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Electronic Repair Questions/Answers and Testimonials- Part 37

By on August 8, 2009

Hi Jestine
Yes i have downloaded the free report and have purchased your e-book, “how to test electronic components”. After one day i have successfully fixed a samsung tv/vcr combo, the hot was shorted.  The book has paid for itself already,i’m fairly new to electronics and your book shows clear instructions on how to test components.
Many Thanks
Ray  U.K.



Thanks sir!, for the updates, especialy the v0ltage check secti0ns it realy helps me alot. I have a l0t of friends here in the Philippines who are also getting consumer electr0nics repair. Back here in the in my c0untry the government offers free trainings in these field. But still I realy find it usefull that the inf0rmati0n that your sharing are advance and some of it are difficult to find in other ebooks. N0w sir I’m enc0uraging my friends and collegues to visit and subscribe to ur site. Again thanks and More power to you & your family. .






Hi Jestine, great newsletter articles.You are doing a great job all around.
Learned a lot from you.
Thanks Jay




Dear Jestine;

it is a long time you hear from me. I was sick.But nouw i am better.
I have down load your book. Thans you. It is very interesting.
I promised you that i will never share;sell or what ever do with the book.

I have some questions. Maby youi can help me with them.

What is de different between COLD en HOT
How must i test a component in the HOT an in the COLD area.
Where must i point mine – probe of my meter.
Thank yopu and see your answer forward.


HI Girja,

Hot refer to the primary side ground while cold to the secondary side ground. When you want to test voltage in the primary side then the black probe put to HOT ground and when you want to test voltage at secondary side then put the black probe to cold ground.





Hi Jestine Yong,


Good Day !


Thank you for the reply.This is mean I must get the oscilloscope then only I can measure the Vp-p.Is it by using other measurement such as digital multimeter not allow me to get Vp-p measurement done ?


Thank you for the kind assistance.





Hi Izzrul,
If the meter (scope meter) have this function then you can use it to check the Vp-p.






Your Name: John Raffaele
Message: Hello,

Im looking for some input, I have a 20″ Dell LCD Ultra sharp monitor, after powering it on a few seconds later half of the display goes out, so you only see half the screen, if you cycle the power by turning it off and on it will come back but then do the same, half blank. what do you think?

Thank you for your input


HI John,

If all the output voltages is stable and good then suspect a bad lcd panel as i have come across this kind of problem.





Respective Sir,

This is DEEPAK MISHRA from India. Sir there was an ATX SMPS in which fan & filter capacitors was bad. I replaced all bad capacitors but the matter of sadness that power supply turns on for a while & gets off. Now what should I check in this power supply. thanks for your co-operation what I got so far.


Best regards
DEEPAK MISHRA Date 26-07-2009


HI deepak,

This is the most difficult symptom to repair because it can be any bad components in the power supply that cause power to turn on for a while and off. Check the all primary side components and if all tested okay then direct replace the Pwm IC in the secondary and retest again.





Hello  Sir Jestine,

Sir I like to know how to use or control the HOT AIR or what range we select to the HEATER and AIR if we can heat the dry joints.

Thanks, Sio


HI Sio,

For me hot air  i usually set to 450 celcius and the air it depends on what components you want to work at. To reflow set to the lowest air, to remove smd components set to 5 or 6.







HI Wael,

hi  jestine  how are  you

I’m fine thank you.

i have   lcd monitor  acer 19 nch  the monitor  has  external  power  adapter  as  its  smps  it  works  fine  but,…..some  times  its  turn off     all  of  sudden  the  monitors  screen  is  black  the monitors  led is black  the only  thing  that is  indicating   life  is  that the  led of  the  adapter  is  still  green  glowing  so  when you  remove  the  adapter  from  the  line  and  wait  until  the  adapter  voltage  drop  to  zero  and then  replug the  adapter again the  monitor  works  again  it  stay good  2  or  3  hours then  goes  black  and  each time you have to   unplug  the  power and  and re-plug it  so  the monitor  can work again  what  is the  component  that  fails  after  some time of  work  and  when the  voltage  removed  and then  re-applied  this  component  back to life  again  ????



note   when  the monitor  shuts  down  i  unplug the  adapter  and  measure it  and  find it  19  voltage  as  supposed  the only  thing  still  have not  done is  to measure it  during the  shutdown to  while  it is pluged  in to  see how  much voltage  its  puts put

It could be the adapter,  the inverter board fault or bad lcd lamp. Sometimes an adapter have the right voltage does not mean it is good. You have to test it with full load. Some LCD design is very sensitive as if the incoming voltage from the adapter is not stable enough, the lcd will shutdown.




HI Atif,

dear How r u i hope u will be fine & enjoying new experiments.

Yes i’m fine thank you.

i have a one Q;..?

today one person come in my shop. he have LCD Dell 17 inch.

 the LCD have falt when u on the button LCD.

the LCD blinking the disply …

when i open lcd & check the  components ( parts)

the near inverter a tansistor is damage no is (small C7507)

tell me replacment transistor which one i fixed it i have no transistor this number

There is no good replacement for this part number. The best is to get back the original number which is c5707.







Hi Jestine,

Thank you for your kindness.Now I repaired viewsonice70fsb crt
monitor.I have a problem.No power orange led is flash.7V,12V and 50V
are not functioning from secondary output of SMPS.Income the video
signal SMPS is working?STR-G5643B is drive the SMPS.I have no data of
this ic.How to repair this problem.Please suggest me.


Hi Win,

Since there is no output voltage i guess you need to test out all components in the primary side. And if possible try replace the power IC and retest the set again.







Hello my boss, i am repairing a CLATRONIC DVD PLAYER the power is not coming on, i checked the parts i notice the two transistors are not good i replaced them with new ones, the original part is E13005 the new too E13005 but still the power is not on, i checked the diodes,resistors,capacitors, they seem ok please i want advices from you hope to hear from you soon, i am gathering money so to buy your LCD manual.


Hi Abdoulie,

I guess you have to test all electronic components in the power side. Sometimes a shorted components in the secondary side could cause no power symptom. If it use the power IC then i guess you may  need to replace the power ic and retest the set again.




Dear Yong,

Thank you very much for interview with STEVE AND DON I found it very helpful and challenging. I am very new to this electronic repair in fact i dont have any hands- on experince have just enrolled with pennfoster college and doing module 2 on basic electronis.
I have been doing satellite installations for 10 years and I realise I have lost so much business by not doing repairs because I referred my customers to repairers.
So as a newcomer how can have a good start?

I stay in botswana in africa next to south africa and looking forward to hearing from you,thank you.

kabelo thedi


Hi Kabelo,

Thanks for your email and as a new comer i suggest that you get this ebook first Once you are good in testing electronic components, you can in fact start to repair electronic equipment. Please visit this link too:






Hi Goodson,

I have with me a Philips monitor which has the problem of the display
jumping I opened it up and on the Inverter Board I saw bulged
capacitors I replaced them with the exact replacement then switched
on, the is no power( The power LED does not come on what could have
been done wrong in the replacement of those bulged capacitors to end
up with now power failure?

Sometimes in electronic repair we could have made more mistakes when troubleshooting them. Check that the cap is not in reverse condition, Make sure all connectors are secured. If possible check that the smps has output voltages. If zero output voltage then i guess you may need to check the components in the primary side.






Ive got a problem with one Acer LCD monitor model AL1717 that has a portion of lines blanked from the right-hand side, top to bottom.

What could be causing this.


Molefi Fume


HI Molefi,

It is lcd panel fault!





Hi Jestine,

Please help to analyze whats going on with the monitor of my friend. It won’t start-up and only a blink of the power indicator was come-up. I already tried to connect the pc in to other monitor and it works normally. What do you think was the problem of my Dell Lcd monitor?


Thanks and Best Regards,



 HI Jeff,

This could suggest electronic faults most probably in the inverter board. I guess you have to remove the cover and test the smps output voltage and make sure it is stable. By the way do you have any experience in electronic repair? If not i suggest that you send to someone that could repair your monitor and the AC current in the Monitor is quite dangerous to work with. Have a good day!




Greetings my friend.Well thanks be to God that you are all fine.Thank you also for doing your best to keep me informed on electronics.I very much appreciate your effort.I really will love to get these books,that is..testing elect.component.. guide for finding burnt resistor value and LCD repair guide…i am not loaded for now so i will settle for the testing electronic component guide..Do you believe in the fact that some people were actually sent from heaven just to put a smile on the faces of others?..If you do,be proud of it cos you are one of them.let rush and process your cash..thank you once again.






Hi Bailing,

About troubleshooting tips from the manual ( no power supply & DPMS failure symptom ), it mentions that I need to measure the IC601 pin 1 whether the waveform is right or not and I am very eager to do it as I have the scope. But to be frank, I still lack the experience to use it and am very afraid to ruin it. From the wikipedia, I find the relation between the peak to peak and rms value is: Vpp is about 2.8 times the rms value.

But from the attachment you could see in the scope figures of the manual, it is written CH1 P-P = 100 V   CH1 RMS = 350.2 V. Why is it not correspond with the above formula? ( 100V not= 2.8x 350.2V )

I’m not really sure about this as i do not have scope like yours that could test the RMS value. What i usually check is the shape of the waveform and the peak to peak voltage. Any changes in these two could lead you to conclude that the signal have problem.

Another question is about using an external regulated power supply to find shorted components in repairing any electronic equipment. Using my DIY external power supply, which doesn’t have short-circuit protection mechanism, it often blows the power supply fuse. Do the built-up external regulated power supplies ( like the one you use for troubleshooting ) have this kind of short-circuit protection so the circuit under inspection won’t blow the external power supply fuse?

Yes it has the short circuit protection feature.

Or do you have simple circuit diagram to add this protection function to my DIY power supply?

Sorry Bailing, i do not have.

Have a great and wonderful day.

Same to you






         Jestine Yong

Plz help me on the topic of transistor as working ? principal ? diagrames ? and ETC ?

and also help MOSFET DMOSFET EMOSFET and related devices ?


HI Falak,

Sorry i do not have all these theory explanation. Try search from google or find from electronics books and you will get lots of answer there.



HI Tarcisio,

Hello friend you know some tester components
coil and transformer tester

tester CCFL lamps

tester SMD components

tester C.I scale and MCU

No information.





HI George,

Good day to you, sir! We have a problem here on ship regarding the two lcd monitors which is just near from each other.Those two lcd monitors are just connected parallel form different means two cpu but 4 monitors. The two lcd monitors that are just near with each other are turning black or with out picture for about a few milliseconds.This is because the ship goes big lean from left side only. I checked the supply if the voltage drops at the time it turns black but their is no change in voltage. And also the the led of the lcd monitor is ot interupted when the problem occured.What do you think is the problem?

Is it the signal interference of the one lcd that caused the other one to turn black at the same time?How can i trouble shoot it?Its giving me a head ache…and also the cables that comes from the cpu are tied with each other.Will it matter if i isolate the two cables from each other so that the other one will not be affected by the blackening of screen?Any of your reply is important to me…Thanks!More Wisdom!

Sharing a signal without a booster could weaken the signal from the Cpu  to the Monitor. I suggest that you test one by one until you can confirm in fact is the Monitor fault. With this way at least you can put your concentration on the Monitor instead of checking the CPU, Signal cable and etc.

If you have confirm is the Monitor problem then check on the backlight and the inverter board especially the high voltage transformer for any dry joints. Check also the filter cap at the SMPS side.




Your Name: Russell
Message: I am working on a personal project, I have a 300kV stun gun that I am trying to reduce to 10%(30kV). Once I get it down to 30kV the device can be used as part of a different project. My problem is that I’m not to sure about the resistor size that would be sufficient. I tried one resistor(100k-Ohm, 1/4 watt, 5%) but it proved to have to much resistance and the item would not operate.

Stun gun – 300kV

Projected Value – 30kV

Resistor – ???


Hi Russell,

Sorry no clue about this type of circuit. I guess you may need few more different type of resistor value to test it out.




HI John,

For quite a time now I have been reading your news letters to me which I have found very informative and intresting for a technician who wants to be serious with his work as a servce to people and a source of income.Am in the process of openning my own companey which will offer repair service in electronics equipment.

Congratulation! and wishing you good business.

The reasion am writing is to request you to be my backup technician incase i need any technical advice.

If you have any repair question you can email me.

and also to help me with a list of the most important tool that i neen to buy and where i can order them from.

What are the tools and meters do you need?

Also give me some advice on how to open up this workshp and how you would like our relasinship to be.
hoping for your reply on this.

This is a big subject as the longer you run your business the more you will learn how to operate your business efficiently. Always start from small first and if opportunity comes you then can hire more staff. Always also keep track of your daily expenses.




HI Noraimi,

hi jestine…!

saya telah membeli buku ebook daripada anda dan ia amat bermakna buat saya..

Terima kasih

sy ingin sedikit kepastian….sebelum ini saya telah banyak melihat di kedai kedai repair tv dan monitor….., kebanyakannya hanya menggunakan 2 atau 3 jenis alat utk mengesan kerosakan iaitu analog multimeter dan digital multimeter, dan capacitor meter.  malahan mereka juga berjaya mengesan kerosakan dan membaiki tv tersebut.

Ya memang betul tapi kemungkinan mereka mengambil masa yg lama untuk repair peralatan tersebut.

berbeza dengan banyak jenis tester yg digunakan di dalam ebook utk mengesan kerosakan. antaranya isolation tester, analog multimeter, digital multimeter, sencore LC103, capanalyzer 88a, capasitor meter.

apa yang sy ingin tahu….apakah alat yang paling asas yang perlu ada dalam mengesan kerosakan..?  adakah memang kita perlu ada kesemua jenis tester di atas atau 2 jenis seperti yang digunakan kebanyakan repairer sudah mencukupi..?

Yg biasa saya gunakan adalah

atau anda ada cadangan yang terbaik jenis alat tester yang paling sesuai digunakan bagi orang yang baru menceburkan diri dalam bidang ini seperti saya….

analog meter
digital meter
digital capacitance meter
BLUE ESR meter
Blue Ring Tester

jika perlu semua semuanya… saya ingin tahu adakah anda menjual  :

a) digital multimeter (autoranging) seperti didalam ebook- saya tidak menjual analog/digital meter kerana anda senang mendapatkan meter tersebut dari kedai elektronik.

b) sencore LC103- Tidak perlu beli kerana terlalu mahal-hampir RM10,000
c) capanalyzer 88a- Fungsi adalah sama dgn Blue ESR Meter malahan Blue ESR meter lebih murah dan canggih
d) isolation tester- Tidak jual tapi anda boleh dapatkannya kat kedai elektronik

Sila baca article saya tentang Blue ESR meter kat

jika ada….berapa harganya dan cara pembelianya..?

Harga BLUE ESR meter adalah RM430.00 dan Blue Ring Tester adalah RM330.00. Harga sudah termasuk kos penghantaran

maaf kerana terlalu banyak bertanya dan terima kasih…!

No problem!








recently i open samsung satelit reciever for not so good reception problem

i was checking the power supply section if there is any problem?

good no sign of fet and ic control  is just a 4 legs ic  1L0380R  and on the board is written

for each leg G D V FB . please tell me how can i test these kind of ic if there is any way?

thank you in advance




Hi Beh,

If the output voltages are good then don’t check the power supply. If it has problem then concentrate on this area like replacing the power IC and retest the set again. G is ground, D is Drain, V is supply voltage and FB is feedback from optoisolator ic. If you have a scope you can turn on the equipment and test for the signal output at G pin. It should have a pulse waveform. No waveform means the IC or corresponding components have problem. Hope this helps!





Hi Jestine,


The complaint for this monitor is NO Power. Actually the Power LED blink for less than a second (red color) a few seconds after being switched ON. After that, nothing happening (as if NO Power). Checked on the secondary voltage, all voltages were present (89V, 55V, 7V, 16V) but 5V to micro-p & eeprom was low. Initially when switched ON, the 5V measured highest about 3~4V (not very clear ‘cos too fast, even using analog meter) then drop to 1~2 V). Have removed the B+ coil and installed a light bulb but still no changes.


Seeking your expect advice on how to effectively troubleshoot this problem.


Thank you.


Best Regards,

C. Tieng.


Hi C.T,

Try unsolder the CPU and the EEPROM ic supply leg and recheck the voltage again?





Hello Sir Jestine,



Thank you for your untiring effort of sending me informative informations concerning television repairing.

I wish you good health so you could continue help us by giving hints of tv repairing.


thank you & God bless.






Hi John,

Many thanks for your help. Hope you are o.k and family too!!!!

We are ok here thanks!

It has been raining here. Weather is fine that is not cold at all.

Weather here as usual very hot and haze!

I undone the suction cap no happening there. I tried to earth it nothing at all.
I found an area burned like colour. Soldered the transistor 3 legged thing no luck
Even though, the fly back transformer is gone, I would not be able to find spare parts for it. It is going to cost money.
I checked all the fuses, they are o.k.
The television is so dusty inside.
Do you think getting rid of the dust will prolong the t.v set. Is that right.


People who smoke easily damage the t.v with nicotine. Is that right.

Sorry no proof on that

Anyway, I have dumped the t.v to the skip plus a monitor.
It will take so much time to find out the fault.
I do not why you are so good at electronic. It is not an easy subject to master.

First learn how to test electronic components and then build lots of project kits and then practice more on junk electronic board. Visit forum, read more books on electronic repair.

Regarding my portable t.v set which I told it was making a cracking noise. Actually, the fault came from video recorder nothing to do with the portable t.v. So it is working o.k now. I have even restored the colour back from the video.

That’s good!

Is it possible to learn a portable t.v.

You can try

Maybe, try to look inside all the components.
Assemble and disassemble electronic component. If I know how to test components, it will be good.

Yes it is a must to lean how to test electronic components

I did at one time try to repair a portable t.v. no picture and sound but no luck at all.

Is there any output voltage from the smps?







Hi Jestine
Thanks for your newsletter, brother can you tell me how can I solder or desolder double side design pcb board. which equipment i can use.



HI Sohel,

Use this equipment:





You are such a good person it’s hard to find a person like you in the Usa, it’s such a rat race.God be you.I told my wife that this person is really a nice person he ‘s thousands a miles away and he will respond to me, I said to my wife that he works hard for what he has, I’m really proud of you!

You don’t have to resond back just remember what I said that will be find,

Thanks Jay






  1. zeb

    October 10, 2009 at 8:20 am

    Mr. Jestine i am very grateful for all you have done for me atleast the newsletter i discover you are good how i wish i am in your country. but that not withstanding i will make sure i published your name to announce your existence on this earth in fact you been of help to me.
    thanks as make you known to my home country believing one day we shall face-to-face.

  2. admin

    October 10, 2009 at 11:42 am

    Hi Zeb,

    Thanks for the compliment!


  3. raf

    February 17, 2011 at 12:51 pm

    i just want to know. After 5 - 10 minute i switched on my Tv,power supply gone. i tried to Off and on again,same problem. After sw Off for long time,the power came.and same happen like begining. why it happen?


  4. admin

    February 18, 2011 at 8:53 am

    Hi Raf,

    I suggest that you visit the link below to isolate where the problem is:



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