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Electronic Repair Questions/Answers And Testimonials- Part 31

By on March 14, 2009

Hi i’m Ray and i would like to tell you that your books are great most of all the TestingElectronicComponents, in only one day reading i have learned many things thank you






Hi Jestine

I have fixed about 3 LCD monitors so far. Chimai 22 LCD ,kept blowing fuse
was a bridge rectifier. 2 HP’s with no power , replaced the electro’s in the secondary section ,works as good as new
Love your e-books, wish i had them 20 years ago.






Thank you very much for the link.I started reading your e-book testing electronic components.This is what Im talking about everything is explaining peace by peace and you cannot miss any I feel a real tech I do not have no fear .I m comfortable and confident. What will be the next e-book?Thank you.












hallo jestine.i am still looking forward to your new book about smps. i have bought your lcd monitor repair book which i find it great.






I had bought your e-book Testing Electronic Components and found it is very helpful..thank you.






Also, even until now, I keep on reading your two ebooks I had purchased , later onI would like to purchase the rest of your ebooks. It was full of treasures. Thank you and GOd Bless.






Thanks Jestine,

Your material are very educative and helpful. KEEP IT UP DOCTOR.






Thanks again for the unending troubleshooting info- you’re sharing. This would improve my repairing analysis and tracing a fault easy. you have a vast knowledge and considered grandmaster in the field of repairing electronics equipment. I salute and idolize you sir;






first of all, many many thanks for the fantastic “LCD Monitor Repair” I bought from you on internet.

It’s a realy usefull and effective book, the best I ever seen about LCD monitors… I’m an autodidact and this book is more than a simple aid for me.

I have understood many things about LCD screens which were mysteries for me once…

I have succesfully repaired several LCD screens, includind the Benq T905 I’m using now…

Thanks too for newsletters …





I have a qeustion? My Samsung 19″ LCD 932N have a problem. When I got athome I turned my computer on but when I try to turn on the monitor it was dead. I discover allot of liquid laying on the bottom stand and smelled almost like capacitor fluid but is to much for a powersuplly capacitor leak. Can this be the LCD and can this be fixed or must I throw it away not

You have to open up the casing but usually a leaky capacitor would not cause so much of liquid to pour out. Somehow it could be also the big fat capacitor that had burst open or cracked underneath and spilled some of the liquid. You need to open the casing and see for your self.

The LCD work through my UPS and is always off. When I came at home the UPS
light was on unbalanced or undervoltage picture on the ups front panel
display. I reseted it and the green light came on and ups was ok. What do
you think could have happend to the LCD monitor?

It could be external factor like surge or it could have been the LCD Monitor itself have problem. You have to open the casing and test it out and see.

Have a good day!













Hi Jestine,
You’re getting this e-mail from USA, Washington. I hope you’re doing fine as well as your students and customers all over the world. I downloaded the “LCD MONITOR REPAIR” Book. I’ve read through it and I can tell you, it’s just so amazing. I would like to purchase the rest of your 3 books as well.







How can i solve the TV problem – OVERBRIGHTNESS cannot controlled by the contrast and brightness control even with the flyback divider. Can you give me some tips to solve this TV problem?




Ricardo D

Technician Electronics


Hi Ricardo,
It could be shorted pins in the picture tube. Refer to this link

and look for the solution to brightness problem.




Hello Jestine,


Thank you for your prompt reply to my problem. I re-downloaded and all went well.

I respect your work and will only use any

of your projects for myself. Thank you again.


William R



Dear Yong,

Thank you very much for useful and interesting information. Your service to people on this field is highly appreciated

Best Regards





Hi Jestine,

From your books it very easy to understand & learned lots of new things. thanks for it.
Thank you,




Hi Jestine


Thankyou very much for the wonderful article on the checking of high voltage circuit in the crt monitor and tv.


This has given me an insight into what I was never learnt or taught about or read in books particularly on the testing of these circuits. The use of the Blue Ring Tester is also something new to me.







This months news letter has been very helpful as the others have been.

Thank you






I received your march newsletter..It is very useful for me..Thanks a lot for your effort.. and where to get the February newsletter?


Hi Jim,


Yes you can sign up from this link
to get the newsletter.



I have an old MICROTEK DIGI SYNC 1556 monitor.In that i loss’d the LOT number..can i get the LOT number some how ? .
Sorry i do not have that schematic thus i could not provide the part number for you.


The problem in that monitor is whenever i replace the HOT,it burnt off & gets shorted(B-E).After that i can hear a “tic tic” sound from horizontal section. But i checked the LOT as like u said in the newsletter(march).I didn’t found any problem in that..what should i do? plz assist me.

Try visit this link:





Thanks for sharing your interesting reports with me.

You are welcome.

Unfortunately there is no way of knowing the cost of your

Yes you do it is mention in the website.

Also to learn the skill of repairing, how much is the cost of tools and equipment require.

Depends on your budget and what kind of repair filed you wanted to be in.

Lastly is replacement of component is easily accessible and not too costly?

Depends on problem and what and how many components spoilt. Some you can get it from junk boards while some you have to buy new components.

Thank you.

You are welcome.





Mr. Yong,

How much and what kind of additional costs and type of equipment will I need to buy to repair monitors??


Hi Jack

Here are the equipment that i use for troubleshooting:

Analog/digital multimeter
Digital Capacitance meter
Blue ESR meter
Blue Ring Tester
High Voltage Probe (i don’t use it everyday)
Oscilloscope (i don’t use it everyday)
Inductance meter (I don’t use it every day)
Smart tweezer (i don’t use it everyday)

The above first four meters are a must in the electronic repair field because i have to use it everyday for finding bad components. As for the blue esr , blue ring tester and smart tweezers you can click on the link to check out the price where else others you have to check from your local supplier in USD. Meters comes in different brands and quality thus i could not give you an exact price. If you have other questions please do email me again.

Hope this helps!





On your page about vertical IC’s you really helped locate it on my viewsonic a90 My question, of you have the time, is…I had wavy distortion and 1/3 of the bottom of my screen gone–so I replaced tda8172 and all the caps surrounding. I got my full screen back but I noticed that after an hour the bottom of the screen is starting to distort again slightly and text on the screen looks like its jittering a bit.

Is something shorting my vertical section?


Hi John,

Try direct replace all the ceramic cap surrounding the vertical ic as some of these cap can test good but fail when under load.







i want to introduce my 12 year old daughter to electronics.

please assist as to where i can find appropriate projects that she can do on breadboards.





Hi Rob,

I suggest you get her some simple electronic project kits first before giving her the tougher project kit. Once she got hold of this field then only you get her to build some project using the breadboard. You can easily find the project from google by typing” breadboard electronic project” Hope this helps!





Hello Jestine,
I now have your book! I asked my friend to buy it for me from the company that sends me the LCD monitors to repair.
I have now read all the books and enjoyed them very much. I like your writing style and found the tips very useful.






Hi Joe,

How to check this filament? Does it just measure pin 7 and pin 9 to find out circuit open or no?

I’m not sure whether is pin 7 or pin 9 (other crt have different pins) but if you have confirm that both the pins is the filament then you can test it using ohm meter.

Once I found this circuit open, it means wire disconnect, I have to get another tube or not?

If there is no reading then the filament had an open circuit and need replacement

Is any other tube can replace that, or I have to get same brand tube?

The best is to get back the same tube.

Have a good day!





I am not sure what step to take next. The Zenith tv (25 inch, model
#A25A11D, made in Feb 1998) I am working on has these symtoms.
: pressing the “up channel arrow” button on the front of the
set brings up the Menu window.
: pressing the “down volume arrow” button on the front of the
set sometimes changes the channel down one station.

Now when I take into consideration that the remote control has no problems,
it sounds like the button switches are bad. Am I on the right track?

I have never comes across such problem but from your description it could be the eeprom data had been corrupted. But before that i suggest that you service the remote control first and see how it goes.

You know as a child in the 60’s and 70’s, I loved to play with electronics
and my favorite store was an electronics salvage warehouse and Radio Shack.
Now the fun is rekindled. Thank you for your wealth info.

Just like me when in the 70’s electronics were part of my toys!





is there any local(malaysia) supplier that you might know…thank you


Hi Allan,

You can visit the website at and try call them for the part.











HI Zafar,

You first have to know the spec of the  crt tube otherwise it will cause your HOT to burn. Horizontal wires have less resistance (low ohm) while the vertical coild have higher ohm.





Hi Joe,

are you basically telling me that the

LeakSeeker model 82 checks only cracks,breaks,shorts

and open tin line continuity ONLY ?

Check only for shorted components in the motherboard. I did not use it to check shorted components in Monitor because the ohm meter can do the job well.

what really is your passion, mr yong ?

ic test troubleshoot ?

replace if suspect,

right jestine ?

Yes you are right and my passion is in electronic repair.

show me something that tests ICs 100%,

Use a scope. Find out the pin configuration of the ic from internet. check for the supply input and output waveform. Have supply voltage but no output waveform suspect a bad ic or bad corresponding components.

Mr. Jestine Yong

i test on board,

then maybe cut 1 leg,

test again after pulling suspect IC.

i do not remove components for troubleshoot.

your videos and books show removing parts

with a vacuum pump.

that is ridicoulous.

That video is for beginners and beginners needs to start from basic first before doing the repair job that involve IC’s.

99% of ICs are soldered to boards.

remove ICs with vacuum,

replace with a socket.

plug in IC,unplug IC.

that is how to troubleshoot(test)

It depends on your preference but there is one test equipment that can compare a good and a bad IC. Please check out

Best regards,



I also have an question about bad electrolytic capacitors found in secondary side of an lcd monitor power/inverter supply

there was two 1000uF/10V/105C ‘bulged’ caps on +5.1V power line, and the main scaler board was dead too

What can be possible cause of this faults? maybe low quality caps or over voltage problem?, from power 220V line or internal problem with p/i board lcd monitor is Samsung 943N (about 100 hours worked) with p/i board IP-35155A by Samsung-electro mechanics primary side is based on Fairchild pwm controller FSDM0456R 

caps are made by SAMWHA

It can be low quality caps and also over voltage problem but from experience it is more likely the bad quality cap plus the heat generated in the lcd monitor.





Yes..thanks,i will buy that 2 types either, i also need a smart tweezers..a peak atlas component analyzer and adjustable DC Power Supply..where can i have it?…


Hi Robianto,

You can buy the smart tweezer at

atlas component analyzer at

and DC power supply at or from any electronic supplier shop.

Hope this helps!





Nin hao jestine,

I just bought your ebook previous day if u still remember. may I ask you something? i want to repair the power supply which I found out that there was no voltage to the input of the op amp IC AD822 but it has voltage supply at the Vcc thus no output from the opamp itself. The power supply is used to control supply current and voltage. How can I figure out the real cause of it? thank you so much.




Electrical and Electronic Engineering


Hi Siti,

Yes i remember. As for your question i was a bit confuse. You mentioned there was no voltage supply to the IC and then you said there is voltage supply to the VCC? For your information VCC pin of the ic is the supply voltage pin. Assuming there is no supply voltage then trace back  the circuit to see at where the voltage source had lost. It could be an open resistor, shorted diode, dry joint or even the IC itself shorted that had pulled down the voltage to zero volt.

Have a good day!





Dear, Mr. Jestine

Baru-baru ini saya mendapat monitor rusak dari konsumen. Gejalanya OSDnya berbayang(shadow). Mohon petunjuknya my guru.



Hi Edi,

Ia berkemungkinan disebabkan oleh pc tube yang telah lemah.





do you prefer troubleshooting circuit boards(independently)completely disconnected without power, or do you prefer to test them ?






Hi Joe,

It depends on the problem. I used both way for troubleshooting purposes.





hi, I’m Ng here.

I would like to know whether you know where can I learn how to use an



Hi Ng,

You can learn from a repair friend or get one and try it on your own. For your information my former senior also does not really know how to use it until i have to bought one and trial on error. You may buy some books from amazon on how to use a scope.





Hi Jestine

Yes it is a normal filament bulb and you can buy this in any electrical/hardware store. You can even buy a 500 watts filament bulb if you want without any requirements.

Going back to Likom monitor, yes I disconnected the B+ fet and it is quite hot for only a few minutes of running. I touched it after switching off. The voltage is 50v along the B+ line up to the flyback primary. I checked the components along the hoz-out from h/v osc ic to the base of H.O.T driver transistor, but I could not find any bad part. I could not check the actual signal because I dont have a scope. Could it be the h/v osc ic giving a wrong signal?



Hi TS L,
Thanks for the tips and yes the h/v oscillator ic could be the culprit if it output wrong signal to the HOT. Is the C5387 is the original number? Try use BU4522AX and retest the set again. Check also for the filter cap at the vcc supply line to the h driver transformer for high ESR.





Hi Dick,

what is the best wattage solder iron and name brand,

Get the Hakko 981 solder gun that have 20w/130 watt. 20 watt is for normal soldering and 130 watt is when you want to remove bigger solder joint like the flyback or the transformer pins.

what testers will I need  and names do you recommend?

and any other helpul tools.

It depends on the field you are in:

In my Monitor and smps repair field i need these equipment

analog/digital multimeter
digital capacitance meter
Blue Ring Tester
Blue ESR meter
High voltage probe and


I will be getting your books soon.

Thanks for the support.






Hello Mr. Jestine, I read your report, and I’m trying to fix the mentioned monitor, I changed the four C5707 by four MJE3055TG, all 27pF/3kV and 0.15uF/100V, but the problem still there, do you think is because the C5707 will be the job and MJE3055TG wont? I read the spec and they are almost the same just for the fT:
C5707 —– fT —- typ 330 MHz (from Sanyo)
MJE3055TG —- fT —– min 2 MHz (from Fairchild)

May i know what is the actual problem? I’ve heard from a forum sometimes ago saying that the MJE3055TG will get hot after working for sometime. The best is to use back the original part number.

Do you think is it the TL1451ACN the problem? can you please help me?

The inverter IC TL1451ACN rarely have problem and very robust.

Best Regards,





I;’m really stuck this time, I need some serious help. I need to repair this DELL E173FPB 17″ lcd monitor that shuts down. This transistor 2SC5707 is always short and i’m not really sure what cause it. I have changed it 3X already, work for a couple of minutes then the display goes dark. I know this is easy for but not for me. The problem for small repair person like me is that we can’t really afford to guess what component is faulty because every single part cost money. Need to sell this monitor in order to have some funds to buy you ebook. It’s a promise I’m making to you right now. I really want to learn the secret of this lcd repair and open a shop in the near future.
Please help.




Hi Arvin,

Besides the c5707 have problem try check the tuning capacitor located near high voltage transformer. It has the value of may be 0.15 uf to 0.22 uf with 160v or 250 volt. Check the value with ESR meter and also with digital capacitance meter. Check also for dry joints in the pins of high voltage transformer. Hope this helps!





The problem is: there is not back light in the monitor, I do not know is there is video either, so I took messure of lamps connector and there in not voltage (it should be around 1000 Vdc) but I do not have another point of test for discard the transistor or another device (27pF, 0.15uF, etc), I still waiting for the book, I gues it will have some point of test and signal picture reference. I’m going to request the C5707 parts from your provider.

When I turn on the monitor (not plug it to vga connector) I can see some change on the screen, like a litlle bit less dark, but I do not see nothing at all when I touch the menu panel or when I plug in to VGA, If I put a light from the back of monitor should I see some image on the screen? (plug it to VGA of course), I’m asking because I even know if the VGA module is working.
Sorry for bother you to much.

The first point that you need to check is to make sure the inverter ic is receiving the supply voltage then use scope to check on its output waveform. If there is no waveform change the inverter ic. If there is waveform then concentrate on the C5707 transistor area. Yes the output should have about 600 to 1000 VAC.





Today I bought your LCD repair ebook via paypal. I read have them in general.

Thanks for your support!

Right now I am trying to work on Acer AL1715. The problem is when I press the power button without or with connecting to computer the sign of ACER first appears and then “No Signal” letter for about four seconds. Then it shut down and the power button light turns to orange color. I tested all the three diodes of the inverter board with digital multimeter without removing any leg. One is big, seems to be fast recovery diode.  The two small dioes look OK as they show about 495:1 ratio when cheking both polarity. But the big one when tested on the circuit both tesing shows about 095 on each polarity. When i remove the diode it tested good with about 490:1. Please advise what could be the problem.

First you need to check that the output voltage from the SMPS is correct. If there is any bad filter cap it will affect the output thus causing the power LED to turn orange. If it has output voltages even to the mainboard like 2.5 volt, 3.3 volt and etc then suspect a bad MCU as the orange LED comes from the MCU.


And please let me know how to enter into your forum membership for support as you mentioned in the ad.

For your information it is not a forum, it is a members site where you will get my monthly repair newsletter and you can sign up at :

If you have other questions please do email me again. Have a good day!





P.T.L Here are the photos of the latern Lamp the circuit and the parts filter Capacitors are 220uf 16V. Hope  the information helps.

For the transformer it seems more like a switch mode transformer and not a linear transformer. For this kind of transformer i could not suggest any information as the winding output is hard to predict as compare to the linear transformer. From experience this kind of transformer is very robust. May i know why you suspect is the transformer problem? and could you tell me again what is the problem with the lantern?

Another thing is The LCD that we changed the backlights have gone faulty again, about 2 weeks after the repair, customer 2 days use than goes faulty.My explaination is the backlight that we changed was old backlight (not new and that’s his backlight that he gave me for subsitute ) so  It’s not our fault. I explained if the Monitor is damaged then it will not stand an hour or…. now it can stand for 2 days that’s what he said. So to your wisdom Bro Jestine is my explaination to the customer is it the correct way? So do you think the backlight shorted again because it was a second hand set or is it other factors.

Since the backlight was a used unit then chances is very high is the backlight fault. I have changed a lot of backlights and not even one come back for warranty claim. However in your case, just to be in the safe side check also the high voltage transformer for any dry joints before you replace with another backlight. Hope this helps!





Hi Jestine


Thank you for the download information that you send about the LCD monitor repair

I am very happy that you help us in upgrading our knowlege about the LCD repair

right now my student and I use your download information as a reference guide in repairing LCD monitor.

Best Regard and more power,

Nick D.C




Hi Young,


I appreciate your concern. I am just the beginner and I found this info and had read it while searching info for diagnosing my Acer LCD problem that I sent you the picture. It interested me so much that I bought your ebooks; Testing components and LCD repair. I am studying right now and hope I can repair one day with the help of info from your ebooks as well as with your email support.


I wished I found your site earlier so that I don’t need to take electronic course online and pay $$$.

Again, I appreciate your keeping intouch with me. Take care.




sir justine,

   Thank you very much for your sending me a guide/tips in troubleshooting techniques it helps me a lot to improve my knowledge in repairing of tv problems and other electonics device. More power to you,good health always and God bless you. Please continue sending on me a different problems in troubleshooting of ctr tv repair.

Thank you very much!






hi Jestine,

thanks a lot for this month repair newsletter,it will be a big help for me who start this kind of business…hopefully more  repair newsletter coming….




Dear Yong,


I received the repair news today again. Thanks alot.


Now I need your helps. As I mentioned earlier I am working on Acer LCD AL1715. I changed the recovery  Diode near the power transformer and it worked. I tested twice before I screw back the case. It still worked. Then I put the case ready to give it to my friend who bought my old computer. I check it again after casing it still worked. After about 15 minutes the screen goes black but the power button light is green as long as it connects with the computer. What could be the culprit please help me again. My friend is waiting me to get the LCD eagerly.




Hi Rik,

If after sometimes the lcd shutdown, it could be fault of dry joints in inverter board or even a bad backlight. I have seen weak backlight causing shutdown after 10 to 15 minutes in operation. The backlight just flicks one time and the display shutoff.

Have a good day!





Hi  Jestie,

 I will always say a very big thank you to you. This news letter is really very helpfull, as for your L.C.D repair manual, I would say it is an asset for anyone in this field, and has access  to it.
Mr Young have a great weekend.


Kebba M



Hi Jestine,

I realy get excited or the concern you have for me. The news letter you mailed me was great and insipirational. It addresses my dreams of becoming a successful man through electronic work.
You make feel I am already succesful. Thanks a lot.

Thanks for making me have hopes of earning a living in this very competetive world

Gonza P





Hi, Jestine

I m working on a Gateway lcd monitor , model FPD2485W .

It powers on , gateway logo shows about 2 seconds then shutts down.

Pictures of the board included. Power supply seems to work fine.

Did you ever came across this model.

Thanks , from Canada


Hi Mathew,

Check the backlight as bad backlight could cause this problem.




hey, Jestine one of my friends CRT has damaged. he saied that it sounds like ””Ckatus!!! chatas!!!” then whole picture gone. whats the problem? can you help?


Hi Mithun,

Can’t get the actual description. If it shutdown then make sure the B+ voltage is correct and also the flyback internal capacitor have no problem.



HI Joe,


Do you have experience to use different brand tube replacing old tube?
Yes i have

What kind of problem will be happen for using different tube?

It will cause display to shrink and also it can burn down the HOT immediately or after sometimes. It can also cause the display to curve inward.

How easy to using TV monitor to replace arcade monitor? Thanks.

Sorry i have not touch any arcade monitor before thus could not give suggestion on this topic.



Your march newsletter is the one that I need most, I wish I had received it earlier. Thank you.

You are welcome!

Talking about GTC monitor, if I got stable voltage of G1 & G2 but the display still flickers ( sometimes bright and sometimes dim ). Is there any other point to check with this problem or will come to the conclusion that the pc tube is bad?

If all the important voltages are steady like the G1, G2, Heater and RGB voltage then you can conclude the tube have problem.

Do you think a measurement of G1 & G2 to be a figure plus minus 1V is still considered to be stable?


About 17″ Logix LGX17H which display is not able to see without turning off the lighting of the room at night. And after checking finds G1 58V, G2 583V, Heater is only  0.1 V so this must be derived from the secondary of FBT, and the glow of the neck is bright enough, the anode voltage is about 24KV although I can hardly hear the inrush current of the pc tube. For your information the GTC is German design while this Logix is Korea made.

G1 is normally negative voltage and since you got positive voltage then suspect the G1 line may be have problem. Heater is 0.1 volt because your meter can’t measure it (taken from flyback winding).  Could you confirm it because generally heater voltage for Monitor are derived from SMPS and not from flyback?

In Desposito’s book tells us that if you could see a glowing neck then we can conclude that HV is OK, is this always true?

It is true unless the heater voltage is coming from flyback. That means bad flyback will have effect on the heater voltage. If it taken from the SMPS a bad flyback will not have any effect on the heater voltage.

As far as I know, this is always so. If this is so we won’t need the HV probe, shall we?

You still need the HV probe because have high voltage doesnt mean that it will always have 24 kv. I seen Monitor that have 18 to 20 kvdc and you thought that the high voltage section is working fine.

About G2 voltage is 583V, how do you think, is that too high? In your article about How To Solve Computer Monitor Display Problems That Caused By A Defective Screen Grid Voltage (G2) you say that a good G2 voltage is somewhere between 250 – 300 + DC volt. Desposito says it should be between 400 – 450 V. The Acrisoft’s e-book says it is between 400 to 600V DC. Which one should be correct?

This depends on the brand of your meter that you used to check on the G2 voltage. I have a China made meter that measured 50 volt at G2 point.

And when I want to adjust the bottom potentiometer of the sreen voltage, I found that it doesn’t have one or maybe the manufacturer had closed the potentiometer, see the attached photo. You can see that this flyback actually has 3 knobs, the top is written as H, middle is the focus and bottom is the screen but not adjustable. This monitor is somewhat old & bulky and also rusted, you can also see on top of the convergence board there are many presets, what are their use? See the attached photo.

The bottom is the G2 knob but manufacturer use the sofware to control the G2 instead of physical adjustment. The three preset is for adjusting the tube convergence. They call it as convergence board.

Could the monitor blur buster be installed on 17″ monitor?
No it can only be  use on 14 and 15″ CRT monitor

Is the junk monitor FBT has to be one from 17″ monitor also?

17″ flyback is more complex as it has circuitry inside the flyback (resistors and capacitors) and external dynamic focus circuit which made it hard to modify it.

Do you think the Logix monitor problem is caused by a bad voltage divider of the FBT or a problem in the secondary side components as described in your March newsletter?

Assuming all the voltages are good G1,G2, HEATER and etc then it could be tube problem.

If there are components like resistors open circuit in the secondary side, high voltage could still be produce but is just that the display may become too dark or too bright.)


It depends on where the resistors located. If it locates in the G1 CIRCUIT YES, it can become too dark or too bright.

Also in this newsletter you say that

However if there is any components shorted like diode and capacitor, it would cause the SMPS to blink and no high voltage. What do you mean by ” cause the SMPS to blink”? Where can we see it blinks?


The power LED blinks and other words for this is power pulsating or recycling.





dear sir,

          Hi, thank you for givimg me all the information on electronic you have a diagram for samsung tv model cs 5029Z may problem is no power i check the Switching transistor but they are good.can u give me any sugestions.thanks and more power.


Hi Gabby,

Sorry i do not have the schematic. Try check all of the components in primary side and also if possible direct replace the power IC. Check also the secondary diodes for shorted.



hello Jestine,thanks a lot for your monthly news letter ,  its really a big help for me, by the way jestine i just want to ask you if its posible to repair burnt letters in plasma computer monitor screen hitachi 42 inches.

This 2nd hand plasma hitachi monitor is came from japan , even if i turned off the monitor i can still see the japanese characters in the screen.

Hi Glenn,

You are welcome. As for the plasma tv if it is burnt then i guess there is no way to repair it-period.




Hi Eric,


Whats the purpose of using Soldering Paste?

To clean off the solder gun tip and also to make sure the solder are properly have a good intact between joints.
It look more neat when you use soldering paste.

Sir can i request i wanna learn how to repair Video Cards from Computer for example it has no Display, coz most of the time if not the PSU then the Video Card in my PC is defective.


It is rather hard to repair such problem because it involve lots of SMD components and also we do not have the spare parts for  the display IC’s




About the heater voltage, I’ve confirmed it comes from the yellow thin cable wound around the core of the FBT. See the attached photo.Yes i”ve seen it but generally Monitor manufacturer do not tap heater voltage in such a way. Could it be repair by someone before?

Today I’ve pulled out all the boards and resolder some of the dry joints and checked internal capacitor of the FBT is 2.65nF. This time I took a lot of photos so I can put it back exactly the same as before.

That’s a good way of taking photo and the internal cap is good.

Now the display is a little bit brighter, the inrush current of the tube is strong enough to be heard, but still must turn off the lighting to see the display on the monitor. Sorry, I know G1 is always minus, so last measurement of G1 should be OK.
This time I got:
G1   -78.5 V
G2    583 V
GK   34.4 V
RK   34.1 V
BK   33 V
When you said to check the RGB voltage, are those to be measured from GK, RK, BK to ground?

I always do the voltage measurement with my Extech 470 DMM ( True RMS ). What do you think about G1 & G2 voltage? Is G2 too high, will it do any harm to the pc tube?

Since i do not have your brand of meter i guess it should be okay.

In fact, I’ve been using this monitor for sometime, but because this is a second one, I had to set to brightness to full to be able to see the display, but the intensity of the display gradually decreases. So what part of the circuit should I concentrate on now? Is it G1 circuit, is this circuit located at the CRT board?

As for the heater wire Try make few more turns and retest the monitor again. The G1 voltage is within spec thus i presume it to be okay and G1 circuit is located at the CRT board and flyback transformer.

I can hardly see the OSD function, but from the guessing game I could adjust it to the maximum. I know from the Desposito’s book that the smaller the absolute value of G1 should give the brighter display, so my problem now is how to make the absolute value of G1 to be smaller than 78.5, am I right? Is there any preset that I can adjust the G1, because this monitor has no brightness knob to adjust.

You have to adjust from the OSD screen and yes if the G1 voltage is low the display would be bright.

About the photo of the FBT which should have 3 potentiometers, the top is written as H, when I tried to adjust it nothing was changing, what is this H actually mean?

Horizontal dynamic focus and it has little effect on on the picture.

I there any precise method to confirm that any picture tube is bad or not?

CRT restorer is not 100 %, Only thru experience and substitution could confirm it.

Thank you for taking the time to answer all my questions.

No problem.




What would be the fastest way to learn how to trouble shoot electronic devises such as lcd screens and walkie talkies or other similar electronic devises and what would be the way that you could help me by listing all cd’s or written books that you have so i can get a more realistic idea about how to start testing various electronic devises that have quit working, can you please list the materials that would give me everything that I would need to do these type of repairs, Some of the information that I bought from you has been lost due to a computer error, all your help is great I want to be likwe one of the people that say they have taken your courses and right away started working on things THANKS, BY THE WAY I AM ANN ELECTRICIAN.The best way is to first must be able to test electronic components and then get books on which equipment that you want to be in. If you want to be good in LCD Monitor repair then get books on this topic and fully concentrate it. After you have mastered the LCD Monitor repair you then can move on to other equipment. Take a step at a time. May i know which ebook have you bought and when? Once i got your record i will send you the download link again. Have a good day!




Thank you for this data on Flyback.

Where do I  measure the B+.


From behind the mainboard. The b+ voltage is the line that goes from SMPS to the Flyback pin.

How do I put the probes to measure the signal at B of  HOT.

You have to use oscilloscope. Just place the scope probe to cold ground and the main probe to the base of HOT.






I had bought your e-book Testing Electronic Components and found it is very helpful..thank you.
Thanks for the support!

.but I have a few questions..
1. What is posistor?

A posistor is a component that use in a degaussing circuit to degauss the color purity of CRT tube.

2. If switch mode power transformer faulty, can it be replaced with a new one? I think every SMPT is a custom made transformer, so it is difficult to find a new one at the market…or

Yes every smps transformer is very unique unless you could salvage it from the same model but generally smps transformer are very robust.

SMPT can be rewinded if fauly?

It depends on the guy who do the rewinding job. At my place here he only rewind big transformer and not the small smps transformer

3. If I not mistaken, some transistor especially power transistor have their body connected to it possible the transistor short to their body?

That is part of the design and yes if the internal transistor have problem it can short to its body.

4. Can computer motherboard be repaired?

Yes unless you have the Spare part ICs. I heard that in China they could repair many types of motherboard because only their country have the parts and those parts could not get from other places. Many problem in motherboard are caused by bulged capacitor and replacing them could solve lots of motherboard problem.

Thank you..

You are welcome.

Best regards,
Jestine Yong


h0i, i’m giovanni from philippines. i have AIWA 20″.model number is AN2010NH. the problem is if you turn the switch ON, it will just standby the power. even if i used the remote control. help me…


Try not use the remote control and directly press on the equipment “on”button. If all tested okay then concentrate on the CPU signal and see why it didn’t reach the optoisolator or relay circuit to trigger the main smps. Sometimes a bad CPU also could such problem.




hello mr jestine. i would like to give me an answer about my problem. i have a tft monitor ( samsung syncmaster 720n ) with a white screen. the osd does not appear. the monitor power on normally ( the led lit green) . but one moment it happen that the raster appears normally and after that the monitor go back to white screen. is the problem in the lcd panel or in the board and how to solve this problem. thanks.


HI Achour,

If the flex cable between the mainboard and the lcd panel are connected properly then suspect a bad lcd panel. Make sure also the output voltages from the SMPS are good too.




Hi Gilbert,

Hi jestine,  thank you for coming back to me as quickly as you did.  The TV Set given to me for repair  is completely dead with the exception of a pulsating noise being heard through the loudspeakers. At first the fuse use to  blow. I replaced a 150mfd filter capacitor,400v and the fuse doesn’t blow anymore, but the clack clack noise is still being  heard through the speakers  and the HOT does not come on. I don’t really know where to start checking from here since I don’t have a schematic diagram as a guide. 



I am not sure where to connect the meter probes from here and where to start looking. One logical thing is that power is not being  fed to the relevant part.  Before powering the set on ,I used a 150W light  bulb  between the wall plug and the TV,   to which it  burnt brightly and then faded out completely. When the light was burning no noise was heard through the speakers but soon as the light was completely out the noise was being heard again? Do you think that it could be the power IC? I don’t know how to check this IC in circuit.  Please help.



Isolate the circuit first by visiting this link:

If the bulb light suspect problemin the flyback and HOT area. If the bulb does not light then suspect fault in the power section and you need to replace the power ic and retest again.

Hope this helps!




Hi Paul,

hi,yes i’m interested.i just like fixing laptops as a hobby.i just listed some parts on ebay to build up my paypal’s like 60 or 70 canadian for your book.will it help me? i took electronics for like 6 months but too much book work,no hands on.had to quit for finincial reasons.worked as electrication for couple i can read a multimeter some what.will it show me what & where to check,tell me what is the most common causes of motherboard failure,besides bad d/c me many types of pico fuses,& so on. i hope my parts sell & your book can help me.thanks paul

Since you are in laptop business i do not really know whether my ebook (LCD Monitor Repair) will meet your requirement. LCD Monitor and laptop have something in common like the lcd panel, lcd backlight, the inverter board and also the smps. The ebook will guide you to solve most common problem in lcd monitor and from the info in fact you can use it to apply to laptop repair. Besides it comes with my own personal support and you can email me juts incase if you have any difficulty in reparing certain problem. Have a good day!




I just finished to read your report for this month .Thank you it is very good and very precise I knew a few steps not like that.You are welcome!

I m working on a lcd Magnavox monitor 19″. the problem that I have like you mention in your e-book the power
supply is not switched .From the reservoir capa-
citor I have 155volts- .From the smps I have 16 v
going to the maim board that a connector with eight wires.Then I have a connector with six wires that I have a smt fuse that contains the five
and 3.3 volts going to the power switch.When you press the power sw there is a red or green
led no effect nothing had power the
set is dead .As you had told a few months ago
This is the micro.I spent 30 mn on it already .It looks you have to replace the main bd.

Yes you are right if all the steps have taken to test the board and it still turn to red light. suspect the mainboard.





My name is Manuel R. R. I have the A+ Certified Computer Technician License since the year 2000. I completed a 1 year career in Computer and Electronic Equipment Repair here in Puerto Rico at the International Junior College ( a local private institute ) with 4.00 GPA ( high honor medal student awarded ). I studied and teached myself electronics and computers with the books that my father gave me when I was 20 years old, before I completed all this courses, because I like electronics due to that it make me feel like a heroe and it is very futuristic from my point of view. I also proved that I don’t need to be a wizard or guru in calculus or physics to be a guru in electronics hardware. I learned in time that all that I need to know to understand it is the ground concept that the majority of books fail to explain. In other words: GND = -VDC but GND is not = to -VAC, in order to know how to use a voltmeter or oscilloscope in any equipment. This ground can be found with continuity or resistance function with any meter when I don’t have an schematic handly and all that I have are the cross reference of the suspected components.

Nice to know you and your background and your wonderful explanation too.

I like to know if the book titled : Television and Video Systems Operation, Mantenance, Troubleshooting and Repair wrote by Charles G. Buscombe ( sold by ) is ideal for me to learn more about tv repair

I can’t give any comment on that because i don’t own that book but i found that “Troubleshooting and Repairing Solid State TVs” third edition by Homer L Davidson is a very good book in repairing TV and it has lots of pictures and practical steps to easily help you out in the repair.

and I like to know if the switch mode power supply PWM IC can be testes with a 9V battery to know if it is good or bad with the DMM to test it’s output pins.
No i’m afraid you can’t because most of the Pwm IC have a feedback pin (to get feedback from other source like from optoisolator and etc) and if there is no feedback to the power ic even though you have the supply voltage, no waveform will be produce. You can do it unless the PWM ic does not have feedback pin.

I like to know also if the switch mode power supply transformer can be tested with a voltmeter or DMM in VAC or VDC ( grounded on VDC only ).

The best test is by using a Blue Ring Tester.Voltmeter could only test if it has output voltage or not but cannot check the condition of the transformer primary winding.


Best regards,



  Dear Sir,
Many many thanks for updateing me in electronic repair tips.Sir I have a one problem with LG L1515s LCD monitor, problem was on display few colourful vertical line shown on display i have replaced main board but problem was same so plz give me some tips.
Thanking You
Your Regards

Hi Abhijit,

From your description most likely the problem in LCD panel.




Hi Jesse,

I have a question about the Ziner diode tester. Can I use a transformer with 115 AC input voltage? And what would be the amp pri and sed?

Yes you can but have to be 24 VAC output and the amp can be from 0.75 to 1.5 amp

And would everything else work ok with the parts as listed.

Yes i have ERG members who emailed me saying that they have succeeded building the tester.

I live in the US and 115 is the primary voltage. Finding a 1 amp is hard to find too. What would be a safe range.

As mention above.

Have a good day!




nin hao jestine,
Ni hao.

I hope u dont mind if I’m asking u a question.

No problem!

before this, I talk to u on my problem regarding the power supply right? I am still  having a problem becoz of it. since I dont have the circuit of the power supply, I have to draw back the circuit in order to know where the voltage input of the op amp is missing while it has the Vcc for the IC(different thing). my problem is I dont know how to read the schematic from the PCB if I want to draw the circuit back. apart from that,

No you don’t need to draw the schematic. What you need to do is to locate the ic part number and find out the data from the internet. From there you will sure know which pin is the supply pin. Then you place your black probe to cold ground and the red probe to the supply pin and follow the circuit backward. It may pass by certain components like diode , resistor and etc before reaching to the source which is the power supply unit. As for drawing the circuit (reverse engineering) it is not that easy unless you are well known of how to really read a schematic first.
You can download some free schematics from to study it first before you can actually draw back the schematic of your pcb board.

I dont know the function of the op amp in the circuit either amplifier/comparator etc.
Here are some information of amplifier and comparator circuit:

Best Regards,



hi,i call you doctor becouse you are a doctor in this field of electronics.keep sending the news.My question is,how can you know that the ic microprocess is fault and when the TV is in standby,what could be the main couses?    


Hi Frank,

If all the signal are tested good then we can say the cpu is working. If there is no waveform output, crystal no waveform and cpu is very hot then we can say the cpu is bad. Tv standby problem could be fault in cpu, bad eeprom, optoisolator ic did not get signal from cpu to trigger the main power supply and etc.




1)A large number of smd component exist in electronic circuits. how can i identify smd capacitor , resistor,inductor,… from appearance?


By looking at the component itself and the location of the board.


2) how can i test ttl or cmos ic ?


Using logic probe






         How r u ?

      Tell me how make PCB & which tools & instruments use. And how make cuircit ?


Hi Pintu,
I’m fine thank you and try search google using this keyword “how to make pcb circuit” and you will find lots of side for this information.




Hie Jestine


I hope you are doing fine, your reports are very useful, and since I started some day ago it has brought great intrest in troubleshooting monitors and Power Supplies, As of now working of monitors and powers supplies I failed to repair some month ago, But now I have a problem with LG CRT Monitor 563N, am not able to access the number of power transistor, it is completely broken, am also able to find the equivalent of diode (damper+modulation diode with three terminals). Is it possible to have a complete circuit diagram for this type of monitor, and also to have the replacement number for the diode? Help me as you have alredy started


Am looking forward for your help

Hi Mathews,

Sorry i do not have the circuit diagram. As for the damper/modulation diode try use DMV1500. Hope this helps!




Hi jestine yong,

I have a Toshiba qosmio g20 laptop.There is some about 10 -12 vertical colour lines (single pixel width)on the right hand side of the LCD screen and a  3 inch white vertical band on the center of my 17 inch wide LCD screen.
when i took it to the service center they said that i need to replace the screen which will cost me around more than 300$.

I am very passionate in electronics repairing and i want to know whether this problem is repairable or not.

please guide me

with regards,



The technician is right the problem is in the screen and as for the price it could vary from one brand to another.




Hi Henry,

Then I replace C5707. How to comfirm or  measure the C5707 is good or bad?

Using the peak atlas analyser. If you have replaced the transistor and the transistor still blow then try check dry joints in the high voltage transformer pins and also the tuning capacitor and make sure the ESR is good.




Greetings Brother Jestine,
Change new motor problems worst motor not running, so exchange back former and doing some adjustments now the set is Okay. TQ for you yr kind concern on this matter. Well U have many things in yr E-Book that we have  learn and brought to good use in our repairs. You are right in all yr teachings like we test the hot in the DVD player solder out while hot it’s faulty when tested,when it has cooled down it was tested okay. So we change it and two other components well the set works up the power praise God, Like once we repair a set of multimedia ACER speaker system with Subwoofer bass distorted tested every component okay, but problem still there. So since its a small circuit we change a number of components suspected, still the fault is there so now left two diodes we have check okay, since these are the ones left that have been change, so we said why not try change these 2 diodes well after changing the sound becomes normal again. So we understand when these components get hot it becomes what u mentioned in yr E-Book that components breakdown when under Full Operation Votage. TQ so much for your theory. As promise I will order yr E-Book LCD Repairs next week. GOD BLESS U RICHLY WITH WISDOM AND KNOWLEDGE so that U can pass onto us. So happy to know U brother ADIOS.





Hi Justine, I am working on a Phillips/Magnavox 16MF400T/37 T.V./Monitor and when it is turned on the screen lights for about 5 seconds than go out but the power light stays on. Turn the unit off and restart, same thing happens. I have checked and changed the capacitors on the Invertor Board. I have 12 volts to the board and 4.5v comes on to turn on the CC lamps and stays 4.5v when the lamps go out. I have no schematic on this. Can you point me in the right direction to solve this problem. Thanks – Dan Sliwinski 


Hi Dan,

From your description it could be a bad backlight. Remove the back light and see the end and if it is dark in color replace the backlight.





  1. Madhusha

    March 15, 2009 at 2:38 pm

    Nice work jestinyong.
    Im from srilanka......
    Thank you verry much

  2. admin

    March 15, 2009 at 5:19 pm

    Hi Madhusha,

    You are welcome!


  3. saunders

    July 2, 2020 at 12:55 am

    Is there a way to fix this e6 error problem on my ymgi minisplit indoor unit without buying a new board? I have check the wires they are giving good continuity , I am attempting to repair the board myself without buying it, I watched videos attached with the problem and follow the steps but I am still getting the E6 code I am an electronic technician, what part or parts would you think will be most probable to cause the E6 error code

    • Jestine Yong

      July 2, 2020 at 1:27 pm

      Hi Saunders,

      I have not repaired this kind of device before thus I'm unable to give any repair suggestion on this...sorry. You need to get the service manual in order to find out what E6 error code mean and from there at least you will know where to start troubleshooting it.



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