convert it is because the pins assignment of the universal laptop inverter board is the same as the one in the LCD Monitor LED driver board and external inverter board as seen from the photo in the next page:

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Universal Laptop Inverter Board Note: Before you replace the Laptop universal inverter board make sure you can find the 4 important pins VCC, ADJ/DIM, ON/Off and Ground from the Laptop Motherboard

You also have a choice if you want to convert the Laptop inverter board using LED backlight.

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Note: Before you convert the Laptop CCFL backlight to LED backlight make sure you can find the 4 important pins VCC, ADJ, ON/Off and Ground from the Laptop Motherboard.

For more information please visit Ebay.com and type in “laptop led backlight strip kit”.

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Bonus X (1) How To Solve Display Image Problem In Samsung 152s LCD Monitor One of my friends sent a Samsung LCD Monitor (Model: 152s) to my workshop for repair. Complaint with this monitor was improper display. When I connected this monitor to PC, I could see the image properly but there were some disturbance at some place. (See the image below)

First of all I check the power supply for proper output. This monitor is powered by 14V 3Amp adaptor. I check the output supply of the adaptor, found steady 14V (Normal). After that I headed towards the main board of the monitor. I opened the monitor and inspected the main controller board for any visual 81

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defect such as bulged capacitors/ burnt resistors etc. Nothing seemed like defective. There were few supply regulators on the board. All the regulators output supply were checked normal on oscilloscope except the 3.3v. After replacing the filter capacitor at output of the 3.3v regulator, the supply restored to normal. But this did not resolve the display issue, the problem was still there. After doing some component testing, I found two open resistors at LVDS signal path.

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Actually those resistors were the group of 4 separate 210 ohms resistors (resistors array) which are combined in single package. I was not able to find the resistors with same value; hence I replace them with 330 ohms resistors. After replacing those resistors, display was restored to normal.

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For your information this type of resistors (termination resistors) can be found in many motherboards. The function of the termination resistor is to help cut down on interference in the electrical system.

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Termination Resistors Thanks Vinay Habib. India.

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Bonus X (2) Shutting Down LED Monitor Repaired. Model: Sense M989C A computer technician brought this LED Monitor to my shop and told me that it has a shutting down problem. It stays on for about ten minutes then it starts to make ticking noise and shuts down.

This was the first time I work on this kind of Computer Monitor. It should be an easy fix since it has to do with shutting down. As we all know by now that most of the shutting down problems has to do with faulty capacitors usually in the power supply area. The moment I took four screws off the back cover I could see the main and the power board. In a way, it looks similar to the LCD screen except that it does not have inverter board.

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The moment I took the screws off the power board, I was able to actually see what was wrong in this LED Monitor.

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Two capacitors were bulged and one of them was leaking. One capacitor was 1000uf/16 volts and the other was 825uf/25 volts. That was my first time I came across 825uf capacitor. The strange thing is when I called the guy to buy such a capacitor; I could not find the exact value. The closest value to it was 1000uf/25 volts and that was very easy to find. I was getting worried about it and I was hoping to see this monitor come to life. Once I replaced the two faulty capacitors, the LED Monitor came to life. I hooked it up to my laptop and let it on for more than two hours and everything seems to be in good working condition.

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As you can see, the LED Monitor is On and working perfectly. The troubleshooting method is the same with LCD Monitor and easier to work on it because LED Monitor does not have Inverter board. It was a new experience for me working on LED Monitor but I was glad that all went well. The customer told me that the electricity went out in his house and came back and then he could smell something burning. He has lost every hope of getting fixed. He was glad to see it come back to life. I was too. Mission accomplished. Thanks. Waleed Rishmawi Palestine ---------------------------------------------------------------------------- Check out Volume 1 and Volume 2

Volume 1

Volume 2

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Conclusion I strongly suggest you to reread this information for few times and start right away all of the tips and tricks you have learned from this E-book. If you have questions about LCD Monitor Repairs, please do not hesitate to email me at [email protected] I wish you all the best and look forward to hearing your success story. To your success,

Jestine Yong Bsc. Eng UK Author of “10 True Case Histories Of LCD Monitors” http://www.powersupplyrepairguide.com http://www.lcd-monitor-repair.com http://www.testingelectroniccomponents.com http://www.findburntresistorvalue.com http://www.electronicsrepairarticles.com http://www.bestelectronicarticles.com http://www.electronicsrepairfaq.com http://www.electronicrepairguide.com http://www.jestineyong.com

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Recommended Electronics Repairing Related Information 1. Samuel M. Goldwasser “Sci.Electronics.Repair FAQ”. Here is

the website link http://www.repairfaq.org/REPAIR/ 2. List of Electronic Spare Parts Suppliers at JestineYong.com.

Here is the website link http://www.jestineyong.com/category/electronic-suppliers/ 3. LCD TVs, LCD Monitors, Laptops and Plasma TVs spare

part supplier: http://www.iccfl.com 4. List Of Schematic Diagram Websites:

http://www.jestineyong.com/category/schematic-diagrams-website/

Electronics Repair Ebooks Power Supply Repair Testing Electronic Components Electronics Repair Articles LCD Monitor Repair Laptop Motherboard Repair Laptop Repair Video Course Basic Electronics 10) LCD TV Repair Tips Volume 1 11) CRT TV Repair 13) DVD Player Repair 14) Find Burnt Resistor Value 15) Plasma Television Repair 16) Basic LaserJet Printer Repair 17) Epson Dot Matrix Repair 18) Mobile Phone Repair 19) Automobile Electronics Repair 20) Computer Repair Mastery Course 21) LCD TV Repair Secrets 22) LCD TV SMPS 23) LCD TV Repair Tips Volume 2 24) LCD TV Repair Tips Volume 3 25) LCD TV Mainboard 1) 2) 3) 4) 5) 6) 7)

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26) LCD TV SMPS 27) LCD TV Repair Secrets Electronics Repair Website-Free Monthly Repair Newsletter 1)

www.ElectronicRepairGuide.com

Electronics Repair Membership Websites 1) 2) 3)

www.ElectronicRepairGuide.com/Recommend/PlasmaTelevisionR epair.htm www.ElectronicRepairGuide.com/Recommend/LCDTelevisionRep air.htm www.ElectronicRepairGuide.com/Recommend/ProjectionTelevisio nRepair.htm

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