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Electronics Repair Questions/Answers and Testimonials-Part 43

By Jestine Yong on April 30, 2013

Thanks man because of your newsletters I can repair a number of electronic equipment.

Brisco

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Excellent job jestine.I knew its really hard to pinpoint some bad components in the circuit especially IC.,but anyway you give us a guidance in actual repair which is very useful .

by the way jestine could you please tell us more technique how to specifically determine and check if the IC is defective.

Thank you very much

Drax

Hi Drax,
It depends on the type of ic and not ic can be checked using scope especially the rom,mcu, eeprom and ram. It is only through substitution then only you will know if it is working or not. For the normal IC, MAKE SURE IT HAS SUPPLY VOLTAGE and check the input and output waveform using scope. If there is input and no output then the problem is in the ic or it can also be in the surrounding components.

Hope this helps

Jestine

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thank you for the info.just wonted to let you know tha i just bought your ebook.your ebooks are great . let me know if you make any knew ebooks.i will alwayb buy them .thanks.

John

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Hi Brad,

I like your simple approach to repairing electronics. I never pursued my interest in this field because of all the heavy theory involved. After stumbling across a few of your videos, I began to realize the difference between the knowledge needed to repair as opposed to design. I have now started to self study repairing electronics. I am a computer tech by trade but your ebook has demonstrated the mechanics behind the magic and has re-sparked my interest.

Noted and thanks.

I have a question. I just bought a used tektronix oscilloscope and I am having a hard time finding any useful information on how it would assist me in repairing LCD Tvs or anything else for that matter. Seems like it would useful only if I was designing or if I knew exactly what signal I was to be expecting from a circuit. Can you point me in a good direction that would help me learn the basics of how to use it in troubleshooting?

I suggest that you get Damon’s ebook on LCD TV repair secret and his ebook comes with his personal support including of giving advice when come to use scope in lcd tv troubleshooting.

And on another note: HOW THE HELL do you use a solder-sucker so well? Your parts practically fall off the board when you do it. I have not yet been able to clean one joint with the damn thing. you make it look so easy. I ended up buying a Hakko desolder which works well on larger components but not good for smaller holes.

Practice will make you perfect. You just have to keep on practicing it on different type of boards.

Hope this helps!

Jestine

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Hi Jestine,
I fully agree with you when you say “Once in a while we should just remove the money sign $$$ from our mind so that we can go back to the basic of electronics repair which is fun, satisfaction and fulfilling!”
Thanks for enlightened approach to life.
With regards,

Jayant

Hi Jayant,

Thanks and you are not the first one who say it. Guess this words are really meaningful to us as electronics repairer.

Jestine

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well i check the horizontal yoke i found out that there are partialy

burn to the winding if i replace it with a new one should they start

the tv normally i dont know how much the cost of the yoke but if it is

the solution to the prob no choice have to replace it i have to

canvass for it thank you for the tip i keep updating you sir bout the

progress God bless.

Hi Fred,

It is hard to find a replacement yoke for tv. If if you can find and fixing it will be difficult because the color convergence will usually out.

Jestine

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Jestine, Thanks for the February newsletter. I kept reading it over and over it is so easy to understand and yet i kept reading it. I have an ATX power supply which i practice on .now i am quite sure i know what to do from this newsletter. God bless and thanks again. you said electronics repairs are fulfilling and so is this newsletter.

Eric

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hi,

Justin, once again thank you for the informative article. However, would you kindly tell me more about your technics of using a 100 w lamp in series with the fuse……how do you do it, please explain a little more, thank you

Hi Bernard,

Just remove the fuse and place a 100 watt bulb across the two points and power on. A good power supply, the light bulb should not be constant bright. If there is a constant brightness then there is still shorted component. A good one, the bulb should not light up or light up once (capacitor charged up) and slowly will dim away.

If the bulb did not light up then you can place back the fuse and power it on. The reason of using the bulb so that the new components that you have replaced will not blow again if there is still a shorted component in the power side.

Hope this helps!

Jestine

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Once again Jestine your articles are amazing to read and full of life. It makes an electronic repairer want to repair stuff and not worry about money all the time. It feel great to bring something back to life. Thank you for all your experiences and encouragements. Keep up the good work.

Best Regards,
Andre G
Managing Director

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Hi there mr.jestine,eric very nice but it is true i have a friend he’s been in the field 30+ years and he says ever since www and ebay and craigslist here in philadelphia pa. people don’t even take stuff to repair like the 80’s and 90’s they just buy new lets say laptop or pc when some older unit are even better more pride in work i have older pioneer stereos and compare to the new ones na my friend only if people knew somethings just can’t be replace electronics always god bless mr.jestine,eric

Hi Eric,

Yes it is true only for certain items in the consumer electronics industries. Electronics repair is not limited to only consumer electronics. There are other fields such as:

medical electronics
cctv/alarm
car parking system
beauty equipment
electronics design
industrial electronics
automobile electronics
and many more.

Jestine

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Dear Sir,
I have some problem in my power supply (SMPS). All the voltage are also fine but there is no display in computer with that power supply.

Your Sincerly
Summit

Hi Summit,

Probably the power good signal in the power supply have problem.

Jestine

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Hi Sir,

Thanks for the reply and for the information. What could be the value of the thermister? The components is really burnt out. Thanks

Randy

Hi Randy,

It can be any number. Try check this link:

https://www.jestineyong.com/no-power-in-samsung-ml-4050n-laserjet-printer/

Jestine

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Hi Jestin i’m asking how can turn on a power supply for computer without putting it in the case or how can we use it without the case what can i do?

thanks in advance

Best regards

Vicken

HI VICKEN,

Short the green wire to ground (black wire).

Jestine

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Thanks Mr Jestine for this February news letter. I had almost overlooked it when i saw it has to do with power supply issues. I have an ESR meter which i bought from you but i have never used it to read resistors. I only use it for caps alone. I will always think those low value resistors don’t matter much since they are below i ohm. today i have learnt . May God Bless you. Thanks.

Victor O

from Nigeria

Hi Victor,

Yes the low ohm resistor could cause low output voltages. Please read the article below to fully utilize your Blue ESR meter:

http://www.electronicrepairguide.com/esrmeter.html

Have a great day!

Jestine

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hi, i purchased your lcd repair book which is great, do you have a repair book for stereo amplifier units? i have been asked to fix a denon avr1603 amplifier which wont turn on, but i have not repaired any amplifiers before. the standby light is on, but the display wont come on and the unit wont power up. where do i start?

HI Adam,

Sorry i do not have amplifier book. But I can recommend you to get this one:

http://www.amazon.com/Troubleshooting-Repairing-Equipment-Electronics-Technician/dp/0070157561

In your case the problem could be bad MCU or flash rom or even eeprom ic. The MCU has to send out an On signal to trigger the main power supply. If no signal coming out from MCU, it is either the MCU did not get a good supply voltage ot the MCU programs itself already corrupted.

Jestine

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mr yong am having a problem with an atx power supply where everything seems to check out fine. connecting the green wire to the ground it works fine but when i connect it to the pc it will come on for a second as soon as i plug in the 24 pin. pushing the power bottom it comes on then after holding in the power bottom to turn it off it does not work . the pc does not work show anything on the monitor but if i try a different psu the pc work as normally

Hi Craig,

If everything is connected to the pc motherboard and all the voltages are good and it does not have display this could point to the problem of power good signal problem. Without a good Power Good signal there will be no display eventhough all the voltages are good.

Jestine

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Hi jestine

Thnak you very mach for your monthely repair information. with the help of you I am well know about electronics how to repair Your e-book a very friend of mine every where. thanks

I wish all the best to you and your familly

Tesfaye k

Addis Abeba

Ethiopia

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Hallo frend mach greeting to you. Thanks for sony bravia it now ok. Next is Hisense 81cm colour tv model: TLM 3233D It can start and display a word Hisense then in 5 seconds it wents off . What is that.

Hi Herold,

Perhaps one of the backlights have problem or one of the high voltage transformer shorted or have an open winding.

Jestine

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Hi ;

how I can select ohm adjustment by testing resistor.

sample 1.0ohm I need check it’s use what ohm selected like X1 or X10??

sample 10 ohm use what selected???

sample 100 ohm or 680 ohm use what select ???

sample 1.0k use what selected ???

sample 10k use what selected ???

sample 100k or 470k ohm use what selected ???

sample 1M or 3.0M ohm use what selected ????

thanks you very much.

can you teach me.

Hi,

The best is to use the digital ohmmeter with auto range. It will solve all your Ohms reading problem. Analog meter is not accurate in testing Ohm.

Jestine

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Hi Jestine!
May I ask you a quick question.
I have just swapped an old CRT TV board for a new one. I also reconnected the four wires on the tube (horizontal and vertical windings) Orange, blue, black and white. The thick one is the Orange one. Reading from left to white.

All is turning on okay only that the writing on the screen is upside down. I can’t remember which two wires need to be swapped around to bring the screen to read correctly.

Someone said it could also be the low voltage supply power connectors that are swapped.

What do you think?

Many many thanks for your assistance.

Jeremiah

Hi Jeremiah,

You need to reverse the vertical wire that have the highest ohm.

Jestine

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hay mr yong weldone sir, please i need your advise , am working on an
LG flatron w2234s
its has a 2inch white line on the left and its video is on and off
always, i bout another main board but it became worse than it was and
it developed two green and red small horizontal lines what should i do
sir
yuors yaku

Hi Yaaku,

Horizontal or vertical lines usually is the problem with the LCD panel and it can’t be repaired.

Jestine

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Hi Mr Yong, thanks for the ATX repair newsletter. I appreciate your tremendous support to me in particular & many technicians around the globe.
Please Sir I need your assistance as regards a SONY LCD power board Model APS-252. The problem was that it was coming on & going off when powered. So I uncovered the cover & discovered the pwr cap(450v/120uF) had exploded so tested some components around it and found no other part bad so I replaced the capacitor & immediately I powered it something sparked in the pack, when I checked it was one IC (MIP2H2) & one Thyristor (K15A50D) that were damaged.
Pls sir I have been able to get the MIP IC but couldn’t get the K15A50D. I will greatly appreciate if you can tell me if it has an equivalent or if its available.
Thanks. Rich

Hi Rich,

I found one at http://www.aliexpress.com/item/Hot-offer-TOSHIBA-NEW-ORIGINAL-K15A50D/697074020.html

Hope this helps!

Jestine

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Hello Jestine, thanks a lot for your very interesting newsletters. I have a question on my workbench is a LCD TV, it turns off in a few minutes running. I have two sense resistors located on the power supply card one of them is .39 Ohms and the other .50 ohms. The .39 resistor with a multimeter I get a reading of 1.1 ohm, the same with the BLUE ESR I get a reading of .5 Ohms. The .50 ohm with a multimeter I get a reading of 1.4 ohms and with the Blue ESR .70 ohms, I think they are not good, am I correct?

This TV has two inverter cards I already checked the 48 transformers with my ring tester, they are good.

I even turned on the TV without the two inverter cards and still shutting down.

Martin

Hi Martin,

The problem of the tv is display appear and then shutdown? Multimeter can’t be used to check on low ohm resistors. The ESR meter has to be calibrate first so that it can measure low ohm resistor more precise. Take a good low ohm resistor and test the value before checking on the .5 and .39 ohm resistor.

If the problem is display shutdown after few seconds then compare all the high voltage transformer secondary winding using ohm range since the ring tester already tested good. all the ohm range should be roughly the same.

Jestine

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Jestine, got a question, My neighbor just bought a plasma TV and it is putting RF noise or spikes out on certain frequencies that is putting loud buzzing sounds in my Ham Radio receivers on these frequencies 1.8 mhz 3.946 mhz and 7.230 mhz and 14.275 mhz and it is really bad enough to jam my Ham radio receiver bad enough to create an S9 plus buzzing noise to where I can’t hear hardly at all. What do you think is causing this? and the plasma TV’s are well known to the Ham community as causing havac to many a radio receiver’s. What do you think is causing this and what could be done to cure this problem? My neighbors house is about 75 feet away from my house, I know it is his TV because I have had him on the cell phone and let him listen to my radio receiver and then had him turn the TV off and he would then get to hear the buzzing stop in my radio when he turned his TV off. Let me know what you think, he is causing interference to my radio’s which is violating FCC rules for my radios, he says where he bought it will not let him return it, he has tried to put ferrites on the TV power cord but that didn’t help. the TV is a LG 50 inch plasma.

Jim

Hi Jim,

Perhaps both neighbors are sharing the same AC mains this could be a noise interference to the ham radio too (unless radio uses Isolation Transformer)
Its possible the tv could be at fault as it is picking up interference it’s not supposed to, and the tv is causing broad spectrum low rf interference.

Sorry I do not have the exact answer for this.

Jestine

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Hi Mr. Jestine,
Your LCD Monitor Repair book page 64 said to buy monitors that are beyond repair.(bad power supply or inverter but with a good LCD panel)
What is a fair price? The customer may think we
tricked him to get his monitor if we repaired and sold it. Power supplies and inerters are cheap online. Would be worthwhile for large monitors. I will be working on larger LCD TVs that cost a lot and are worth the price of a power supply/inverter/Tcon board. Am I wrong?
Thanks,
Lynn

Hi Lynn,

Do your best to repair the monitor first. If you really can’t solve it or too expensive to get the replacement part then you may have to give the customer the options. I usually bought the monitor in between USD10 to USD17.50 depending on the size and the brand of monitor. Recently I bought one 19″ samsung (mainboard spoilt) with only USD10.00 and I have salvaged the LCD panel for another broken Monitor. I still keep the backlights and the good power/inverter board for future use.

Jestine

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Hi Brad,

I did what you had said and practiced with the solder sucker for a few hours. Doing much better now.

Good to hear that.

I finally found out that most TV repair manuals include images of what a scope signal should look like on particular circuit. That’s good to know.

Yes you are right!

More questions:

What resources do the pros use for finding repair manuals on TVs and or vintage electronics (60’s and 70’s Stereo amplifiers). Is their one resource that stands above the rest?

Try this eserviceinfo.com or you can try this link.

My next goal is to study SMPS starting with your book. I am working on a Sylvania LCD that turns off in 3 sec. I hear sound and see an image. All the boards are integrated into one board with the exception of the inverter board. If I unplug the inverter, the TV will stay on for 10 sec before shutting down.

This could be one of the backlight have problem or one of the high voltage transformer is faulty.

My question is this:

Will a SMPS detect that a board is disconnected or not pulling any voltage and go into protection mode? Another words, is disconnecting boards from the SMPS a valid test for finding a faulty board.

It depends on the smps design. Some will shutdown when no load. The best is to test with a load.

Thank you Sir,

You are welcome!

Jestine

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Hi Jestine

You haven’t heard from me for a very long time, I hope you are doing very well. I’m doing fine. Thank you very much for the Newsletters you’ve been sending me,they are very informative. Jestine, I have a problem with a Sansui 74cm TV model SV2918. Resistor R842 connected across the anodes of two secondary diodes has burnt beyond recognition. I can’t even make out what the track looks like. Can you help me please Jestine if you know its value.

I tried the Internet for a diagram, but the one I got did not have such resistor. I’ll appreciate your help very much Jestine. Thanking you in advance. Keep well.

Eric

Hi Eric,

I’m fine thanks. Are those resistors connected in between the transformer pin and the anode side of secondary diode? If yes then most probably they are low ohm resistors (0.1 to 1 ohm) and they act as protection. This means you may have to check ahead of the supply line to see if there is any component shorted.

Jestine
http://www.JestineYong.com

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I found blotted 3 Capacitor on Motherboard PC a 6.3V 2200uf…my problem is No replacement her in the Philippines with that kind of 2200uf 6.3V….The available her is 6.3v 3300uf…is this okey sir???? see picture on my attachement..

b’ regards..

RICKY OF PHILIPPINES

Hi Ricky,

Yes you can use 3300uf 6.3 volt.

Jestine

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hello mr jestine

how are you ?

iwant to ask you about how to find the detaileOF SIMICONDACTOR

i have two vrt volume (a-z,1n) when i opened transistor from old board its nomber . is (8050 )

i did not found it in volum (1n….)

but when i searched in internet i found this transistor SS8050 then i found it in volume A-Z

so without internet i didnot know its SS

my qustion how can i search the transistor in vrt if there is no letter on it (just nomber)

WITHOUT DEPOND ON INTERNET?

THANKS

Hi Badr,

It will be quite hard because sometimes the manufacturer did not put in the full part number. For example

1) P70N70 is actually STP70N70

2) C9013 is actually KTC9013 ( which is a PNP transistor and many thought that it was a NPN transistor because of the word ‘C’)

One just have to read lots of schematic diagrams, visit forum and even to use wisdom especially looking for the right part number.

Jestine

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Thanks for the info. I’ve just d loaded your precious book after payment using my friend’s credit card as usual. I mentioned ‘precious’ because from the preview of the book my inner feeling urged me to buy it immediately as it contained some more repair secrets from you.

I’ve the past bought all your books except one as well as two ‘blue’ meters. Please continue to bring us more books one repair. Due to time restriction I send you less mails & comments but I always keep a watch on your blog.

Thanks again.

Abdul H from Sri Lanka

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Good afternoon Jestine.

Many thanks for the reply and help.

The Flat “LED TV” Brand “Ario” made in China is working perfectly good for only 20mins.

and back to standby mode. Try to turn ON again but no avail. i have to wait until cool then turn On and its ok again for 20 mins.

Test almost every component parts and found OK. of course because the TV is working good for 20mins. I decided to remove the power supply board from its chassis and let it hang then “Turn On The TV.”

i was delighted because its works for several hours. I tried to put back again to the chassis the problem back again after 20mins.

I think the power supply board might be getting to much heat from the metal chassis where it attached. because when i touched the schottky along with the elec capacitor near the schottky its drew to much heat.

i remove the schottky and capacitor from the circuit and checked and its OK.

So i decided to not to attached the power supply board to the chassis anymore instead i attached it at the back cover of the TV which is a hard plastic.

Then TURN ON the tv and observed for several hours and its working perfectly good.

Sir, i just want to ask your analyzation with this kind of problem.

I’m still saving money for the “SMPS” guide and “ESR”.

Thank you so much and have a nice day.

Hi Boy,

In this kind of situation the best is to use a hair dryer and a coolant to detect such fault. Semiconductor gives lots of problem. Try direct replace the optoisolator ic and retest.

Jestine

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9 Comments

michael sebatana

December 5, 2013 at 7:09 pm

your report is interesting. it open my mind.

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Nkuleh

April 15, 2014 at 9:26 pm

hi i got a sansui 74cm model sv29276 clr tv firrst it was showing horizontaly line and i hv chhange thi ic wth 7pin on board no.ic301 for screen and 1 resistence r431 and now it showing small screen wth white line plus it was playing chanels now it not playing it just making noise and showing dis lines.all i wana know what could be the problem coses dis fault

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Reply
- Jestine Yong
  
  April 18, 2014 at 10:31 am
  
  Hi Nkuleh,
  Check the dc supply voltage to the vertical ic. If low dc supply it will cause the problem you have just described.
  
  Jestine
  
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  Reply
Kebimen

December 8, 2014 at 7:19 pm

Superfine 14" TV the screen is very small than usual
It shows very small size approximately 4" size only on the center can you help me on this problem?

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- admin
  
  December 8, 2014 at 9:29 pm
  
  HI Kebimen,
  
  Try check for improper dc supply voltage and bad vertical output ic. Read this article also:
  
  https://www.jestineyong.com/tv-single-horizontal-line-repair/
  
  Jestine
  
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- Alexander
  
  December 29, 2018 at 1:15 pm
  
  Hi,I got tv Hisense model 3233d it is switch on and show me is on and then screen it comes black so I can not see operating menu can assist me please.
  
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Gert

April 24, 2018 at 4:03 pm

I urgently need a cicuit diagram for a Sansui SV2918 CRT Television. It blew the STR and line output transistor which I've replaced but the output voltage remain low. please assist!

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George

September 19, 2021 at 4:17 am

Sansui TV 2918 keep blowing horizontal transit d1556

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- Jestine Yong
  
  September 19, 2021 at 7:32 pm
  
  Hi George,
  
  Check this link https://jestineyong.com/why-horizontal-output-transistor-in-crt-monitor-get-shorted/
  
  Jestine
  
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