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Electronic Repair Questions/Answers And Testimonials-Part 16

By on October 5, 2008

Hi Jestine!

Thanks for your ebooks that i’ve received them from you. They’re helpful.

Jestine! I’ve had the “red raining dots pattern” on the screen, it’s worse at the top.

I changed the Y,Z Sus, Control Board and even the Y Driver Board but it’s still the same.

Have you seen this fault before? If you have it experience of this. Can i share it with you?

Thanks so much


Hi T,
Thanks for your support on my ebook. As for your problem, i’ve never see before in LCD TV but in LCD Monitor-Yes. It was caused b a defective LCD panel. If you have other questions please do email me again. Have a good day!


Gud Morning sir Jestine,

Sir can u help me to determine what is the problem of my monitor SAMSUNG

Hi Clifford,
Have you check that the G2, heater and the G1 VOLTAGE at the CRT Board is within spec?


I am working on this tv that have a major problem with it. I replaced all the burnt parts in it except one resistor that is really burnt and can not find the actual value of it. any way to find out? It is connected in series with another resistor that has the value of red red sliver and it is measuring .5 ohm. Does that sound right to you?

Hi W,
I’m fine-thank you! But the red, red silver should be 0.22 Ohm. Then the burnt resistor value could be another low ohm resistor for protection purposes. The value could be 0.22 Ohm too. You have to try it out and retest the set again.


I just started to read your book “Testing Electronic Components” and I’m stuck with a real-life problem for which I do not had found the answer yet.

I have a Switching Mode Power Supply to troubleshoot (and hopefully repair). When I opened it I saw some kind of rust on two electrolytic capacitors.

My questions are:

(1) Should I simply replace them or is this rust can be successfully removed?

I guess it could be decayed glue. If the capacitors tested good then you may keep them.

(2) If the rust can be successfully removed, how can it be done?

Scrap it off with test pen and then use thinner with the help of a small brush you can clean off the rust/decayed glue.

Thanks for having taken the time to read and for this wonderful book you wrote.

You are welcome!

Best regards,
Jestine Yong


I have read your report. It’s good.

Great to hear that!

I just have a power supply for CISCO switch which started malfunctioning after being hit by lightening.

The power supply switches on when power cord is inserted, and holds power for few seconds then goes off.
the output voltage are 12v, 5v, 48v, 3v and input voltage is 240v.

I replaced the IC’s 3844B but it continued malfunctioning.

If it hit by lightning then you have to check all of the primary part components. Before that i suggest that you check components at the optoisolator area (secondary side) as any components breakdown here (which include the optoisolator itself) could cause the problem you have just described. If possible could you take some photos and show me by email to this address ?


So it is not worth the money to repair it? I thought I could replace the

glass panel or something.

Hi Vincent,
If it is a LCD TV then it has an outer layer of glass to protect the internal screen. However in LCD Monitor, if it cracked then most probably is the whole LCD panel have problem. In other word, the LCD Monitor does not have the protection glass. If the repair technician has confirmed that the LCD panel have problem i guess you get a new unit because as far as i know the LCD panel price is almost the same as when you get a new LCD. Remember you have to pay for the service charge too. Hope this helps!

Best regards,
Jestine Yong


From Manny

PS I love the LCD Repair manual, I fixed 2 out of the 5 SCEPTRE’s I own.

Blown/Bad caps!!!



Hi Tom,

Sorry i do not have such part number. Try email lavinci luca at to ask for the parts.



I’ve just bought an ESR meter recently.

I’ve got a problem in reading/interpreting a graph on the ESR meter.

For instance, if I want to measure a 470uF 63V. What is the proper value

to get from ESR meter.



Hi Simon,
Try this link


Hi Justine,thank you for your great site. Is there a source that can provide a 3ez24d5 diode or a non zener substitute. Thank you for any help you may provide. THE BEST TO YOU AND YOURS. JOE

Hi Joe,
Try from my blog list of electronic suppliers below:



I’ve got an analogue meter which doesn’t have x10K scale, but a 100K.

Can I use the 100K scale instead of 10K scale when testing diodes/transistors

on x1 & 10k scales. (According to your notes on testing components )



Hi Simon,
I have tried it and the result is not accurate because the X100K analogue meter internally does not have the 9 volt battery.


Dear Jestine,

I had a problem regarding the BenQ LCD Monitor that I’m repairing the model is Q7T3 the problem is in the inverter first I find the fuse PF751 open,this goes to the off/on transistor going to the VCC of TL1451ACN Inverter IC. I had replace the fuse.Do you know how many ampere is the fuse.But now i power it will display a BENQ logo and shut off and you say in in the feedback section . How can I diagnose the problem. Do you had a diagram about this model or any diagram that uses this TL1451ACN IC.


Hi D.H,
The fuse is between 2 to 3 amp as i don’t have the set with me now. Try visit this link
for some repair tips.

Since you found the fuse open circuited then this means you have to check for other problems too like shorted FET transistors. You can compare both circuit using ohms range to locate the fault fast. I don’t suspect a bad backlight because usually if backlight have problem it won’t cause the fuse to open.

happy to have found your site. I have a problem. My projection tv. Trying to turn it on and it seems to get hard and harder to turn on. Nothing’s wrong with picture or sound could it be the flyback transformer? A repair man mentioned something about the power but he wants alot of money to fix it just was hoping you can help.



Hi Robert,
May i know what do you mean by hard to turn on? Do you mean the on off switch stuck or the power slowly come out and etc? If there is picture and the sound then the flyback should not have problem.



Dear Sir

I am involved in Historic Radio Restoration (Valve Technology), and wish to use some older (out-moded) computer power supply(s) to provide 4 volt and 6 volt DC for this purpose. I believe that this is (relatively) simple to achieve. What I am seeking is either:-

(a) a (typical) circuit of a Computer power supply made 10 to 20 years ago.

(b) a physical diagram etc to identify the components that set the plus 5 volt output, and suggested values to adjust this to plus 4 volts and to plus 6 volts.

A “typical” Power Supply is 200-250 watts such as;-

Sorry Geoff, i does not have the info about this kind of circuit thus i could not give any expertise advice in this topic.


Hi Jestine,

On your advice, I made attempts to acquire & should be receiving by this weekend (i.e. from the USA based ANATEK Corporation), both the Blue ESR Meter and the Blue Ring Tester. Many, many thanks for your offer of continued guidance as I try to progress in building my skills.

Yours Truly,


Hi Y.P,

Great to hear that you have put your vision into action-that’s the right way of doing it. Start now, look forward and expect result!

Hii Jestine,

Any new e-book from you Jestine? I have question to ask you and need your help, I got a crt monotor model Acer AC713 14″ when power on and power led lights but with tic tac sound from its relay and no display? What is the problem and really need you help.



Hi A.S,
Selamat Hari Raya- Raya also have to work? I’m still writing my ebook and the more i write the more ideas i have and in fact today i’m still writing it. When you said tic-tic sound does the power LED blinks? Is all of the output voltages fluctuate at the secondary side? I need this info in order to give suggestion.


Hi Jestine,
I came across 2, would be, 680 ohm fire-proof–2 watt resistors in a
Dell E 153 FPb monitor, not burned or dis-figured in any way, they
both measured 66,700 ohms, color coded blue-gray-brown- gold==5%. I
suspect the higher value may be correct, since these resistors are in separate circuits, but they are close together on the power supply
board. Sound familiar? Unit had sudden failure of back lights.

Hi Harry,
Yes it should be 68 k ohm (start up resistors). Sometimes the heat could change the color of the resistor band into a dull color.

Sir Jestine,

I have a Samsung Syncmaster 173V with the problem described below.


1. LCD standalone (not connected to cpu) animated box “check signal” can be seen moving on the screen, upper & lower backlight lit. (normal display that can be seen when monitor is not connected to the cpu)

2. LCD connected to cpu screen black no backlight no animated box power LED green steady.

Test made with the above scenario 1:

I momentarily connect the vga connector to the cpu then the display will turn off (as stated on scenario 2) but after removing it from the cpu the display will appear again (as stated on scenario 1). If connected for a minute then remove the display won’t appear anymore you have to turn off the LCD remove the vga connected to the cpu then turn on and scenario 1 will appear again.

Only 2 boards can be seen on the LCD power supply and the mainboard with the following IC SE7889-LF and bios GM 1.6EK 09.03.2005 G (A4E9).

Since the i can see “signal check” animation on the screen i assumed that the power supply & inverter is ok. That leaves me to suspect the mainboard.

What could be the problem? How could it be fixed?

Thanks and best regards,


Hi Noel,
Your problem is very common and the problem is in the MCU (MAINBOARD). I bought the mainboard from my repair friend and i have replaced many of them. Try find samsung distributor to ask for the board.

Hello Jestine,

My compnay would like to inquire if you do trainings here in the Philippines for a group 5 to 10 people. If you do how much do you charge for the trainings and how long is the training? Hope you can advise on this inquiry.

thank you and regards


Hi L,
Thanks for the interest in the training but sorry i don’t provide training in oversea as it is not easy to set up all the necessary tools, boards, test equipment and etc in other country.

Do you think the Huntron Tracker 2800 would be justifiable for troubleshooting laptop motherboards?

Hi Danny,
Most of the people that buy huntron tracker is use for comparison purposes. That means you must have identical board to compare the signature. However there are also some techs that don’t repair circuit board if they don’t have the huntron with them. I have use the huntron to test on the coils, resistors, capacitors diode and etc and i found that digital meter is more accurate in reading the resistor value (huntron can’t check value of resistor), Blue ESR meter for e-caps, Blue ring tester for coils and analogue meter for diodes.

If you don’t know the right signature of the laptop motherboard, you would not know if the signature that you got is correct or bad. Invest in scope is much better than huntron unless you have the similar board for comparison of the signature.

Best regards,
Jestine Yong


Hi mr Yong,

Many thanks for the update.
Also your LCD repair book is great…lots of information inside.
you and your family and friends doing a great job.

Greetings from me and my family too.





I want to know from you that how to test electronic circuits? I want to learn abt different kinds of testing.


Waiting for your favourable reply.


Hi Bobby,
By using scope, voltage testing and understanding of how electronic circuit work so that you know where to do the test.



Hi Jestine,

How are you? Do you know how i can get some help? I am looking for used or nonworking LCD monitors or Tv…Need to practise the info that i am getting from your ebook……….

Pleaseeee help

thank you


Try buying from ebay dot com or any local tv repair shop for junk tv and i believe they have a lot waiting to be discard.


Why dont you write an ebook all regarding how to repair the crt monitor beside the lcd monitor repair and all the symptom?

I wish to but have to finish my SMPS repair ebook first.

For the zener diode tester sure i’ll make one like i make one dick smith fbt tester and it works pefectly.I have 2 fbt tester the one i made it myself and the one i bought it from you.

Thanks for the support and hope you can make one soon.

Thanks alot for your support that give me more knowledge regarding repair tips.

No problem!

In future sure I will go to your place to visit you and any way if you come to Kuching try to contact me.

You are welcome to my place and if i have the chance to go Kuching i will contact you.



Hello, I was wondering if you could help me solve a problem. I have an Acer AL1916 LCD display. It powers up for a few seconds and then turns off. The green LED stays lit on the power button; and I can see “acer” for a few seconds on the screen. I have replaced the inverter board and the logic board, and the power button panel to no avail. I am suspecting a lamp problem. What do you think?


Hi Jason,

It could be a bad backlight problem, bad inverter ic, dry joints in the high voltage transformer area and etc. Please visit my blog post at

for more lcd monitor repair tips.


hello sir,

im just confirm if i buy LCD Repair Monitor Book the price is just $47.7? no other fees included?


Hi Kay,

The total cost of my ebook is usd47.77 but it depends on your country whether any credit card transaction they would charge more or not. In my country there are no extra fees included if i buy book/ebooks online. Have a good day!


Hi Jestine,

I had downloaded and read your e-book and others. It was an excellent
resources and it helped me to understand more about troubleshooting LCD
monitors. Thank you very much.

Best Regards
Hung Nguyen


Hi Noel,

Where can we buy a good MCU programmer?

You can key in the part number into google and there might be some company is selling it. But it is a blank IC.

How much is it?

I came across one few months back where an american company is selling for usd2500+ just for the programmer alone.

Also, where can I get some hex files?

You have to get from a good board first and save into your computer.

Since i do not have the programmer thus i could not get any hex files, otherwise i would just email to you.


Hi Jestine,
Well whether it’s the remote or manually pressing the power button it lights up then turns off then the power button light will blink 3 times. You hear a sound in the back of the tv like it’s trying to turn on. Before I would have to press the button a few times until it finally turned on then it seemed like I had to keep pressing it more and more until it finally turned on. Like i wrote before the picture and sound were fine it’s just that now it doesn’t matter how many times I press it or use the remote it doesn’t turn on. But the light on the power button comes on. I would appreciate any help.
Thank You,

Hi Robert,
It could be a sign of electrolytic capacitors failure in the power side and possible of dry joints too. You have to open up the tv set and test it out. Please let me know how is your outcome-thanks!


Hi again,
I’m wondering if you’ve had any experience with repairing GPS devices?
Someone brought one to me for examination after it had been thrown across a car with the auto power unit plugged in. The power socket inside the unit was ripped loose on one side & the battery (Lithium cell) won’t charge, even from a house current adapter. The battery itself is good, the protective circuitry is not allowing it to charge. The unit seems to be built on a multi-layer circuit board with few traces visible. I could find no connection from either + input & the battery connector or any thing else. I had re-soldered the auto adapter input power socket. The house current adapter connector is different than the auto-adapter connector & doesn’t appear to be damaged.
I’m also wondering if these devices use elastomeric finger connections to the display, similar to hand held calculators? If so, throwing this device would ruin it.
Any thoughts on this would be welcome.

P.S. The Auto-adapter only puts out 3.5 V, however it’s rated at 5 V.
The system is a MAGELLAN 3100 Maestro.

I wish to help but have no experience in GPS repair thus i can’t offer any expertise advice to you-sorry!


Hi Farid,

Wishing you “Selamat Hari Raya and Maaf Zahir dan Batin”. Okay back to your question:

Still got the blues using the ESR meter when testing the HV capacitor. Recently A friend of mine come to me with a faulty electronic fan controller. Upon receiving it I tested and found the control voltage is going up and down between 3.2V to 3.8 V. Judging from the zener diode marking it can produce 5V. from experience the voltage up/down is a capacitor breakdown. There is 3 capacitor A. 2.5uF400Vac -ESR 0.1 , B. 1.2uF350Vac -ESR 11 C. 0.1uF275Vac ESR 19 .Not to waste any time I bought all the capacitor.The ESR reading is very near and it confuse me. So how exactly to use the table since the capacitor is partially breakdown. The problem is the 1.2uF350Vac -ESR 11 upon replacing it the voltage stabilize to 4.9V and the controller return to working.
Have you check on the capacitance value of the three capacitors? Some capacitors can breakdown when under full load (insulation problem) and you need an insulation tester to test it out. If the capacitor breakdown when under full load then the BLUE ESR meter can’t play it part in finding the problem. If you have the time i wish that you could come to my company and bring along all these caps (the good and the bad one) so that i can test it out with my insulation tester. If you have other questions please do email me again. Have a good day!


Hi Mark,

A 2SC5707 transistor in your Dell 173FPb monitor is shown. The report says it should have an hFE of 320 to 390 for a good reading and a bad reading is like 490. What did you do to determine the range of 320 to 390 and is your calculation method able to be applied to other transistors for determining their good hFE reading? If I use a data sheet for hFE on the 2sc5707 it notes that minimum is 200 and maximum is 560 with 2 volts at 500mA applied. Any idea what the Dell LCD monitors have for their specification about the correct voltages and currents applied to the transistors?

From experience, i got one exact type of C5707 that have a shorted leg at the center and it has HFe lower than the original reading and transistor run very hot and eventually brokedown. I returned the batch to my supplier and got back the batch that have long legs and the HFE reading is from 320 to 390 and the transistor worked with no problem. Sorry i do not have information about the correct voltages and current applied to the transistors.

By the way I had another Dell 172FPb monitor come to me for repair. It had the blinking power light. I checks all the backlight inverter transistors and had 2 that were totally shorted out and 2 were Ok including hFE reading. I replaced the transistors and it came right on.

Good to hear about that!


Hi B,

Today I practised to desolder SMD components from some bad industrial board, and I hardly managed to desolder some capacitor and diode. I wonder how could you desolder SMD Inverter IC, do you use SMD Rework station to do that?

Yes i do, with rework station you can extract IC within seconds or a minute

I found that the SMD diode has 3 pins, what is the function of the third pin? The one that I desolder and checked with analogue multimeter has no reading with this third pin.

The SMD is actually two diodes inside connected facing to each others or some have the cathode of the diode connected to the anode side of another diode. You must know the internal connection before you can test with a meter especially when you are just starting out dealing with SMD components.

Could you recommend good and yet cheap SMD rework station, I also want to invest one in the future.

The one that i bought was made in China and they come in with many different brand. A good one is the Goot or from Hakko.

I also run into what is called PIN diode, what kind of diode is that?

Please refer to

Due to difficulty in finding parts here in Indonesia especially SMD parts, how do you think if I buy some bad LCD monitor to salvage some of the components?

Yes, its a good idea to do that.

How to estimate the price, since I couldn’t open it up to see the internal board condition?

Bargain till as a cheap as possible and get the seller to make sure that there is board inside and no one had touch it before.

Could we salvage many parts from computer motherboard to be used when repairing LCD monitors?

Not many parts-mostly i bought it for my students to practice on how to use rework station.

How do you get dtr SMD, for example A6J & A8J?

Surprisingly i got these two transistors from used motherboard. However both transistors rarely have problem.

Is there any coil SMD? Because I saw SMD components labelled L1 in PCI modem board.

Yes there is.

Last time when you went to Pasar road you also got some heat compound & shrink tube, could you describe what are their use?

Heat compound- use to apply to the back of transistor so that it can be attached to the heatsink and causing the transfer of heat faster.

Shrink tube-use to cover the area of any connection between two jonts of wires, cables etc. When heat is apply to the shrink tube it will shrink and become very tight and this will look more professional compare when you close the joints with black tape.

Best regard,
Jestine Yong


Thanks Jestine,

The lord is my helper am only having problem in getting the part for replacement, like mosfet here in Nigeria is a big hindrance to my side, after testing equipment and seeing the fault you cant repair what will you do, on your own side try and see how you can help. cos i will not give up

Hi Henry,
Usually i will get used equipment as spare part and if i really can’t locate one i will offer the customer to buy over the equipment for future use to salvage the components.


Hi Jestine,

Thanks so much for all your letters and advises. Really I am finding them interesting and educating. I am slowly becoming a better technician. Recently our small company won a tender to repair equipment for the Police Service. This includes Power Supplies, Oscillators and radio equipment like Outdoor and Indoor units. I will need more specific advise on those when the items are collected or when I get more information about them. Again I would like to express my gratitude for your assistance so far and in the near future.






  1. sam

    February 12, 2009 at 10:59 am

    Hi Jestine
    Just receintly bought both the bluering tester and the esr meter which i havnt as yet constructed,im having problems with the ring tester,when the battery is connected all the leds light up,switch them off ,all is ok,then switch it back on ,nothing happens,when i disconect the battery and then connect again all the leds light up again, is this a problem with the ics.looking forward to your comments

  2. admin

    February 13, 2009 at 10:56 pm

    Hi Sam,

    It could be the problem with the IC or you may have some components that are wrongly installed. Here is the link to answer your blue ring tester problem at:


  3. arthur

    February 22, 2009 at 5:39 pm

    Hi Justine. I am one of your viewers on your website. I need help regarding my samsung syncmaster 591s. No display but no animated box “check signal” when I disconnect it from the CPU. When I connect it with CPU, I observe the power light, power steady when the CPU running and when the windows logo comes out, blinking and then steady light. Still no display.

  4. admin

    February 22, 2009 at 9:12 pm

    Hi Arthur,

    When you say steady light, what color is the power LED? If it red suspect a bad mainboard. If it green then check for the supply voltage to the inverter ic. The inverter ic should have voltage otherwise there will be no display or the display will be very dim.


  5. arthur

    February 23, 2009 at 11:20 am

    but the problem no, where do I located the inverter ic? thanks for your reply.

  6. admin

    February 23, 2009 at 11:32 am

    Hi Arthur,

    The inverter IC is at the inverter board and nearby to the high voltage transformer.


  7. Danny

    March 8, 2009 at 10:23 am

    I have a Dell flat screen model #e172fpb,, when ever I turn it on, the power button blinks and I get a vizual only for one second.
    I can slightly see the picture flashing, but its real dark after that.
    Is repair within reason?

    Thank you for your time !


  8. admin

    March 8, 2009 at 4:14 pm

    Hi Danny,

    It could be dry joints, bad transistors or even bad backlight. Try visit this link for more lcd monitor repair tips:


  9. pigkho hestanto

    May 12, 2009 at 6:24 pm

    i have some trouble with samsung SyncMaster 591S.
    my monitor have red color to strong, ......
    i have to try, with manage color setting on monitor.....
    but nothing ....

  10. admin

    May 12, 2009 at 7:58 pm

    Hi pikpho,

    You need a softjig with the Samsung software to adjust the color setting.


  11. Renato Valera

    August 7, 2009 at 10:18 am

    hi jestine,
    i need your help about hex file of samsung 153v model. i need this file to correct the problem No display.
    i hope you can help me.


  12. admin

    August 8, 2009 at 12:22 pm

    HI Renato,

    Sorry i do not have the hex file. Do you have the programmer to program it and where did you get it?


  13. sai

    September 18, 2009 at 7:02 am

    hi jestine,

    my dell 172fpb lcd monitor power light is flashing,no display.can u please give me solution for that......cheers.

  14. admin

    September 18, 2009 at 11:20 pm

    HI Sai,

    Is all the output voltages stable or fluctuating?


  15. mohd

    November 26, 2010 at 12:07 pm

    gps saya mempunyai masalah tidak dapat dicas dengan sempurna menggunakan
    charger in-car. walaupun sedang dicas,screen pada gps mengatakan battery low
    dan semasa cas,belakang gps tersebut agak panas.saya kini bekerja di perlis
    dan membeli gps tersebut di sebuah kedai di kangar.saya telah hantar gps
    tersebut untuk repair di kedai asal saya membelinya,akan tetapi masalah
    tersebut masih lagi berlaku.harap pihak tuan dapat membantu.Model gps saya adalah GPS MEDIATEK 5" SCREEN LCD, S/N : AN849MA64M128M1007P yang dibeli pada 22/9/2010. Saya bertanyakan kepada kawan saya, beliau kata kemungkinan besar model tersebut adalah buatan China. Saya berharap agar pihak tuan dapat membantu saya atau memberi suggestion atau advise.thank you.

  16. admin

    November 29, 2010 at 8:53 pm

    HI Mohd,

    Oleh kerana saya tidak repair gps maka saya tidak dapat memberi jawapan yg tepat tentang masalah gps itu. Dari penjelasan kamu, saya dapati bahagian charger circuit dalam gps ada masalah. Ia kemungkinan masalah voltage regulator ic ataupun semiconductor yg lain dah menjadi panas. Barangan buatan China biasanya tidak mempunyai kualiti.



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