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Electronic Repair Questions/Answers and Testimonials- Part 54

By on May 8, 2010

Hi Jestine Yong,

I want to let you know that I have retired from the industry and that I have
enjoyed your newsletters. I’ve learn a great deal from them and I was able
to reduce the amount of time in diagnosing and repairs computer monitors and
LCD’s because of them. I want to thank you for keeping me informed and
you’ve been a valuable asset to my operation.


Tony G





Dear sir,

Your troubleshooting guides have been so much so useful that I can now tackle any job confidently. What else I can say “All my gratitude for you helping me so nicely”.


Khalid Babar












Hi Jestine !


I’ve operated a Plasma TV fix and thanks to all the very good information given by you I have succeded to make it functioning perfetly !!!

Thank´s as always for your friend e-mails… All the best to you too!!!


With the best regards






Hi Jestine,

I am very grateful for your e-books on LCD monitor and reading electronic components. they have made me deeply involve in electronics.

Best Regards
Godwill N.




Hi Justine,


              Just want to thank you about sharing your skill and experiance of how to

troubleshoot a faulty motherboard and be able to repair it .The way you explain is more

clear than any technicians,i stand it and follow the different tips in how to takcle the problem.







My name is ihab i m running computer maintenance center in Abu Dhabi, I m really impressed to your website I m wondering if you could help me or assist me regarding mean motherboards diagnostics tools or system can find the problem.

your reply will be much appreciated.


Hi ihab,

Thanks for your email but sorry i do not repair motherboard .Perhaps this product can help you:






HI Noorishkandar,

Kamu kena check  G2 dan heater di bahagian CRT board. G2 kena ada voltan antara 250 to 300VDC dan heater mesti ada 6.3 vdc.



Hai Jestine thank you for the information….dgn tips yang anda berikan telah menyelesaikan masalah no display yang saya hadapi dan ada adalah seorang kawan yang baik hati dan saya ucapkan terima kasih diatas pertolongan yang diberikan.

Yang benar,



Hi Jestine


Thank you very much for the May repair newsletter. The interview with Mr. Steve French and his Staff is quite inspiring.


Once again, thank you.






HI Timo,

First of all thank you for all your valuable Internet teaching and tips. I plan to buy one or two of your ebooks within few weeks, when I will have few more success in LCD monitor repairing!

Thanks for the support!

I have a question about it: after the Paypal payment is sent, how can I get my ebook and bonuses?

You will immediately get the download link that have the main ebook and the bonuses report.

I have an other question: I discovered today that the characteristics of capacitors is a major problem in SMPS: some people on websites claim that you have to use low-ESR high-ripple current series from certain well-established brands (Nichicon, Rubycon, United Chemicon for instance) to fix SMPS and motherboards VRM They say if you don’t do so, the device is likely to fail again. Even worst you may not be able to repair it at all even with brand knew standard capacitors, and spend time looking for another failure! What do you think about it? Is it true only over a certain capacitance or in certain part of the boards?

Yes they are right because branded capacitors will usually last longer than non branded caps

I am very confused with this because I would like to sell some screens I fixed, but I don’t want them to fail again in few weeks at peoples homes! Even if I sold them to a second-hand buying company, which sells monitors with a 1-month guarantee, I think it won’t be nice of me if I am aware of this possible issue.

Don’t worry about this because even if you use a non branded caps it can at least will last up to more than 1 and a half year.

I get Jamicon, BC, Frolit and REC general-purpose caps from my local supplier, I only ask for 105°C versions… Am I wrong?

It is good that you use the 105 celcius cap

Should I manage to import caps even if they cost me a lot more money?

If you really want to make sure that the equipment that you are selling can last and if your place do not have such caps then the only way you can do is to import the caps. Again it depends on how much margin that you will make from the sales of the equipment.

Thank you very much for having read me, and in advance for your reply.
I would have so much other questions to ask you because I have few screens I didn’t manage to fix yet!
Thank you again for what you already did for me!

You are welcome! What is the problem with the screen?




Hi jestine

Thanks for your help, and i have a small question : i see 3 fet transistor in the primary section, its code are 1(2N60) and 2(13007) , i remove the 3 trans. w/ heat sink to test outside the board.
the 2(13007) looks ok, but 1(2n60) have only one reading between to pins just. is this trans. have a different test. would you please advice me testing this trans.

thanks in advance


HI Yahya,

Since i do not have the 2n60 transistor with me thus i could not show you the correct reading of this transistor-sorry.







how does a short resistor behave when testing by an ohms meter?


HI frank,

Resistor rarely short circuit. Usually open circuit or turn into high ohm.






Respected Sir,

      I have a CRT tv 19″ in which only half the picture tube works.

                    Means in the picture tube only half of it lights up and remaining vertical half remains dark.

      Would you please give me some repair tips to solve this particular problem.


Hi Shiharan,
Check the supply to the vertical IC. Some vertical IC have two supply inputs (one is positive and the other is negative). Missing one of the supply voltage could cause either one the screen black or missing. If both the supply are good then direct replace the vertical IC and retest.





HI Philippe,
Hi Jestine , how were you and your family?

Fine thank you but just a bit busy conducting repair course lately

just sorry for disturbing you,

No problem.

i need your help can help me please:

i have 4 problem with 4 television

1st  a 20” gold star TV vertical problem

You mean the display have one horizontal line or one vertical line?

2nd a 20″ samsung TV no raster

Is there high voltage? Any good output voltages from the SMPS?

3rd a 20″ samsung TV as raster but no video and turn off after 12mins, the output ic or transistor and some resistance get hotter when i touch them

You may need to isolate the problem by following this link:

4th a 14″ Philips TV no raster but have vertical line, i try to adjust luminance on line switch but it remains the same

One vertical line is the problem in the horizontal section. Please check the horizontal yoke coil area for dry joints and bad components. An open horizontal yoke coil may cause such problem too.




Thank you so much.

I’m already buy your LCD monitor repair guide yesterday using with my paypal account. Today I’ll like to buy a blue ring tester.
For your info I’ll already buy your book. 1) Trouble shooting& repairing SMPS
2) Testing electronic component
3) LCD monitor repair.
NOW! I can say you are the best teacher to me.
Now I know to test and enhanced my basic knowledge.
For a long time I’ll be looking someone can be teach.
Now your the best because mostly people that I’ll seen before always hidden their knowledge or
limit knowledge.
Thank you so much again.





HI jestine


I have finally managed to download your ebook SMPS troubleshooting & repair, PayPal accepted my payment. It is a real eye opener. It answered many questions I never asked, and I can believe this part of keeping as far away as possible when testing a set after repairing the power supply, expecting the fuse to blow again. It has happened many times with me and I got so traumatised. But now I’ve got the solution, thanks to you.






HI Saeed,

I tested the capacitor with blue esr meter and it showed .26  the normal esr value of a 470uf e-cap in accordance with cataloge of the meter is .15 and .26 isn’t very high. if i haven’t capacitance meter and only  esr meter i didn’t replace the capacitor.what is your openion?(in your articles you have told that best way to test electrolytic capacitor is using esr meter ! )

I guess you don’t worry so much about this value. If you do not have the capacitance meter and if you tested the cap with esr meter and you found that the value has out then just directly replace it and retest.

how much increased esr value is symptom of a bad capacitor?(2 time, 3 time,etc)

It depends on where is the cap located. If the cap located in the supply rail to power ic then an increase in esr value will affect the power output.

(in my openion if a capacitor esr value be higher than the esr meter cataloge  that capacitor is spoilt. am i right?)

Generally yes but again it depends on where you found the cap because some cap although have slight increase in ESR value  the equipment will still functioning.





HI Rik,

Thanks for your prompt reply. I just realize the picture I sent you didn’t show the Resistors I mentioned. I hope this attached picture shows well. Yes, I ever read in your ebook the correct measurement of resistor. Even when measuring onboard the value should not be that much different if the board is in good working. Am I right?


My question was the big difference in resistor reading (2K Ohm & 15 Ohm), I believe, is due to a bad a component on the board and could this bad component be major components like IC or Transformer or minor ones like small SMD capacitor, diode etc.

Yes it can be. Generally if the resistor value that you check on board lower than the original one then suspect a parallel circuit that had pull down the resistor value. If the resistor that you check is higher many times than the original value then suspect that the original resistor may have gone up in value. No matter what, the best test for resistor is still remove one leg from the board.

This inverter, when connected with external power adapter, the adapter light turn off and the board didn’t accept the power. Please look at the picture and give me suggestion which component you think could be the culprit. I am very glad that you patienly reply my mails even though you must be super busy.


If the external power supply voltage immediately drop upon power on then suspect something that had shorted like the transistor, ic, diodes and other semiconductor components. Since this board have top and bottom lamp, i suggest that you compare the resistance between the top and the bottom using X1 ohm. One probe place to ground and the other probe use to touch on the top and the bottom components. Any changes in resistance is the clue for you to trace on that line or component.

Have a good day!





HI Nooriskandar,

Hello Jestine..maafkan saya kerana sering menyusahkan awak dengan soalan2 yang saya berikan.Sebenarnya saya memang berminat dengan elektronik cuma saya tiada kemampuan untuk belajar dikelas yang awak anjurkan kerana saya dari golongan org yang sederhana. Saya cuma banyak belajar menerusi buku2 panduan elektronik,dari elektronik dan juga youtube so jadi kesimpulannya pembelajaran saya itu taklah berapa advance.Maybe suatu hari nanti bila saya ada kemampuan saya akan menghadiri kelas yang awak anjurkan ya.

No problem

Saudara Jestine,saya nak tahu apakah sebab-sebab utama yang membuatkan Horizental Output Transistor rosak?

Sila masuk laman web ini:

2.Boleh ke kita switch on power crt monitor dan check voltage di G2 or G1 di crt board kalau cover grounding crt itu dibuka?

Boleh tapi kamu kena pastikan bahawa ada sekurang-kurangnya satu ground dari crt board ke picture tube.

3.Kalau kita repair Laptop dan sekiranya ada komponen ic yang burn ada ke jual dikedai-kedai spare part elektronik?
Biasanya sukar didapati di dalam pasaran

Oklah..saya berharap sangat saudara Jestine sudi memberikan jawapannya kepada saya dan saya ucapkan ribuan terima kasih diatas setiap pertolongan yang diberikan.hanya tuhan yang dapat membalas jasa baik saudara Jestine.

You are welcome!






HI Yong,

Have you ever heard that so called” IC tester” that costs about RM40,000 (china made),does it really help us for pcb repairing?

It depends  on how you use it. Yes i have heard of it like Huntron, ABI, Polar and etc

I just know a new repair friend who sharing his repair method that he removes out  all the ICs in a pcb board and use the tester to check !

Remove all the ICs ! What’s a tough jobs for me ! Is it a practical way?

If he has the tester, the tester should pinpoint to him at where he should check so that this can save his time. This also depends on how well the repair technician in troubleshooting motherboards.


Anyway can you share your method how to check ICs in pcb board?


Identify the type of chip, measure the input and output waveform. It depends on what type of IC you want to check like the MCU, EEPROM, linear IC and etc.

For memory IC you need a programmer.




Good morning Jestine,
I have not tried your suggestion yet because i am a little worried that i might be wrong. However, given your experience and qualification in Electronics, i am going to do it. There are three voltage regulator IC that shares the same heat sink as the two STK 412-410 ic. I had already replaced them too. But i must ask, in your own experience repairing these kind of equipment, is it possible for a faulty STK 412 iC to cause all these problems? Thanks for an early response.



HI Reginald,

Well, any components can be possible to cause problem. Since you have check all the components then i suggest that you take a risk to try it out. Sometimes, in this repair trade we just have to replace and retest. If it still can’t work we then can keep the IC for future use and at the same time concentrate on other area.







I got you book a couple of months ago and it was really helpful. But now I have to test ICs.

Witch IC tester (digital and linear) would you recommend? In your experience witch one is the best?


Best Regards



HI Javier,
It depends on what type of ICs that you want to test. For digital IC you can buy a digital ic tester, for linear ic you can test it using oscilloscope (find the supply, input and output pins), for memory IC like the EEPROM or MCU, you need a programmer.





hi,justine, now spanish:yo estoy ablando de el dick smith ESR meter negro con 2 digitos
rojos tu lo mostrastes en tu pagina web,haciendo un click en electronic repair tools
se tu me dices como trabaja yo te pagare o.k. muchas gracias por tu atencion
y que dios te bendiga siempre you have a nice weekend,,,,
atte,,,,,armandotvs ,,,,,,


Hola Armando,

Le sugiero que visite este sitio: bobpar ~ / esrmeter.htm

el herrero Dick metros esr ya no está en producción.

Para saber cómo trabajan esr metros por favor visite:





Hi June,

gud pm jestine if the blue ring tester can’t detect a shorted diode of fly back so what was the real use of the blue ring tester?as a device that can detect 80% of fly back problem. thanks.

It is designed to test on the primary winding of flyback transformer. Flyback have lots of primary winding failures compare to diode shorted. If diodes shorted you can test it with an ohmmeter. The Blue ring tester also can be used to test on SMPS transformer primary winding, B+ coil in CRT Monitor or even the horizontal yoke coil in CRT tube.





Hi Li,


SMD components which I want to remove or replace needs a specialized tool, a SMD soldering iron. In the Jaycar catalog from 2009 I found a 60W SMD soldering iron (Cat. TS-1701) which was available for about NZ$95 (AU$75). Unfortunately this product is discontinuu and therefore I was thinking to ask your help and see if I can buy through you such a soldering iron at a price similar to that given above and send it to New Zealand, in case you have such tools there.


I suggest that you get a rework station to remove SMD components. The soldering iron is just very slow. You can get a middle range price of rework station. A too cheap one will easily have problem. After removal of the smd components by the rework station, you then can resolder it back with a normal soldering iron.
This is how a rework station look like:






dear jestine what can happen if you insert a wrong flyback by number? thanks




No high voltage, high voltage shutdown, HOT gets hot and burn, display problem and etc.






How much is the Backlight Tester and where can I buy it ..


You may check more info from these websites:






Hello Sir Jestine
Good evening sir hope your ok, sir can you help me i have a DELL LCD Monitor the problem is have a display but after few minutes shutdown no display but the power button light is ok, the filter capacitor is ok, then when i plug the monitor i touch the scalar IC is very hot, then my question this scalar IC is possible cause the problem? i will examine no parts is the damage inside, can you help me sir. thanks God Bless and more power.

Philippines Tech


HI Arnold,

Sometimes it can be backlight problem. Dry joints in high voltage transformer and bad components in the inverter board may cause such problem too. You may use a freezer to spray on the ic while the monitor is working. If no more shutdown, you will know is the scalar ic problem.









Best regards:


Laptop service technician





what is a switch mode power supply



HI Anthony,

It is the power section of any equipment and it supply DC voltages to various circuits in an electronic board.






Hi Jestine Yong:


I just has a quick question to you. I am working to a finishing equipment manufacturer and my question is if you has any reason of that a Main PCB board that has logic circuit and if the excessive heat can create a lost of ROM memory of E PROM IC?


HI Jose,

So far i experienced only static discharge from equipment like CRT Monitor that can corrupt the eeprom data.Never heard of heat that can erase the data. Once reprogrammed, i place a small metal shield on top of the eeprom ic to prevent future problem.




Hi Jestine
Thanks very much for your patience during the time i repaired this LCD, you did give me many suggestions on how to test. Though it seems like hard for me to make it work again, because i don’t have proper testing tools and schematic to test the mainboard in hand, I have tested the outputs to panel, it doesn’t have 1500V outputs (output is 0V), so i thought probably the mainboard is faulty. Any way, thanks very much for your time.


HI Webster,

If it is zero volt, it can be mainboard or inverter board faulty.






Hello dear friend, please if you have any idea about Dell Monitor model E173FPC the screen comes on but later it when off.


HI Abdou,

Check the dc supply voltage, dry joints in high voltage transformer and the backlight. A bad backlight could cause such problem.




Hi jestine
I received two laser printer model lbp 2900b canon with a problem ,
a segment of column paper when printed ,is colorless or low
color(this is a black and white printer),I disassembled printer and
clean roll another part but problem exist ,yet .i am sending a picture
of paper printed till you see this problem,i read your email ,WAIT TO


HI Hadi,

For your information i do not repair printer. However, since i could see the photo, the problem most likely in the toner (try shake the the toner horizontally) or the scanner assembly. Clean the scanner mirror and retest.





Thanks for the reply! I checked voltages on the pins that are connecting
Power Plate and the baza.Pe these pins have these tensions: 12.33
, 3 and 1.5 V. The replacement electrolytic I never seem to like us.


Hi Gabi,

You mean the power supply output are 12.33 and 1.5 VDC? If yes then the 1.5 volt  line have problem. It should be about 5 volt. Check along the line and direct replace the cap and retest.





i have an ipod docking station made by fidek called itallboy and where you put the ipod onto the docking station the circuit board where the ipod goes broke all it did was fall forward and pull two little pieces from the board and i cant seem to find a replacement part for it i tore it all apart and this little board has two really easy quick connects that i disconnected thinking this may be a common problem and a quick fix with a replacement but when i contacted the manufacturer they told me to buy another so why would this circuit board have parts numbers on it im totally lost and could really use some help if u have any suggestions or maybe know how to receive hard to get circuit boards

sincerely bobby


HI Bobby,

Those parts are controlled items and usually can only be found from their authorized service center. The circuit boards have part number is for their internal people to have reference.






  1. singka

    May 12, 2010 at 5:17 am

    Hi Mr.jestine,
    I would ask i have problem with CRT monitor HP 21'inch tha shaking,
    any idea to solved the problem

  2. admin

    May 12, 2010 at 8:10 am

    HI Singka,

    Shaking can be caused by many section. Is the power supply output voltages good and stable?


  3. singka

    May 14, 2010 at 4:54 am

    Hi Mr.jestine,
    I would ask i have problem with CRT monitor HP 21′inch tha shaking,
    any idea to solved the problem

    admin May 12, 2010 8:10 am
    HI Singka,

    Shaking can be caused by many section. Is the power supply output voltages good and stable?


    I already check at power supply output section and found the output little reading not stable.i has replace 4-unit capacitor at primary and secondry and testing the monitor running in fine.


  4. admin

    May 14, 2010 at 11:02 pm

    HI Singka,

    You mean you have solved the problem?


  5. singka

    May 21, 2010 at 12:54 am

    Hi Mr.jestine,
    I have i case notebook LCD screen,problem half display,another half screen got image,i has been doing the rework using the rework station at the IC at the back panel.My question what that cause problem.I should i have to check.The case with CRT 21"inch i have solved the problem.


  6. admin

    May 21, 2010 at 8:50 am

    HI Singka,

    The notebook problem is in the lcd panel and there is no way to repair it. Most probably the lcd controller IC have problem. Congrat on your successful repair on the 21" Monitor.



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