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Electronic Repair Questions/Answers And Testimonials -Part 24

By on December 8, 2008

WOW, really fantastic book. I started to read the lcd repair book and the bonus reports and wow, they are fantastic. very simple yet full with a lot of rich information. No regrets, on the countrary, I need to buy more of your books. thanks Jestine, for taking the time to educate us in this way, May the Lord bless you fully and richly.




Dear Mr.Jestine Yong.

yes i have read your report and your book.i would say that you have done a great work for the development for people who are in need of it. it is a great book with many repair techniques.



greetins my friend. I am still reading your ebooks and loving every minute of it. I printed all the books and having them as a refrence in my workshop. thanks again



Hi, Jestine, I have received your email as regard samsung 153v LCD monitor’s part 4532m. Unfortunately, The client has rejected repair. Anyway, thanks for your help. I have repairing one BENQ FP71G+ LCD Monitor. The Symptom is Power off once switch on a second, power led just on a second then off. Troubleshoot power boad discover P7NK80ZFP short,

Fuse open and filter capacitor 100UF 450V  no capacitance. Replaced all and switched on, The problem still the same.Check surround the capacitor 100uf and 470uf are ok. Replaced 1200AP40 still no used. I suspect the voltage regulator IC701 fault but the part number hardly see, I search the net saying can use L1117-3.3 substitute, But this part no selling in shop. Any other part number can be used for it, Please tell me.

First you need to get a steady output voltage. Did you get the steady output at the secondary side?




First of all i would like to say thanks for all the newsletters you keep sending me every month Its very interesting.

You are welcome!

Sir i have a question regarding LCD Monitor repair i have here a Benq model Q7C3 with inverter board problem shorted c5707,stD10PF06 also shorted and fuse blown on b+ line the fuse rating is bel MS 3a what kind of fuse is this?

About the fuse you can view here

Can i replace small 3a glass fuse?

Yes you can

and what is the replacement of stD10PF06 P- ch.


I cant Find this parts here in my place.

Try email luca lavinci at

Best regards,
Jestine Yong






Hi Z,
Her108 should be okay  but HER503 is too big in physical size. UF4007 can also be use to substitute-no problem!



How do you test these transistors that have the center pin clipped off of
it? What are they called? Is it a transistor? If I buy them online will they
come with all 3 pins and I should clip off the center pin?


I thougt transisters had a base, collector and emmiter.


Hi D,

Infact that is a transistor and the metal attached to the board have connection to the center pin. Placing the probe to center pin or the metal casing is the same. In other word, the metal part is the collector. If you would like ot order online you have to email the owner first of which type you will be getting. Hope this helps!









Hi A.G,

If you get correct output voltages from the power supply and the display is white then possible the lcd panel have problem. Before that pls check on the connection cable between the mainboard and the lcd controller board.




Hi Mr.Jestine

I have monitor philips 15”. it is failure in horizontal driver. I am looking for a replacement transistor for a BSN254A N channel FET. in my place not for sale for this transistor.Can you help since I cannot find an equivalent


sebelumnya saya ucapkan terima kasih untuk semua newslatersnya. semoga mr. jestine terus berjaya.


Hi E,

Sorry i don’t have information for this transistor too. But i have seen two fet part number that were use as horizontal driver transistor. the part number are 2n7000 AND K941. Hope this helps!

sebelumnya saya ucapkan terima kasih untuk semua newslatersnya. semoga mr. jestine terus berjaya.



Yes, thanks a bunch. You’re an enormous help to me…..





I have a fairly new Samsung 2493HM 24in LCD that powers completely off for no reason. You can turn it right back on and it will stay on for hours again. Any idea what I should look for that would cause this? It powers down completely just like you turned it off. No power light. You touch the power light and it fires right up to a big beautiful display and runs again for hours. I just spent 210 bucks for it and don’t even know where to start to find this issue. I thought it powered off all the time when I bought it but every 2 to 4 hours sounds hard to diagnose.



Hi D,

If the power off and there is still have supply going into the mainboard then chances is high the mcu have problem. If the power off with no output supply then check the primary side for dry joints, bad high ohm resistor and even a bad power IC.

Best regards,



Hi Jestine, my passion is to gain indeepth knowledge about electronics
repairing especially on this new tech LCD monitor and to acquire more experience regarding troubleshooting techniques through access to your web site. This web site is really very informative, and asking within myself why only just now that i’ve came accross to it. Anyway it’s never too late??? yah







Can I still use an analogue DC power supply ( 0 -30V, 5A ) for testing

for defectice ICs on the motherboards.





Hi Simon,
You can only supply the voltage to the ic and you also need a scope to test the input and output waveform.




Hi Mr. J. Yong
I have studied electronics and currently repairing electronic devices, and I am
very interested in your book. To further my knowlegde I would like to know if I would
need practical training after reading your book or is just reading the book sufficient
enough to carry out complicated repairs.
Best Regards
A K.
Hi A.K,
 My ebook is the starting point to learn electronic repair. It teaches you on how to
accurately test electronic components. Once you are strong in testing electronic components
you can actually start to repair any electronic equipment. Lets say you want to be a
professional in tv repair what you need to do is to get my ebook and buy another book in
tv repair. With these two combination of information plus some practical you will be good
in electronic repair. Hope this helps! If you have any other questions please do email me
again. Have a good day!


Hi A,

Here are your questions and answers:

hello sir how r u sir i have a IBM E50 color monitor.complaint of the
monitor is horizontal rolling in dos mode.and its working fine in
windows.and width also reduced in windows mode.sir pls suggest me to
rectify this complaint.

It seems that the cpu have problem. check that it has 5 volt input and crystal show a sinewave.

and i have another monitor of same type with
different complaint there is no display only plain white raster while
connected to CPU.

Make sure all the RGB,G1 and G2 is at correct voltage. you can measure the voltages at the CRT board. If you are not sure about the voltage, you can compare with other monitors.


Hi J,

Here are your questions and answers:

No problem but i want to know the exact price of your book in INR

It is 1840 INR for the Testing Electronic Components Ebook.

and in how many days i could get that book here.

It is an ebook thus no physical book will be ship to you. That means once you have made the payment you will get the download link and you can print it out and read.

Do you conduct any workshops here in INDIA.

No sorry, i only conduct courses for the local

Have a great day!

Best regards,
Jestine Yong


Hi Sir Yong,


Sir thank you for emailing me last time and sharing your inspirational experiences. I just started studying electronics last October 16, 2008 and I really find it very interesting and it will be more fun if my teacher will not just focus on theory. Right now, I am working with my am radio project, unfortunately, it is not working. So sad. I have problem identifying the emitter, collector and base of a bipolar transistor. Sir I would like to ask some help of how I can easily identify the collector, emitter and base of any transistor.


Sir Yong thank you very much.




Hi J,

The fastest way to identify the pins is with the help of data book. Search engine like google could also point to you websites that have many datasheet for transistor. in google just type in your transistor part number followed by these words:

data sheet
part number

Hope this helps!



Hi Jean,


Thank you for the link below,

No problem!


The repair center should be able to repair consumers’ equipments (TV, LCD TV, etc…) but also it will be focusing the most on repairing all IT related equipments (Power supply, LCD Monitors, Printers, MBs etc…) Are there any best practices or advices of how to build such repair center and how to run it?

Take a look at these photos for some ideas:

what to avoid or is mandatory to exist?

Backlog-always call customers to get back their machine.

Tell customers the price of repair first to avoid argument later

Hire good and dedicated repair staff

Have a good technical software to track customers record

Good working environment

Constantly get new customers

Have some commonly used spare parts

Don’t give up and many more!


I’ve read your comments on this business and now I know that customers relationship is a must. My friend is very good in this, in fact he started to get clients now 🙂

That was a good news! Without clients nothing can happen in a company!


And the books you suggested, we already read some



Best regards,
Jestine Yong



Hi Chester,


Here are your questions and answers:

The problem I have with the TV is No Power.

1. Stand By LED Blinking Three Blinks No Power Intermittent.

2. Stand By LED Blinking Three Blinks No Power Intermittent.

3. Stand By LED Blinking Two Blinks No Power Intermittent.

4. Stand By LED Blinking Four Blinks No Power Intermittent.

5. Stand By LED Blinking Two Blinks No Power Intermittent.


I will like to know if you can help me solve this problem.

If you have a good and stable output voltages from the smps then the blinking LED (the LED signal come from CPU) could indicate failure in CPU and related circuit like a bad eeprom data.


If all the output voltages fluctuate then this could mean a primary side components have problem or a shorted component (like a shorted HOT) in the secondary side.

To isolate this problem i suggest that you visit this link:

Hope this helps!

Best regards,



Hi Irvin,

I am glad that i always a newsletter from your electronics guide website, It helps me a lot and looking forward to receive more for newbie like me in electronics repair world.

You are welcome!

Right now…I’m having this problem solving a 15inches Vista 58E color monitor. These are the common problems I found on VISTA monitor:

* pink screen display – video cable are OK.

Check that all the three RGB transistors have the same voltage, check for dry joints and direct replace the color ic and retest again.

* blurred screen display – even i already adjusted the “screen” on the flyback. it wont work.

It is a flyback problem. Replace with a monitor blur buster or with a new flyback

Best regards,



Hi Sir,

How are you,Thanks for your earlier reply.One more clarification I required from you.

We are servicing  SMPS, which gives +3.3V.8A,+5V.12A,+12V.1.5A.,-12V.0.3A and +5Vsb.0.8A out put. This SMPS is having option of  230V or 115V AC input.

In this SMPS  circuit Fuse,MOV and FPS gone bad .FPS is burnt only …65R can be read. Can you please give the reason for failure  and which FPS can be used.




Hi M.A.N,

This is my first time of hearing such short form-usually we refer it as power IC. In your case why it blow, there are few causes:

1)Other bad components caused it to blow and a too high surge.

You have to get back the same part number if possible. its a bit difficult to find equivalent for power IC.

Best regards,
Jestine Yong


hi Jestine,
my friend’s projection tv was hit by high voltage and a technician told him that the lamp driver is bad. I would like to purchase it. Can you shed some light on the diagnosis. The tv won’t power up. It did so once after the surge and shut down.Thanks Jestine


Hi Allan,


As for the power shutdown problem, once it had shut down did the power LED lit or not? If it lit, then make sure the output voltages from the SMPS is good, if it too high it will shutdown, Sometimes a shorted components in the secondary side may also cause the power to shut down too. Since the set been hit by high voltage chances is very high the problem would be in the primary side and you need to test out all components in this section. Hope this helps!

Best regards,
Jestine Yong


Hi Danny,

That’s going to be a tough one with my inexperience. I also have an older inverter and testing the zener with markings of T2X B 3V3 that has reading of Positive to cathode shows 1 ohms and Negative to cathode shows 3.5 ohms. Reading your book on testing components I could decide if this was ok, you said 0 ohms one way and 2 to 4 ohms the other way this one is close. Seems to me it pretty much shows the same in both directions. I know this one is 3.3 volt, don’t know what t2x B means.


Normally for a low voltage the reading would be very close. If you suspect it has problem you can always compare with a good one. The t2xb does not mean anything to me. The most important one would be the voltage and the watt


The other by it reads A1 II. Doesn’t tell me much but it reads 60 ohms Negative probe to cathode and 1 ohm when reversed with positive probe to cathode. Could you give me some idea of what Im seeing?


I’m not sure about this unless it is a 11 volt. If it is a 11 volt zener diode then this diode have problem. Again you can compare the resistance of a new 11 volt to see the reading should have.


Also I have an Atlas DCA tester, would this tell me if the diodes were bad?


I don’t think atlas could check zener diode.


Or what would I look for to determine if its leaking or bad, the forward voltage reading? It analyses the diodes and does not read say they are bad.


Normally zener diode only develops short and open circuit. If it leak then you have to build this tester to check it out at:



You are welcome!



Thank you Justine,


Your insights are very valuable, we highly appreciate this.


I started to work on the list of test equipments, but I think we can start with minimum needed,


Attached is the list, I suppose should be sufficient,


Please advice, from your experience, what is mandatory and what can wait?


Thank you and kind regards,




Hi J.H,

Here are your answers:

  Ammeters-Many digital multimeters already have the ac/dc ammeter
  Cable Testers- Not necessary as you can test the cable with your ohmmeter or continuity tester
  Capacitance Meters-Yes you need this
  Continuity Testers-Already built into digital multimeter
  Datacom/Telecom Test Equipment-It depends on the field you want to repair.
  Device Programmers & UV Erasers-
It depends on the field you want to repair
  Function Generators-
It depends on the field you want to repair
  Miscellaneous Test Equipment-Yes you need an analog/digital multimeter
  Multifunction Counters
-It depends on the field you want to repair
  Parts Testers- If you refer to Atlas peak electronic tester then Yes.
  Prototyping Equipment-
It depends on the field you want to repair
  Test Clips- Yes if you do lots of motherboard troubleshooting
  Test Equipment Accessories-Not necessary
  Test Leads-All new meters comes with test leads
  Thermometers It depends on the field you want to repair

Hope this helps!

Best regards,





I pulled that beautiful 24″ Samsung apart and looking for anything that would cause the power off after 2 to 4 hours. I noticed the big transformer stinks. Does not really smell burned but close to it. You think that could be going bad? The thing about this one is that you can power it right back on immediately after it turns off and it will stay on for hours again.


Well I got 7 out of 8 lights on my ring tester so it appears to be good, is it normal for the big transformer to smell almost burned?

Hi D,

It could a weak backlight problem. Some transformer may have that kind of smell but they are good.  If the shutdown happen and you got all the good output voltages then it may not be the transformer.

By the way wishing you a Happy Thanks Giving Day!

Best Regards,

Jestine Yong


Dear Sir, I visited your website and I am very much impressed about the practical training offered by you to your student. There are many who are interested in North East India. Is it possible for you to tie up with some institute in Guwahati, ASSAM like IIHT or others so that student from North East India can benefit from such training. Thanking you,



Hi H.W,

Thanks for your suggestion but at current moment i’m not ready for that as i have local market to be covered too. Have a good day!

Best regards,
Jestine Yong


Hi G,

Here are your questions and answers:

I just wanna  ask if you a any other solution when it comes to blurred problem n CRT monitor  considering that the flyback and picture tubes is good.,

Normally a blur problem is cause by either bad flyback or bad crt. Sometimes a weak heater voltage could cause the display to look blurred too.

and is there a posibilty that we can repair the flyback transformer and CRT?

If a bad flyback transformer (for 14 and 15″) you can add in a monitor blur buster.

For a crt the best is to replace with a good one.

By the way I’ve already bought your LCD monitor repair ebook..I gained additional knowledge about ur book specially modifying the feedback cicuit..Tnx a lot.

You are welcome and glad that you liked the ebook in LCD Monitor Repair.

Best regards,


Nice to hear that you are on your holiday with your family & your wife family members to Port Dickson. Have a nice holiday.

Thank you.


I heard you are bringing along few RC helicopters (Micro 3-channels and E sky dauphin 4 channels helicopter) too. That’s great. To me after a hard tiring working days, that is the best hobby to release the tensions other than singing & etc.. Am I right?

Yes playing RC helicopter even in the room also consider very fun already. This is one of my destress tool beside fishing.


Anyway how much is the cost of these 2 types of RC helicopters. The other day I can’t find it near Jalan Chow Kit. So I plan to buy one from you. Which type do you recommend? I ask this, coz you are more familiar after flew them for these while.


The four channels (for beginners) one you can buy it online at while the small one i can help to buy one for you. In fact chow kit has lots of toy shops.

I bought the 4 channels because i can play it at outdoor while the 3 channels are mainly for indoor. It depends on where you want to play it. The 3 channels that i showed at my blog was the most stable one and it cost about RM70.00 each. I may be going to chow kit to buy few more small heli next week and if you are interested i can help to buy one for you.

Best Regards,

Jestine Yong


What happens if you reverse the DC polarity into an LCD display with your
variable power supply? If you put the clips on backwards. Will it burn up
components or just not work?

It depends on the designs

I think I did that. And now I have a micro
controller chip (attached pdf) that gets fire hot when I plug in the regular
external power supply.

Can I replace this chip?

Yes you can but most of the electronic supplier does not sell this kind of chip that have information in it.

The micro controller?

Yes this is a MCU.

Or is this the chip that is
programmed for this model LCD?

Absolutely Yes!

Best regards,


i’m an owner of internet cafe here in marinduque, philippines and i would like to repair on my own the monitors im using.

i have read the report you have given me, but i don’t have much knowledge to do the repairing of my monitors.

thank you very much for the information.

You can visit for more repair information.

the LCD monitors in my shop are HP 1730 models, but when i look at the inverter it is a BENQ model. the common problems of my monitor are no power but when i unplug the ribbon connecting to the panel there is power and standby light on the led, when i place back the ribbon the display is ok. when i turn off the lcd monitor. no pwer asgain.

hope you can help me.


It could be filter capacitor problem as this model is famous for its bad cap. Make sure also the cable between the mainboard and the lcd controller board is secured.



Hi Kelvin,

Here are your questions and answers:I bought your LCD Monitor repair book a couple of months ago and have found it very useful in helping me to repair monitors.

Thanks for your support!

However, I am now a little bit puzzled. I have 2 Benq FP731 monitors which came in with similar problems. On both monitors the Pico fuse had blown but I am concerned that the voltage at the pico fuse is rather high. I am getting a reading of 25 volts DC.

It could be normal as an open fuse means there is no load in it thus the voltage shot up! Have you check the other line voltage to see if it normal or high?

On replacing the pico fuse one monitor immediately blew the fuse again

This indicate something had shorted. Particularly check compare the resistance of the semiconductor between the bottom and the top backlight. Any differences indicates problem in that area.

whilst the other continues to display a green power on light but no display.

Is the inverter IC have any supply voltage?


Hi A,

Here are your questions and answers:hello sir how r is your trip.i hope all are well.

My trip was fantastic!

sir i have ACER AC511 color monitor.whats the problem is when ever i connect VGA cable to CPU there is small hissing sound from monitor and picture is disturbed i.e. thin black horizontal lines appear on display.when i remove VGA cable then there is now sound. please kindly help me,thanking you sir.

Check the big filter capacitor in the primary side of power supply. Sometimes a bad filter capacitor in secondary side also could cause this problem.


Hi, Jestine yong, I have received your LCD REPAIR MONITOR BOOK. It’s very helpful knowledge for my repair career. Thanks god to know u.



I hope you well and in good health. My name is S, and

im from the UK. I am very intrsted in electronics and want to study a
course in Electronics. I have done slot of research on course in the
UK. I havent found anything as good asvwhat your book teaches. I
wanted to ask to you hołd an electronic course in Malaysia. I would
be very intrested in coming over and studying. Please i would
appreciate if you could help me thank you Jestine

I hope to hear from you soon
Kind regards


I very much enjoy getting your news letters. Enjoyed your LCD course. The
best to you over the holliday season! Peter.



Thank you for your repair report , it is very instructive !

best regards,
Liviu V.


Hi K,

Is this a Oscilloscope that I could using for my LCD testing or what? Oscilloscope cost a lot of money. But this one could be my answer if you have that is would be very good or perfect for electric or lcd monitor testing.

In fact you can buy a used unit from ebay or even from your country test equipment shop. It would be an added advantage if you have the scope when comes to troubleshooting electronics

Quick Question,How long to you thing LCD monitors will be Around?

At this moment there is no sign of slowing down in producing LCD Monitor so i guess it would be still around for may years. By the way it takes many years before it go fully obsolete.





  1. Mitch

    December 5, 2010 at 9:39 pm

    Dear justine

    I have a BenQ monitor FP767 17" but power is on (blue light) but display isn't.
    I have seen a very faint picture from the monitor.

    I checked 4 c5705 but they were ok,
    Would you teach what else is to be tested please.

    Thank you so much for the website


  2. admin

    December 6, 2010 at 7:44 am

    Hi Mitch,

    Is there supply a 12 volt supply voltage to the inverter ic?


  3. ANKIT

    January 26, 2011 at 5:40 am

    justine sir
    i had found very useful information on ur site n i had repaired my smps a little bit .... the problem exit right now is that whenever iturn it on it fluctuate the voltage output..i.e 12v fluctuate 11,7,2,12,13 like this it happens with all voltage 3.3,5,12,-5 ..... plz me out to figure out how to solve it but i think its problem in secondary section ihave zebronics 400w desktop smps... plz help me thanks

  4. admin

    January 26, 2011 at 6:19 am

    HI Ankit,

    Make sure you connect the power supply to a load and check that thee is no bad filter cap in the secondary side.


  5. ANKIT

    January 26, 2011 at 6:33 am

    i will defiantly do it n inform u ...

  6. ankit

    March 8, 2011 at 4:16 pm

    jestine sir
    i have a microtek double battery ups... all is going fine charging voltage is fine but when i switch it on its relay start to flicker rapidly i have tested its output during this period by connecting a bulb
    n seen its allso flicker but it goes normal in 5-6 second ... plz help me
    its having ic 339*2 , sg3524n , 4028 n ne555 *4 suject me how can i repair it
    your student

  7. admin

    March 9, 2011 at 11:47 pm

    Hi Ankit,

    I wish to help but since i do not repair UPS thus i could not provide any advice on this matter-sorry.


  8. EPPY

    May 20, 2011 at 3:21 am

    hi justine

    i have dell LCD monitor..have no power...i have check the power board.get the fuse open..capasitor 100uf 450v blow..then i replace the fuse and the capasitor but still the fuse blow....

    then i discover the PZNK80ZFP it that the 3 elemen on PZN readings are O in analog meter?...and buzzing when im using the digital it email me plz...

  9. admin

    May 20, 2011 at 9:51 am

    HI Eppy,
    The power fet and the power ic you need to replace and check all components in the power side. You can try to use 2sk2645 as replacement if you can not get the original power fet.


  10. EPPY

    May 20, 2011 at 9:17 pm

    is it the P&NK80ZFP is the power fet..tq..

  11. admin

    May 23, 2011 at 3:20 am

    Hi Eppy,

    If it is located in the power primary side then it is the power fet.


  12. eppy

    May 27, 2011 at 2:21 am

    dear sir...

    i have replaced the power using 2sk2645...and it really works..the LCD monitor is ok now...thank you very much sir...

  13. Gagan Deep

    September 29, 2011 at 8:07 am

    Hello sir,

    I am pursuing a repairing course and in these days i am on LCD topic. I am glad to see your feedback to all who need to know something. Thanks you have here for us.
    BENQ FP71G Model, Please tell me how can i find the transistor values in inverting section in LCD. like there are 4 NPN power transistors and 2 PNP transistors were there but somebody has removed them before. So if you can send any track or circuit diagrame to my mail.

  14. admin

    September 29, 2011 at 8:37 am

    Hi Gagan,

    Since i do not have the same model with me in my repair workshop thus i can't locate the exact part number and location for you-sorry.


  15. Gagan Deep

    September 30, 2011 at 7:38 am

    Hello sir, This is gagan from india. I got your answer. I agree that you don't have the model in your workshop. But can you tell me please what transistor i can place there in inverting section around the capacitors. Please guide me sir.
    Thanx and regards,
    Gagan Deep

  16. admin

    October 1, 2011 at 2:22 am

    HI Gagan,

    Usually the 4 NPN transistor are C5707 and 2 P channel transistors are FQU11P06 or FU9024N. You need to try it out



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