Electronic Repair Questions/Answers and Testimonials-Part 44
I can never thank you enough for the free education you gave me, you are one of the kind.I wish it was that easy to get to your office and get training from you I would love to work towards a certificate with your name on it that I will put on my wall and just bless it every day, and one day tell my children I have done it with the help of a Man that I have respect for. I would love to have all your ebooks if you can send me all the price lists and see how I can sort it out and would like to show it to my friends too. I am sure we can put our money together to pay for our books. we are craving for the knowledge and we often end up buying thick and expensive books that we do not even understand.
I have eventually found the culprit, why the 5V line down to 3.76V, it was a leakage transistor C945. I was hard to believe it, because the DCA55 told me it was OK! See the photo. If I was to believe the DCA55, surely I will fail to repair this monitor.
Components can break down under load. That’s why whenever if i suspect a section have problem and can’t find the fault, i will directly replace the components and retest. This experience will stick with you forever!
So, this is how this monitor works : because the 5V DC line was too low, there is also no 12V DC. Once I replaced the transistor, the 12V DC came up as long as there was input signal, and got back the HV again. Do the other monitors work the same way?
Not really as some Monitor 5 volts is taken from 7805 voltage regulator.
Last time after I replaced the B+ 47u 200V capacitor, there is no more black area on the screen, even though the Blue ESR meter told me it was good! See the photo. I do understand now, why the professional repairer believe their own judgment more than those component checker, what do you think?
Same answer as the first one.
To make the repair process fast, I should have only replaced these two components. Also, I’ve found where are the brightness and contrast control, they are not in the menu, but pressing the minus sign directly will pop up the brightness control, while pressing the plus sign will pop up the contrast control. Have you seen these kind of controlling the brightness and contrast before?
No, i wonder why the Monitor designer wants to make things so complicated.
Also you can see in the photo attached, someone has picked off the label of the picture tube of this monitor. I just don’t know what is his aim of doing it?
Some second hand tubes were used to put in with a new board and sell it like a new Monitor. That’s why lots of people collecting used Monitor for this purpose.
Thank you for this month newsletter, your continuous guidance will surely make me better in this repair field.
No problem and glad that you had solved the Monitor and of course making money!
Brilliant !!!!!!! A very comprehensive informations. Thanks a
million. Although I encountered bad solders and loose connections , I
am aware of those decayed glued.Now I am educated by you , and this
would be great help to my hobby and sideline as well. To tell you
frankly, but modesty aside , I could compete several technicians from
our neighborhood now. Advance Merry Christmas to you …….God Bless….
This is to acknowledge receipt of the November 2009 newsletter regarding the intermittent fault finding in such electronic equipments. Really oftenly I met this kind of problem and sometimes I am thinking that repairing dead sets is better to work on than such intermittent. However we can not get away with it as trouble like this always arise in electronics and we must solve the cause of the faults. Intermittent depends on what kind of fault cause in the curcuit sections, as you said really your tips are a great help.
Sincerely thanking you again.
Hello Sir Jestine,
I would like to thank you first for the wonderful eBook. You bring me inspiration and improve my knowledge in the field of electronics. It is very interesting, i never experience it before its a amazing.
Can you please help me a bit on this fault?
I have this monitor Brand Linda KT170A the problem is picture color green and in the bottom of the pic
you can see 2 horizontal lines (green ) like these….
———– _________ ———– __________________________________
to be honest on power supply faults I am doing quite well. But on color and picture problems it is still hard for me
on how to troubleshoot and which components should I look for and how to find the color section area in
the circuit board and the exact components. Thanks in advance
Compare the green circuit with the red and blue circuit. Scope test would be the best. As for the 2 horizontal lines i guess you may need to check the vertical section or directly replace the vertical IC and retest.
Thank you again for sending this month newsletter, Yes, based on my experience on my previous years of repair most likely to encountered such trouble particularly those with only 3 to 5 years in working condition. The most common trouble is what you call a dry solder and some leaky component which sometimes physicaly noticeable, but i never try to use your technique by using a hair drier and followed by a freezer. This technique will help me a lot to boost again my knowlegde in repair especialy in this kind of trouble which is very difficult for us technicians to solve and time consuming as well…
Thanks again, Hoping for your patient in sending me again these very helpful newsletter.
yes dear i read that report its nice.
but i have a problem that in my benq FP71G+ LCD 17″ two vertical lines are appearing.
some 1 told me that it appears due to fault on panel but tell me in detail with pictures how to fiz this problem i will be thankfull to u if u solve my problem
Yes it is the fault of bad LCD panel.
how are you and your family.i hope you are all fine.thank you very much for the monthly newsletter and also for sharing your secret with people like me.i have been able to use your secret to bring life back to some lcd monitor.thank you very much sir.i hope i will have the opportunity to meet you one day.
Me and my family are fine and in good health.
Sir i need suggestion with respect to these monitors.
1—17 inches samsung (model 172x) and 15 inches video seven lcd monitor.these two monitors are working fine.but after some hours they will go off (that is there will be no power again).if i try to on it,it will not on.but if one allows it to rest till the second day then it will be on again.i have checked the panel but i did not see any spoilt capacitor.
please your advice and experience will be highly appreciated.
2–17 inches samsung (model 701N)-this monitor come on but it continues to show
Not optimum mode. Mode recommended 1280X1024 60Hz.So i used another monitor to set my computer to 1280 x 1024 60hz. but the problem did not go.it continues to show the same message.Sir your suggestions will be highly appreciated.
In anticipation of your positive response i wish you and your family a blessed day.
Both problems are caused by the bad MCU in the motherboard. It is very common in Samsung Monitor.
thanks a lot for sending me these newsletter. i was able to get a lot of very important things from them.
I’m going to make this circuit ( A LED lamp using Phone line power, this was found from internet). In this circuit, the well-known LM317T volt regulator is used to control the voltage. However I have a doubt of the arrangement of these components. As per the data sheet, In order to control voltage, two resistors need to be used as my 2nd pic. So please tell me whether this is correct…..
The resistors arrangement is wrong and you have to follow exactly in the lm317 datahseet.
Tks for all infor given to me and really helpful. Somehow I need yr support – a friend of mine gave me 2 unit of 29” tv same brand (Toshiba) but different model. On this tv ‘A’ I noticed cracked on the screen but the card is still in good shape. As for tv ”B” screen looks fine but the card around 50% sign of burnt on it.
My question is whether I can swab (inter change) tv ”A” card to tv ”B” ?
Appreciate if you can help me.
Looking forward your email.
If both Tv panel have the quite similar part number and yes you can try to swap it.
Thank you very much for this Newsletter. I remember you everyday. Because I refer to your instructions every day. I salute all people around you.
May God bless you.
I have a problem with an Panasonic TV , in fact with horizontaly deflection > I found foulty The transistor D 2095 witch looks to be same with BU 2515. In my country i can’t find the original spare D 2095 ( supose to be SD 2095 ) . I change the original device with the BU 2515 and was OK 21 days after that BU 2515 blow up again. I check everything on board , transistor never go’s more then 30 degrees celsium, or something wrong, and still blow up . WHY ? .
If possible replace back with the original number. Try visit this link to get more tips:
You have a great site, very helpful and interesting.
I’ll appreciate if you can give me a good advice how to fix the Power board of IBM 20.1″ LCD L200p (6736-HB0 chassis CL-35)
Attached is the picture of the module.
I can’t fine the schematics of it.
There is no 18V nor 5V at the output. The 18V is only ~9V and the 5V is only ~2V.
I checked the electrolytic capacitors and its ok.
The diode also looks ok.
Can you help me with this?
Thanks a lot,
I’ve seen the photo-thanks. Since there was no output (too low) i suggest that you check all the components in the primary side and if all tested ok then direct replace the power IC and retest. Check also for secondary output diode that can cause no or low power symptom.
Hi, I got a problem with my friend video. IF you could help me to solve this problem. The case is, when it power on te screen display (resolution) is very slim that you can’t see your movie on screen, the screen display suppose to be 24 inch but it looks like it squeezed in the center of the video so that the when the person in the movie stand you can only see is stomach as the whole body his face and leg can not display.
I am not good in English but if you could help me with this problem then it highly appreciated
It seems that the pincushion circuit have problem. Check the pincushion transistor and also the modulation diode that is nearby the flyback.
I am Iregular reader of your repaireguide latter , I have benqfp71g lcd monitor but it become blank after few sec I have changed 2sc5707 and fu9024 transistor . please help me what I do .
thanking you sir
Have you check the pico fuse and the tuning capacitors that is located near high voltage transformer?
Thank you for the free report on how to repair any type of electronic
equipment, is it possible to find a testing equipment and software for
analyzing faulty components on any electronic circuit board.
How much can a complete set cost? I am running an electronic repair
shop and would like to purchase a complete kit for trouble shooting
any type of electronic circuit board.
It depends on what equipment you want to repair. The Most common test equipment are:
digital capacitance meter
So far never come across software that analyze bad components in circuit board.
So, I have a LCD screen made by TOPCON, 22 inch screen, and the problem is that 1/3 of the top of the screen is brighter then other 2/3 of the screen. This 2/3 of the screen is displaying pictures normally while the 1/3 area is to bright, so much that is hard to see any thing, in addition when you move cursor in to this 1/3 area then cursor is slowing down and having lost of “ghosts” while in the “2/3” area is behaving normally. I was wondering what can cause such problem. I don’t have yet such advance tool as you recommended in your book but was hoping that I can figure out from description of the malfunction where the problem is and which part it can trig such problem. Unfortunately for me i did not find any similar (enough) problem in your book that would give me a clue. As I mentioned above, I am not so good on diagnosing by using tools as i haven’t done such things for long time ( about15 years ago and with no such advance devices like LCD screens). Is there any way you can help to solve this problem?
From your description the problem is due to bad LCD panel (assuming if you have check the cable between the mainboard and the lcd panel. I had came across such problem in other brands of LCD Monitor and replacementof the LCD panel cured the fault. The problem is most likely the bad LCD CONTROLLER IC (IN THE LCD PANEL) that can’t process the right signals to drive the top part LCD driver ICs causing a bright screen in the top area.Usually this IC can’t be get from the market and the best way is to get a used lcd panel from ebay (if ebay has one).
Hope all is well my man?.You know,i was wandering whether a resistor with the inscreption R60 the same as 0.60 and 2R2 the same as 2.2 ohm. Things by the grace of God are fine,bless.
I’m fine thank you. Yes the value is correct- R60 is .6, 2R2 is 2.2 Ohm and 2K7 is 2.7 K ohm.
wht causes this bad gate signal to B+ fet increase the B+ voltage to the flyback thus killing the HOT so hw can i solve such a problem
It is the on time signal that cause the fet to conduct longer thus increase the voltage. It can be the horizontal oscillator IC problem and bad corresponding components that you need to check.
hi jes, thanks for the news, im always following your site…im admired you always…
jestine yong i have question for you related with capacitor. we know that capacitor charging circuit in AC supply and block DC current and also we no that capacitor working as a filter circuit. But my question is that why we used in capacitor in DC supply circuit and what is function?. Thank you
To store current and filter off ripples. It can use in timing circuit as a waveshaper and etc. Try google and you will find the full explanation there.
Thanks a lot for subscription to your website.
I found your work very helpful for all electronic fans.
You are welcome!
I would like to ask you a problem.
I get a new SMPS (power-one MAP55-1024)
It has fluctuated voltage with high noise output from the beginnig. (12v…24v)
In order to solve the problem I checked all semicoductors (mosfet, SCR, diodes, TL431)
I could not find any defective parts.
It is interesting that new power supply should not make this fault.
It is difficult to send it back, so I have to repair it.
I am using it to drive motors.
What do you suggest to do?
Check the filter capacitors and the low ohm resistor value. A slight change in the low ohm resistor (0.01 to 0.82 ohm) could cause power to blink. Direct replace the power IC and retest.
I would like to check with you, some of the power supply modules have a kind of white glue used on capacitor(please refer to picture). If I replaced the capacitor, do I have to glue it back? What kind of glue is that?
Not necessary because the manufacturer apply it to avoid vibration during transportation that can cause dry joints and etc. That glue is made of silicon.
good morning Sir,
please i am working on dell computer, the fault is, power blinking
please if there is solution to it
Power blinking can be from bad power supply board, bad inverter board or even bad mainboard. Is the oputput voltages from the smps fluctuate? If no suspect a bad mainboard and if yes then you may need to check the components in the power and the inverter board.
Hi Justine, originally monitor came on all ok for about an hour then it would turn off. if you switched it back on all ok for about 3seconds then it would turn back off again. If it was off for a few hours when you switched it back on it would stay on for about an hour then go thru the same as above.Unfortunately while troubleshooting the board shorted out and the resistor you mentioned and a (smd103 or105 resistor hard to identify) a capacitor also burnt out so I am now further behind than original problem but I shall keep reading and trying to fix the problem.I read the columns about troubleshooting you advised but being a novice and not having variable volt/amp transformer I dont want to connect to full 240ac incase it blows again basically all I have at the moment is a DMM.
Your first problem seems like a dry joints problem in the inverter board area or even a bad backlight. I guess you have to solve the first problem before checking on the original problem. If the resistor blown as seen in from the photo, that means you have to check the power FET as well and if it bad then you have to replace the power IC and retest. The 103 is a 10k ohm resistor and the 105 is a 1 meg ohm resistor.
Dear jestine ,
i have here a seleco tv set and it’s problem is a width of the screen because it becomes very wide by itself, and i think the troubles comes from the east-west pincushion cicuit but i really has forgoten how to locate the east-west pincushion ,is it in the horizontal circuit or in the vertical cicuit .
It is in the horizontal circuit. It can be cause be dry joints, bad caps or even a shorted modulation diode.
Sir my many costomer come and ask to refill the laser toner but i give the toner to refilling center but i have no gain for the refilling do u tell me sir hot refill the laser toner
Sorry no information on that because I’m not into the toner refilling industry. However, some says that you drill a small hole and fill in the powder and then seal up the hole but of course this method did not replace the drum and etc in it.
You are a great teacher. Until later when I have a question.
Hi Jestine, The blue thing written on it is 12.J and 3 kV.
I think it represents 12 Joules and Kilovolts.
It is 12 pico farad 5 % 3000 volt. It is a resin ceramic capacitor.
I have a problem with my cro computer monitor. It seems to purple and recover back after some time. Some time after a few knocks or bangs it recovers back. What could be wrong with it ? I ask a technician and he said the motherboard could be leaking current.
Whats your idea on this?
The problem is dry joints in the CRT board and not in the motherboard. Guess you need to remove the cover and solder the CRT area especially the RGB transistors.
Thank you Jestine for your reply.
About the network switch i was repairing. i removed it from the circuit and it is a semiconductor of KBP206 MODEL.it has 4 terminals and i tested the 2 terminal on the + sign and the digital multimeter showed me a 1 reading even after interchanging the probes. the other terminals on the – sign gave me the same readings as on the + sign. i think the bridge is short. what could be your suggestion?
thank you in advance Jestine
i am waiting for your reply
I guess it was shorted and you need to replace that. Get a new bridge rectifier and test it again with your meter before installing it.
I would like to thanks for your guideness.I have repaired my Acer LCD monitor.Now there is no flikering and waves in display.The two capacitors having 220 microfarad value was bluged on thier top.I replaced new capacitors with same values. I hope you will support me in future.Because you are my real teacher in Electronics field.
Please give me a tip on how to repair my monitor BENQ T705 LCD monitor. The trouble is No Power. When i open up the case and check it i found two transistors shorted C5707 and another component GKOS6530 also shorted and a fuse color yellow/orange 3A is open. What kind of fuse is this?
Can i replace it an ordinary fuse?
Yes you can but you have to modify the big fuse into the small space.
What is GKOS6530 component? Is there any other replacement for these transistor coz’ it’s hard to find that component here in
Sorry no info on this. Could you take some photo to show me the component part number and the where it was located in the inverter board?
I’m also worry if upon replacing these components the trouble is still the same. I need your advice. Thanks!
Is there any output voltages from the SMPS? If no then i guess the shorted components may have affected the power board and you need to test out the power board components. If there is voltage then replace the bad components and retest the set. One more thing, check also the corresponding components that relates to the bad components that you found in the Inverter board.
How are things there, wherever you are? I hope you are doing fine. I here in
In the course of my business venture i have discovered that most digital multi-meters i come upon are not accurate in measuring transistors leakages especially small signal transistors and diodes.Now the question is are there any digital meters in the market which are accurate?And they exist i would kindly request you to send me the names of the brands.
Digital meter is not as accurate as an analog meter when test on transistors and diode. Even sometimes the analog meter may also missed a bad transistor. Usually what i did was if i suspect that the section have problem and could not locate the fault i will directly replace the transistor, diode and capacitor and retest. Hope this helps!
My dear friend, thank you for your message which I received in exceptional circumstances have passed days away from the profession of her love passionately more happy was the existence of a person to be credible, highly experienced in electronics corresponds people without wages and deceive… We very much I was happy with this magnificent site.. May I ask you to continue in the dissemination of science for all people.. Thank you once again., and I wish you success and excellence
The maintenance of an expert
First of all, Thanks for your response!
Well, as a student of Electronics stream (Electronics and Communication) I really want to try my hands on newer Technology. I am a 2nd Year student. I don’t want to be that person; holding a Degree in his hands but not having any practical knowledge about his Subject. So, I really want to have some practical knowledge about each and every electronic device and you better know that this can only happen with the Practicals or Electronic Projects. So, to start on……I need to ask you about the real-time classification of Electronics Branch.
Like, we can divide it into various categories like Alarm Systems (CCTVs), Computer Hardware, Medium Electrical Devices, etc………
I was wondering, according to you (as an expert in Electronic Repair Works) how we can classify this branch. So, that I can pick a branch and further can pursue my practical work in that particular branch.
One thing which I wanted to know about myself is that I am really a novice in “this practical work” having no proper knowledge about the devices whatsoever (which I think is bad on my part).
I was also wondering that if this “classification” can really narrow things on me to choose one best for me from so many options or here I am making a mistake………or I can have a Generalized Approach of handling my Practical Work (which I haven’t started yet)……….
About which field you want to be in, i guess you have to analyze for the current trend in your country. For example, there is no point in learning repair DVD or VCD because they are too cheap and usually users will throw away and get a new one. Alarm and CCTV system, i guess it would be a good choice as nowadays, many houses, factories and even shopping complex are fixing it. You still need to do market research before venturing into any business. All the best to you.
Good Evening to you, I would like to ask you a question as follows:
The value 1000uf – 16V Temperature 105 original but faulty.
Replacement with Condenser 1000uf – 16V but the temperature is 85 degrees Celsius
Now the Question is can the temperature value be used as replacement a different of 20 degrees Celsius
If possible get back the same spec. However, if you found that the cap was use in the equipment that was not too hot like in CRT Monitor and CRT TV then you can use a 85 degree celsius cap. If the cap use in laser jet or LCD Monitor/TV that the ventilation is not good then better use the 105 degree celsius cap.
Hi sir ,
I swicth on Tv automatically fuse blow and I found “off~line swicthing regulator aready””kong”
And chance the new
Tv sukses and after one night ,i swicth on again and fuse blow again,and I check off-line switching regulator” kong “again also fuse resistance
This is another component problem ? or what you suspect?
I attached pic together
Thanks you so much sir
Check for bad corresponding components in the power circuit and clean the power board with thinner. Apply heatsink compound to the power IC too. Sometimes a dry joints in the secondary side (power transformer) could cause primary side to blow too.
hi mr yong.
As you know ,there are fusible resistors in electronic circuits. i have come across blue color body fusible resistors in circuits board which open circuit when to be failed.my question from you is that: how can i know that a resistor is fusible type resistor ?(from its appearance )
thanks a lot.
Sometimes it is very confusing to distinguish between these two resistors. The best is to see the colour body of the resistor. If it is different from the normal type of resistor or even the surrounding circuit resistors, then you know that the resistor is a fusible resistor. The fusible resistor value is also very small. It can be from 0.1 ohm to 1 ohm.
My name is Glenn from Manila
Nice to know you.
I came across your website a few weeks ago. Your articles is very useful and helps me a lot, Im very thankful for sharing your knowledge and experience to everyone..
You are welcome!
I am a repair Technician from one of the Semiconductor Test Company in the
I am using 2 pcs of iluminator bulb (21V 150 watts) as a dummy load one for 5V and another is for 12V when i began to use a dummy to 5V measuring of 4.7V and 12V measuring 12.7 volts without a load but when i put a load to 12V power supply is shutting down. I checked already all resistor,capacitor,diode, transistor and ic it’s all seems okay in my digital tester. can you me to roubleshoot this ATX?
Try use a motherboard with 2 harddisk as a load as a lesser load could cause the power supply to shutdown. In some models the ATX power supply have to be connected back to its original motherboard if not the power supply will shutdown.
Hope u fine in God’s grace.Yesterday by mistake i dropped my creative
home theater adapter.Now a huge hissing sound is coming.But system s
not working.Output voltage is normal.Can we rectify that adapter or
i’ve to buy a new one.?
I’m fine thank you. It might be the transformer have loosen and when it vibrates you will a hissing sound. Try tap the transformer to see if the sound go away and if yes then dip the transformer in shellac to silent it. If no then i guess you may need to replace the adapter.
Please could you tell me what value resistor/s I would need to step a 25v dc battery down to 6v. This has to be very reliable as it will be used in a pretty expensive radio control plane.
Thanks in advance for any help you may be able to provide,
Just use a 7806 voltage regulator will do. It will produce a 6 vdc with 1 amp output. Please visit this link:
Ignore the 18 VDC voltage because it can support up to about 40 vdc.
dear jestine i have a problem with a tv that is showing violet picture the tube is ok, i expected a problem in the output stage by taking voltage of transisters the blue and the red are about 140v which is ok the problem is the green which is only 30v i changed the transister and even the driver transister but no luck, i examined all the crt board and find everthing good ,could be something around the colour
decoder? as i don t know else
It could be the color chip problem. The best way to troubleshoot color problem is to measure the output signals from the color chip with scope. Use the scope to check the input and output signal.
Yeah I checked the filter cap on the primary side also. I’m using a Cap. Wizard so it just tells me good,bad,or compare. No values. It did register good. I have put it on the load and still the same. I checked the resistor on the primary side. There was one that was 0.47 ohms read .8, 100K ohms that read 102, and a 32K that read 30K. They were all the same type of resistor as far as apperance. Large and grayish. I think I will resolder the board next as I did find alot of questionable solder joints that I have redone but I’ll do the rest of the board.
The .47 ohm current sense resistor have problem. .8 was just too way out the tolerance. Direct replace and retest.
I am so sorry for many questions.
I am trying to buy 250V insulation tester for testing capacitor of 220 microfarad 400 volt in my country . but it is difficult to find 250V insulation tester. So I have one question.
Is it possible that I buy 500V insulation tester and use it safely and stably by connecting it with capacitor in series to decrese the applied voltage to capacitor.
if possible , what resistor must be connected ?
I suggest not as it will be not stable. Have you try ebay.com? At the moment you can try direct replace the cap and retest. A shorted high voltage cap in circuit is not common and an ESR meter will do the job fine in finding out bad caps.
hi mr yong.
there are switching transformers in most modern electronic circuits.As you have seen there are some numbers and letters on any switching transformer.
what ara these letters and numbers?
how can i find specifications of these transformers?
thanks a lot.
Those number could only be understood by the manufacturer. There is no standard numbering system for it.
If i should purchase the LCD or PLASMA repair kit will i be able to repair
it component level or complete board change.
For your information i do not sell the LCD TV and Plasma TV repair information. Assuming you want to get the package by Mr
I am slowly busy with my own repairs now Jestine not working for a boss
so far i’ve tried to make up a company name but failed so far cause
i have no idea of a good electronic company name or the name has already
been taken. can i ask you if you can assist me in good name to register
myself for a CC,I would be so glad if you can help me.
If your business is about electronic repair then put something as Your name electronic repair center, or some techie name such as