Electronic Repair Questions/Answers And Testimonials -Part 41
gud day,sir!it really feels good when you did your first time!I just finished troubleshooting the deffective lcd here in our vessel.i only did it for less than an hour.It should have last much earlier if i have some available parts here.i only salvaged the needed parts from old pcb boards that i have found.eventhough the parts are not exactly the same specs,it is still working.i only replaced 3 sec filter capacitors.
I just finished reading
You are really good, Mr. Jestine Yong!
Thanks very much!
Hi,how are you?Hope you always fine indeed.Its been quite a long time i dont send you any email.Repairing electronic and electrical component is my part-time job and since i buy your ebook it like a huge momentum to my career.I can repair tv set,monitor,dvd player,astro decoder,asto antenna installation,washing machine and anything that has electronic component.Your ebook is the best way to understand about electronic.Once we understand,follow the guide,experience it and never give up its bring great result.
Hey Jestine thanks for you great email I appreciate.
Man o man my email in working like before.
Jestine have a nice day and remember that I appreciate you.
Thank you very much for sending me the October repair newsletter. As I go thru the article it seems that my knowledge in electronics will go deeper and deeper with the nice presentation that you have. Hope someday I can be able to reach my goals. Again, many thanks & God Bless!
Thanks for these wonderful and educational emails! I am impressed. You are a
Woww….tat was an excellent newsletter about the transistors and
their functions sir…
Very interesting to read & extract the stuff….
i read your blog about your trip to shenzhen
and just in time too cos i will be going to hong kong
and shenzhen in october
please provide some information on the
hotel rate – simple , low cost one will do ;
Good to hear that but sorry i do not have the information of the lowest hotel rate. Guess you may need to google to find it out. The hotel that i stayed was Holiday Inn express and is about USD45.00 perday.
i am in the notebook repair business and
going to shenzhen to buy notebook spare parts
and test equipment
hope you can guide me where to go in shenzhen for these items
in your blog you said there was one floor where got a lot of notebook repair shops
also do you have any recommended test equipment for me
as i am mainly doing notebook motherboard repairing
thanks and best regards
Once you reach HUA QIANG BEI you can ask the cab driver to show you the “SAI GER” electronic building. The notebook repair and spare parts buiding is just directly opposite ” Sai Ger” building. It is located in the 3rd or 4 th floor. Ground floor is mainly selling electronic components.
Have a good trip there.
I live and work in
If you could find the replacement or the spare yes there is chances of bringing the set back to life again.
sorry for interrupting you again…
i have a Samsung LCD monitor for my computer.
since this morning, the picture comes on only when i remove the video
cable and replug it again…otherwise the power light is on but no
when, i remove the video cable from the computer and as soon as i replug
it in then the picture comes up and lost again.
personally, i think there is faulty capacitor inside the LCD monitor…
what is your suggestion.
Yes there is a possibility of cap problem and if all output voltages from the SMPS tested good then i guess is the Mainboard problem.
I just downloaded today.I have a CRT proview monitor and a FET(IRF630) keeps
on shorting after been replaced.It acts as a high current switch for the
horizontal output. We have tested at least most of the componentsaround the
HOUT circiut.Do you think the FBT could be the fault?I did not remove and
test the FBT yet.Can you give me some hints?
Thanks hope to hear from you.
Try visit this link:
Thank for reply and information.
I have now lcd Lg flatron 575 which is flickering. It is powered by external adapter 12v 3A
so there is no power section inside. I think it is back light ?
Bad backlight and sometimes bad caps inside the LCD could cause flickering.
I to know if it is possible to adapt TDA6107AJF to function as TDA61O7AJF/N1.I will be very please if you help me out.have a niceday.
As for the IC i guess you may need to try it out as sometimes the different version of IC may not work and you need to get back the exact same part number.
I checked the supply voltage & components of the Ic as u said…but all items are in good condition..also Vs is about 35V..
Pls tell me that,can there be this problem happen with the flyback trnsformer,neck card or
Thanks in advance…
Check the vertical yoke coil (deflection yoke coil) for resistance test. Flyback usually would not cause such problem unless when you say that the supply voltage to the vertical ic is derived from the flyback. If all corresponding checks to be okay then i guess you may need to directly replace the horizontal/vertical oscillator ic and retest it.
i am working on an acer AL1916 lcd monitor. I have found a problem with the Reset IC. The output keeps 5 volt (high) ,
so i guess the mpu/scaler is resetting all the time. I removed the reset IC and the monitor came back to life.
so i guess the reset ic is defect?
So far have not come across such problem. Congrat on your finding.
The reset IC is a smd part ASM810MEURF . I can`t find the component anywhere in europe (i live in
is it possible to leave this reset ic out of the mainboard? Can it work fine without? Do you know if it`s possible
to put another reset ic in? (i have some scrap board/parts) ?
I could not get the parts here too, i guess you may need to use the IC from scrap board to try it out.
thanks for your blog and information on repair
Gdam sir Jestine i am very greatful and gaining more knowledge reading all these letters from you .And i believe that God Blessed you . I am proud to say that Sir Jestine Yong is my instructor and has the expertise in all electronics .computer circuits. Thanks a lot sir Jestine God Bless you always and your family
Its ok sir..once i changed A1281 transistor which was found short in a
samsung monitor(2001model)..it was working fine for 3days..now the
problem is,monitor switching off automatically wit a vertical
line(green light glows)..display coming back if i disconnect nd
connect it back from the pc.wat will be the problem..
Plz suggest me..
Try use this method first to isolate the problem:
Check also for any dry joints in the yoke connector.
I purchased you book about a week ago and it has been of great help on to understain how to repair the lcd monitors. I want to purchase the Atlas Peak Analyzer and i have come accros the DCA55(the one on the Book) and the LCR40. would the LCR40 be a better equipment than the DCA55?
Thanks for the support of my ebook. The LCR40 is different from DCA55 so each of the equipment has it own capability in testing different electronic components. For more information you may visit http://www.peakelec.co.uk
I have a query regarding Humming noise from my Intex 2600W 2.1 speaker system. Whenever I power on my speaker system, it just starts making humming noise and doesnt give any sound. I opened the circuit and found the diodes of bridged rectifier burnt out. I replaced it with four new diodes of same rating. But still the humming noise was coming and the temperature of the audio amplifiers(TDA2030)increased dramatically. So i am now in a fix, how to repair it.
I would be extremely grateful to you, if you suggest some solution.
Have you check all the filter cap? Because failure in capacitors could cause humming noise.
SIR JESTINE YONG,
I HAVE PROBLEM ABOUT MY LG FLATRON CRT COMPUTER MONITOR I HAVE A 5 UNIT OF LG MONITOR THAT ALREADY NOW SHUTDOWN I MEAN IS THEY HAVE NO POWER I AM A ELECTRONICS 1 YEAR STUDENT BEFORE BUT ITS TO MUCH INCOMLETE ABOUT MY KNOWLEDGE IN ELECTRONICS REPAIRING I’LL CHECK ONE BY ONE MY MONITOR LG AND I ALREADY CHECK THE IC REGULATOR BUT ITS OK, THE OTHER IS HAVE NO POWER OUTPUT GOING TO B+ FLYBACK, AND THE OTHER MONITOR IS THE IS HAVE A LITTLE SOUND LIKE A “TIK” “TIK” “TIK” LIKE THAT BUT HAVE NO POWER AND OTHER IS THE LED IS BLINKING ONLY, I WANT TO BUY ABOUT YOUR E-BOOK ELECTRONICS BUT THERES A LITTLE PROBLEM BECAUSE I HAVE NO CREDIT CARD NOW IM IN PHILIPINES NOW HOPELY YOU RESPONCE AND HELP ME A LITTLE MR. JESTINE YONG.
THANKS FOR A KIND CONSIDERATION…
JOSE BREGIE CASTRO FROM PHILIPINES
First you need to make sure the SMPS is generating output voltages, If not then suspect SMPS. As for the tic tic sound please refer to my website link at http://www.electronicrepairguide.com/testing-flyback-transformer.html
I hope you are keeping well. The B+ from the SMPS measures about 110V. Initially the G2 gave no readings, when I disconnect the G2 wire from the CRT neck board it reads 86V. I replaced the resin coated ceramic capacitor in the G2 line and reconnect the G2 wire, it read 86V and rose up 160V. Then I adjusted the screen voltage control on the flyback, the reading now fluctuates between the ranges of 160 up to about 310V max, with a blurred display and a few of vertical lines.
The flyback transformer may have problem. Try remove the G2 cable and retest the voltage again to see if it fluctuate or not?
I left it on for about 20 minutes to go have coffee. Upon my return only to find the TV had shut down completely. I pressed the switched switch several times but there was no picture till now. I removed the G2 wire from the CRT board and no voltage was present (0V), the anode high voltage is also not present.
This is because the high voltage already shutdown
However, all the supplies from the SMPS including B+ measured fine. The horizontal output transistor also tested ok. I am wondering that the flyback transformer is faulty.
Possible transformer fault but you need to make sure that the safety cap value is good before buying a new flyback
The voltages on the flyback transformer are:
Pin 1-6: 110V dc
Pin 7-9: 0V
Pin 10: 110V dc
Following are the voltages on the pins in the CRT neck board (from bottom left, going clockwise:
GRD – 0V
G – 100V dc
G2 – 0V
R – 104V dc
H – 0V
H – 0V
B – 100Vdc
GRD – 0V.
Since I am still new to TV repairs, may you kindly provide me with the specs for the pins in the CRT neck board and any clues on how to overcome the situation in view of the details I have supplied thus far. I read that the G2 is normally within 250-300 and the G1 about -30V.
From your description it looks like the flyback have problem. Heater (H) usually derive from flyback and since it already shutdown thus you are getting 0 volt. By the way the heater is a high pulse AC and your normal meter do not have the capability to check it. yes you are right about the G2 and G1 voltage but different model the voltage will have different reading.
Hi Mr. Yong,
It’s me again would like to ask you who expertise on this.
I have another problem on my DELL LCD E153Fpc, the screen is too dark and button menu doesn’t work.
This DELL LCD has BENQ PCBoard which is different with the original one. C707 is for the Capacitor 16V 1000microfarad.
What should I change to make the screen bright and the menu buttons work? Please advise.
Thanks and Regards,
The dark screen could be problem in the inverter. Does the inverter ic have supply voltage? Button won’t work is either due to bad button, loosen connector between the front panel and mainboard or bad eeprom IC data. Hope this helps!
1) I was trying to repair a Compaq monitor having similar power blinking
problem shown in your article on LG Monitor .I connected the Ring tester to the primary side of the FBT and found 5 to 6 lights glowing. Does that mean that FBT,O/P ,HOT etc are out of suspicion .
If any shorted capacitor just as shown in your article “Power blink problem in LG monitor”. Could it be detected with a ring tester since it is located after the diode.
If the diode shorted then yes it can detect and since the cap was located afetr the diode then the ring tester would not be able to detect it.
2) How can i detect if there is a problem in the primary side or secondary
side of the SMPS.I tried disconnecting the +B load. Still the problem of blinking remains.
Blinking in smps could be caused by many factors like bad filter cap, leaky transistors, diode and IC. Bad Optoisolator IC, open resistor, dry joints, circuit track broken, decayed glue and etc. I guess you may need to check all the components if you have confirm that the SMPS is the cause and not the load.
A few weeks ago I sent you a message concerning a Sanyo AVL-279 LCD TV’s defective power supply. When the power button is switched on, there is a repeated and steady “ticking” sound coming from the switch mode power transformer. Your first suggestion was that maybe there is one or more bad capacitor(s).
So, I went to a local electronic shop and bought the capacitance meter TES 1500. Just like the one you displayed in your book (Testing Electronic Components).
Then, I calibrated the capacitance meter, removed all electrolytic capacitors from the power supply’s IC board (except the BIG one – see the attached image), discharge them, and test each one.
Here’s the results:
Cap. Rated Value Test Result Value
35V – 1000µF = 864µF
35V – 1000µF = 883µF
25V – 1000µF = 877µF
35V – 220µF = 209µF
35V – 220µF = 200µF
25V – 47µF = 30.2µF
25V – 47µF = 46.5µF
25V – 10µF = 9.1µF
Since all results are under the rated value, is it means that all the tested capacitors are faulty?
Capacitor have tolerance but from the result yes the value is a bit down especially the 47 uf one that down to about 30.2uf. If possible get a Blue ESR meter that will be more efficient in testing electrolytic capacitor.
What’s the next step? Should I remove and test the BIG electrolytic capacitor?
Yes you should test that cap too.
Also, as you can see in the attached image, there is a ceramic capacitor under which the IC board showed a brownish discoloration like if this capacitor has became very hot (or overheated) at one time or another. Is this normal?
The change in color could be due to heat from the nearby 2 watt resistor. If the value check to be okay then it is good.
Should I remove and test this capacitor? It’s rated at 472K – 1KV.
Yes you may check that cap too.
Is this means that it is a 47 x 100 = 4,700µF (micro-farad)?
No it is 4700pf or 4.7nf or 0.0047uf
Can I test it with my capacitance meter even if it’s a non-polarized capacitor?
Yes you can-no problem!
Thanks for having taken the time to read.
You are welcome!
I check and found that it is ISL9R460PF2, Sorry i wrote r460pfz instaed of r460pf2
The spec is 600V with 4 amp and i still could not get the replacement. Try connect UF5408 in parallel to increase the amp. UF5408 is rated as 800volt 3 amp.
ANOTHER CRT TV WITH SAME SYMPTON
Another CRT TV was brought into the lab with similar problem, no G2, no anode high voltage. Except for the B+ measured 62, which I think was low.
Yes the B+ is low.
There were no indications of shorts on the flyback transformer and the horizontal output transistor tested ok.
Try use this method to isolate the problem:
I understand a voltage or current drive must be applied to a transistor base for it function. What I did was, I desolder the HOT from the main board, power the circuit and measured the voltage at the base terminal. No voltage was present on the base terminal in both sets. I traced the source of the base drive signal to a small transformer. No voltage was present on the secondary, but there was voltage on the primary and it appears to be driven a small transistor.
You must get the h.OSCILLATOR signal to drive the small transformer first before you get siganl at the secondary side of the small transformer (horizontal output transformer)
I am a little confused but since I am still new to TV and monitor repairs, may you kindly provide me with any clues on how to overcome the situation in view of the details I have supplied thus far, for instance the specs for the pins in the CRT neck board, the role of drives and their expected drive voltages. I read that the G2 is normally within 250-300, the G1 about -30V and a drive contains a mix of ac and dc signals of about 5V each.
I guess you may have to visit this link for more tv repair information;
hello dear jestine yongas per yours advice ,I have checked b+ circuit & modulation diode , but all things r good, now tell me about my problem,s solution, I have sent u schematic diagrame of chasis njf 9905, i have replaced powering transistor, j-306 fet, 7 33UF. 250V CAPACITOR. NOW POWER IS TOTALLY ON BUT GEOMETRY & PINCUSSION (PCC-AMP) IS NOT FUNCTIONING, I HOPE WITH THE HELP OF SCEMATIC DIAGRAM U WILL HELP ME TO REPAIRING MY MITUBISHI 900U MONITOR, NOW THANKING U VERY MUCH SEE U….. FROM ZINDADIL
Sorry the diagram is a bit blur and hard for me to see. First did you get 24Kv from the anode of the flyback or not? If not then suspect B+ supply problem. If all tested good then trace from the horizontal yoke return wire (H2) till you locate some components like cap and transistors. You need to trace the pincushion signal from one of the transistor to see at where the signal had gone missing. Normally the pincushion signal comes from a CPU or from h/v oscillator IC and go to transistor circuit. I have come across shorted yoke coil could cause pincushion out too.
How are you amd how is the family/ I hope every body is fine.
I was working on an LCD Toshiba colour TV model 37A3030D, which fell down and went off. I checked the power subly board and found a fuse and a 37 ohms resistor blown, I replaced them, now the power light indicates that there is power when I switch it on and the relay clicks too, but the screen does not come on, it seems the inverters don’t come on, and I don’t have the diagram, more over I have not come across any other component that is faulty, can you please give me an idea of what to do next.
Thank you in advance and have a nice day.
Me and my family are fine thank you. I guess you need to check if the inverter IC have any supply voltage or not. This is one of the most important point that you should check. Sorry i do not have the diagram too.
I have a Plasma monitor here in my workshop to repair
The monitor is LIKOM BRAND
MODEL NO : CT150 N
MADE IN MALAYSIA
It has this malfunction According to what owner of monitor says At the beggining the buttons do not did any performance so when he wanted to turn on and off the monitor it could not did any of the both actions
Now when we plug it immediately the whole background display appears with RED COLOUR after with GREEN COLOUR after BLUE after WHITE and at the end the whole display it is covered by these stripes with these colours that i mentoined above
IT IS THE SAME PICTURE AS YOU EXPLAIN IN THE PAGE 180 OF YOUR BOOK ” HOW TO REPAIR LCD MONITOR”
If you need the picture from the problem or even video I can send
Thanks for the videos. From the video it seems that there was no signal going into the scalar IC. For some Monitor, without the VGA signal from computer it will display the graphics as what you have described. Use your scope and trace and make sure all the 5 important signals (r,g,b h, v) is going into the scalar IC. Assuming all signal present then this could be the problem of scalar IC. Sometimes a bad MCU also may cause this problem. If you have other question please do email me again.
I have purchased the Blue ESR tester and I was wondering what is the range of caps that the tester can test. I tested a 47000 uf ecap and the tester read 18. Shouldn’t it be below .1 according to the >500 uf scale on the meter? The cap is new and I have tested 2 of them and get the same reading.
I’m afraid the value would be too big for the tester. Here is a link of what the meter could test:
If you have other question please do email me again.
I have a deficiency like that it LCD that there are coloured the display.
And sometimes will be black , sometimes good.
The display himself good only the controller IC wrong.
I don’t know from where I obtain a component to it.
You would be able to help me with this.
Whole LCD would be expensive.
I wait for your answer
If all the output voltages from the SMPS is good then suspect a bad LCD panel. It is hard to get lcd controller ic in the market.
Can you please tell me if you can build your own Isolation Transformer. I’ve seen on the internet that they suggest that you must do it like beneath.
You can buy one in many electronic stores, but if you want to save some money, you can build one using two identical transformers.
+–) || || (–+
( || (————–) || )
115 Volts ) || ) 35 volts ( || ( 115 Volts
( || (————–) || )
+–) || || (–+
This is how I built mine. I used 2 transformers which were not too expensive. I have included a switch, which is very useful.
Now if it would work can you please suggest how much the ampere rating of the transformers must be.
Thanks for the email and since my country volt is different from yours i guess you may need to visit this link for more details information of how many amp that you should buy:
Other things of the meter is OK…tested done except at the x1ohms where the pointer does not move at all when the 2 probes are shorted together.
If you could see a 18 ohm resistor then check that resistor. It is quite common that this resistor value will go open circuit.
2. Fuse? Where? Opened the tester…found no fuse at all. Please advice.
By right should have a fuse but since all the function is working except the X1 ohm range then the meter is functioning
3. The e-book Testing Electronic Components is very interesting. Lot of pictures…so far so good.
You are welcome. Picture speak of thousand words!
Have a good day!
K sir..What r al the sections controlled by Ic TDA4866?It has
something called guard circuit wit it..
Wats the use of this circuit?
Actually there are lots of circuit meaning in every IC. I guess you may need to print out the ic data and read from the manufacturer about that pin.
Your Name: Charlotte
Message: I’m looking for some GCI flybck transformas part# G074294LF. Do you know where I can buy from please?
Have you try http://www.hrdiemen.com ?
Thanks for your continual support, in order to locate some test points in electronic circuit ,I need
to access to the scheem of monitor TE770 model TE770B Fcc ID:E80TE770 MFD: June 2002 Made in china
Have a good day!
Sorry i do no have the schematic . Have you try from this link:
Apologies for emailing you, I’m sure you get 1000’s !
I have a belinia (systemax) 20″ TFT that had a faulty PSU. I’ve replaced the capacitors and it worked for a while, now it’s faulty again.
It’s not the PSU as the monitor starts up, the on screen display works, and when you connect something it shows the refresh rate and the resolution, but no picture.
If you could give me some pointers on where to look it would be much appreciated !!
If all the output voltages are good then suspect the bad MCU in the mainboard. Samsung LCD Monitor have lots of this problem and it was the bad MCU.
HELLO DEAR JESTINE YONG, THANKING U VERY MUCH FOR YOUR RESPONSE, I HAVE CHECKED THOROUGHLY PINCUSSION STAGE OF MY MONITOR, & FIND FAULT WITH YOUR HELP & SERVICE FORUM OF MITSUBISHI 900U MONITOR, THE FINAL FAULT OF PINCUSSION, WAS IN Q-507 IN MAIN SCHEMATIC , TRANSISTOR ET-453 NPN WAS FAULTY, I CHANGED WITH NEW ONE & PROBLEM HAVE SOLVED,, SO THANKS AGAIN, & SEE U NEXT TIME FOR NEXT HELP, GOODBYE & TAKECARE,
TQ for the prompt reply…really unexpected! TQ again.
2. I did a full checkup again on the analogue multi tester. DVC&AVC voltage ok.Did not check
3. When checked ohms…actually found x1, x10, x1K all not working when shorted together.
Only the x10K is ok. Please advice again.
Then check the 1.5 volt battery connection.
4. What do a fuse in this multitester look like? Where located? Other info which could help me in my lst.problem. TQ
The fuse look like the one in this link:
The glass fuse is located on top of the battery.
im one of your reader @ erp..and its amazing i can repair by my self thank you for the repair guides in your site..
by the way i just want to ask if it is posible to check the ic chip..analog type..like 74f74pc something like that..by using analog multimeter?
please give me instruction on how to check that parts…
hope to hear it soon…
You are welcome. To check the ttl ic 74f74 you need a logic probe. Search from gogole how to use logic probe and you will get the answer there.
Hi Sir Jestine,
Thank you very much for the newsletter you have send and also your ebook. I have learned a lot from it and it enhanced my little knowledge in tv repair. Your ebook is great because the explanation and examples is really focusing on tv and crt monitor with pictures as a guidance. So far, I have repaired three tv sets. The two have cold solders only and the other is a bad vertical IC. Currently, Im repairing my cousins samsung syncmaster crt monitor. It has a bad HOT. My problem here sir Jestine is, the part number D5404 is not available here in our electronics store. Ive searched the internet but no data is available or about the replacement. Can you suggest any replacement for me. Thanks and more power to you.
Thanks for the support on my ebook. I suppose your number is C5404. Try use C5411 or C5803. After replacement, On it for sometimes and touch it with your hand and make sure it is not hot. If it is hot then find another number. If it is warm then you can continue to use it.
Note: Make sure you remove the power cable before touching the Hot.
Hope this helps!
Yes I’ve your report and thanks so much.
It was problem with the inverter I’ve change it and now is OK.
I’ve fix ATX power supplay for computer It is seams to work
OK but wen I connect it to mainboard not working
5v. 12v are OK what’s the problem with that please
advice me.By the way my english is not good
please try understood me
Best Regards Suren
Have you check the power supply filter cap? Try trace back the 5 volt and see why it was missing. It could be dry joints in the inductor and etc.
recently i face a problem abt my panasonic 1131. it print out empty line between word( refer the attachment).
I already delete my computer driver and install new 1131 driver, change to other computer to test , problem still the same….
can u enlighten me?izzit mainboard problem????remark: i already change a new print head
From the photo that you sent me i guess it could be the fault of the mainboard. Usually you may need to reprogram the MCU inside the board which can be done by panasonic.
I have finally been able to get the service manual for the Sanyo AVL-279 LCD TV and its power supply’s schematic plan (see the attached image). With this plan, I had been able to see that all the capacitors that I have already tested seems to be on the secondary side of the transformer (the “ticking” transformer). All those capacitors’ (identified by a red arrow) test result are under their respective rated value (see my previous message for detailed values). So, I tested two more capacitors located on the primary side of the “ticking” transformer and those capacitors’ (identified by a green arrow) test result are right on their respective rated value (a rated 4.7nF tested at 4.7nF and a rated 3.3nF tested at 3.3nF).
This means the non polar caps are good.
Is it possible that all those faulty capacitors (identified by a red arrow) have simply gone bad by themselves or could it be caused by a known electronic state and/or problem? In other words, have you already seen this kind of problem?
It can go bad by itself due to heat or the capacitor quality problem or it can also be cause by bad corresponding components.
Is there something else I should test before replacing all those faulty capacitors (identified by a red arrow)?
Try replace the caps first and retest it again.
If all those faulty capacitors (identified by a red arrow) have gone bad by themselves (maybe because the rating has been underestimated by its developers), should I replace each faulty capacitor (identified by a red arrow) with one of the same rating or should I get a higher rating?
If a higher rating is best, how much higher should I go for?
Yes you have the choice of using a slightly higher voltage BUT ONLY FOR electrolytic capacitor and not non-polar cap. For example, a 470uf 16 v cap can be replaced by a 470uf 25 v cap. For a 25 volt you can replace it with a 35 volt and so on.
Well I am having some difficulty with a 13.5V 20 amp SMPS. It works fine for about 5 minutes than makes a sizzle sound like something being fried in a pan. I then shut it off to prevent the high speed transistors from burning up. I have direct replaced all the capacitors and diodes and checked all the resistors. I did noticed that the big sized circular coil with a total of 8 leads gets extremely hot and has become discolored. I checked it with a Bob Smith coil tester id it appears to be fine. I have attached some photos including a Pic of my work station. Please let me know if you have any suggestions that can help me with this power supply.
Thank You for your precious time. It is truly appreciated.
From the picture it is for sure the coil already burnt up and you need a new replacement for it. Sometimes a burnt coil could breakdown when under load but test ok with coil tester.
Hi jestine ,
Can I use a 2200uf 35v cap as replacement for and 1500uf 35v in power supply unit on rail of 24volts to the invertor of a lcd boad.
Yes you can but you have to make sure the cap can fit into the space.
i want to aski if how to measure and test the micro resistor please see the picture for the reference
i want to check the value of this resistor so i can make some replacement due to no spare available
Those are SMD resistor and you can test it with any ohmmeter. You need to test it offboard.
I have been enjoying your repairs reports and i know how to repair a bit and i really want to become a professional and i will like to open a vocational centre where i will like to teach people in my community on how to repair electronics devices and how to design things electronically to help improve our environment.
Jestine what do i really need.
Thanks for your email and you need to be good in electronic repair first before setting up the vocational center. Try visit this link:
i am facing the problem with IBM laptop LCD.The problaem is vertical colourful thin bar.i have already tried to rectified the problem by removed lcd cable, cleaning the cable and installed it but problem was same plz give me some suggetion to rectified the problem
From your description, it is the LCD panel fault.
For newbie of electronic repair I know that the Blue ring tester is better than the LOPT/FBT with model K7205, for starting of repair is it ok to use K7205?
What is the different between the two when it comes from testing?
Appreciate your reply,
Both are the same. The Blue ring tester is a newer version. The market don’t sell K7205 flyback tester anymore. Testing result is still the same on coils, flyback, yoke coil and Power transformer.
I do enjoy your articles and I am proud to say that I am on the way to re-open my service shop. As you may know I am a Customs Officer now buty original career is that of an Electronic technician. Believe me. Your first love is always your best love! Reading your articles and keeping up-to-date with what’s going I am almost ready to put my repair sign outside the door again. Just a few more basic test equipment I need to get cracking. I can kick start with what i have at the moment.
So thanks again for you enlightening material. keep up the good work.
Nice to hear that you are reopening your shop. Yes i agree with you “Your first love is always your best love”! All the best to you.
I would like to ask you to help me.
I have a colour tv SVA model no. C545T which was brought to me for service.
I check evrything and it was fine but when I switch it on it blew the power transistor (BU508A) and the fuse. I removed the BU508D and tested it, it was ok. I put in a BU508A and replaced the horizontal circuit with a 60W light bulb but it still blows Th BU508A. What might be the cause?
the attachment wth the transistor 2SC2498 that usually goes short and the circuit when tested has no short circuit. what cause the short circuit on the tranistor?
Try this link:
You can test the components using analog/digital meter, digital capacitance meter and blue esr meter.
I’ve been trying to repair my laptop but the problem is when components are in parallel, measurements are very different.
You need to solder out the components to avoid parallel circuit which can affect the reading.
The only way i see is to unsolder every single smd component out and check it with a multimeter.
Yes, that’s right but usually smd resistors are quite robust.
That’s a lot of work. Is it impossible to repair laptops. What tools do i really need in order to figure out the problem. Please tell me the truth, i will appreciate your honesty.
I personally do not repair laptop but it has the boards that quite similar to LCD Monitor. You can repair the inverter/power board, replace backlight, check on the mainboard except the lcd panel. LCD panel hardly can be repaired.
HELLO DEAR JESTINE YONG. ONCE AGAIN I HAVE CAME TO YOU FOR HELP, AS U KNOW MY MONITOR 900U MITUBISHI, I REPAIRED IT WITH YUOR KING HELP & USE IT 4- DAYS DAILY USEAGE OF 3 HOUR DAILY, THE FORTH DAY IT AGAIN FAULTY, I HAVE REPLACE PARTS … Q502.. 2SC5244A+ Q511 J-306 FET FORMING +Q506 TRANSISTOR NPN ET-453 & 22 UF 250VOLT CAPACITOR C509. AS PER SCHEMATIC DIAGRAME OF NFJ9905(MAIN). NOW 5244 TRANSISTOR & FET J306 N CHANNEL FET IS AGAIN BURNT, NOW IT IS NO POWER LED LIT, MEAN NO POWER, MAY BE FAULT IN HORIZENTAL YOKE SECTION, DEAR SIR PLEASE AGAIN LEAD ME, SCEMATIC DIAGRAME OF NFJ9905 IS ALREADY YOU RECEIVED ME , PLEASE SEND TIPS FOR ME , THANKS, SEE U NEXT. FROM SAIF….
Have you check the flyback? Please visit this link: