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Electronic Repair Questions/Answers and Testimonials- Part 27

By on January 11, 2009

Hi mr Jestine Yong

Thank you so much for all you have done

I am very happy by your all e-book, by your news,  by your sending blue esr meter



thank you so much




Hi Jestine,


I have purchased several of your ebooks and have found them all to be very informative, well set out, but mostly very enjoyable to read. Thanks for sharing your unique knowledge with us electronic enthusiasts.


Warmest regards,





hi jestine


I did look at your report and I did buy the book last week,look forward to reading it thank you for all the great effort you are putting in along with your family helping with the book.its people like yourself that put in the dedication that help people like myself thank your family from me G.B for all there efforts.



Good Day Jestine Sir,
I am studying the LCD Monitor Service Manual its Amazing





hi good evening! do you a website where i can find the pin orientation of some ic? i mean the location of the supply and others in a particular ic.


Hi B,
You just have to type into google search the ic part number and hope that the manufacturer have release the spec of the particular ic.





Can an oscilloscope be used to test a resistor or a ceramic capacitor?
Or an electrolitic capacitor?


Hi T.K,

You got to use some additional circuit in order to do that. Please visit this link:

As for me i prefer to use digital meter to test on resistor, digital capacitance meter for ceramic capacitor and ESR meter for electrolytic capacitor. Anyway it depends on one own preference. Have a good day!





Hi Teck,

Here are your questions and answers:

hi jestine, I did some measure on  the power board and found out that the power supply to the main board should have a 3.3v but I get a 0v that means the problem should  the power board itself am I right?

If i’m not mistaken there will be two power supply. One is for the sub power supply and the other one is main power supply. The sub power supply have to work first to trigger the CPU so that the cpu can send an “On” signal to make the main supply work. If both power supply working you will get the display.

so if the problem is really coming from the power board where do I start to check? I did a check on the bridge it seems ok and the fuse is no blow as well as dry join also but the power board still no V. so I don’t know where to check now haha

Any components in the power section. First you got to make sure the supply dc voltage must be present to the input pin of the power ic. Since the sub power supply consist of not many components, in fact you are encourage to test all of them which include the secondary side.





Respected Sir
Hi sir and how are you.I would like to know that if in a monitor HOT blow off frequently then how to solve this type of problem and how can i start a monitor without a HOT.                                                                                                          Thank You

Hi M,

Please visit this blog post at

and you can’t start a Monitor without HOT!



Dear Jestine,

The downloaded “Short Report” is clear and useful , Thanks! I believe you about your hardworking creation not only in this “Short Report” but also in your work with students and in achievement of the Book “LCD Monitor Repair” unique in the whole World.Congratulations!






Now,here is my issue:my LCD-TFT Monitor “CAPTIVA E1703″is out for order : after pushing “POWER”button,the dysplayng of very good coloured image only light 0,3-0,5 sec.,and after that goes out.No sound.Isuspect the digital Microprocessor :TSUM16AL-LF-1 and found nothing about this IC in entire world of Internet not with Google,not with Yahoo! search engine at all!  It is a Top Secret ot the Chinese “MSTAR”,”TSUNAM” and Japanese” PANASONIC” manufacturer? Howewer,do you know somwhere a Datasheetcatalog or at list the pin-assignments of this TSUM16AL-LF-1,in order to make some voltage tests and labeled signals(oscillograms) before to take the decision to remouve it?Or you have something in your Book about that?Or about circuit diagram of the TFT-LCD ASSUS VK191D,LCD-TFT SAMSUNG SYNCMASTER 720N ,that content this IC?(they have too sound incorporated) I would be greatfull for your answer and thank you for your patience reading my issue!


Hi M


Thanks for the email but sorry i do not have the information you are looking for. If the display shutdown you have to make sure that the inverter is still getting the supply input. Without input suspect a bad MCU and if there is still a supply, suspect inverter board have problem.







Thank you for your LCD repair course. I found it very easy to follow. The diagrams and pictures made learning easy. I have a background in electronics but I am new to LCD repair. I am excited respecting the prospect of a new and rewarding business.






my teacher jestine happy new year for you and thanks for your greatful job to help us best regard






I am building this simple pic programmer but I cant find the problem. Can you please help, sir? The green LED lit. Thus, this shows that there are power to my circuit through USB but the red LED should blink when i pressed the push button but it doesnt..n i read in the net, they say its either the microcontroller or the crystal problem. The biggest problem is that the programmer doesnt detected by the computer!. Thank you. I hope to hear from you soon.  ^^


Hi J,

I could not open the file you sent me. By the way i’m not into this pic programming thus i could not give any expertise advice on how to solve this problem. As for the crystal you can always use a frequency meter to test out the value or to use a scope to check for sine wave. No waveform could meen the crystal, related components or even the MCU is at fault.





I will not lose hope and will not give up… Thanks very much Sir, i have read and undestood your report. Very usefull i must say, especially when you mention of the basic operation it reminds me of when i was still at college. I feel like i am thrown in a pool of… well, let me say GOOD THINGS. Thanks. Hope to hear from you.






Dear Jestine


thank you for all the usefull newsletters and maintenance information you sent along the last year ,

you really make agreat effort collecting and writing these news ,i hope you happy new  year full of achievments .

Happy new year






Thank you, and a Happy New Year to you and yours from me and mine.
Your benevolence and commitment to excellence-are good examples for others
to follow






It is a very useful for all electronic people thanking for this.100000000000000000000000000000000,thanks for mr.jestine yong.





Hi Jestine,


I have a Dell 2005FPW 20″ LCD that has to warm up before it will start working properly.  Once it warms up, after several minutes it works perfectly. Starting it after it has been off for a while, the display is completely scrambled.  All you can see is all kinds of colored lines running across the screen.  After several minutes the display become intelligible and finally it works normally. While it is warming up, I can hear a faint hissing sound coming from the monitor.  It goes away in the end as the screen image improves.


Thanks for your advice.


Alex K.


Hi Alex,

From your description, it could be dry joints or bad electrolytic capacitors at the power supply. Check also for connection between the mainboard and the lcd controller board.





hi and hello,


My name is Alex. I had try your testing electronic component book….it is good….now i can repair some electronic equipment by myself…..last time i can only repair car electrical wiring starter alternator and now i can repair in electronic as well……hope reply from you soon…….






Thank you very much and with your ebook will guide me as I’m just a part time job since I do not have much information before. But now I’m very happy even though I have read not all, somehow your ebook is really valuable information to me.


Again I thank you, Jestine.


Z ++




Hi Steve,


Here are your questions and answers:

I am so grateful that I found your site about electronics. Just what I was looking for to get some knowledge. I am basically a newbie as many of your clients are. As a pro keyboard player and musician, I want to be able to troubleshoot AC power, circuits, amplifiers, bad cables, etc. Right now, my solid state keyboard amp needs servicing and I want to find the trouble, but don’t know what to do or where to start. I also have an old original Yamaha DX-7 that needs the lithium battery replaced and some other repairs so I can restore and sell it on ebay. I need service manuals I guess and troubleshooting guides.

Sorry for the late reply as there were too many holidays and after i have sent out my monthly repair newsletter got too many emails. By the way sorry i do not have the service manuals. Have you try ?

I honestly am lost though. Where do you begin to get hands on electronics experience?

From technical institutions, books, repair forum, repair friends and from working in computer firm.

We live in Los Angeles and the local city college has many courses in beginning electronics up to advanced. I may take some course this Jan 2009, but my time is limited and I really don’t want to go that route. I would prefer to work at home on my own and use your tutorials and ebooks, which I purchased last week online.

Thanks for the support and if you have any electronic repair questions you may email me.

Now as far as equipment. What brand of digital and analogue mutimeters do you recommend? I have searched online and there are so many, that I don’t know what to buy. Is a $40-50 investment a starting point for a decent beginner model, or do you need a $200 Fluke? If you know of something, please advise. Also, what online electronics supplies and parts sites do you recommend?

I like Fluke digital meter but if you are on budget you can always buy a cheaper version of digital meter and as for analog meter you may buy a cheap Sunwa analog meter. About the parts you can visit my blog list of electronic suppliers at :

Although my goal in electronics is not to be a pro repair guy right now, I mainly want to build more advanced kits, such as pre-amps and solder circuit boards on a pro level. What beginner kits would you recommend to learn more electronics techniques?

First get a non complicated less components kitset like building a simple power supply and once you got hold of electronics and all the skills of handling tools and have the ability to test most of the electronic components then i suggest that you get any kitset that have more components in it. Building kitset in my opinion can truly help beginners to start off with electronics especially in the filed of repair.

Have a good day!





i am E from phillippines and i am a tech support but b4 i am a monitor/lcd tech and i have problem looking the IC regulator TOP247F here in our local elec. stores, could pls tell me where i could buy this, i have a computer shop and i have more than 4 lcd(samsung)having the same problem, thanks in advance. GOd Bless to all.


Hi Efren,

Try order from this link:





Hai Justine…saya ada membaiki LCD 15″ jenama Dell dan kerosakannya adalah no power.Saya dah replace diode dan power sudah ok tapi masalahnya display yg dipaparkan di screen tak terang (gelap) Saya nak minta tolong dari awak komponen apa lagi yang perlu saya check untuk mengatasi masalah ini.

Ok..thank you.



Hi N.
Sekiranya ia gelap  kamu harus check sama ada supply ke VCC PIN of Inverter IC. Kalau ada suspek kerosakan pada inverter ic, dry joints kat high voltage transformer ataupun kerosakan pada lampu.





Hi W,


 Here are your questions and answers:

it is all well here. a new year, a new motivation and new future a head of me and I am very excited about my work in the lac field.

Glad to hear that!

I have a question for you. I took the backlight of an lcd monitor out to see how they look like(bad one actually)just to have the feeling of it and how to do it. it is exciting to do it myself, my question is if I connect these backlight to 220 would I be able to light them? or the voltage too low.

No because the voltage too low at least in certain model it require 500 to 1000vac with at 50 khz. Our line frequency only 50/60 hz.

another question. what is the job of the two ballast capacitors at the hight voltage transformers?

Please refer to page 36 of my ebook as there is an explanation there.

Thanks and have a good day!





Great website, very impresive work. Appriciate your hard work and time you have put into this.





Hai yong,
Hor r u hope u r doing well, I would like to buy sum tools, like meters.
what is the difference beteween esrblue and esr meter plesase advice me

Thank you


Hi Ganesh,

The Blue Esr meter is to test electrolytic capacitor and can check on board while Blue ring tester is use to check on coils like smps transformer, b+ coil, flyback primary winding coil and horizontal yoke coil.





Hello Jestine.

Happy New Year, I am sending you these pictures to let you see what

I am involved with. As you know I do car electroincs.I have already bought the book

Component Testing and I am very happy with it. Thanks for your help.




Hi Marion,

Here are your questions and answers:


i write this message to enquire on certain issues troubling me in this ATX power supply. the problem is that its not switching the motherboard but when connected to the motherboard the mtherboard L.E.D will light up, even the USB mouse, when i press the power button the Fan will not turn hence it will not switch.when i remove the power supply and try to shot curcuit the PS-ON to Ground, sometimes it only kicks less than a qaurter revolution clockwise. when i go to the curcuit the area around where the PS-ON line is, i find some BLUE resistors and can’t really tell their values. the color coding is as follows: All these resistors are Quarter Watt Pliz help me on how to get their values

Brown Red Brown Red Brown

12100 ohm or 12.1k ohm 1 %

Yellow Yellow Red Brown Brown

4420 ohm 1%

Red Orange Red Brown Brown

2320 ohm 1 %

Brown Blue Red Brown Brown

1620 ohm or 112000000 ohm (112 mega ohm) 1 % ( you need to test with meter to confirm which value)but i guess th 1620 oh  should be the answer.

Brown Red Yellow Brown Brown

1240 ohm or 11400 (11.4 k ohm) ohm 1% ( you need to test with meter to confirm which value)

Brown Orange White Yellow Blue

Read from blue color band first 649000 ohm (649 k ohm) 1%





Hi Rolly,

Here are your questions and answers:

Many thanks for your quick response. Upon reading some of your articles pertaining to different

repair report you ever made about the different power supplies, LCD & CRT monitor failures with

solutions. I made my myself so curious to be more interested on your articles. This is the reason why

I push my self to be one of your subscribers.

Thanks for being my member!


Likewise, I have some questions about the problem of my TV set, the brand is KONKA with model

KV14-730. At first, my TV suddenly shut-off as in no raster & sound. When I open-up and check

the parts, the flyback have found culprit. After buying a new one and install it, unfortunately, my TV still

doesn’t work.  I tried to pulled out & I check the Horizontal out transistor, I just read a very low resistance

for about 47Ω only between B-E which I beleive not basically normal reading. I realy doubt if it is really

defective for I have no same part to compare. The parts is quite difficult to find locally.

Try visit this link to isolate the problem first at

If you have set your analog to x 1 ohm and place the black probe to collector and read probe to either base or emitter and have reading then the HOT is shorted and need replacement.

Hope this helps!





Hi Jestine,


Compliments of the new season.

I’ve got one Phillips TV that plays for some few minutes,

then starts arching and plays again. What could be the

cause of this.





Hi Simon,

If the arcing comes from the flyback then most probably the flyback have a cracked and need replacement.






Just want to wish you a blessed new year. I have learned a wealth of information from you.  Your websites are superb. I’ve always dream of understanding how to measure those small electronic components.  Thanks to your websites, your comments, tips and encouragements.


Now all the junk electronic boards I’ve collected over the years are now beginning to pay off….….and mum told me years ago to throw them out….ha ha ha…sorry mum for being disobedient but it was a good sacrifice.


Thank you Jestine and have a blessed new year.








 i have problem with my monitor..please help me to fix it..

it has power but it goes on and off.. and im hearing sound on its relay like a tik tak sound with a gap of 2 seconds for each sound..what seems to be the problem?


plaese i need your response…


Hi D,

It could be filter cap problem, shorted flyback internal capacitor, shorted HOT and etc. Guess you have to open up the cover and start checking on the filter capacitor first and make sure all the output voltages are okay.





Hi Mr. Yong



Thank you for the wonderful greetings. I’m so glad being the member of this organization, it helps a lot in upgrading my knowledge in this field. Once again thank you and God bless.


Mr. Elne D.




Hi ! Jestine,

Can you help me about the Television power supply because the fuse blown. and I dont know what part have a problem, can you help about this.


Hi Joal,
If the fuse blown then suspect a bad bridge rectifier. Check also all the components in the power side especially semiconductors.




Hi Bailing,


Here are your questions and answers:

Good news, my friend eventually gave me her monitor for me to repair.

Good to hear that!

After opening the case, I didn’t see any burnt component and this monitor is the first time to repair. The problem is there is no inrush current heard when turning on the monitor, and the led indicator is green when there is a signal.

You already replied my earlier e-mail saying that there could be missing B+ supply to FBT and missing drive signal to the base of HOT. I did the voltage testing, I got 110 VDC at the B+. I checked the hor. drive transistor C1213 to be OK, but I couldn’t trace where the signal coming to its base. I only see the vertical deflection IC TDA8172, cannot see where is the hor drive transistor base signal coming from because I cannot see where is the horizontal oscillator IC. Could it be SAMSUNG U242 IC? Please see the attached photo.Please advise how could I find the missing drive signal to the base of HOT. Thanks a lot.

Yes the Samsung U242 ic is the horizontal oscillator ic. Another way is to trace backward from the HOT base and you will definitely find the horizontal driver transformer and horizontal driver transistor.

I can see the heater filament glowing, the smps transformer and FBT primary winding checked to be ok with the ring tester.

If you get the green light this mean the smps, cpu and probably eeprom ic are working.

All Mosfets: IRF630, K2645 checked to be OK. I wonder why the big diodes mounting always be above the pcb surface?

Are you referring to secondary diodes? I have seen many models where the secondary diode were very close to the pcb board and there were no interruption from the diodes. I guess it does not matter whether it is very above the pcb board or just above the pcb board.

What is the function of the WinWay IC on the CRT board?
If i’m not mistaken (i have never repair this model before) this ic could be an OSD ic that controls the ON screen display.

Hope this helps!







  1. aqeel

    February 13, 2010 at 3:31 am

    model no samsung syncmaster 720n

    One Horizontal Line or Bar Across The Screen?

  2. admin

    February 13, 2010 at 8:48 am

    Hi Aqeel,

    The LCD panel have problem and you need to replace it.


  3. Jeetu Das

    August 31, 2010 at 2:32 pm

    Hello Jestine,

    i am reparing a tsum16al-lf-1 based 15 lcd monitor, the problem with it is dom display, the main power board hold the smps and inverter board and a smaller pcb is the tsum16al-lf-1 circuit for display, the power supply, lcd ccfl is ok. The problem lies in the tsum16al-lf-1 circuit, how do i check the circuit. Please help, do your book contains these details.


  4. admin

    August 31, 2010 at 10:07 pm

    HI Jeetu,

    Dim display is usually related to bad backlight and bad inverter board. Is the inverter board getting the right supply voltage? If yes then you need to check if the inverer ic is producing output waveform or not.


  5. Jeetu Das

    September 1, 2010 at 12:19 am

    Hi! Jestine,

    Finally i bought your books, thanks for the same.

    Initially i also thought that panel was a problem or the inverter board, i have few lcd monitors of the same model, so i swapped the cards and panel with a good one, and it is the video board with the tsum ic on it which is the problem. the osd is comming.
    Please help me..



  6. admin

    September 1, 2010 at 12:40 am

    HI Jeetu,

    In your case then the mainbaord MCU can be at fault because if it did not send an On signal to the inverter board the display will become dim. Check that the MCU have sinewave and all voltages are present in the mainbaord. A bad MCU can cause many weird problem like OSD locked will appeared, OSD intermittent comes and go off and etc. You need a programmer to reprogram the MCU but the problem is the MCU programmer is quite expensive.


  7. Jeetu Das

    September 1, 2010 at 2:47 pm


    Can you tell me about the service codes of lcd monitors, i want to open the service mode of this monitor using tsum16al-lf-1 ic. can you please help.


  8. admin

    September 1, 2010 at 7:48 pm

    Hi Jeetu,

    Sorry i do not have this service code because only manufacturer or the authorized service center have the way to enter it. Service code only can work if the lcd monitor is functioning normal. You may need to try different way to press on the front panel button plus power on to turn on the service mode. Without the right information, it will be hard to locate such way.


  9. Jeetu Das

    September 3, 2010 at 11:39 am


    Jeetu here again, i am stuck to this lcd monitor, i want to ask you a very imp thing, in the tsum16al-al-1 MCU ic, pin 86 is a pwm output of 4.9v to pwm ic tl494 to on the cfl. I have checked the good and bad board but the on drive voltage is there in both. Is there any method to drive the cfl directly.

    One very basic question ?

    when we increase brightness and contrast control what happens? does in both cases the cfl bightness increases and decreases.

    Thank for your help and support.


  10. admin

    September 4, 2010 at 4:21 am

    HI Jeetu,

    I have not done this but you can try to drive it directly by bypassing the start circuit. That means the supply voltage of 12 to 14 volt (depends on model) will be directly connected to the vcc supply pin of inverter ic. This will cause a problem of white screen display because the lcd panel will always on.

    If you have other question please do email me again.


  11. Jeetu Das

    September 4, 2010 at 1:34 pm

    I have i done that, i have given a 5 volt directly to the drive circuit. which gives 12volt to the tl494. In off condition the panel becomes white or fully bright. but when given the vga signal the panel becomes dark again?

    I am planning to make a isp circuit, let me try flash this ic. Thanks for your help and support.


  12. Jeetu Das

    September 9, 2010 at 11:17 am

    Hi !

    I discovered a new this about this defective monitor scaler circuit where tsum15al-lf is used, the lvds signal to the panel are all in +ve volts, where as all the voltages should be in -ve, why this is happening can you please let me know.

    Thanks in advance.


  13. admin

    September 10, 2010 at 12:53 am

    Hi Jeetu,

    I have not seen any negative voltages in lcd monitor motherboard before. Do you have any diagram as i need to see this- thanks. In mother board RAM yes they need negative voltage but not on LCD Monitor.


  14. Ruwan

    July 14, 2014 at 11:44 pm


    I'm having problem with Acer LCD monitor (Model AL1717) with TSUM16AL-LF. The problem started few days ago, by restarting the monitor after few minutes the monitor turned on. Some times it worked few minutes without problem, and starting to blink led and turning on and off itself.
    I checked the power supply, it seems ok. LCD panel and back lights are ok as I tested. I think the problem probably be with the chip or the chip mounted board components. Now I cannot turn on the monitor anyway. No any LED is turning on, and power button not work at all.

    I checked the voltage comes to board, is 5V. I tried giving separate 5V supply to board, but it does not turning on anymore with power button. Can you please point me in right direction to solve this?

    • Jestine Yong

      July 15, 2014 at 11:06 am

      Hi Ruwan,

      Check the front panel switched and if all ok it seems that the data in the MCU IC could have been corrupted.



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