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Electronic Repair Questions/Answers & Testimonials Part 13

By on September 14, 2008

Good Morning jestine,

I am S from Durban (SouthAfrica) i got one mecer lcd screen model no TJ777 the fault on the screen is display is coming for a half minute and display goes off but the power light is on .pls help me on this fault.



Hi S,
Try visit my blog as it may have some ideas for you.


hello Mr.yong

how r u

this is P from chennai.i decided that try make one esr meter of my own ,
for that i need ur help ,ihave bought z86e0412psc micro controller,
is that ic already programmed to this project or we have to do it .i dont
know, pls give an idea . then i need pcb lay out for it .i got components layout and circiut.

thanks alot

with regards


Hi P,
Normally a new one is blank and you need to program it. You can ask from the supplier whether the ic had been programmed or not. I’m just a reseller thus i do not own any pcb layout, schematic, programmer ant etc. For more information you may visit the website at
Have a great day!


hi jestine,
i read ur article on why people are not successful in electronics repair & it interests me alot because though i have made some progress i’m in need of improving my skills, speed & income in electronics as a whole. pls let me have a list of things to do & invest on, in order to meet my target. especially as regards test gears; let me know the most important & necessary test gears that will improve my work with their prices. is there anything like computerised fault finding? i need details on that also.


Hi George,
May i know what type of electronic equipment your are dealing with now so that i could suggest some test gear for you?


sorry my response has taken a little long. i had some family matters at land. i’m actually handling a wide range of electronics equipments; monitors ( both crt & lcd ), tv sets, dvd/ music system, microwave oven, industrial panels. However monitors & tv sets are major areas where i will really like to improve on greatly. Thanks

Hi George,
These are the test equipment that you need:

analog meter
digital meter
digital capacitance meter
esr meter
flyback/coil tester
inductance meter
laser power meter
high voltage probe
and please visit for more information about the test equipment that can help your field out. Have a great day!


Dear Jestine young,

I am S.A an Electronics and Instrumentation Engineer. am using your testing electronic components book which i have buyed from internet(Through my brother),i am working in plant and i have to troubleshoot all types of electonics boards(which get failure).I want to buy some advance testing tools and equipments(specially i want to know how to test any type of ic is there any ic testing instrument) as you have mentioned some testing Instruments in u r book,

3.Trasistor Tester
4.Frequency Counter
5.Dc power Supply
6.Capacitance meter
7.Inducatnce Meter
8.Esr meter

If you know more Advance Testing Instruments (Specially IC Testers) Please tell me and also suggest me from where i have to buy and also if we send any type of electronics boards to you for repair do you accept(by taking reparing charges).

Waiting For Reply,


Hi S.A,
Thanks for your support on my ebook. You can visit and also

Hope this help!


How To Repair LG 710E CRT Monitor With Power Blink Symptom

Hi S,
There are many problems that could cause the power to blink such as shorted HOT, FLYBACK, yoke coils, secondary output diodes, faulty components in power side and etc. You need to check them out with your meters. You must first learn how to test electronic components before you can further to check out those parts.


Dear Jestine,

I have also test the defective horizontal yoke it test good on the Blue ring tester all the led light but when I connected in the circuit it will not start-up replacing a new one solve the problem how can you explain this.


Hi D.H,
The only answer that i can give you is that the pc tube breakdown when under full load. I have come across before couples of Monitor crt tube that broke down when the full voltage was applied to it and yet it tested good in any other meter. I removed the crt yoke and open up and some slight burnt marked in it. This kind of problem not only could happen in crt tube, it could also happen in the flyback.

That means if the blue ring tester tested bad for a coil, then the coil is 100 percent have problem. If the blue ring tester shows full LED light this doesn’t mean that it is 100% percent good. The good news is it was not that frequent the coils breakdown when under load. Have you test the faulty yoke coils with your digital impedance meter and how is the result like?

As for me if i suspect that a particular section have problem and i could not locate the faulty component, i will just direct replace the components and retest again as i know that all electronic components (which include the crt) have the chance to breakdown when under full voltage. Actually the best test equipment is still the equipment itself as it will test out all of the voltages, signal, frequencies that across it. Have a good day!


Hello mr jestine Yong i want to thank you for your formation and correspondence about LCD monitor repair and i want to ask you about a problem in back light for a monitor dell the back light is coming few seconde and it shut down .what is the resolution . finaly, thunk you so mutch

Hi M,
You cay try read from my blog at for some good tips.



Dear Jestine,
I have fixed my LCD monitor power board problem (hp f1723) by following the explanations given on your web site. I would like to thank you very much.



Hello!I have a BenQ T705 and i see something but the screen is too dark what is the problem it might be the cable from pc to BenQ???i bough it from a store on the cable are written: Computer Interface Cable 300V 80C.Please help me

Hi K,
There could be few problem causing the display to go dim such as bad capacitors, bad back lights, bad inverters and etc. I suggest that you visit my blog for some tips about lcd monitor repair at

Have a good day!
Best regards,


Hi, Mr Jestine Yong,

Thank you for your report. I found your web page the other day I glad of all the information you have I have been reading it, an your utube videos. I have a Venter DVD VCR Home Theater System mfg 2003 the vcr board power fuse blows when powered up. I replaced bridge rectifier, still blows the fuse. Other fuses ok I look on the internet to find a schematic for this unit.

Thank you,

Hi D.S,
Besides bridge you also need to check for power fet, power ic, secondary diodes and also primary winding of the switch mode transformer. Sorry i do not have such schematic. Have a good day!


One more thing, I would like to ask from you a picture of a CRT monitor PCB where
I can test for B+.. i am not that really sure of what i am doing..

B+ line is at the secondary side of the power supply. Look for the output line that goes to the flyback transformer. That line is the B+ line and usually has filter capacitor of 100 to 220 uf with about 100 vdc.


Yes, I downloaded and saved in my Pc the report about the LCD BENQ fp731. I”m very excited for this new experience in the LDC monitor repair. I made a “ring tester” . With this tool I can check the high voltage transformers of the LCD, TV flyback and other high frequency transformers. I am grateful with you for your information. Last weekend I repaired two LCD monitor and i made money with this work. Thank you very much.

José Miguel Acuña Fallas.
San José. Costa Rica


hi i have a DGM model ; l – 2041w monitor that starts up and runs ok but at the bottom of the screen there is vertical coulored lines right across which are about 30mm high. can you give me some idea were i should be looking at as i,am new to this side of electics. i have brought your book which has being very helpful, many thanks steve.

Hi Steve,
First make sure all of the e-caps are tested okay as bad cap could cause such problem. Next it may be the LCD panel problem as i came across few LCD Monitors that have vertical color problem. Replacement of the lcd panel solved the problem. If you have other questions please do email me again.

Have a good day!


Hi Leo,

Here are your questions and answers:

I try to fix monitor philips model 107S51 17″ with no standby power mode and no sound coming out. I checked at primary power section and found that resistor 320ohms burn near the ic “TEA1507P”.
I checked the ic “TEA1507P” was still good.

Usually whenever a resistor burnt, chances is high the power ic also may have problem. Check all components in the primary part too.

I checked “capacitor 250V ~X2 0.68uF” near the fuse there, I tested that capacitor with my digital capacitance meter, the value was show up 0.47uF, I not sure this capacitor is still good or not? and I find at electronic part supply shop, they dont had sell this “capacitor 250V ~X2 0.68uF” , they only got sell “capacitor 250V ~X2 0.47uF” value. What should i do? can i use this “capacitor 250V ~X2 0.47uF” for the replacement?

This capacitor value doesn’t play an important causing the no power problem. even if you remove the capacitor in a good monitor, the power would be still okay.

and what was the cause the resistor 320 ohms burn?

Probably shorted semiconductor in the circuit.


Hi Lim,

Here are your questions and answers:
I just browse through your web and i found some interesting equipment like ESR meter. How much it cost you? Can I get them from pudu?

You can’t get the meter from pasar road as my company is the only distributor for Asian region. The kitset is RM330 and the fully assembled unit is rm430.00

Is there any equipment or apparatus that would come handy when dealing with pcb,smt and etc? Thanks.

Analog meter
digital multimeter
digital capacitance meter
and smart tweezers


By the way i read alot on your LCD Monitor repair Guide most of our monitor here was LCD now i have a problem regarding some of the power supply was damage hope you can help me to solve this problem we using a power supply Model A25B1 – 12MB main problem the out put supply dropped to 12vdc and power indicator light continues blinking i change already the parts CM3842 ( current mode PWM controller) but still the same problem do i miss something to change some parts. hope you can guide me more how to solve this problem

More power and always God bless you

Best Regards,


Hi Ronald,
Nice to hear about your background. If i get the chance to repair your unit, i would first test out all of the electronic components in the power side and also the diodes in the secondary side. Remember to check on the optoisolator ic too. If all tested to be okay i will then direct replace the semiconductor as semiconductor are prone to failure when full voltage applied onto it.



Hi Joe,

Here are your questions and answers:

1. One of my 29″ NANAO chassis screen with SEGA game did not have any screen and no glow fire from tube, but it has power B+ into chassis. Do you have any idea what kind of major problem cause that?

Check for the heater voltage at the CRT BOARD. I’m not sure about your monitor but some comes from flyback and some from the power supply. IF it from flyback then the tube uses the ac pulse and if it come from the power supply it uses the DC 6.3 VOLT.

Also, is any universal chassis to work out 29″ monitor?

As far as i know not all brand of 29″ Monitor have the same circuit design.

2. Area 51 site 4 game always reboot once a while for playing game. There is no reason cause that. If I keep system running overnight, the screen will not show any picture and sound. Once I turn off system and return on power, system works fine except reboot problem again.

It could be the power supply fault as in computer cpu, a self reboot normally caused by a failure in Power supply

If you have any idea about the problem solution, please let me know. Also, Let me know your consultant fee if you charge that. Thanks.

There is no consultant fee.


Hi Jestine,

I had been repairing a Telefunken Palcolor MR260 tv. It will play for about

two weeks and then blow out the switching transistor of a power supply.

What could be the cause of this? I had replaced several components, but in vain.



Hi Simon,

There are few reasons:

1) Not original component used

2) did not have enough heat compound and

3) corresponding components have problem.

Hope this helps!


Dear Sir.

I want to thank you for accepting to help to support me in my monitors repairs. Dear sir i have some problems with monitor power. But I promise that I will send the money for the ebook as soon as I get it.
if a monitor does not receive power when the fuse has not blown, what may be the components which may be bad. Which component or group of components should be checked first?

Hi Kenneth,
The components that you need to check if you are not familiar with the model is actually all components in the power section. Check power fet, replace power ic, check for secondary diodes shorted, horizontal output transistor and B+ fet for shorts. Start checking on the resistor first as if the start up resistor (usually very high ohm) open circuit, it will cause no power symptom.



Dear Jestine.

What had the problem on on my BenQ LCD is when i turn on the LCD power had a rainbow then flash on for a second then automatic switch off. But now i can’t even see the rainbow again and is only when i turn on; just flash on for a second then auto turn off. Could you give me some idea to fix it?

Best Regards


Hi David,
There are only two things that i can suspect. Bad electrolytic capacitor in the power supply circuit and the second one would be a faulty LCD panel. Don’t overlook that a loose connection cable between the Main board and the LCD CONTROLLER board could also be the cause.


What is the purpose of the 5VSB of a power supply?

Hi Bryan,
Here is the good explanation of the 5VSB:



Hi there. I am very interested in learning how to fix LCD monitors as a second income. I wanted to ask if this is possible with your book, if i have no electrical background. I build computers, but have not ventured into the electrical repairing world. Also, I wanted to ask if it’s very dangerous to repair LCD monitors. Is there a chance of electric shock? Thanks, i look forward to purchasing your book if i can get these answers. Have a nice day!

Hi David,
Thanks for your interest in the LCD Monitor Repair ebook. If you do not have any background in electrical/electronic work i suggest that you get my other ebook first which is Testing Electronic Components . This ebook explains about the safety and also the important of testing most of the electronic components. Once you are strong in testing electronic components in fact you can start to repair any electronic equipment. Getting the LCD Monitor repair ebook would be an added advantage. Besides i will be guiding you just in case if you come across any problems in electronic repair. If you have other questions please do email me again. Have a good day!


Hi,Mr Jestine

Sorry about my email. I need your help. I have tree sets with same
problem. Two Phillips chassis TC2.1A using the cpu TMPA8821 and one Nikai
chassis M113 using cpu TMPA8827.
Faults: the TV became “crazy” switching on and off, displaying randomly
without any control. Sometime it shows “ASM IN 3 SEC’, all this randomly.
What I did: I checked and replaced the memory chip, the crystal, checked the
reset circuit and passive components around the cpu, WITH NO RESULT. Do you
think the micro should be responsible for this problem? I believe that
hundred of equipments using this cpu, has same problem. As they are very
expensive I would like to be sure about this. Thank very much.

Hi Seleman,
If in Monitor, a bad CPU could cause quite similar problem too! Sometimes we have to take some risk in the repair work, if it stills the same problem, perhaps you could keep the CPU for future use.



Hi Jestine,

I need some help on my video arcade machine, it has a 5 pin video output but the monitor I have replaced is a Neotec NT-500DX which have a 15 pin VGA connector. is there anyway of converting the 5 pin video signal to 15 pin VGA? Thanking you in advance.

Lito Ricohermoso

Hi Lito,
Normally only 5 signals that is important, the red, green , blue, h-sync and v-sync. Follow the link below and see how the 15 pins configuration look like.:


Hi Jestine

Still using your great book Have repaired several monitors using your



jetine youg pls am having problem of reading i.c, pls can you let me know the way how to do it pls or is there any sowftwere of which we can use , pls if there is any pls let me know.


Kenneth Dodo

Hi Kenneth,
We can’t use software to read IC. You need to read IC from the marking on top of the IC. Some part numbers of Monitor IC’s are :

TDA 4856, TDA4886, LM1237, LM2469, TDA9533, UC3842 and etc.



hello. i have a problem with my aiwa tv model no. is cn201 it has a retrace line. what seem to be the problem? i actually replace the jungle ic and system control. tnx. gud day.

Hi Edwin,
Some called it as flyback lines. It can be caused by a defective vertical IC or bad corresponding components. Some vertical output ic have the blanking output pin and you can trace from this pin up till the CRT board. Anything goes wrong with this line will cause flyback lines. Hope this helps!


Dear indefatigable Mentor,

Glad to let you know that I have now just paid for an office rent to start the electronic repair career you have been mentoring me on for over the year. When the year was about to begin, you did tell me to set a goal. When the half of the year drew near, you did remind me about the goal and asked how far. I will not disappoint you. All your efforts will not be in vain. Though I am not that strong yet and I still have some fears while starting out, I am confident I will excel most particularly with what you have taught me so far.

The next thing I want to do now is to buy books:

1. Testing Electronic Components (By Jestine Yong)

2. LCD Monitor Repair (By Jestine Yong)

Then I will also buy from you the necessary tools and equipment such as the ESR Meter you deal in on sale. They say Rome was not built in a day. So, I need to be taking steps. I know my God will provide the money to get all these things and I will be well equipped for this admirable career I am about starting out on. You are my confidence. When I get challenges I hope to call on you. Once again I thank you for your support and mentorship.



Hi Jestine,

I want to inform you that my newly purchased Blue Esr meter that I used to troubleshoot intermittent / no power casio keyboard was easily repaired by using the meter.I found out that a surface mount capacitor causes the trouble. Using the meter I measured capacitor with high ESR value around 14 while the same caps measured 0.95. Actually I used my Cap analyzer but cannot read the value. Thanks to Blue ESR Meter.




hi mr yong

i read u book u send it to me it’s more valuable and it’s more interested. mr yong i read free report about lcd repairing book and im interested about to buy that book about lcd repairing soon may be on sunday , mr yong im working in pc maintenance and im intersting about notebook reapiring also beside lcd monitor if you have notebook repairing book please told me soon>>>>thx and have agreat day.



Respective Sir,

I receive your free report regularly & really it is quiet useful for gaining the knowledge electronic repairing. By this mail I need your valued guidance. I have a 15″ Digital colour monitor. It has a vertical line problem. I mean to say when I turn on my computer only a vertical line is shown by the monitor. I want to repair it so please tell me which part should I check & replace in the monitor.

Best regards

Hi Deepak,
Check for the supply voltage to the vertical output ic and corresponding components and also dry joints. If all found to be okay then direct replace the vertical IC and retest the monitor.



Hi Dear how are you doing thanks for ur all information all electronics equipment repairing.did u face on dell computers chipset blowing. mostly on the model GX270 chipset it happens this problem and capacitors also same problem.i did changes the caps.but i have no tools for changing chipset. how can u help me in this way.

thanks for all things


From Africa (ethiopia)

Hi Girma,
It could be the power supply problem that is supplying a too high voltage. Check all the output voltages with your digital meter.





Hi Fid,

Besides credit card, i do accept western union or money gram payment. I do not know whether your country provide this kind of service or not. If yes then please email me so that i can send my details for you. As for the plasma repair, thanks for the nice photos. From the photo i could see at the secondary side of the filter capacitors, there are lots of black decayed glue surrounding the area. I suggest that you remove all the glue and clean the board with thinner solution and then switch the power On again. Check also for dry joints and ESR problem in the capacitor with ESR meter. If all the above checked to be okay, then the only choice you have is to measure all components in the primary power part.


i have a problem with ibm e74 monitor the horizontal size not work
please help me
my best regards

Hi M,
You need to provide more data for me such as which section or what components have you checked as this will speed up the repair. There are many reasons why horizontal size does not work. It could be a shorted modulation diode, dry joints in the horizontal size/pincushion area, bad h/v oscillator ic, faulty eeprom data and defective corresponding components in the horizontal size/pincushion section.





  1. Dave

    November 30, 2008 at 10:51 am

    I was given a Benq FP731 lcd monitor. When it works it really is nice. It has a strange problem in that the display will work fine then the display will white out or will be just about washed out. It might blink flash a bit and sometimes settles down to a normal display. Turning the monitor off and on will restore a perfect image sometimes for an extended time.
    I've checked the data cable,blown out the dust and resoldered a few of the transformer pads. They definitely had stress cracks. This seemed to stabilize the display for a few weeks but now the problem is back. I've not done any repairs on lcd's so I don;t know what these symptoms are telling me. Bad caps? or what?

    Thanks for any help or hints.


  2. admin

    December 2, 2008 at 11:38 pm

    Hi Dave,

    Seem likely the filter cap have problem and you need to test it out with the help of ESR meter. If possible check all the output voltages and make sure it is stable and do not intermittently fluctuate. The best test with an analog meter instead of Digital meter. Hope this helps!


  3. Ujjwal Goswami

    February 10, 2010 at 6:20 am

    Dear sir
    I am repairing a 17' color CRT Monitor.Its problem is White display is coming always.No changes when put sink signal from computer.Kinndly give some advice where is the problem is .May be video ic LM1237 is faulty?

  4. admin

    February 10, 2010 at 6:29 am


    It could be that IC.Have you check the supply voltage to the IC and what about the dc voltages to the RGB cathode? Without the DC voltage, the display can become white.


  5. saif

    July 18, 2010 at 3:59 pm

    dear jestine yong, there is a thin horizental strip at top side is exsist on my iiyama tft monitor screen model ple-430 s 17'' lcd monitor, pls fix my problem, can i fix it with software, or tell me tips about it thx a lot from zindadil_aries

  6. admin

    July 18, 2010 at 8:54 pm

    HI Saif,

    Try gently press from the front screen to see if the line gone or not. If yes then the monitor internal joint may have loosen and you need to apply some force to make the joint to have contact again. If the line is still there then the lcd panel may have problem. It could be the lcd driver ic problem or bad tcp package.


  7. saif

    August 1, 2010 at 4:19 pm

    dear jestine sir i have mitsubishi 900u diamondtron 19'' crt monitor, chasis njf9905. problem is that in primery side pwm controller ic 920 TDA4862 WITH ITS ZENER 18.2 VOLT ALL TIME BURNT, PLS SOLV MY PROBLEM, THANK A LOT

  8. admin

    August 2, 2010 at 5:30 am

    Hi Saif,

    You may need to check all components in the primary side. Check also the primary winding of the switch mode transformer.


  9. vishal joshi

    September 3, 2010 at 9:00 am

    i m vishal joshi. i have a casio ckt 601 synthsizer which is not working. there are many problems in my synthesizer. my synthesizer is dead position. how to repair its power problem.

  10. vishal joshi

    September 3, 2010 at 9:04 am

    i have asus P5RD1-VM mother board. in my motherboard SATA ports are not working. how to repair it.

  11. admin

    September 3, 2010 at 7:44 pm

    HI Vishal,

    Sorry there is no info about this.


  12. admin

    September 3, 2010 at 7:45 pm

    Hi Vishay,

    Is there any output from the SMPS? or plain zero output voltage?
    The first thing you need to do is to check the fuse and components in the primary side.


  13. moses

    September 4, 2011 at 4:20 pm

    hi mr J. i have a mecer LCD monitor model TJ777. its giving no response on the screen but its just flashing a green and orange LED.. what could be the problem?? please help

  14. admin

    September 5, 2011 at 8:47 pm

    HI Moses,
    It can be bad/bulged caps, bad mainboard and etc. You need tomake sure first that the output voltages from the smps is good.



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