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Electronic Repair Questions/Answers and Testmonials- Part 58

By on July 7, 2010

Hi Jestine I did buy your book and it is a huge help. I successfully repaired my own Panasonic TV and is currently busy with a DVD player that has a faulty smps. With the help from your book I found a resistor that is open that I otherwise wouldn’t have found. So currently I am still busy with the smps, seeing there is still a fault on it but with the new found knowledge from your book I am confident that I will find the fault. Thank you very much for your support and knowledge I really appreciate it.  P.S ! I hope that I will still hear from you from time to time ,from Marius !!




Hi Azwindi,

I can see that this tester can test 78xxx and 79xxx but i want to know if it can also test SE090, SE140 and so on and how?

No it can’t test on that type of components because SE090 is an error amplifier device.

I am also having a problem with an LCD monitor. When switched ON, it lights ON and turns Off. Which stage could be responsible for this fault?

Check for bad e-caps, dry joints in high voltage transformer or even bad backlight.






Hi Fahmy, 

   Here I have another several questions related to TV and monitor repair:- 

1)    What is the website or book that provides info about TV and monitor circuit?

Try for free schematic and also to look for tv and monitor servicing book.

2)    Where can I get certain component which not available at my town area such as zener diod, transistor Fet , Darling and etc (component test). Tester & equipment also hard to found here like insulation tester & isolation transformer. Could you provide any other dealer name in KL if possible. 

Try check this website to see if they will send the components to you.





after completing  my scr tester  i decided to test my scr s in my stock i found 6 scr in stock all not used
and same  part no BSTCC0246   but not sure are they from same producer or not . do you know what was the results of the tests . tester reject 3 of scr s as not good   is not this amazing . of course this tester has very simple diagram but how much is useful during the job  even give bad result to unused parts
thank you for this





HI Gopal,

In continue to my previous question i have changed the Vertical IC but found one more problem is that in SMPS, it is using TDA 4601 IC and BU508D. The problem is that there is a sparking type of sound comes from SMPS intermittently, but there is no loose contact. it appears that the sound comes from inside of SMPS transformer. Due to this output voltage fluctuates about 5 v (115-120) and picture also get disturbed as well as sound. The problem is very intermittent between 3 to 10 sec. gap. My question is how will i solve this type of problem. Which section of the SMPS should i check.

Turn off the light and gently knock on the power supply with the handle of screw driver to see if there is any spark or not. Knock on the transformer too. Just make sure there is no components that is touching the heatsink in the power supply.






Thanks Justine,enjoy reading it. Could you please tell me how to test Inverter IC LCD thru multimeter. Thanks


HI Jericho,

Find the inverter vcc pin from datasheet. Place the black probe to cold ground and the read probe to the vcc pin and turn on the monitor. Remember to set your meter to measure DC voltage.

Have a good day!





Thank you Jestine! I consider u the best in the world and I am so grateful to have met u my friend. I just can’t wait to purchase this kit so I can begin to repair those LCD’s and power supplies. I want it to take it step by step. Cheers my friend. All the best.







I would like to convey my heartfelt appreciation to you for your’s efforts of given me these technical information
Its help alot in improving my carrier

Ali ngoa



HI Russ,

I haven’t quite finished reading your LCD monitor repair ebook and it has already helped me to repair a ELO 15″ Monitor!

Congratulation on your success!

A few questions have come up and I was wondering if you had some info on the following.

Can you recommend an Analog meter or what to look for when buying one. I see the Sunwa YX360TRD for $18.00 but is it good enough? What would be the best analog meter you could buy if you could choose any one?

Yes i will get that Sunwa meter that have the X10 K ohm range. Dont’ get a too cheap one, get one that have a moderate price. I have used a branded Kyoritu analog meter before but the selector broke inside. I have been using this Sunwa meter for many years and so far no problem. If it spoil i will continue to get another one.

I saw this LCD CCFL tester and wondered what you thought of it and if it is really worth it or needed.

If you repair lots of lcd monitor/ lcd tv then you may need it. In my place here, since i have many spare backlight thus i did not buy one. I may buy one or build one if there is a circuit on this tester.

Have a good day!





Justin long time we didn’t communicated I hope you still doing fine. I just want to have your taught if I want to open a repair shop in my own garage.One ingredient for any business  to successful is to have low overhead cost which mean the parts have to be cheap and very reliable source. For example LCD screen, mother board, ic, power supply and so on. Do you have those information for me? If you do it would be fantastic for me thank you! Justin hope to here from you soon.


Hi Vannolat,

Sorry i do not have those information. For the parts i either get it from my local electronics shops or salvage it from junk equipment.






Dear Sir,

Thanks for your prompt reply, i do not know how do you manage to reply so many emails. But you are doing really a great help to us.

Thank you.







HI Phua,

I have bought the component repair ebook and going to purchase another monitor ebook and i had noticed there arn’t for CRT monitors!.

Thanks for the support but sorry i do not have the crt monitor repair ebook.

Time is against me. I am working at a semiconductor industry and I have 2 pending CRT monitors case and need to be completed by next week!! I hope Jestine Sir can offer me some valuable tips here

No problem

Case 1:
A oselette CRT monitor had broken now. A slim straight vertical line formed across the center of the CRT monitor. The monitor had been taken for 5 days untouched. When i opened the back casing, i heard a “air” leaking sound. What is that sound? Can the monitor still be repaired??Any tipes on where to troubleshoot if it a vertical line issue?

Vertical line means the horizontal area have problem. Check the horizontal/vertical yoke coil for dry joints and make sure the horizontal yoke coil have low ohm reading when test with ohmmeter.  The sound most probably because the horizontal is not working or it could be accidentally broken the pc tube while you open the monitor. Check the neck of the pctube and make sure it is not broken otherwise it can’t be repaired.

Case 2:
Another different brand of oselette monitor had broken down. The problem is distorted image. Any tips on where to troubleshoot on distorted image issue?

Do you have a photo? Make sure the output put voltages from the power supply are good and stable first before checking on other section.






Message: Could you tell me what is the P/N for a glass envelop diode that has a green band near Cathode & black band in the centre. Your previous info to others on diode color codes or what I tried to get from internet was fruitless. I have a photo but how do I send to you? Thanks for you help.



HI Shaun,

Sorry no info on this. However from the color code it seems that it is a 50 volt diode.  Since this is a glass type diode so expect the amp to be less than 1 ampere.







Hi Jestine,


Thankyou for the about building your own tester.That is good.


Jestine i have one tv problem,that is samsung 42″ HDtv;the first problem of this tv was one gun the green gun was bud,i replaced with new and the same replacement,after the new green gun replacement another convergence problem apeared i corrected this convergence problem by intering to the foctory setup menus,the tv worked for about six monthes good;but after this six monthes the tv shuted of and showed a horizontal line with a convergence problem while the three guns are lite normal,i opened the buck cover to see what could be the problem but i found one of the STK ic’s get too hot almost you can’t touch it with you hands.I replaced the STK ic with a new one; still there is no change.At this point i stopped to get some ideas or tips from people like you JESTINE.







HI Abraham,

Is the supply to the STK good and stable? Have you check the surrounding components to the STK IC? When the IC get hot, it can be the problem of the IC itself, the supply voltage and failure in corresponding components.






Hi Phua,

Thanks for the reply sir.

You are welcome!

I am a beginner at rerpairing monitor here. Sorry.
How do i know where is the horizontal circuit?

Try follow the read and the blue cable from the crt yoke coil to the board. That circuit is the horizontal circuit.

HOw to differentiate which is verical,horiztonal or even colour circuit?

Colour circuit is at the crt board. The board that attach to the pc tube. Vertical circuit is the two remaining wires from the crt yoke coil to the board.

Are there pictures to guide me? Thanks

Please read the article here too:

Have a good day!





Hi Jestine,

I recently bought your LCD monitor repair ebook and SMPS repair ebook.

I’m really learning from those books. I espacially like the way the books

are organize ( to facilitate the understanding).The books are simply very

very interesting.
The english also is simple. I’m  francophone but till today i have not

seen a part of your book i’m not understanding.
Thank you for your work and courage

Electonics teacher and repairer




Dear Jestine
You seem to be a very generous person especially in this world where no one is willing to share even the cheapest information possible, but amazingly here you are trying even to bring professors from their sleeping beds!!!
I am making an effort to purchase all your books as long as you are up to date with the pace at which technology is moving. I have been practicing alright but not as practical as your notes are!!
Soon i wi ll be giving you all types of circuitry that we want assistance here in Africa




Dear sir Jestine

a monitor viewsonic Model E53 in power on but no display condition. On checking all components in horizontal section are ok and there is no B+ at the Drain of B+ FET as well as on collector of HOT. B+ FET and HOT are quite OK. I have also change oscillator IC TDA 4853 but status is same. Kindly help in this regards.


Daud, Pakistan


HI Daud,

You may need to trace from the B+ gate with scope to see why there is no waveform. Without gate waveform the drain will be zero volt assuming that this monitor is using the buck B+ circuit.






HI Noorishkandar,

Hello Justine…Saya ada satu LCD komputer jenama HP yang menggunakan adapter power supply 12 V 4 Ampere.Masalahnya power supply adapter dia dah meletup.Boleh tak saya menggunakan power adapter 12V yang ampere dia tak sama dengan yang asal punya?Contoh macam 2 ampere ataupun ao ampere?

Kena guna 4amp dan ke atas. Kurang tidak boleh.

2. Saya sedang cuba membaiki crt monitor jenama dell 17 inci.Problem dia No Display,Ticking Noise sometime like chirping noise di bahagian primary power supply semasa saya switch on.Untuk pengetahuan saudara Justine api dibahagian heater menyala.Saya harap saudara Justine sudi membantu saya dengan memberikan tips untuk mengatasi masalah ini.

Kemungkinan, internal capacitor shorted;






hi jestine , this is saiprasad koli

i have ordered for blue ring tester and i have received it

i go to the website o f assemble and user manual

but there is not given any information about how to use it on smps trns, flyback trns

please provide me full details about how to use it

thanking you

saiprasad koli


HI Koli,

The manual did not mention about testing smps and flyback. Please visit this link on how to test flyback transformer primary winding:

As for testing the primary winding of smps what you need to do is to locate the positive pin of the big filter capacitor and follow the track to see it reach to which pin of the transformer. Then follow the middle pin (drain pin) of power fet till it reach the transformer pin. Both the pins are the primary winding.





Hi Jestine,

I enjoyed reading your book and the free reports.
I have learned a lot more about testing electronic parts.
Keep up the good work.






 This monitor already repaired by me about three weeks ago, the problem is both left and right side are waving and if  I beat lightly the cover it came back to normal. It was dry joint problem. 

Now the owner brought it back to me as there is likely another dry joint problem. I searched for the dry joint for 4 hours including on the CRT board, resoldering but the problem remains. Finally, I try to beat the FBT and found that when I beat it, the display sometimes becomes blank ( entirely black with shadow ) and beat it again, the display comes back to normal. I’ve checked all the solder joint should all be OK.  

Now the question is whether inside the FBT has a problem similar to a dry joint problem? What is the actual problem inside the FBT? Have you ever found this kind of a problem. Do you think we could open the FBT to cure it?

I have not seen such problem before. It could be intermittent winding short internally. Before that, try use magnifying glass to see if there is any hairline crack surrounding the flyback area especially the circuit track. By the way, the flyback can’t be opened to repair because it is sealed with epoxy.





What Digital capacitance meter would you recommend I get that would test
without removing caps and has a large range and is good quality?




HI Mel,
Digital capacitance meter usually can’t test caps on board. As far as i know, only ESR meter that can check capacitor on board (only electrolytic capacitor). For more information you can visit the BLUE ESR meter site. If you have other question please do email me again. By the way please check on this quality and expensive test gear:







In my openion, one of the important cause of defecting electronic components in circuit boards is excess temperature.

what is your openion?

Yes, like lcd monitors, there are lots of e-caps problem due to heat.

i work in an industrial corporation as an electronic technician.
In this environment, when temperature increase or decrease very much (also in machines housing,electrical cabin), operation of machines become abnormal and marvelous.
i want to know that what happen on performance of electronic components when temperature
become very low or very high.
(in other words, what affect does temperature(very high and very low) have on performance of electronic components
such as mosfet,transistor,triac and etc?

The effect is that it will shortened the life of the components. Try install AC fan and make sure the environment is not hot.







HI Joey,

Good morning Mr. Jestine Yong, I am very much interested in doing repair works on my own. I have here two 15 inch crt monitor. The first one is samsung crt color monitor with power but no display and the other one is AOC crt monitor but with yellowish display and when it gets hot it turn off by itself. I want to do DIY repair on these two monitor but I have no idea on where to start. I have a zero knowledge in doing repair works on crt monitor. I just wonder if you could give me a guide on how to repair a crt color monitor. I know this is wild shot considering that you are selling your book.  But I’m appealing to your generous heart to provide me a step by step guide on “How to repair a crt monitor”. Your help Sir is deeply appreciated.

If you are good in Testing electronic components and know the safety about the danger of electricity then you can proceed to troubleshoot the monitor. Monitor with power but no display, you may need to check if there is supply voltage (B+ voltage) to the flyback and also there must be a horizontal pulse present in the base of the HOT. As for the yellowish problem, you may need to check the crt board for dry joints and make sure the vga cable is good. I suggest that you visit this link for more information:

Have a good day!





sir,good afternoon,i already repair the viewsonic lcd monitor sir,sir i ask you a question ,the tv i repair have problem in the display,ther is a interference in the display sir,when i switch to video there is also,the display is not clean,there is a small interference sir,what can i do sir,to solve this kind of problem,what do you call this interference in the display sir?thanks,,,,god bless.


HI Roger,

Try check all the filter cap in the power supply secondary side. Sometimes a failure in the big capacitor in the primary side could cause interference in the display.





HI Abbas,

1- What is the Technical and Common name of the Cable?

Usually we just refer it as as VGA cable and it is not easy to get from the market. What market is selling is the cable (without the connector, connector (female and male pin) and the whole cable that already have connectors at both sides.

That means once you got the above cable you need to cut and modify it.





HI Rich,

Thank you for the reply. How often do you replace the backlights in monitors?

Not very often because a good backlight can usually last for more than 50,000 hours.

The ones in the Phillips LCD monitors are real fragile and I checked CCFL warehouse for replacements and I find it hard to find the right ones. let me know if you have a tip on sliding the the lamps out without causing any damage. Thank you for your time.

In certain cases if i could not pull out the backlight (afraid the tcp package broken) i would just cut off or bend the casing  so that i could pull out the backlight without damaging the panel. After replacement i would slide in thick rubber to seal/cover it.





Justine good day,


wow very nice article,,


please help me about resistor…


i have 5 band resistors and i have a very hard time to got a same resistor here in phils,

can i make replacement of it? should i use 4 band resistor?

also its wattage, the old resistor is only 1/8 watts


the 4 bands was in 1/4 watts..what will happen if i use 1/4 watts?


thank you very much,




Hi Carmelito,

As long as the value is the same and the watt is slightly higher than original, it should work. Yes you can use a 4 color band resistor.







  1. Russ

    July 11, 2010 at 9:29 pm


    I saw this web page on repairing the tape carrier package on LCD monitors using a heat gun and I thought I would pass it on to you if you had not already seen it. When you suspect a problem with the TCP heat it slowly with a heat gun and use a pencil eraser to press down on TCP and hopefully repair the problem. This was done on a cell phone LCD but applies to most LCD screens. Here is the link.

  2. admin

    July 13, 2010 at 10:03 am

    HI Russ,

    Thanks for the link and it was very informative.


  3. jun sanchez

    July 15, 2010 at 9:51 pm


    just finish my scr tester..i can easily find ways scr which are deffective...thans .

    jun sanchez
    baguio city ,philippines

  4. admin

    July 15, 2010 at 10:26 pm

    HI Jun,

    You are welcome and congratulation!



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