remember the question I asked you about a philips LCD computer screen that was shutting in and off and you told me to reflow the main board..well, i did that and it is working fine so far. I just want to say thanks for your time and help. God bless you



I have been following your work for some time now.

Really helpful book by the way! Thanks

I really hope you can help me out here.

I repaired a Samsung SyncMaster 226CW which had bunch of blown capacitors. Now, replacing capacitors did fix the monitor but a high pitch sound is coming out of the PSU when the monitor is on. Is there any hint on where such a sound can be coming from and how to fix it?

Best Regards


HI Radion,

Thanks for the email. High pitch sound can be from the power transformer or there could be bad component that had caused the transformer to produce the high pitch sound. Try gently tap on the transformer or the coil with the handle of the screw driver to see if the sound will stop or not. Please update me on this case-thanks.



Hi Jestine,

Thanks for the download links.

I have successfully downloaded all the ebooks.

Your ebooks are really a gold mine when it comes to electronic repairing and

I have never felt so confident in this field until I got hold of your ebooks.

I trust that once I’ve read and learn them all, it will pave the way for me to

success in electronic repairing. Many thanks again for sharing to many your extensive knowledge and experience.

Wishing you all the best and success in your career and family.


I’ll be in touch, whenever I need your help.

Have a nice day!

With my best regards,




Hello Sir,

I have solved the problem.

There are some factors:-

1.            The blinking of bulb and power led was in right way because monitor was generating OSD (check signal cable).

2.            The fault was in FBT. I checked FBT with FBT tester, it showed good condition.

3.            I had a working monitor of same type and took out FBT and        installed in faulty monitor, it came in life again.

Now there is a question that FBT tester passed component OK but why it did not work?

Thanks with regards.


HI Daud,

It could be the internal capacitor problem. Please check on this link:



sir can you pleace tel me about monitor deflection yock coil matching for being television kit.

Hi Salman,

As far as i know monitor yoke coil is only for monitor. Putting it into the television will cause color patches problem and if the yoke coil is from different spec the HOT will burn.



sir jestine
my tv is under repair because of its fly back is bad leak and many holes.
and i decided to change it on my own experience,and theres a flyback i bought that is
less than one pin to the bad one original,is there any conflict? because the store said to
the one  pin is no purpose?. and it seems same specs and brand only the pin is less than one..
thanks and more power,more technicians to help from you,godbless.

Hi Ryan,

Although flyback usually have 10 pins (excluding the voltage divider pin) not all of the pins have function. If your supplier says that it can work then you need to try it out.



1) Benq Q7C4 LCD I replaced shorted C5707, 9024, pico fuse and bulged .22µF cap but still the inverter was not powering up. Finally found SMD transistor (digital?) shorted and I couldn’t find any No on this transistor. Pin No 9 of inv IC TL1451A is connected to one leg this shorted transistor. Could u please let me know if this tr is PNP or NPN and replacement part No. For ur info I’ve found that hp & Dell too use Benq boards in their LCD monitors, surprising, huh!

Sorry at this moment i do not have the same model in my workshop thus i could not locate the component.

2) Is it possible to use 220 to 110Vac step down transformer with high current out put as an isolation transformer since the secondary is isolated from primary winding?

Yes you can since nowadays most of the equipment have ac voltage autorange.


3) Viewsonic 19″ LCD after 5 minutes of operation screen becomes black. Switch off and on the unit picture comes back. I replaced the p/supply+inverter board module with another one of same model the problems is the same. Is it the small m board or the LCD panel defective or any thermal related problem? The unit about 1 1/2 years old.

Probably one of the backlight have problem.


HI Doug,

Hello I am thinking about buying your ebooks but I am not sure. Is the way you test all of the part is to take them off of the board and test them or can you test parts on the board with a multimeter?

Some components can be tested on board like, fuse, coils and electrolytic capacitor. Other components you need to test it off board.

And what about the one’s you can’t test with the multimeter do you use a oscilloscope and show using it to test stuff?


Most of the components can be test with analog/digital multimeter, esr meter, digital capacitance meter and blue ring tester.



Hi Jestine,

I came across a faulty Zener diode in a SMPS. On the same board I saw one Zener, with the same colour code. A reverse bias it, with my Fluke 289, I thought that with was a 2Volt Zener since I saw on the meter 2V in diode mode.

Wrong! The multimeter does not tell us the reverse voltage of the zener!

I have made this mistake an hope that you do not make the same mistake that I did!


HI Bruno,

Multimeter can’t tell us the voltage and you need a special circuit to find the right voltage. Anyway thanks for the info. By the way, the lowest zener diode voltage that i have came across in my career was 2.4 volt.



pls, sir i need you hlep, i have a samsung tv model cs-21z57ml, the problem is the screen is very dark .no raster, no glow, no picture, in fact dead, but there is HV as i can hear the sound, and the audio is uses tda6107q as R G B drive, there is no voltage at 1,2,3,7,8,9, of the ic. the set uses tda12156ps/n1/3 as function ic,and there is no data of this ic in the net, pls where do i start, help me.thanks


The high voltage could have shut down. Check to see if the g2 voltage is till present or not. if zero volt then the high voltage already shutdown.



the problem of my tv,when I swtich on the power the fuse were blown therefore I found that the power transistor were shorted then I replace it with the same transistor same number after that repair then I switch the power on and then no power on almost what can I do next do slove the problem to that tv to make it on,is there any test to go ahead.

Hi Netane,

I suggest that you check all components in the power side and make sure all components are good before turning it on again. Pay particular attention on the semiconductors. A shorted primary winding in the transformer also could cause the power section to blow.




Very many thanks for your email and information about your book on LCD monitor troubleshooting and repair.  I hope to get to buy it soon.
I used to learn about electronic servicing in the 70s and 80s as a hobbybut I never got to do the job seriously.  I have now got left behind with these new inventions and what not.
My greatest problem now is that i do not have any good sophisiticated equipment except an analogue and a digital meter and an old 5Mhz oscilloscope which seems to have had its day.  Still I do not wish to embark on any expensive equipment and schemtic acquisitions.
Anyway, my promary problem is troubleshooting power supples especially the SMPS in Tvs and other equipment. I never seem to get it right.
In view of your offer of help could you please give me some tips.
I know this sounds most selfish and I will be most grateful for any information.
Best regards and keep up the good work.

HI Tony,

Yes the 5mhz scope seems to be too low for troubleshooting job. Besides the analog/digital meter you need a Blue ESR and Blue Ring Tester to speed up your job. Both tester is not expensive.

You can visit this link for more smps repair information:



HI Gary,

Actually this TV is for my brother in law, so if possible  I want to fix, I couldn’t see any speaker inside the tv is there any built-in on it?
There must be speakers located at the side of the Tv.

LG DU-42PZ60 model, one thing more is the half line problem its from the board or the screen itself? if the screen I don’t wanna waste my time, If from the board maybe I can get the parts on this model..

It can be x sus board or the lcd screen problem. If you have replaced the x sus board and still the same then the problem is in the lcd panel.



Hello Mr. Yong

One day I was working on my computer suddently it stops working. I am working on computer more than 5 yrs. but the way it stops everything in a moment makes me worried. After checking it i find that this part of computer has stopped working.

I have gone here to the persons to whom I understand that they give best service. First one has took time, given somewhere to repair this part of computer called SMPS. When I go to collect it they says you come again after three days. This way they have spent some time. At last they say, it cannot be repaired because it is seriously damaged.

I come home and keep it on table. Then my mother get injured and I have to do all works. One day I have opened this SMPS and I have find no part of this piece looked damaged but the repairer have done it more complicated as some of its pieces were hanging to the board due to one or two soldiered pieces which he might have not been able to unsoldiered.

Then I have gone to one Electronic shop whose mechanic is known as best for his work. His boy have take it as i know him but they also have not repair it and when i have gone to their shop they said you get new piece of this part.

The problem i am getting is that now new technique’s (called SATA) SMPSs are available but my SMPS is old one. Its plugs are not matched.

Then I have gone to computer accessory shop which was near to that electronic shop and has got wires, which i think may solve my problem but this way i also not succeed.Ultimately I searched on net and find your site. As I do not know anything about its parts but i get happy that there at least one person i come to know who can repair it.

Though I cannot understand your all newsletter but I want to give you thanks and I am also very happy that you have really done very hard work for this part also give this site.

Thanks very much again for your newsletters through which you shared you experience with us.

Best of luck



Dear Jestine

I would like to know if you can please advise me if I can use 10nf 2KV ballast caps instead of 10nf 3KV will the 2KV be okay say just to test for a short while this is on a 26″ inch sansui lcd television

Kind Regards


HI Dana,

Yes you can use it for the short test.



Hi Jestine

I have a DMTECH flat screen tv that the power supply went dead.I fix the power supply but as soon as you plug it in it destroy the power supply( no output once more).What should I do?I notice there is a short on this component 8050SD(pin 2&4) could this be the fault? Please advise



Hi Joe,

I suggest that you recheck all the components again. If all tested good then directly replace the power ic and retest. Check also for shorted diodes in the secondary side. Sometimes a shorted primary winding could cause no power symptom too.



HI Anu,

But i also read on some other site from Google that black horizontal line on LCD screen is caused by a bad filter capacitor and can be repaired by testing and knowing the exact filter capacitor then replacing it with a new one.

That usually a fused filter capacitor is caused by over voltage,long term heating and also improper manufacturing………And my friends LCD had those black horizontal lines right after plugging 2 power wires to the LCD monitor. Please Sir help me to rectify the exact problem so that i can work on it…I would so much appreciate your help thank you.

Those are not steady lines. If yours are permanent nice black line than the lcd panel have problem


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