Electronic Repair Questions/Answers & Testimonials- Part 28
Thank Mr. Yong, it is great book!!! You doing great work!
Hi Justine. I recieved your books on LCD Monitor repair and its great. I have succesfully repaired 5 monitors with various inverter/power supply faults in just two days. My business is very rapidly growing as in my country not many people repair LCD computer monitors. Can’t stop reading, again thank you.
I have read your LCD monitor repair guide and found it quite informative –nice work!
I bought your eBook “Testing electronic components” and I like it very much I have learned allot already I am now trying to buy some tools I just ordered a kit to make a flyback tester and I would like your opinion on this meter.
I have just finished reading your book ‘LCD Monitor Repair’ for the second time. Thank you for a simple, straight forward manual.
hey jestin,thanks for now until i read your book.i already download it along with the bonous report.i really trust u because i dont even know u so much,but u are reliable.i wish the world have more people like u living all around,today it will be a better world.thank you once again to value others money and for the service u offered.i just want to know the time and day in Malaysia because in Guyana (South America) it is 11:15hrs and it is T.hursday
Dear Sir How r u
i hope u &
the monitor detail is …that. (Dell 15″inch. Samsung picture tube. & Samsung Kit)
(model no, 828FI..800F series) the picture is doing wobling i attached the vedio u see & tell me the problem.
how to solf this problem plz send me the detail & diagram this monitor???
I shell be very thankfull to u. As Soon As posible…. have a nice day.
Try check the internal capacitance of the flyback transformer. It should have about 2.7 nf.
My problem with Epson LX 300 is the paus does not react when i press it and when i try to print some forms there are combinations of letters and mubers that are printed which has no meaning because it is not part of my layout plus they dont spell or mean anything if you want to read it. please help.
Please visit this link:
We used to repair CRT monitors in the ‘90s. Now, with the assistance of your book we have been able to make a very smooth transition into LCD monitors. I have Sencore test equipment that is very useful.
Happy New year.It Has been a long time i have’nt response to your messages.Just awaking in the morning going to work and back home.Its kind of fustrated but i guess everyone encounters the same.Anyhow i was reading your book on testing electronic components which is very interesting.
I just purchased your book on Testing Electronic Components. So far it appears to be a great book.
you’re best teacher, professional person. thank you very much. success for you !
thanks so much for the Fuzion website. it’s just what i was looking for but had no idea of it’s existance. however one of the resistors was far too way out of tolerance range. i replaced it with the one i got from the old power supply, the problem still pesited until i finally saw one 2,2ohm quater watt resistor which was reading 4,9ohm. all this time i was missing it because it’s so small and mounted in between a heat sink and other small capacitors. Thanks once again for the most valuable website.
Thanks for the fast response Jestine,
I’ve already been reading your book and just fixed my set top digibox using your methods, which is amazing as until now the only dealings I have ever had with electronics is wiring the odd plug and changing the occasional fuse!
I’m now searching the house trying to find other things to fix! I just lost my job working as an insurance assessor in the automotive trade and your book has got me seriously considering a career change at the age of 48!
I will let you know how things progress.
Thanks once again!
Dear Mr. Yong,
My husband already load your informative link of the e-books. He would like to say thank you very much to you and he said that please tell you that your LCD repairing book is very useful and very good for developing his skill.
Could you give me your expertise as to what are the measurement techniques I should use of various components while debugging a circuit with power ON and without power. I have a similar type of good board which is working.
Eg. I am trying to debug a GPS navigation circuit which has 5 Volts DC input. If I want to debug this board with 5 Volts DC plugged in, what are the measurements I have to do with Resistors, Capacitors, Coils, Diodes, etc.
This only can be done when you have the circuit diagram because we just cannot expect voltages/ampere after every components. In other word you must first understand how the circuit work before you can apply the method. For example i know that the crt monitor heater voltage must be 6.3 volt and if i don’t get 6.3 volt i will trace back to see at where the signal has lost.
Saya mohon jasa baik, saya nak beli ic4600, boleh kah saya dapati di Jalan Pasar
Today I look more depth into the problem of missing the base drive signal, first I check the FBT internal capacitor, just to make sure, finding its value is 2.81 nF. By the way, when we want to check the internal capacitor of FBT, do I have to desolder the FBT out? Because I found that the checking result are the same whether the FBT still on board and out of board.
Not necessary as once the anode cap have been removed you can test it on board.
Then I check the HOT, just to make sure, and the result is OK. But after reassembling the whole unit and power it on, to my surprise the LED indicator is not lit at all, and I can hear the weak tictic sound every second, and the filament is also not glowing anymore.
I just wonder why now the monitor cannot be turned on anymore? I just don’t want to make the problem become more complexed.
It could some mistakes that you have made without you knowing it. Try recheck all the cables, joints that you have soldered (make sure no bridge joints between components pins and etc) . Check again is there any output voltages from the smps.
I enjoy reading your article about “How to repair Likom monitor with no display problem” and I think my problem is similar. The difference is that the Likom monitor uses TDA4858 h/v osc.,but this GTC monitor uses Samsung U242 for its horizontal oscillation.
Yes you are right
Before the monitor developed the tictic sound, I managed to measure the base drive power resistor of the horizontal driver transformer and the voltage was 12V, that is normal according to your article about Likom monitor. So the problem is very likely caused by the bad Samsung U242 IC, what do you think?
If there is no output driver signal most likely the ic is at fault!
But just now I searched for this IC on the net and can’t find this part supplier. If I cannot get this IC, does that mean this monitor is not repairable?
I could not get this part number too in my local supplier. If one cannot find then i guess you return the set back to customer or buy it over for future use/analysis.
In another article about ” Be alert of the surrounding components in Electronic circuit” you mention the modulation diode part number is SUJ30, but why I cannot find the datasheet of this type of diode on the net?
Not all manufacturers will release the datasheet of their manufactured components and some since already obsolete they will remove it from it database. By the way the equivalent number for suj30 is UF5408.
Hope this helps!
Can you help, i have a schenider 29 inch it is showing frame, when i open the Tele i saw TDA 8177, it has been change before and i dont realy know if the real value is TDA 8177 or 8177f, pls can you help if you are familar with it
or equivelent to use. pls urgent.
Sorry i do not have that information. Have you try to find the schematic from http://www.eserviceinfo.com ? Try putting the vertical ic and power it on and see the result-hope it will work!
Sir thanks for ur explaination :on how to rewind a B+ coil on the Sept2 newsletters sent to me Pls some of my up-coming friends in the world of electronics would like to see pictorially or understand what B+coil,B+FET or circuits are? b’cos I’ve tried to explain to them in my little understanding and it is still not clear to them as to whether B+ is a name of components or coil.pls i know it is a difficult task for u to undertake such inconvieniences but i just want them to hear from the horse’s mouth and enjoy with me these packages\tutorials of yours. thanks
B+ coil is actually a normal coil. Because of this coil use in the Boost circuit in Monitor, many techs refer to it as B+ coil. This coil normally located very near to the B+ fet in the Monitor boost circuit. It is in round/radial shape and in some monitor model it could be like a small transfomer but it is actually a coil. The function of this coil is to store energy in the boost circuit.
How are you???
I’m fine thank you.
I have two Sansui QRX-7500 stereos. They both needs power transistors and Power output transistors. Do you know if there is a book I can buy with substitute or equivalent parts for my Sansui stereo. They are over 30 yrs. old and in great shape and I don’t want to buy other stereos. Nothing I checked out sounds like my Sansui. I would really like to repair them..
You are the only one I know who would have some answers. The internet and ebay are more interested in selling.
Thank you very much and have a great day.
Try this link:
Guess you have to check with them first to see if the components you are searching listed in those books.
Have a good day!
Hi, in your book “Testing Electronic Components,” you suggested to purchase the Dick Smith shorted turns tester. I did and had a fun time building it. When I turned it on, all the lights came on and would not turn off regardless of what I did. Even shorting the test leads did not change it. I have searched the web and found nothing to help me. I have rechecked the solder connections for shorting and the components for the correct placement. All is correct. Do you have any suggestions?
Try replace the two ic and retest as both IC’s are easily get from local distributor. May i know at where you bought the tester because as far as i know dick smith had stopped the production of the shorted turn tester.
Hi Jestine i have already made the comparison with a known good scr anyway thanks, i have a sansui tv with an smps that dont have a pwm nor a fet the only active part is an scr and and an optoisolator the flyback transformer # is fcm 25c001 signal processor is m61250 and system ic is ec7073acan you give some information on this set for me it is not powering up.
If the smps does not have any output at all then i suggest that you check all components in the primary side. It could be a bad resistor, diode, transistor and etc.
saya sudah terima u'r report dan saya sudah baca..thank's buat u'r report
saya ada masalah dgn LCD samsung sync master 151s.diagnosa saya itu
IC Gain controlnya rusak. berikut adalah nomornya:
gamZANI - A
Jumlah kaki adalah 160 kaki, bisa bantu saya cari ICnya, pls…
Maaflah tiada informasi tentang ic ini.
Still reading your fine book, many thanks.
We have three 17 inch NEC’s LCD about 4 year old attached to Radiology CR units. They are on most of the time.
Now the display goes off after 2 or 3 minutes, without flicker of reddish screen.
The Power PCB has 15volt and 5 volt supply OK, ‘On’ signal 3.4v ;
The 15v goes to 18/19v after display off , inverter X/former off.
If front “on” pushed the display will return for a few minutes, also switch on and off will return display.
The inverter PCB has 4, 8pin IC’s (BE3419/4607???) I can’t fine any info!
Could the inverter be shutting down from over volts or from bad backlight?
At turn on the screen will sometimes last for 5 minutes but later, less time.
Any advice please.
From your description, it could be bad light problem as i came across before lcd monitor after used for certain time, the backlight just flicker in a split of seconds (very fast) and the display shutdown. Try check the backlight first. Make sure also the high voltage transformer do not have any hairline crack (dry joints). Please let me know how ‘s the outcome-thanks!
In SMPS units, which voltage amongst the secondary voltages is being
used as a reference to see if all the other outputs are correct.
It depends on the designers. In fact any one of the output will do.
Hi Jestine I have any problem with LCD monitor HP mod. HSTND-2A04 Product no P8726AA
i have not dc power after the optodiode i have 350 volts dc over the ic SG6841SZ the 8 condeser are well and i have not power over the display. What is the prise of youy book? and delivery for
I guess in your case you have to remove the power transformer and check all the components in the primary side. It could be a bad resistor, diode, power ic and etc. Check the secondary output diodes too. The price of the ebook is USD47.77 and this is an ebook and not physical book thus there will be no shipment to your country. Once the payment is done you will get the download link and you then can save into your computer, read from the screen or even print it out and bind it as a book.
I really want to learn about electronics..especially understanding the basics, learning the components incdluding its functions, reading the circuit and eventually designing perhaps.
Please recommend what should I do first.
I do have some knowledge on it but not totally understand.
I need your help.
Please visit this link http://www.repairfaq.org/REPAIR/F_Repair.html
and read and practice as much as possible. Hope this helps!
I just try to replace the fbt but the problem still remain.Do u know about static n dynamic focus?Is it related to this problem?If yes,how can i find the location and whats component involved.
It could be related to the static n dynamic circuit but it could also be a problem in pc tube.
The location is normally can be trace from one of the pin from the flyback (one of the pin coming out from focus divider) and lead to a small circuit that consist of spark gap and hivg voltage capacitor. Check this circuit components and if all tested good then i suspect it could be the pc tube problem
By the way,thks for your ebook.It’s very helpful.Thks for the ring tester circuit also.I have built it myself and its really works to determine bad fbt.
Hi Mr YESTIN
I am B from Albania that i bought your book concerning resistor
I am reading your book so so slowly step step every evening trying to understand it better.
I thing that the things here are so so clearly.
I wish that you & your family wife and your lovely children be in a good health and always glad and believing in GOD.
Message: does it matter wich way i wire a resistor? does it matter how the current flows thru it? does a resistor have a positive and negative end? thank you for your time.. mike.w
Thanks for the email and resistor does not have polarity (no negative/positive end), current can flow thru it either way. You can install a resistor either way you like.
I’m fine thank you!
i’ve an oscilloscope of tektronix “tds350” up untill now i have’nt use the oscilloscope
apart from digital and analog multimeter. there for i want to request you if you can help me. for example; a tv that there is only horizotal line. how can i check the problem by this oscilloscope? or i need service diagram?
Actually one horizontal line problem is one of the easiest to repair. First get the ic schematic then check the supply input, check for dry joints. and make sure there is ohm reading in the vertical yoke coil. if all tested good direct replace the vertical output ic. If it still not working then use oscilloscope and check that there is waveform from the h/v oscillator ic. If no replace the h/v oscillator ic. Check also the surrounding components in the vertical output ic. Hope this helps!
Dear Jestin Yong
I have a pc ibm power supply, the problem is : when i turn it on it will
on , but just a while about 3 second then it off again. please tell me what to do.
Try check for dry joints in the power supply and also look for any bulged electrolytic capacitors at the secondary side.
i have fixed the monitor and you help me a lot.thank you..
thanks and god bless
Hellow Mr Jestine Young,
I am realy very interested to read your E-book and to take the whole courses of your trainning, however , for the time being I don’t have enough money to do that. I am just saving some money for this pupose and I hope after some months I will pay the legal payment and then I will be your student. however, if you could help me in other way for the sake of my great interest in repairin electronic components and devices, please help me.
Thank you !
yours sincerly A
Yes please visit my blog for more electronic repair tips at http://www.JestineYong.com
my problem is about gericom lcd monitor model 900p 21inches. the display will show and disappear in30 seconds if you off it and on it it will come and go but the green led light will still stays on 1.capacitors has been changed transistors are ok diodes are ok idont know how to check likage transformer also abuot the book we dont have it in ghana here even the money will be another facter all the same whatever the mind conceive it can achieve.thank you for help
From your description it could be a bad backlight problem.
Mr. Jestineyong, I have a color tv philips PT, which has no model, and is out of horizontal frequency, I have no scope, how can measure the frequency with horizontal frequency tester who has this TV does not have horizontal driver transformer, frequency is coupled to output horizontal transistor and countess. and to know from where it alters the frequency, it is possible that you created, I have searched several ways and I have not had success for service. I hope your help. thanks.
If you do not have scope that would be difficult a bit. Try use a frequency meter range from your digital meter as nowadays most good digital meter have the frequency tester range.
Sr. Jestineyong, tengo un tv de color PT philips,que no tiene modelo , y esta fuera de frecuencia horizontal, no tengo osciloscopio, como puedo medir la frecuencia horizontal con tester que tiene frecuencimetro,este tv no tiene transformador excitador horizontal, la frecuencia se acopla al salida horizontal, por transistor y condeso. y poder saber desde donde se altera la frecuencia, cre UD que es posible, yo he buscado varias formas y no he tenido exito para repararlo. espero su ayuda. gracias.
Si no tiene el alcance que sería un poco difícil. Intente utilizar un frecuencímetro digital de su gama de metro ya que hoy en día la mayoría de buena metros digitales tienen la gama de frecuencias probador.
” The point is not just in initial, turn-on current — by replacing
capacitors with higher-value and higher-quality (i.e., lower-ESR) parts in
Switching Power Supplies, it is possible to change the overall transfer
function and to cause them to go unstable, especially given that some of
these early SMPS’s may have been a bit “marginal” designs.
Input and output filter often involves adding special damping leg (capacitor
with extra resistance added) to make sure the entire
converter is well-behaved under all operating conditions. And, of course,
resonant converters rely on their component values to be correct, also.
I have an 11402A where the power supply won’t start, messed with it a bit,
finally found a high ESR cap, replaced it, it worked for a while, and now
won’t start again. ” – From a colleague
When you said “It won’t start again”-Is it due to the replacement e-cap again or some other bad components?
Generally, I use the lowest ESR cap I can find at a good price (Nippon
I used that too but mostly salvaged from good quality board. Generally for Monitors, a medium quality caps could last for quite sometimes too.
But what about the above issue, in older SMPS’s? How can a tech like me determine whether I should be using a low-ESR KY cap,
or a standard regular-ESR KMG 105-degree cap as replacement in the SMPS?
I guess this link may have the answer that you are looking for:
By the way, sometimes it has to come from your experience. That means from your own testing and from the record of how long it has been in service. With some of the feedback you will have some conclusion on what type of e-caps that best suit the SMPS.
thank you very much for your “suggestion” any way, but i did’nt mean the “horizontal” line, i mean the oscilloscope. how can i check the problem by the oscilloscope? because i have never used the “oscilloscope. i know there are many different type of wave form which one is “ok” and which one is not “ok”. for example; there is sound but picture is black and white, usually i check the component around the croma ic if these components are ok then i change the croma ic or some time even on the crt base. again justine, please if you have any suggetion for me that how can i repair the electronic instruments by the help of oscilloscope. i appreciate you, keep in touch
thanks a lot!
The best when i started to use scope (no one taught me how to use the scope) is to compare a good equipment test point and then compare the waveform with a bad equipment. Draw it down and practice more by adjusting the knobs and i’m sure you will get the art of using scope in a very short time.
I have a monitor that has a dual 8-pin FET labeled as 4425 BA W39A.
Do you have any idea what this is? N or P ?
Is there a web site with many FET listings?
Here is the link to the ic spec : http://www.datasheetarchive.com/pdf-datasheets/Datasheets-12/DSA-236400.pdf
and if you would like to buy this part then please click here:
Hope this helps!
Thank you for your report.
My table fan got stuck with the switch on for several hours. I switched it off and found the motor area to be quite hot. As usual I lubricate the shaft until it turn smoothly. But when I switched on it dosen’t move at all! There is no sound whatsoever. What could be the problem? How do I fix it?
Thanks for your help.
Fatimah u. s
I guess the first thing that you need to do is to make sure the AC SUPPLY is reaching the motor otherwise the motor would not work. Have you try turn the fan blade to see if the motor start working again or not?
I am fixing a Samsung CS-7277ND TV. Screen is dead but when switching ON LED goes green, solid red and starts blinking and goes OFF. CRT gun doesn’t glow. Heater voltage is missing and other voltages are there G2 =382,7V ; 13.5V;200Vand 130V on the CRT. Heater voltage is coming from Flyback transformer pin.
For your information our meter can’t measure the high pulse of the heater voltage.
I disconnected the ribbon cable that connects to the CRT and test voltage on the Flyback transformer pin but still no voltage. EHT voltage is there. I am not sure if the Flyback transformer is faulty or not.
If there is high voltage then most probably the flyback is working. By the way just to check how do you know that the EHT is present?Do you use a high voltage probe as sometimes a tv could produce high voltage and then shutdown due to some other problem.
Happy Chinese New year…
Thanks and same to you!
I have spare part problem here when repairing the LCD monitor. eg the PWM IC, i found each brand is use different IC as PWM IC, like TEA1532, TEA1530, NCP1203, NCP1200, LD7552, LD7575, TL1451, TL494I etc, are they can be substitute each other or other IC?
No you can’t substitute the ICs unless you have the internal schematic for comparison.
How do you handle if you plan to repair any kind of brand of LCD Monitor(in term of Repair spare part concern)?
Buy from oversea, buy from local electronic supplier (not all parts) and salvage from used LCD Monitors like the backlight and etc.
DO you have a list of substitute part for those common use component in LCD Monitor?
Sorry i do not have.
Hope this helps!
here is the update on the monitor that I told you about. the model number is M9178LL/A and I need the DVI (not VGA like I said before)cable pinout schematics for it. please help.
Try this link http://en.wikipedia.org/wiki/Digital_Visual_Interface
Dear Mr. Jestine,
After one hour of switching on one new Acer 19″ LCD monitor, little more than quarter part of the screen became black vertically on the right side of the screen. There are some vertical lines as well at the left edge of the blackened area. As it is under warranty we are sending the monitor to the reseller but I’m eager to know the reason for this fault as I’m new to LCD monitor repairing.
Chances is very high the lcd panel unit have problem. I have came across few that have similar problem!
I am a LCD TV/monitor repair technician in
I also saw those photos of repair course, your student are so lucky, in HK we have no such professional repair here. !
Hi Jesine thankyou for your exellent books
i also have lcd monitor repairand finding both books very informative keep up the good work!.
I need to know fully about earthing and how to make earthing pits and other accessories and taking care of earthing pits.I have a earthing done in my office but it does not work. Whenever i touch my computers back i get a shock.Please suggest a solution for my problem.Can i connect the ground of my computer to a pot with soil which is watered daily and can be used as a portable earthing.
Normally every house or building already have a good earthing. I do experienced shock from computer casing. What i did was to make sure the ground from the 3 pin wall socket is reaching the computer power supply. If you can make sure that then there will be no more shocking from the computer casing. Hope this helps!
I have two problems that I hope you can help me with. First I am asked to repair a Samsung 240T with no image. There is power and the buttons make noise when touched.So the power supply works. I have checked all fuses and the caps with ESR meter.I cannot find a service manual to go from here. Any suggestions? I have enclosed the tag for ID.
First you have to make sure there is supply to the inverter ic otherwise suspect a bad mainboard. Samsung have a common fault of bad MCU.
Second. A doctor asked me to try to correct a problem with a very nice high resolution monitor. I have enclosed the ID tag and a picture of the problem. The screen is split into two identical images, The driver card and DVI-D cable should be able to drive the monitor. Supposedly, this can be corrected in service mode. I have contacted the company. They are willing to help FOR A FEE. Do you have any idea how I can resolve this?
Sorry as this information are usually well kept by the distributor/company and they would not easily release the tips.
Have a good day!
sorry if i disturb u.
Its okay-no problem,
but i know that you can help me with this error of crm monitor i always encounter. almost 4 of our monitor having this kind of problem right now and luckily i was able to fixed 3 of them by resoldering all the vertical and horizontal section of the monitor. but the other 1 is the same as it was. i resoldered same part of the monitor but nothing happen. pls any advise from will be very much appreciated.
Make sure the B+ voltage is enough. If it is too low the display will be curved. If the B+ voltage okay then check on the pincushion/horizontal size circuit that locate nearby the flyback transformer.
Sir, i really like to buy some of your ebooks but i dont have to money to buy it in cash. i am just wondering if u can sale in to me in installament basis. like every 15 days payment scheme.
You can accumulate first and once you got the money then only you buy. In the meantime if you have any electonic repair problem just email me.
Have a good day!
I need your help, to repair our Kyoritsu 3124 unit Instrument for I can’t find the local repair center of Kyoritsu here in our country. And even the electronic parts of the unit are not also available here.
Can you please help me to fix up our instrument or even atleast refer to as your known Kyoritsu repair center.
Test meter usually needs precision test equipment plus calibration to do the job and this only can be done by them or their distributor. Here is the link to the website:
After few days i got an email again:
I already visited and sent inquiry in the link that you gave. Their local repair center here in the
Thank you very much for your kind concern and help.
Mr. Yong I would like that you recommend me a good solder and desoldering tool for IC component that is not too expensive but work fine.
Thanks very much
If you are referring to the smd rework station hakko and goot are the best but very expensive. At my workplace i just use normal
I am not getting any sine wave at the cyrstal. what does that mean?
It could be missing supply voltage to the IC (corresponding to the crystal), bad IC, bad