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Electronic Repair Questions/Answers and Testmonials- Part 61

By on August 15, 2010

Hi jestine,

 

Thanks a lot for your electronics repair. I am very appreciated you send every month to me.

 

Your information is very helpfully for me to improve my repairing and troubleshooting skill.

 

THANKS AND REGARS

 

 

RAMLI

 

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Hi Tyrone,

I am repairing a Samsunc  television, which is proving very difficult at this moment.
I believe that this television was manufactured in China, and it is very difficult to find components for this television.
When the flyback transformer is on the circuit  board the television is not turning on, but when the FBT is removed from
circuit the power light at the front of the television is lit. The FBT has tested good, and the B+ and the voltage supply which goes
up to the CRT board is  ok, when the FBT is removed from the circuit board.The B+, CRT voltage supply and other voltages
all drop when the FBT is reinstalled on the circuit board, and a very low pitched squeal can be heard somewhere on the board.

FBT can be breakdown when under load. try remove the anode or even the crt board and power on-but you need to be careful.

On Monday two transistors in the powersupply shorted while I was working on this television,and I cannot find these components in
any of the electronic shops here.The two transistors are 1802FX and DA3807.I have tried to find a cross  for these components without any success.Jestine if you have any information on these transistors please let me know, and also tell me if there are other transistors which I can use.

Sorry no info on such parts. These manufacturers made us repairer have headache by coming out with those funny part number.

Jestine

 

=========================

 

 

 

Dear sir jestine

 

 

Request you to please reply me ,if it is possible to find out the faultycomponent with your esr capacitance meter in circuit ,without disconnecting the components in a switch off mode situations.

 

Waiting for your kind reply?

 

 

Regards

 

s.chandra

Goa-India

 

Hi Chandra,

Yes you can check it on board but you must turn off the power

Jestine

 

==============================

 

Hi Endale,

I Thank you VERY VERY MUCH for the support you done for
me. In fact this is my second mail , I fill shame when I say this.

Please don’t feel shame-no problem

Because with out any payment you have been sending every month the news
letter. Those mail made a change in my electronics know how. I apperciet
and respect your help, done for me again. On top of that I am trying to
have your e- books from another country by asking my relatives who leave
in USA and they promise me, we shall see, and I am very eager to read those
books like lcd and plasma tv books.

The LCD and Plasma are not ebooks and these two websites belong to Mr Kent.

I hope I will have it in the near
future. This time our world languch is (skrach my back and I will scratch
yours). But Mr. Justine is not such a person, I will give the witness
because I am one of the user of your system. What I can say here after is
LET GOD BLESS YOU, YOUR FAMILY, AND YOUR JOB TOO.

You are welcome-take care and May God bless you and family too.

Jestine

 

=======================

hello sir 

sony crt tv…what cause of single bright horizontal line across the screen (sometimes red color,yellow,and white bright color…?when i replace the vertical and horizontal ic theres no reaction.the b+ is 115 and the back of the picture have light…the sound is clear…

Hi Jayron,

Have you check the supply voltage to vertical ic? Make sure the vertical yoke coil have ohm reading.

Jestine

 

=============================

 

Hi Watneigh,

I have been trying to find an analog meter with a X10k  ohm  setting and which uses a 9V battery .

You said the 3V (powered by 2 x 1.5V batteries) meters cannot trigger the transistors when checking for faults so I cannot buy a 3V meter for troubleshooting components.

Yes you need an analog meter that have the 3 v and the 9 volt batteries.

 

However I found an analog  meter on the internet that uses a 9V battery but it has a X 20k ohm setting( it does NOT have a X 10k ohm setting) . Can I set this meter to X 20k ohm setting and use it to check electronic components?

 

I have not seen such meter before. If this meter use another 3 volt battery than you can get this meter. That means if you the the meter probes with another dc voltmeter and it should have 12 volt. For your information the Sunwa analog meter is very common in the market nowadays and you should easily find one in one of the electronics shops.

Jestine

 

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Hello Jestine,How are you?

I’m fine thank you.

Here i want you to help me to solve this problem,”I have my own Tv 21″ panasonic the problem is : One time my Tv is fall down into the wood floor by my son.so after the incident had happen my Tv still working properly like power,video,picture,sound and everything ok but only one problem i have it is:In the screen have rainbow colour from bottom to the centre of the screen,i mean like flower,just like little Y,(rainbow little Y).

            so can you help me to show what i should do,and what i check first and what the part of the Tv i should replace or what else?please……

thanks’very much i will wait you bye….bye. god always bless you Amin…..

I guess the internal shadow mask had came off thus this problem can’t be repaired. To confirm it, just use a degausser to degauss it and if the color patches problem still there then you need to replace the pc tube.

 

oh ya i forget to tel you last two week i had purchase on line your e-book “How to find burn resistor value very nice but right now i don`t have any time yet to red at all but very-very good.thank`s jestine.

Thanks for the support!

Jestine

 

===========================

 

sir,good day,,,i already fix the 14 inch,color tv,polytron…now i realize what is the cause,,i already replace a total of 4 deff.components,and re solder all dry joints,,,the tv is back to life again,,,thaks for your support sir,,,,and also your advise,never giveup attitude,,and your tips,,study the function of the board,,and understand it,,,you know sir,to fully trouble shoot the tv,,i dismantle the anode cap and pull out the whole board,in order to acces theme,,,thanks sir,,,

 

Roger

 

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Hi Roger,

sir good day,i try already the dvd to the other tv is working,but when use in sanyo they cannot detect the dvd player,,,,the tv board has a smd component,,,this tv has 2 output ,infront  of tv and at the back,,two output audio video,,both have no function,,,there is the posibily the ic that controlling theme sir?pls,give me a idea sir,,,thanks,,,

I have not repair such problem but yes it can be the ic problem that controls the interface. Check also the supply voltage to the control circuit in the TV.

Jestine

 

============================

 

Hi Damian,

Jestine: I have two LCD Mon HP1740, boht use the 2sc5709 in the inverter that is part of the Power supply board. The CB goes in a second board. Both monitors uses a configuration of 4 2SC5709 and two p-channel Mosfet fairchild FQU11P06. One of the Monitors Power Supply is very damaged because two of the 5709 was burned and one of the Mosfet also.

Noted!
In the other PS i could replace the two burned 5709 and the Monitor works perfect, only the problem is that it is not possible to switch off the Monitor. When you switch off the monitor screen appears white and can not be switch off. If you push the switch again the monitor will start working completely normal until you try to switch off and every thing repeat again.

Noted!

I used the “good” Power supply (better say the working PS) in the Monitor with the bad PS and the result was the same, so the problem remains in the PS and not in the CB neither in the screen. I take off from the working PS many Caps trying to solve the problem but the problem still remains. Have you any input that can help me to solve that problem ? If you need photos of the board I can send. Thank you in advance, Regards, Damian Dubrocq.

After you have pressed the power button, i assume the Mainboard still sending the On signal to the start circuit thus the inverter will be turned on. This will cause white display. This most probably due to a bad MCU in the mainboard.

Jestine

 

================================

 

Hi Bailing,

I had checked all the e-caps at the primary & secondary with the ESR meter, all are OK, and after replacing some e-caps the problem still remains.Now giving a 24V bulb as a load, the bulb is blinking.

Since this board had been repaired by someone before thus it may give a little bit problem for you. You have to make sure no hairline crack, no dry joints, no adjacent shorts between components and etc.

I have taken some voltage testing at the KA3842A pins, and found the voltage at VCC (pin 7) is also fluctuating from 10 to 15 V. The voltage at pin 8 is almost zero. After I took the SMD IC out, the voltage at Vcc became 20V ( stable ) and the voltage at pin 8 VRef was still almost 0 V.  What should be the voltage at VRef? What conclusion can be made from above measurements?

The Vref is 5 volt if only the power ic and the surrounding components is working. It may be the power IC or the surrounding components have problem. Check also the primary winding of the transformer.

About replacing the inverter card in repairing LCD monitors, what would be the result if ENable and ADJ pins are reversely connected?

Sorry i have not done this test before thus i can’t give any comment about it.

How to know these two pins exactly if there are no marking on the board?

Enable voltage is usually constant and the adj can be adjusted

We all know today the notebook repair is the best in terms of its repair fee, but only a few of us doing this kind of repair. Do you know what are the difficulties in doing this kind of hardware repair?

What i could see is the motherboard and the lcd panel. The power adapter, inverter, and backlight have the function as the lcd monitor except that it is smaller. When i was in China, those shop sells lots of panel, inverter board and even i could see the repair tech repair motherboard (i presume that they can easily locate the motherboard parts). I wish i have more time so that i can venture into laptop repairing courses and write an ebook on laptop repair.

Jestine

 

=================================

 

Hi Mervin,

The transformer is original.The leads of the transformer goes in to the PC board sockets,one leave the socked goes to a 1N4004 diode exit the diode and goes enter 55ohm resistor connected in series with another 55ohm resistor (at the series point the board has burn black not making a proper connection so restricting the current flow)the resistors is fine I just solder a Brig piece between the 2 series points.The controller is testing fine now.

The transformer output 26vac, controller input asking 24vac,why did the resistors series points burn?what can cause it to become so hot?The controller only energise 6 coils for water sprinklers in the garden and 1 water pump.Could the coils be damaged and send a feed back of some sort? I will test them tomorrow to see if i can find something.

Sorry i thought the board is running on a 24 vdc. Usually when a resistor burn, it could be due to extra current draw from the load. The extra current draw can come from shorted semiconductor like, diode, ic, transistor, scr and etc. A shorted coil can also cause the resistor to burn. Hope to hear good news from you.

Jestine

 

=================================

 

Simon,

 

My Instructor,

be informed that i have been receipt of two meters respectively

Blue esr meter and Blue ring meter on 27th july,2010. They are perfectly well (in good condition)

Thank you very much may the God Bless you and your family in

abandunce for your kindness to people like me.


Good to hear that and thanks!

 

 i would like to bring to your attention one of  a Plasma Tv

Model number no.MP-42HU32-SINQTECH -42 inches.

on the lumination part (inverter board-ic.no.BD9897FS,H46SN like P channel,in form a transistor H4 Z smd device ) they are two separate circuits for back lights buttom and top.It is stuck in standy by the voltages and currents are present and correct from power supply, there is five (5) volts in the stand by circuit,when i press the power button on the remote control the 24 volts is always present on both  pico fuse and this pico fuse they are not open circuit.

There is 24 volts on both inverter ICs BD9897FS.at vcc but no voltage out put on H46SN,H4 Z. In this situation  what could be the fault? Is it possible that all inverters IC on both sides can be at fault?

This is a LCD TV and not Plasma TV. Plasma TV does not have backlight. It is unusual that all inverter ICs have problem. I have not seen this problem before but you can check to see if all the inverter ICs is receiving the voltage or not. If it is in standby mode then the main power supply may not producing good voltage but you mentioned that there are 24 volt! Check to see if the mainboard ICs especially the MCU is receiving good voltage or not and make sure the MCU crystal have sinewave.

Jestine

 

========================

 

 Dear Sir Jestine Yong,

 

The output of the voltage inverter is in between 300-1300V.Is it possible that i can measure the output high voltage of the inverter using an analog volt meter having a capacity to measure a large amount of voltage?Is there any other component that might be damaged if im going to measure the said circuit?just to know the presence of high voltage

 

Thanks and more power!

 

HI Abet,

You can test it using analog meter and if you see that the needle kick up very high then quickly pull out the probe. Usually when the inverter have problem it is either no, low or produce full ac voltage.

Jestine

 

===============================

 

 

I came across your excellent site while searching for the info regarding the repair of the SMPS. I am a research assistant in University, and we have very important piece of equipment which SMPS stopped working. Initially, I found two blown main fuses, replaced them, and they blew again. I replaced them again, that time the internal fuses (somewhere after the secondary winding of the transformer) blew. Also, some diode or Zener was burned out. I replaced the Zener and the fuses, the fuses blew again. The main terminals are shorted. Now, I disconnected the transformer – no short circuit across the main terminals. Does it mean that the transformer is defective? Or maybe the problem is somewhere in the other place, downstream of the transformer (IC, switching transistor)?

Thank you,

 

Hi Anton,

Yes it can be the transformer or the components downstream that draw too much of current. I suggest that you connect a light bulb 100 watt in series with the mainfuse so that you do not need to replace the fuse just incase if there is something shorted.

Jestine

 

==================================

 

 

 

Hi Jestine,

 

I need help or advice please.

 

it seems that i have lost my touch with some LCD’s

 

I find a lot of LCD’s have a similar problem of loosing the display after some time.

 

Some switch off after +- 30 seconds others after 5 minutes and so on.

 

i normally change all the caps on the power supply.

 

But lately i have had little success.

 

I check the all the power that go’s to the controller board.

 

 

Please give some better guidelines for these problems.

 

I also find that LG displays do this often.

 

looking forward to your reply

 

 

many thanks

Hi William,

You mean the display or the power switch off? If the display switch off then check the backlight because if one of the backlight have problem it will switch off.

Jestine

 

========================

 

Hi Dear Mr Yong;

hope you are doing great!! i need your expert comments on following issue, please reply me when  you are free.

I’m troubleshooting somewhat old “YF-1150A” capacitance meter. When I received it didn’t work at all. I found some signaling transistors got burnt. Having replaced them, I was able to fix major issues and now it’s reading is almost correct. However, after 3,4 hours of repairing , the meter’s idle value is changed to -00.2,-00.2.-0.4 (idle value should be 00.0 when any button is not pressed.).

The mystery I found was this, when the idle value is changed (to -00.4 or -00.6) If I remove some parts (ex: transistor, capacitor..) from the PCB and resold them again as they were on the board, idle value comes to “00.0” again. but after 2,3 hours it go wrong as it was.

So I thought this can be a result of a “bad capacitor” somewhere in the PCB. so I replaced all caps and checked all transistors. But the issue remains same.

This meter circuit is based on The ICL7106 A/D converter. Please see the diagram and pics I have attached herewith. Could you please let me know what should I check.

best regards!
Kushan

 

Hi Kushan,

Although i have not repair this capacitance meter before but from your description you can use a hair dryer with a small nozzle (you create it on your own the nozzle) and point to the components one by one.If the value change then you know that either that component or the corresponding component have problem. You may also use a freezer spray to locate the fault. The CPU can be the cause too.

Jestine

 

===================================

 

Hello! Jestine,

 

 Could you give me more information regarding HOT and Cold grounds and its testing. I am a newbee on this subject your assistance is solicited .

Hi ALZA,

Hot ground is the negative side of the big filter capacitor in Switch mode power supply. Cold ground is the earth ground. That means if you want to test the voltage in primary side of power supply your meter black probe has to be connected to the HOT ground. If you wish to test on secondary side then your black probe has to be connected to the earth ground.

Jestine

 

=================================

 

Hi Simon,

i would like to hear from you first as my instructor,it is in respect of e-book for Mr.Kent (plasma tv repair book ) which i came across on your web-site,what is your recommendation?

His one is not ebook. It is a membership website and consist lots of  plasma schematic and some related information. If you plan to repair Plasma TV then you are encourage to join otherwise don’t get it first.

fault report.

(corrupt display very dim) with vertical lines

the LCD monitor 19″  Meccer ,model:no.JM777  is taking too

long to show good display and the mouse pointer moving very,very….slowly on the screen but when there is good display

the mouse pointer will be moving normally and immediately when i

remove the VGA cable or off and then on ,it will return to the corrupt display, the proccess will start again.i have changed the capacitors on the secondary side of the SMPS that had gone high or low in value with the help of ESR meter at least it has improved  a bit. looking forward to hear from you.

 

If all the voltages to the mainboard and the LCD CONTROLLER board are good and stable then suspect a bad LCD panel. The only thing that you can do on the lcd panel (which include the lcd controller board) is to reflow the board. Hope this helps!

Jestine

 

==================================

 Hi Justin,

I have problem with my Samsung Syncmaster 633NW wide LCD Monitor,

“muncul garis2 horizontal berwarna putih tebal dan warna lainnya kecil2
disebagian kiri layar, apa penyebabnya dan bagaimana memperbaikinya?”

Thanks for your kindly help and advise

Rgrds

Andree

 

Hi Andree,

Kerosakan pada filter capacitor, kelonggaran pada cable dan juga kemungkinan besar kerosakan pada LCD panel (very common).

Jestine

 

============================

I do have a question I have a view sonic 26′ monitor how do I check it when the light bulbs are no good, thanks

 

HI Mario,

You need a ccfl tester to test it:

http://www.hrshop.es/index.php?command=viewProduct&id=73211

Jestine

 

=============================

 


Hello sir,

Hope u fine in god’s grace

I’ve got a dell monitor in dead condition. I’ve found some bad resisters in B+ area which i’ve replaced with new resisters.

Now the problem is, the resistors gets burn’d out when i switch on the monitor..

what will be the problem?

pls help me out sir.

 

Hi Jim,

I suggest that you check the surrounding components that have connection to the burnt resistors. Sometimes a shorted flyback could cause the resistors to burn.

Jestine

 

=============================

 

Hey
Jestine,

I wanted to see some tips on repairing CRT monitors from their blogs launched in 2007. But I do not know where to find these tips. I would appreciate your help.

Thanks,

Manuel

 

Hi Manuel,

Try here:

https://www.jestineyong.com/?cat=27

Jestine

 

=========================== 

 

 

Hi Clodualdo,

Good day to you… just wanted to inform you that I have requested my employer to order your fantastic Blue ring tester and Blue ESR meter. As I have learned in your site that this testing device is really important in electronics trouble shooting.

Thanks but at current moment the blue ring tester is out of stock due to overwhelming demand after i sent out the August repair newlsetter. However, i have the ESR meter. The new stock will be arriving by end of this month.

I am an electronic engineer on the ship under the Entertainment Dept. In electronic trouble shooting, I have always having a hard time in testing of some electronic components, specially electrolytic capacitors. it is true, some bad caps shows good in digital and in analog multi meter. and it needs to disconnect each caps for testing and its really time consuming.

Yes it is true and i have collected lots of e-caps that tested good with capacitance meter/analog meter but fail using ESR meter. You can test on board too saving your repair time.

This testing equipment was registered to our consumable tools fleet wide. And if I found out that this is really helpfull in electronic repair, I will strongly recomend this instrument to all electronic engineer in every ships.

Thanks for recommending.

Adding up, I am still enjoying your very imformative E-book (testing electronic components and LCD repair by: Kent)

Thanks for the support and hope you have a great time working on board the ship.

Jestine

 

===========================

HI Bailing,

Before the photo of genuine and fake C5297 was taken from the front, now see it carefully from behind. Again you could see the fake one at right has some uncut plastics between the pins.

Thanks for the photo.

This LG Studioworks 452V monitor has 2 black cables from mainboard to the top of the convergence board ( several rectangular turns, see the photo ). What is the use of these turns?

If I’m not mistaken, it is for horizontal centering.

Another LG 15″ CRT Studioworks 520Si is still having tic-tic sound after replacing the flyback with a new one and confirmed that internal capacitor of the new flayback has 3.05nF, though not so often heard ( longer period between the tic sound ). Why is this
monitor still having the tic sound after replacing the flyback?

The internal filter cap can be breaking down when under load. You may need to use another flyback to retest if you are really sure the tic sound was from the flyback.

Is the method of removing B+FET is applicable to both buck & boost circuit?

Only for boost circuit. If you remove the fet in buck circuit there will be  no voltage going to flyack thus no high voltage.

Jestine

 

===========================

 

 

Hi Jestine,

 

     I have 1 question about TV IC part num: LA76931S,is this component type having  program installed inside Or it is same as other common IC. Because some people told me that this kind of IC is a programmable type and need a program before it can be used for a new replacement. Just for a clarification.

 

Regards,

Fahmy

 

HI Fahmy,

No this is not a programmable IC.

Jestine

 

===========================

 

Thank you for this month newsletter about full use of the Blue Ring meter. Yes, this meter helps me a lot with the monitor repair work.

 

Bailing

 

============================

 

Can i use blue ESr meter to check Ceramic and Non-Polarity Capacitors On Board

 

Hi Tamel.

Yes you can but the value has to be .1uf and above.

Jestine

 

==========================

 

 

Sir, i had already buy your 3 set ebooks, testing electronic, lcd repair, and find burn resistor.

i just curios about lcd, i have one case which the lcd was hit by lightning, is there any cure/fix for this??

 

HI Hendrik,

It depends on how severe is the strike. You may need to check all the components in the power side. If there are too many components burnt then it is not worth to repair.

Jestine

 

============================

 

Hi Jestine, (My mentor)

 

Thank you for your latest update. I have a 100 cm large LCD screen for repair. It is part of our screen wall. It keeps bringing up an over heat alarm. Have you any clues as to what this may be please?

 

Kind regards,

 

Dave.

 

Hi Dave,

Could yours is a Plasma Tv because rarely hear of LCD TV have this kind of problem. In your case the internal fan or the circuit that drive the fan may have problem and this cause overheat in the circuitry. I suggest that you check on the fan first.

Jestine

 

===========================

 

HI Mickey,

i have a dell 15″ monitor E156FPb and it has a black 2″ verticle line down the right side  of the screen I changed two resistors  68k and 22k on the main board
and two capacitors on the secondary board when I hooked the monitor up the screen came on without the line thhen after about 2-3 mins the line returned.

Usually, vertical line are due to problem in LCD PANEL.

I’m interested in this stuff and I like fixing things for myself it has always been a part of me since i find that some repair persons give you the runaround and lots of stress when you try recovering your money from a bad job or none at all. I find your way of explaining things to be very simplisic and once you are openminded enough you can accomplish the job .This is my first real try at fixing a lcd monitor .

I’m just like you-fixing things but in your case the LCD panel could be the cause. I have seen  lots of LCD Monitor with this problem and it turned out to be bad LCD PANEL. There is nothing much can be done on the panel except to reflow the lcd controller ic in the lcd controller board.

Jestine

 

=============================

 

 

Dear Jestine,

Sorry, I’m too quick to tell you about the new replaced B+FET shorted again without confirming it. Actually, it was not the B+FET that had problem this time, it was the HOT problem. Originally this monitor has been repaired by me about a month ago, the only problem was the HOT, the origin type was C5297 and at that time I replaced it with J6810.
So this time when the monitor sent to me again, I think it’s better to replace with the original type. But it’s a pity that the C5297 I bought was fake ( the plastic package is smooth like the original, see the attached photo. The left is original and the right is fake ), it’s blown upon turning the monitor on. So now the monitor works with J6810 HOT.

The important lesson I got from this monitor problem is when the hor driver FET is open, it gives the B+FET to much stress, making it always shorted.

Bailing

 

Hi Bailing,

Congratulation! Never give up will see success.

Jestine

 

=====================================

 

HI Azli,

nak tanya monitor gambar kecil kiri dan kanan dan bergulung kadang – kadang
berwarna merah… bahagian mane nak check dah tukar vertical ic dan i2c ic yang ada signal vsync dan hsync, capasitor dan
resistor output yang di defl. yoke pun dah check ok.

Dah check supply voltage? Berapakah voltan kat B+?

selalu keliru dengan vertical dan horizontal…

kalau saiz gambar kecil kiri dan kanan atau ada garisan menegak
-bahagian vertical rosak

Tidak-ia adalah bahagian horizontal rosak.

kalau saiz gambar kecil atas dan bawah atau ada garisan melintang
-bahagian horizontal rosak

Tidak-ia adalah bahagian vertical rosak.

Jestine

 

==========================

 

 

 

Jestine,

 

I have encountered some problems on SMPS(usually used on DVD players)and it took me a while to fix it. what I did is check the component individually and hate to do it as it will take time. Can you please tell me how to make a fast track repair it instead of testing the parts one by one. Thank you so much for your help

 

pedrito 

 

HI Pedrito,

You can use voltage testing to pinpoint which section have problem for example checking the supply voltage to power IC and the output voltages from the SMPS. However, if I’m not familiar with the design i myself too have to remove all the components and test it. Because i have the speed in Testing Electronic components  thus checking the power side area may only take me 10 to 15 minutes.

Jestine

 

================================

 

justine, the power supply is receiving power and puting out power.

But when i connect the board containing the invertor ic and the display perfection(gm2621),

the power supply starts to produce a sound like a capacitor leaking,and the screen cannot display.

 

The equipment in question is hp product____GTG001

 

Peter.

 

Hi Peter,

When you said the power supply produce sound-is the output voltages still good? This could be the inverter board problem too because if there is any thing shorted some power supply will produce sound. Try check on all semiconductor components. If all testes good then suspect Gm2621 IC have problem.

Jestine

 

==================================

 

Hi Jestine,
Thanks for more support about this TV. Actually, only sound problem balanced, I found, blurd picture caused
of substituted YOKE.Because I’m third technician do repairing of this unit,So,we’re looking also what other
technician’s done.I think sound problem coming from TDA9365PS/N1/3S0519 (PHILIPS ) which is comprising of system and chroma. Quite difficult to buy this kind of IC specially here in Philippines.
SMPS working normally, and also sound amplifier section is also working.
Anyway thanks a lot for helping me,.and keep sending me some tips. Someday, I plan to buy some books
and tester like ring tester and other instrument.
Thanks and god bless,
Ega

 

HI Ega,

Sometimes it would be tough to repair others people left over job. All the best to you and thanks for the support!

Jestine
http://www.JestineYong.com

 

==============================

 

HI Nasir,

Bought your testing electronics book couple of weeks ago. It was very informative as I am totally new to electronics.
I always had interest in gadgets but lacked the knowledge of how the physical components work together. And your book helped in providing general knowledge and good tips on how to troubleshoot a scenario.

Thanks for the support!

Having said the above. Their is also another delimma. The specific analog multimeter is very difficult to find. I have already bought two from Ebay which turned out to be the ones with 1.5 V AA battery and are of no use when testing FET’s , diodes and rectifiers. Also information is a little bit confusing (may be due to lack of theory at my end).

The analog meter that you need to buy must have x 10 k ohm range.

The reason I bought your book was to troubleshoot a smps power supply for an external hdd drive. Their was a three legged FET on the hot side of the SMPS board. It’s number is “WFF4N60” 723.

It is a n channel power fet.

A search on the internet states it’s an N channel MOSFET. Question is
1)How can I test it?

Follow my ebook at chapter 27 testing FET.

2)Can I replace it with some other FET?
Yes you can try this number K1118 but i can’t guarantee. The best is to use back the same number.

If yes then how to find out the power of the current FET?

You need to check from the spec:

http://pdf1.alldatasheet.com/datasheet-pdf/view/145546/WISDOM/WFF4N60.html

3)Where can I find the analog multimeter that you are showng in the ebook?

From ebay :

http://cgi.ebay.com/Top-Analog-Multi-Circuit-Tester-Multimeter-Multitester-/320203566013?pt=LH_DefaultDomain_0

If you have other question please do email me again.

Jestine

 

==========================

 

Hi Olaf,

 

First let me tell you that I’m not an electronics professional. I’m the type of guy who takes things apart to fix them and does whatever I can to figure things out. I don’t even really have the necessary equipment but if I know what to look for, I’ll go buy what I need.

Noted.

The other day my stereo went out and a puff of smoke came out of the box. So I opened it up and it was easy enough to identify what blew. Went to the store, bought a replacement, re-soldered it and its back to use. I would have paid upwards of $100 to get it fixed and it literally cost me a trip to Fry’s Electronics and $3 for the part.

That’s the good thing about DIY.It can save the cost.

 

This time, the problem is that it has not burnt out all the way yet. Its very intermittent. It will be on for a while then it shuts off. I opened it up to look for anything obvious but I really couldn’t find anything in particular. However, I did see something that shows signs of over heating since its a little brown.

 

I’m attaching pictures. Feel free to file and use these in your business, they’re large enough to have in case some needs to compare boards and doesn’t have another monitor in hand.

Ok thanks!

 

There are 4 images, one is the power board, the other I assume is the inverter. The third image is the power board but I circled in red what i think may be the problem. The last image is just a pic of the monitor itself.

 

Thanks for the photos. Well it could be that device but chances for a bad lamp would be higher. Try clean up the device first and turn it on for sometime. When the monitor shutdown then quickly touch on the device to see if it hot or not. Before that you need to make sure you have discharge any big caps around. In fact if you have a tester you can try to check the condition of the over heating component.

Have a good day!

Jestine

 

============================

 

How can I solve power supply fan not functioning Sir?

 

HI Lazarus,

Make sure there is power to the fan. If no power you may need to check on the circuitry. If there is power, then you can either service the fan by applying the oil based to the back of the fan (you need to peel off the sticker and spray to the center point) or to replace the fan since nowadays the fan price is so cheap.

Jestine

 

==================================

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12 Comments

  1. Samuel

    August 26, 2010 at 6:17 pm

    Hi Jestine,
    can you please help solve the problem of knowing the actual value of a burnt component. I am working on a Panasonic video monitor that has a resistor burnt in its video input board, i could not determine the value but used a resistor that has same value with the adjacent resistor to th eburnt one, the Video monitor now shows picture but in black and white instead of colour.
    Best regards.
    Samuel Ojo

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  2. admin

    August 27, 2010 at 9:52 am

    HI Samuel,

    The video board usually consist of three section R,G and B. If one of the resistor burnt you can check on the other circuit to locate the value. By the way, when a resistor burnt there must be a reason. You may need to test out all the components that have relation with the resistor.

    Jestine

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  3. THILANGA

    January 25, 2011 at 3:45 am

    MY SAMSUNG 633NW LCD MONITOR SUME TIME DISPLAY OFF HOW TO PROBLEM

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  4. admin

    January 26, 2011 at 6:16 am

    HI Thilanga,
    You may need to check the filter cap in the secondary side of smps and make sure no dry joints in the high voltage transformer

    Jestine

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  5. melusi

    August 19, 2011 at 4:14 am

    Can u pls help me with my two hisense tv model tc2108d.the first one shows pink lines down the screen wen on vedio mode and no speech on tv mode only a hiss but good picture.sound system has faild to bring back speech is it my la ic? Pls help

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  6. admin

    August 22, 2011 at 8:49 am

    H melusi,

    The one verical line could be caused by bad t-con board or the lcd panel have problem. As for the sound problem, have you tested it on a dvd player?

    Jestine

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  7. george

    April 11, 2012 at 11:02 am

    hi jestine i have a laptop compaq model when i try to switch on only the power LED blinks then the laptop doesnt switch i have checked the battery,RAM and harddisk but they are ok .what else might be the problem and also tell me can a laptop switch on without the harddisk and RAM

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    • Jestine Yong

      April 12, 2012 at 11:42 pm

      Hi Geoge,

      Have you check if the output voltage from the power adapter is good and stable or not. If it is good then the problem can be in the charger power supply circuit. Yes you can turn on the laptop without ram and harddisk except that it does not have any display and in some model the power led will blink indicates there is no connection.

      Jestine

      Jestine

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  8. Fidel Alfonso

    April 25, 2012 at 10:16 pm

    Hi Justine;
    What is the problem of my Samsung syncmaster 633nw it only displays white screen??
    'Thanks..

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    • Jestine Yong

      April 26, 2012 at 8:12 am

      HI Fidel,

      It can be the lcd panel problem, no supply voltage to the lcd panel and even mainboard have problem either no supply voltage to MCU or the MCU ic have problem.

      Jestine

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  9. Fidel Alfonso

    May 21, 2012 at 8:38 pm

    Jestine
    Thanks for the reply it seems to me that i have to replace my monitor?????
     
    Fidel

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    • Jestine Yong

      May 27, 2012 at 4:05 am

      HI Fidel,

      Yes if all the voltages are tested good because it is not cheap and easy to find the lcd panel replacement

      Jestine

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