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Electronic Repair Questions/Answers And Testimonials-Part 20

By on November 2, 2008

Thank you for the online information, I was able to fix my Dell 15″ LCD monitor. My monitor had the same exact issue with a fuse having high resistance and dropping the voltage. I will recommend your website and information to anyone interested. Thanks again!!!




…….Thank you soooo very much for all your efforts in sharing your knowledge
with us technicians. I think of what you do is like a ministry. I mean this
as a sincere compliment.









Hi S,

Here is your questions and answers:

I have the blue ring tester. is it possible to test the small transformers in the inverter in tft monitor?
Yes, it can test only on the secondary side. Normally it will lit 2 to 4 LEDs.

I have a neovo s-19 tft monitor with a problem. The backlight is shutting down. Green led is on, 12 volt stay on inverter IC. I did not found any defect component yet. So i wondered if one of the two transformers have a problem.


Power supply is good ( it use an external good supply).

It could be a bad backlight problem.



Hi R,


Here is your questions and answers:

Few years back I bought a SANWA Multimeter (Japan made), which is powered by only two AA size battery type.

I guess it has the X100k Range


But I remember previous SANWA model are powered by two AA size battery & one 9V battery type, which I suppose is the same as SUNWA Multimeter (Taiwan made).

Yes it has the X10 K ohm range.


Is there any different between thses two types of multimeter when we use it?  I remember in one of your article you mentioned you preferred the second type (which is powered by two AA size battery & one 9V battery) .

Yes the X100k Ohm range can’t be use to trigger the FET under test.



Jestine, I bought your books online and want to tell you I really like them.  I’ve learned a lot………





Hi K,


Here is your questions and answers:

Hello Mr. Yong…I have a RCA HD52W59…I believe it is the Flyback as the fuse keep blowing upon start up…I’m pretty handy would this be a hard job to do my self,

You have to confirm it because sometimes a shorted HOT may cause the fuse to blow too. You need a coil tester to check the winding in the flyback and also the crt yoke coil. Any shorted winding will blow the fuse.

Also is there a prt number I should look for?

The part number is normally printed at the flyback body. Hope this helps!



Hi A,


Here is your questions and answers:


It could be power/inverter board problem or a  bad backlight.


If the problem is in the inverter then you just buy the bad components. If it is one of the bad backlight problem then you can modify it to run on one light instead of two light. This modification need a repair skill and is mention in my ebook at


Different models and inches of lcd monitor have different pricing for the backlight. For your information, i do not sell back light. Try visit to ask for the price of your backlight.

Best Regards,
Jestine Yong


Hi A,


Here is your questions and answers:

thank u very much now i finish from print course .iam not belive that iam get this course because , that day ipay for a programmer for motherbord  since 7 monthes not reach until now.sure u not like them because i see most sites  for u  you are great man .and itrust from the first day.thank again iread little from book  very good explain and easy in the first pages..

Thanks for your compliment and it is sad that there are many scammers nowadays.

iwant to ask about testers  u speak about it  likk esr blue . and flopt for test transformer,

Yes you may visit the link to know more about the tester:

and tht ,. twezers  for smd i see another tester iwant the important  and  iwant to test the piece in board  to safe time,and tell me about them and price .

I don’t sell this tester but you can check out the latest price visiting their website and email them at

is esr blue can test resistence  thank because i found friend in malysia.

Yes it can test resistance from 0.01 ohm to 99 ohm.



Hi K,


Here is your questions and answers:

Sorry just came back from holiday. Here are your questions and answers:

OK I have another question. First I bought the LCD repair ebook last night.

Thanks for your support.

OK,I got a Envision Model #:en-LM:500.
My question :1.Ok ,how to repair this model? screen turns off after 5 minutes)

First make sure there is voltage entering the inverter ic after the monitor turned off. If no voltage then trace back see at where it had lost. If there is voltage then possibility high the back light have problem. Check also for dry joints in the high voltage transformer area.

2. What happens if I come across some LCD monitors that is not in my manual,how would be able to fix it(rpair it)?4. suppose a come across 10 LCD that is not in you manual,Will give help?and show how to fix that model type?

Study my ebook first as most of the lcd monitor problem falls into only few categories like no power, display dim, display shutdown, no display and etc. Once you understand the principles you will know the rest.

So ,lets say there where 15 new LCD model types taht came out this year,and oh course they have problem.Will I be able to get some help from you. will you do what you did in you manual? Can or will I be able to get going help for LCD models and types that are not in your manualand youw will prvide solutions for.(ways to fix them)?I beleive this last equestion with the ongoing help is very very IMPORTANT because there will be much more LCD monitors coming out.

Don’t worry my friend, i will be with you to help guide you to become an expert in lcd monitor repair. Just email me and if possible show me some of the photos and i will show you where to start troubleshoot. Remember to visit my blog to learn more about electronic repair.

Best regards,



Hi Aan,


Here is your questions and answers:

Where do i find Flyback Transformer,MCU (microcontroller) IC ,Eeprom Ic ,the data file for MCU  and  Eeprom for all brand TV,Monitor,LCD if they corrupt.

Normally this kind of files only repair technicians and engineers kept it and seldom share it out.

Could you show me tips and trick for looking from google or show me the website links. and can you show me for complete electronic spare part shop (TV,MONITOR,LCD,etc).

Try visit my blog list for the electronic suppliers:

in the link—The-Easy-Way-To-Repair-It&id=632013
the photo that you mentioned disappear ,could you show me the link so i can see the photo.


Here is the link:

Best Regards,
Jestine Yong


Hi A,

My real passion is also electronics as what you said since i was young im also have an ambition to know how the tiny or little things works in the circuit board its realy interesting to know as of now i have some knowledge about electronics but honestly speaking im still confusing for some other components like ic’s or chips and other components also the optoisolator  and  PWM ic.
as of now im encounter a problem with our UPS the actual trouble is when it is on the ac power its working and the output is normal but when the power ac is cut off suddenly no output voltage ussually its hold atleast 20 mins or less but the problem is no hold the voltage im suspecting the battery may be its dead but whrn i checked them they are still good and the voltage is normal  the model of our UPS is SU2200 which is 1600 watts 220VAC output. Mr. Yong would you please give me some idea what is the cause of this problem? Im looking forward for your help and I do really appreciate it your help

Most of the time it is the battery problem. Although you got the right voltage but the voltage would not sustain when there is a current draw from load. You have to replace with new batteries and retest it. If the batteries are new then suspect board problem, if the batteries are more than two years old then direct replace it.



Hi B,


Here is your questions and answers:

I’ve assembled my ZD tester, but mine will work normally only if I cut-off the line connecting the adjust pin of the IC with the line after resistor 220 ohm at Vout pin of the IC. If I connect it again according the your schematic, the result of the ZD test would be much lower than it should be and the IC getting hotter. Could you tell me where is the fault? Also after cutting off the line, the result of the ZD test is about 1V higher than it should ( I’ve rechecked with my digital tester ), so I must adjust the zero point of the voltmeter 1 volt under zero.

The diagram is correct and i have three ERG members have successfully built it. Perhaps it could be still some problem in it? As for my tester, once power on i have to short the probes and do the calibration so that the pointer will go to zero. Once i power OFF the tester the pointer will drop below 0 Volt. I think may be you need to recheck the circuit connection again.

I’ve also finished my isolation transformer DIY project and it works fine. Now, the question is should my oscilloscope and other repairing tools also be powered from the isolation transformer or only the bad monitor?

Power the monitor and the oscilloscope to the isolation transformer. Spare the solder gun

Suppose I couldn’t manage to repair a monitor and I’ve replaced some bad components with the good one. Should I mount the bad component back into the monitor before returning to the customer, how do you do in this situation?

We will normally put it back as i don’t want customer to accuse us of stealing components after they sent it to other electronic repairer.

Can the TOP 247F substitute the TOP245YN IC?


Can the AS1117 regulator be substituted with AP1117 or LD1117?

I guess it is the same and you can try it out.

The other day I dismantled my own acer 1706 LCD monitor, it is still under guarantee and working, just because I’m very curious about the components. Inside I found blue resin coated ceramic disc capacitor with label printed as below:
JY 222W
400~ X1 250~
250~ Y2 66C
I know it is a 2.2nF but I don’t know which one is its working voltage, 400V or 250V? What does the letter X1 and Y2 represent?

Click here for the answers:

I usually do the soldering with 60Sn-40Pb solder, but now I have the lead free solder with 99Sn, 0.3 Ag and 0.7Cu. Is the latter mentioned supperior to the former when we do repair? Which one makes more reliable solder joint?

I observed from some of the Philip Monitors that the lead solder free have a more reliable joint.

We often talk about dry joint solder but actually I don’t know for sure to determine which one is the real dry joint. Is it the point where the solder is not shining and there is so little solder on it?

Dry solder means there is circle of cracked around the components pin.

For your information when I use the 99Sn solder, the result is not as shining as the 60-40 solder. Could you please describe the term for more detail?

Good question! Perhaps it could be missing some contents/materials that made it not shining.

I often see the white hard paste on power supply board, mostly covers the HV non-polar capacitor, electrolytic capacitor. What is the actual use of it,

That is a silicone glue for prevention of components from any vibration during shipment

what is the bad effect/ influence if the manufacturers don’t use it at all?

If it use in the high voltage section and you remove it, there is a chance of arc over across adjacent components but this are very rare.

Thank you for helping me to become a pro repairer.sy7

No problem!

Best regards,



I am troubleshooting Sony TV Model KV-AW21P50 with no power.
I found The Horizontal Out transistor C5885 shorting. I replaced it
with BU1508DX, it has not shorted but no power yet.

In the primary side of the SMPS it uses IC STR F6267 pin4 being Vin
has about 3.7V. Measured all startup resistors they seem ok.

Question: What other components may I check?

Hi M,

The supply voltage seems to be very low. Try remove the power IC and On. If you get back the normal voltage (typical power ic voltage is from 10 tp 20 vdc) then suspect  a bad power IC.




I have browsed your report on the secrets of How to Repair BenQ And the Acer 17″ LCD Monitors.  However, I still haven’t got hold of a copy of your e-book.  Still have to save for it.

I would like to inquire if the repairing process on Acer 17″ LCD Monitors holds true to its bigger LCD monitors?


Thank you and more power to you.



Hi R,

Yes basically most of the LCD Monitor working principle are the same. Once you know how LCD Monitor works you will surely know other models too.



Hi Jestine

I hope you are well. I need  TV and Monitor repairing steps.

> When I saw a problem on TV or Monitor Screen then what is the necessary section faulty.

—– Like   Problem :    One Horizontal line on screen
Solution :  1.  Check Horizontal Section.

If possible need more specific solution.

Thanking you



Hi M.D,
I’m fine thank you! Sorry i do not have articles on such repairing steps. Have you try this link

Best regards,



Hi Danny,

how can i get an esr meter?

You may visit this link:

but for the mean time is there any possible way to test this filter capacitor?

The best tester is the ESR meter. Using other meters like the digital cqapacitance meter and the analog meter will not give an accurate result.

and can you show what it looks like because it has many components inside and i’m confuse which is the one

As shown from the photo in the link given above where the esr meter is clipping on the electrolytic capacitor.



Hi M,


Here is your questions and answers:

First of all, you are really a person who make things happen, and make change on the global not gust around you. Thank you.

You are welcome!

I have been working on power supply of a medical equipment, but i have failed to repair it. I need you support about this matter.

i will summarize what i have analyzed and describe the problem.

1- the power supply provides +5, +15 (not regulated) , -15 (regulated with AN7915T). also one line of the out put is feed back to a reference circuit if IC TL431.

2- Input 220 VAC, filtered & rectified by a bridge & Filter capacitor (400VDC 100 mic.f), the DC voltage is converted into high frequency through and MOSFET BUZ71A, that drives an NPN power transistor (BUT11)that controls the line of the high frequency transformer. the MOSFET is drived by a controller UC3842AN.

The problem is:

Output voltages +15, – 15 are less than should be and fluctuate (while the +5 volts is OK 4.9 to 5.2)

If all the other output voltages are okay then suspect the -15 volt line. Direct replace the output diode, an7915, filter cap and even the inductor. I came across once where the smps transformer have problem. That means the bad transformer only affect one output (may be due to winding problem etc) and other voltages were tested okay. hope this helps!


Hi Don,

Here is your questions and answers:

I have a dell adapter that doesn’t charge my battery.  But if I use my niece’s or father’s adapter it will charge my battery.  I measure the voltage on there adapter and its 19.65 while my voltage was 19.45.  I replaced a faulty capacitor and MOSFET on my adapter.  While it did raise the voltage to 19.65, it still want charge my battery.  What could be wrong? Could you give me an idea where I might look?

I suspect that the output components may have problem try direct replace all the e-caps at the output. Here is a way to test the adapter whether the voltage would drop or not. Get an automobile 24 volt break light bulb and connect it to the adapter. The bulb should lit very bright and voltage measurement should be around 19 volt! If it drop below say 15 volt or less i guess the output line must have problem. If you could take a picture to show me, i guess i can help you to speed up the repair.

Should I be measuring the amperage?

Not necessary as measuring voltage would be good already.



Hi Casiano,

sir jestine good day!

Good day to you too!

sir jestine can i post regarding tv crt repair problem?

I will try to help because my expertise is more on the Monitor repair. Monitor technology was from TV by the way!


i had a tv set for repair. this set was already repaired 8 months ago but here again my costumer came back complaining of a dead set. the model is sharp 21s-v100, with normal b+ (122V) when i removed the collector of HOT, but it is increasing when i connected the HOT( 122V to 180V). here’s what happen:


removing collector terminal (Q602) of HOT:
– b+ normal at 122v
– led goes red when switched
HOT (Q602) collector connected:
– b+ goes higher
– led goes orange-green when switched
– then R792 start emits smokes

I think there is no horizontal oscillation or there is a problem in horizontal deflection,

it was already 3weeks to try solving this problem but hopeless, i hope you will help me or give me a clue for this problem


– the resistor (R792) is 1.2ohms 1 watt going to crt socket from pin 4 of FBT, there is a socket at the end of this resistor designated as (al1, al2, al3 & al4) this R792 is connected to al1, al2 & al4 is connected to ground and al3 supplying 170v. this socket is going to crt board.


i had already resoldered all cold joints and replaced all elect. caps, 9v regulator and vertical (ic501). but nothing happens. any help and ideas may help a lot…
god bless,

In your case, since you already got the B+ voltage then the concentration must be checking on the waveform of the HOT. The base of HOT must have a signal from the H. oscilllator ic. If there is no signal then trace back to see at where the signal had lost. Please update me with your progress-Thanks!

Best regards,
Jestine Yong







    March 13, 2010 at 7:00 am


    I am troubleshooting Sony TV Model KV-AW21P50 .
    In the primary side of the SMPS it uses IC STR F6267.
    When the power is On after few seconds power automatically off.

  2. admin

    March 13, 2010 at 9:18 am


    Try use this method to isolate the problem:


  3. False

    October 20, 2010 at 7:55 pm

    Great tip! I will add this site to my bookmarks.


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