Electronic Repair Questions/Answers and Testmonials- Part 62
your site is very nice it really help me a lot in repairing and understanding electronic circuitry.I always read your blog
every time you send me a monthly repair tips thanks very much .I use it as my daily reference in trouble shooting.some day, I can buy your special instrument w/c is the blue ESR meter & also your e book. actually im working at the ammusement company as a technician. you are really a great help to me, you are improving my trouble shooting skills.hope you still send me monthly repair tips. Thank very much.
Thanks Mr Yong for putting together this e-book.
After reading the e-book (testing electronic components) I am now able to test lots of board level components. All so thanks for making the price affordable.
After I practice lots more and become good at using your techniques in this e-book, I will order your LCD – TV / MONITOR e-book.
I am glad to receive newsletter containing so many interesting news.
I thank you very much for for all these things you are doing for us.Every
months you take your time writing and sending newsletter to the world.I
believe all of us feel so happy about them.
I have read and learn a lot from your monthly reports thanks so much for each one.
You are welcome!
I have a question for you sir, in a crt television i found 153 volts dc at the main filter cap which is normal but only 38 volts dc at the b+ line at the flyback transformer i have checked the resistors and caps on that line and all checked good. Where is the next place to start looking for faults?
I suggest that you follow this link below to isolate the problem:
I ordered and read your e-book on testing electronic components ( pages 1 to 176). Your e-book
tells me how to test components that while they are not on the PCB or to disconnect one pin. For example to test say a resistor I colud de-solder and remove one pin.
Now I want to know how do I actually isolate a faulty component on a PCB because taking out one component at a time and testing all of them is not practical or would waste too much time.If I did that I may unecessarily take out good components.
Yes this is for accuracy purposes. I myself most of the time also need to solder it out otherwise if you miss just component checking onboard- you will waste your precious time. The best is to understand each section in the board so that you would not checkk all the components. For example, if we see one horizontal line in the tv then we know the vertical section have problem. Vertical section consist of only less than 15 components and it takes only 10 minutes to check all the components.
I think I would use an oscilloscope to trace the input signal (ac or dc) and find where there is loss of the signal or distortion of the signal. I would then isolate and remove the suspect faulty component and test it . Is this a good idea?
Yes that’s right but you must know what section that cause the problem. This you may need to study the service manual or even the schematic diagram.
If you have other question please do email me again.
a monitor AcerView 34TL 14 inch analogue problem with horizontal lines like high resolution. i d’nt know about this fault. kindly help.
One horizontal line is the fault in the vertical section. Please check the supply voltage and replace the vertical output IC and retest. I guess the part number may be TDA4866.
Hi.Jestine Yong how are you, I am very happy to receive your letter and expect further
help from you.
I’m fine thank you.
I have a acer lcd monito AL1717, I could repair the power supply part but it is not coming “ON” now I suspect the IC A41DC, it is a programmed IC, I dont find this IC in
If you help me out to get this chip, I will be grateful to you, even I am ready to the amount whatever it is going to be. The IC A41DC is voltage controlled temperature compensated crystal oscillator. Thank you.
This could be an eeprom IC. I believe this ic have 8 pins. Is there supply voltages to the mainboard? If yes then suspect the MCU because if the MCU have problem the inverter will not get supply voltage thus there will be no display.
Dear and respected
A monitor Compaq S720 came to me with pincushion problem. During solving the problem the OSD disappeared suddenly but front panel buttons working properly without any OSD menu. I tried to restore factory setting but failed.
Kindly help in this regard and also tell me the possible causes of same problem.
Your student and faithfully
It may be the eeprom ic data had corrupted. Please check for dry joints in the cpu IC, EEPROM IC and the crystal.
Thank you sir im excited to start learning and now that i recieved this i might start testing components and by the way sir i have a question about analog multitester is their any specification i planning to buy a analog tester but i dont know what kind and how do i know if the anallog i bought is not defective? thanks again
Buy Sunwa multimer that have the X 10 K ohm range. Use that meter to test on the Ac/dc voltage and check some resistors. From there you will know if it good or bad meter.
These could be special part number that can only be understood by the manufacturer. That means the manufacturer did not follow the standard code. Sorry i could not even find it from the search engine. Is both the transistors shorted? Sometimes we may have to use a replacement number and test it out.
I appreciate your answer about this question, but it is a pity that the customer already took back the set, so I cannot do as your suggestion.
By the way, once in a while I go to Surabaya to buy some parts and want to know the exact part number of the hor drive transistor C200Y and HOT F5804 ( see the capture of the schematic ), because I cannot find the datasheet on the internet.
Thank you and have a great day.
I AM TRYING TO FIND OUT WHICH WIRES TO JUMP TO START A POWER SUPPLY WITHOUT IT BEING IN A COMPUTER.
Try this link:
hi thanks for the info. i have encountered many power supply problems. like one i currently troubleshoot it’s an HP lap top power supply a 19VDC , 4.7A, autovolt , the problem is it has no output and the owner can’t use his laptop anymore.
i check the Power IC something K3797 on the face it’s shorted, the voltage in the capacitor around 400v does’nt drain, there’s no available parts here in the market maybe it’s an OEM part for HP exclusively. can you give some hints why it has no output voltage? what are the steps n locating the fault?
I suggest that you check all the components in the primary side since you said you found the bad power FET.Usually when power FET shorted the power IC will also turn bad. Check also for bad filter cap in the secondary side. Here is the spec of the power FET K3797 or 2sk3797:
may i know what is the different of Fuse 250V/0.5A, 250V/8A, 250V/13A?
Can i use 8A or 13A fuse to replace 0.5A Fuse?
The different is in the ampere. You can’t replace the original ampere with a higher amp as this will burn the equipment or even the house. You need to replace with the same spec of ampere.
Have a good day!
Today the customer sent back this monitor again. This time the problem is the display not stable, sometimes the display narrow, sometimes become bright, sometimes become dim as you could watch in the attached video.
I think I had resoldered all the dry joints. Could this problem be caused by another dry joint or some other problems?
Hope to get your answer soon and wishing you happy fishing
First you need to use digital meter to check if all the output voltages are stable or not. If no then check on the power supply side. if all the voltages are stable then check on the secondary side like dry joints in the flyback, yoke coils connector, pincushion transistors and etc. If possible directly replace the h/v oscillator ic and retest. Make sure also the eeprom and cpu is receiving 5 volt supply.
long time no talk, i am sorry that i need to bother you again.
i bought the dy294 tester and i followed the test procedure for testing the non polar caps you talked about in your article. i am confused.since most of the non polar caps are less than 1000v in working voltage, how can i test non polar caps that have working voltage that is less than 1000v? you said we need to add a resistor in parallel to the non polar caps. also on the picture shown, you didn’t insert it into the capacitance test socket when testing. anyway, i am confused. please teach me. thank you very much and have a good day.
The answer is in this link https://www.jestineyong.com/?p=2841 and it was inserted between the C and E. The resistor already covered the E hole for connection.
Hello sir it has been a wonderful experience reading and following your trainning am so glad for your help in making men become what they want to become, may God richly bless u. Sir i ecanter a problem with one samsung color monitor it does not come ON, when you connect power cable to it, it will only flash on green light for few seconds and then it goes off, if you put it ON again it will do thesame thing. Sir please what do i do in this case?. Thanks from Ehimwenma.shalom
Is a CRT or LCD Monitor? You may need to check for shorted components in the secondary side, and check for bad filer caps too. If it is a LCD Monitor and all the voltages are good in the mainboard the the MCU is the culprit.
1) Merujuk muka
iaitu mesti mempunyai empat kaki.
B+ coil mempunyai cuma 2 kaki, yg lagi 2 itu adalah untuk hold kat board supaya ia tidak longgar bila set di hantar dari luar negara. Tv tiada B+ coil.
2) adakah kedudukan B+ coil pada TV selalunya berada selepas capacitor sederhana bernilai contoh:
100uf 160v yang akan masuk ke FBT sebagai ‘primary’ dan keluar ke collector (HOT).
Ya, ia akan masuk ke primary dan keluar kat collector. TV tiada B+ coil.
3) Pada TV Sharp 21” saya dapati B+ coil itu hanya memiliki dua kaki dan berbentuk bulat.
Bolehkah anda confirm kerana kemungkinan ia adalah coil biasa untuk filtering dan bukan untuk menyimpan tenaga (B+ coil menyimpan tenaga dan dipindahkan kepada kapasitor)?
hai justine , saya ada 1 LCD monitor model SAMSUNG 2043swx , problem blur . apakah kerosakannya
Sekiranya semua output voltage dari SMPS adalah baik maka LCD panel ada masalah. Masalah LCD panel biasanya tiday boleh dibaiki.
Gud day Sir Justine, I need your expert help sir. I have a UPS APC Smart-UPS 600I which when switch on it go to the normal process of checking AC, battery, etc. then after it test to battery mode, Overload Alarm and LED activate. I check all output Mosfet and other components around the circuits, it seem all are good. One major thing I observe is that upon checking its 220V AC Output, few seconds after switch on, when it test to battery mode, the 220V AC output goes up to 350V AC, thus, trigerring the Overload Alarm. Any help on this one will be much appreciated. This UPS is a very good one and I want to repair it. Thank you for all the guide you give to us thru your Repair Newsletter and it help me a lot in my repair works. Sincerly, Eliezer
I suspect this APC may have the problem of corrupted EEPROM IC data. Replace the batteries and retest and if still the same then suspect bad EEPROM IC.
Hi I am looking at the
DY294 Digital Transistor FET DIODE Neon Cap Tester
I seen your review on you tube here http://www.youtube.com/watch?v=ReLHnmPsz_4
Is this a good tool ?
Thanks for your time.
Yes it is a good meter and you can read the full review below. It is cheap too.
Terima kasih kerana menjawab pertanyaan saya, coil yang saya maksudkan itu bertanda 151K G, ini mungkin coil biasa, Adakah saya boleh gunakan teknik ‘Isolation Method’ dengan menanggalkan coil ini dan memasang mentol 100w disini.
Ya anda boleh sekiranya coil tersebut adalah siri dgn B+ litar ke flyback.
Satu lagi soalan iaitu ‘If any the output voltage lines show two same reading’ dalam Resistance Test Method adakah bermaksud jika terdapat lebih daripada satu line voltage yang mempunyai bacaan sama (low ohms readout).
Maksudnya sekiranya salah satu line mempunyai rintangan yg rendah ohm.
thanks i hop you ken help me we nee to tes ic chips and eepros eprom flash epros
we and the ecu automoviles thanks
For testing ic we need an oscilloscope. First find out the part number of the IC then look for the datasheet of the ic. Look for the supply voltage (vcc) pin, input and output pin. Make sure the voltage is good and stable when measure the ic on board. If the voltage is good then you need an oscilloscope to check for signal at the output pin. No waveform could be the ic have problem or the surrounding components have problem.
The EEPROM ic store programs and we can’t test with scope. We can only test the supply voltage.
Sorry no info on the vehicle ECU.
Seek your advise on some LCD repair….I have 1 unit Samsung 920NW and 1 unit Acer X173,.. both having the same problem..display on for 2 sec, then dim… I have check all the cap with the ESR meter and all are within the spec.. I have measure the power mos fet for Samsung (AP9971GM) and the Acer is (AP9567GH and AP9962GH) and it seem normal without shorted.. what else could be the possible cause of the problem for these 2 models?
One of the backlight may have problem. Check also for tiny dry joints in the high voltage transformer.
hi mr jestine.
please excuse me because i’m bothering you with my questions.
my crt tv has a problem and that is:the screen is dull and
sentences(comments below screen) can not be read easely in other words
screen isn’t transparent. i had this problem 4 months ago and i
adjusted the screen and focus volume and it became good but 2 days ago
it became bad again.
(the tv worked without any problem for 4 months)
what is the main problem?
what components are faulty?
If the heater voltage is good then the pc tube may be weak.
saya dah terima BLUE ESR METER yang tuan hantar…terima kasih…
di sini sy ada sedikit masalah berkaitan penggunaan blue esr meter…
1. sy kurang jelas cara membaca carta tersebut… boleh bantu sedikit cara membaca dan contohnya…
Andaikata kamu check 22uf 250 volt dan carta itu tunjuk nilai ESR 3 Ohm. Ertinya capacitor yg baik mesti mempunyai nilai kurang dari 3. Kalau kamu dapat nilai 7 ohm ertinya kapacitor itu sudah rosak.
2. sy pernah
nilai seperti itu adalah baik. Sebelum kamu test kamu kena tekan on butang, lepas itu short clip tersebut dan tekan sekali lagi butang tadi untuk initialize meter sebelum mengulur kapasitor.
3. carta itu mengatakan cap yg baik bacaannya mesti berada di bawah line biru. tetapi jika cap 16v 10uf mendapat bacaan .01 iaitu terlalu jauh di bawah…adakah ia juga baik….atau bacaan mesti tidak terkeluar daripada petak line tersebut..?
Jangan tengok carta itu kerana ia mengelirukan. Guna carta ini:
4. bolehkah blue esr meter boleh membaca capacitor elektrostatik & cap ceramic semasa power tv atau monitor dihidupkan..? atau cara membacanya masing masing berlainan teknik..
Ia tidak boleh check kapasitor semasa set dihidupkan. Ia dicipta khas untuk electrolytic capacitor sahaja tetapi anda boleh menggunakan untuk banyak tujuan lain.
5. saya pernah terbaca blue esr meter boleh membaca dgn tepat tanpa menanggalkannya daripada papan litar…tetapi apabila sy buat percubaan membaca 2 cap yg sama nilai di crt yg sama….16v 10uf..masing masing berlainan bacaan; cap pertama – 4.3, cap kedua – .00 …..apabila sy cabut daripada papan litar dan test…. kedua duanya baru dpt bacaan hampir sama..iaitu 4.3, bolehkah tuan terangkan kenapa..?
Adakah anda sudah initialize meter tersebut? Kadang kala ia bergantung juga di mana kapasitor terletak. Sekiranya kapasitor itu mempunyai satu perintang yg menpunyai nilai ohm yg rendah sambung secara selari dgn kapasitor tersebut maka nilai ESR ohm yg anda dapat adalah sgt rendah.
1) First I must say that I bought your e-book on finding burnt resitor values and I found it to be very good.
2) I took a SMPS( power supply ) out of a printer and there is a IC chip with 4 output pins and chip is
labelled “PC” on the circuit board.
Part # is : cosmo
What does “PC” mean or what type of IC is it?
May i know where is this IC located? If it is located between the primary and secondary side then it is an optoisolator. The part number could be PC817.
3) Now I need some tips on how to repair a PA system which includes the mixer , amplifier and also how to repair a speaker.
Also if you could give me a link to a website that teaches how to do these repairs I would appreciate it.
Since i do not repair PA system thus i do not have info about it. I guess you may need to google it to search for the relevant information.
Hi,Mr.young,Thank you for yours mail,i already enjoy yours book,its great and very useful ,but i want to know in yours book you mostly use analog multimeter for troubleshoot but i think its out of fashion ,usualy in USA mostly use Digital multimeter its easy to use but i think you feel comfortabe from analog meter,can you explain me what advantage this meter?
Thanks for your email. Analog meter is much precise when checking on diodes and transistors as compare to digital meter. That’s why lots of repair tech can’t repair certain problems because a faulty diode/transistor they think it was good when tested with digital meter whereas it is actually leaky when tested it with analog meter. Analog meter has higher output voltage from the probes as compare most of the digital meter in the market.
Have a good day!
first of all thanks for your kind reply.
You are welcome!
well the ic p 607 is receiving the supply voltage (29.5 volts).and also the smps is working well, the 5 volts,12 & the 30volts are available from the smps.
5 volts for the ic OZ9932DN is getting drop (0 volts insted of 5 volts) .
there is no voltage (input & out put) for both the invertor transformer.
This could be the problem with the MCU in the mainbaord. If the MCU did not send an On signal to the start circuit thus there will be no supply voltage to the inverter IC.
I just have a question aside from the capacitor , does the diode, bi polar transistor, and a mosfet has a possibility that can also break down during under full operating voltage?
Yes any components can breakdown when under full operating voltage but the percentage is not that high.
thanks for the nice article…..its a good reference.
can you show me the input voltage of an inverter…
i just can’t get it i think there is 5v, 12v, grnd and i dont know the rest
You need to locate the part number spec and then look for the word VCC which mean supply voltage. It can be any voltage and you can refer the exact voltage from the spec of the inverter ic.
a crt computer monitor made it to my shop with the problem of screen start with picture then it starts to go black..picture then black and it goes like this all the time..checked all capacitors and they all checked ok..what cause the monitor to do that..please help
Is the high voltage on and off too? or just the display? Check the voltages in all the main points in CRT board R,G,B,G1,G2, Heater to see which line that fluctuates. From there you can know where to trace.
HI: I have jailbars adnd a horizontal line across the screen in a Sony Bravia KDL-4000 LCD. Can you help me with the solution? I have the cap Analizer 88A Thanks
If all the voltages in the mainboard are good and stable and there is no loose connection between the mainboard and the lcd panel then the lcd panel is the cause of the problem.
HI Mrs Dimartino,
I have aPlanar pl2010M LCD monitor that turns on and goes black. The green
lights also turns orange and stays orange? I bought a new genericpower
adapter for it off ebay because the original got lost and it seems to be on
but the LCD is not showing anything.
Do I need to change the backlight? Can’t see any image when I turn
flashlight on it. Or do I need a specific Planar power adapter for it?
First the power has to be the same voltage and ampere otherwise it may create problem. Usually if the backlight have problem and shutdown the power LED will remain green. In your case it was orange. If all the voltages in the mianboard are good and stable then the MCU in the mainbaord could be at fault. Try use original adapter and test it out again.
Thanks for reply.. ya.the Samsung backlight cable is broken 1.. but unfortunately I broke the LCD edge when fixing back after repair the backlight..
as for the Acer X173.. LCD backlight is good.. all the cap is within range.. and have resolder all the joints.. but problem still same.. even I have checked the cap on the video board.. I have recheck and remeasure using the ESR meter.. and found no prob on cap.
Do the non polarity cap give prob with this systom ?
Yes those non polar cap could cause the fault too especially the one located near the high voltage transformer. We call it as ballast cap that is located near the backlight connector and tuning capacitor that is located near high voltage transformer.
Thank you for your quick reply to my e-mail it is much appreciated here
You are welcome
and thank you for the links as well I have got my hands on a digital capacitance meter now but still like the Blue ESR Meter.
The strong points for me liking the Blue ESR meter are the parts seem to be off the shelf components so if I ever had the blue unit go wrong and it needs a new component I can get it with know problem even the chips in the unit I have seen on the internet I can order them as spares.
You got a point.
The problem with the peak ESR meter for me is that if that unit developed a fault after the garantee had run out I would have to send it back to peak electronics to have it repaired adding to my cost this is what I like about the Blue ESR meter I don’t need to send it back as the parts can be got from the net easy I have seen the chips advertised as well.
You can enjoy the troubleshooting too.
I have had a chat with www.rf4u.co.uk as they are the UK distributor for the UK I will be buying one from them in the next two weeks the Blue version has had a lot of very good press on the internet you your self have given it a good write up as well.
Yes, every electronic repairer should own one.
I like the press you are getting with your ebooks I will be ordering this some time next month as at this time I am unemployed and on a budget but reading your own web site you seem to be using a lot of photos in your ebooks this is a grate help when you talk about fault finding.
Yes, photos remove lots of guesswork. Thanks for the support on my ebooks.
I for got to ask last time can you use a simple Signal Injector/ Signal tracer to locate faults on TV sets VCR,Computers also Computer monitors, DVD players.
Here is the Signal Injecter/ Tracer kit: http://www.quasarelectronics.co.uk/velleman/k7000-signal-tracer-injector-kit.htm
I have not use the tester before but it is more for those who deal with audio repair (any set that have audio section) and not Monitor repair.
Have a good day!
Check for dry joints in the G1 pin at CRT board.
Dear mr Yong;
I’m using a Philips CRT monitor. When I was working on the computer, all of sudden the monitor brightness got changed and now the screen is too bright. The brightness can’t be control with the front side controller!! However the screen contrast can be changed! . After I got this problem, I saw a very bright light appears in the middle of the screen when the monitor is power off. ( just like a camera flash light) .; if you have time please let me know your suggestion.. what can be the problem ?
Monitor : Philips 104E
Thanks for the testing electronic components book you share with us the beginners. It was realy great it gives me 100% confident to work on my own. I am know working on repairing my TV shut down 2 days ago before i bought your book and i found the HOT transistor short. It was amazing to found out something that i never expected i can do. However I have questions and i need some help please. I went to find my part and i couldnt find it so im trying the internet and it still the same. So
Q. Where can i buy electronic components on the internet?
Thanks for the support. Try check out this link: https://www.jestineyong.com/?cat=12
Q Do you think just the transistor short or anything else should i check? My tv has no power but only non stop pip sound coming out.
You may need to check other components as well. Please visit the link below:
Today another customer brought in this lcd monitor ( local brand ). The problem is quite strange, the display is always white when being switched on ( with input signal ). The display is always the same ( white ) no matter how I change the input of signal generator. The display is only black ( dark ) for a brief moment when I change the pattern of the input signal, otherwise it will be all white display.
Also all the function keys are not functioning, including the power switch. So one must pull the ac cable out or stopping the ac line to turn it off.
What kind of problem is it? Do you think this kind of problem is repairable?
If all the voltages to the mainboard are good and stable and there is no loose connection between the mainboard and the lcd panel then most probably either the lcd panel or the mainboard have problem. Check to see if the lcd controller board in the lcd panel is receiving voltage or not.
Thank you for the helpful repairing e-books you are providing. I bought all except for the LCD monitor repair. I am planning to get soon.
My query here is that I am repairing a UPS and I came with a burned power MOSFET. The component No. is AP9972GP (Click to view data sheet). I searched for the same component in local market but I could not find. After deep searching using the ECG replacement manual I found that this can be replaced by BUK456-60A (Click to view data sheet). Also this one is not available and the available one I found is BUK456-200B (Click to view datasheet). The question is can I use the one I found to replace the original one.
I’m afraid it can’t be used because the BUK456-200B has small drain current as compare to the original part number, you must find one that has the same or higher current or voltage.
I am writing to ask you how much it will cost me for you to repair my PC power supply because I am not good in repairing things, I have five PC power supply unit that need repair, please if you can help me out, can you let me know on below address.
Please find attached pictures of the PC power supply unit for your attention.
Please do not hesitate to contact me should you require any further information.
Thanking you in anticipation of your co-operation. I look forward to hearing from you.
Thanks for your email and the photos. Sending the power supplies to my country and sending it back will cost a lot of money. Besides there is no guarantee the internal parts can be found from the market. I suggest that you send to computer repair shop in your country which is much faster and cheaper.
Have a good day!
My email has been down for a month now as my pc crashes and I wasn’t able to contact you.
Thank you for the laptop repair tip you gave. I had open the laptop and check the voltage regulator but I wasn’t sure which one is the voltage regulator. I’m attaching a pix of the board and if you can identify me the component I should test.
The picture was very blur and i could not see it clearly. Trace from the supply input and if you see an IC that have more than 4 pins then that could be the voltage regulator. Confirm it also by checking the part number from the internet.
I’m also thinking, that it is better if I look for a second hand motherboard to use on this but its very hard to find one here. Do you sell second hand motherboard? This is a acer laptop 23000 series. Maybe I can buy it from you.
Sorry i do not have those board.
Hi,Mr.yong taank you for your relay,I am still confused!i purchase Analog meter,fo testing diode,now in my hand that is zener diode(IN40B),when i am going to test this diode on meter scaleX10, when i put my red lead on cathode its showing 4 ohms,but red leads put on cathode black on anode its showing infinety,but in book page 78 talk about opposite,in my meter not scale 10 kohms,pl give me advise i have confusion,i new meter sanwa have all necessary scale already ship,i hope one two days i will received.
Thanks for the email.You really need the X10K Ohm meter to test on any zener diode. You will confuse if you use the x 10 range. Wait till the meter arrive and see how it goes.
Thank you sir,
sir i facing problem in hitachi 42PD380TA plasma, there is 3″black bar on the right side of the screen,so i want solve the problem,please let me know
It could be the buffer board have problem (burnt IC and etc) or the Plasma Panel is bad.
I am working on a Sharp 27u-s60 TV…the high voltage output keeps blowing….can you help me with this problem
Please refer to this link:
Hi Jestine – Thanks for replying. I learned from you how to display things using pictures!
You got wonderful pictures!
I have attached some picture of what I think is the problem. The one shows the top of the PCB while the other shows the underneath – It is burned and some of the components appear damaged there – The problem is that I don’t know the value of the components as there is no circuit diagram.
I have googled for a circuit diagram.
I guess no because the information for UPS is very limited in the market. Usually if i see this kind of problem i will send it back to customer or buy over the faulty unit to salvage the parts. The only solution is to find the same exact model for comparison.
Have a good day!
Have you come across this Phillip LCD 150BS? .. I have 1 unit which problem is can’t switch on(no power).. have check and found no supply in to ractifier..have replaced the big cap of 450V 68uf… what do you think could be the cause?.. initially the fius was blown due to a faulty non polar cap 103 … the non polar cap have only this digit on it..103… I replaced it with a new non polar cap 103 2kv… do you think this could be the cause of no supply to the ractifier?…
The bridge rectifier should have dc output voltage and if there is no voltage then you need to check if there is any ac voltage entering the bridge rectifier.