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Electronics Repair Questions/Answers and Testimonials- Part 41

By on January 8, 2013

 

Happy New Year Jestine;

I am writing you this letter with tears of joy running from my eyes. The answers to the  questions below. I found them in the SMPS ebook.

The book i read it 3 times. You have outline each stage  sooooooo simple. I can't believe it.

Good work Jestine!

Buchanan.

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gud day…
what is the best replacement parts for RU4A diode?

Hi Ruri,

Usually I will use original one. Try UF5408 and not 1N5408. I can't guarantee if it will work but you can try.

Jestine

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hi,
Jestine Yong
with the help of your article i repaired my dead
pc smps in just 10 minutes .By careful observation input filter
capacitors ,one elctrolytic capacitor was bulged that caused two
transistors( sxw 13007 ) shortened and also fuse( 5A, 250 V).blown..by
replacing these components my smps got live. thanks for your
suggestion and articles.Happy merry Christmas.May god bless you.
thanking you,

M.Vallaiah(India)

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Hi jestine,
how was day i hope you are fine, please i want know about blanking circuit, how it was work? what are the compönents to be found in this circuit. Thanks 

Hi Mukthar,

Blanking circuit is to remove the retrace line and can be found in the vertical output ic circuit. If you check TDA1675 datasheet you will see pin 13 is the blanking output:

http://pdf1.alldatasheet.com/datasheet-pdf/view/25029/STMICROELECTRONICS/TDA1675A.html

Jestine

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respected sir,

            

i am engineering student and i have diploma (3 year) and B.E (3year) both stream electrical engineering but i also intrest on electronic engineering i am belong to normal family background and i want to do something ahead as compare some new which is change the life & easy  so please sir suggest me suitable path for my futur .

NILESH

Hi Nilesh,

It depends on your passion. You have to ask what is your passion. You could choose

electronics design
electronics programming
electronics repairing (troubleshooting)
etc.

Once you have decided then go full force to achieve it.

Jestine

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Dear Jestine,

 

Hi! I just want to inquire the trouble of my laptop, The font have shadow and the background turn into pink color. Before this trouble i notice a flickering display during the boot process. What is the cause of this trouble:? My laptop is Acer aspire 5920G 

Berlin

Hi Berlin,

Try run from external monitor. If problem still the same I'm afraid it could be the graphic GPU chip problem.

Jestine

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HI Roman,

I have 2 broken crt monitors, first one is LG studioworks 700B where the screen became stretched horizontally. There is no reaction to horizontal settings on the front panel and the same with video driver settings. Vertical changes work fine and everything else too, but it doesn't react to any horizontal changes at all. I'm not a technicial ,and only understand the basics in electronics (like how to take it apart and replace the broken component) so I found 2 blown capacitors which I have replaced, but it hasn't solved the problem.

Can you at least guide me where to look for the faulty component?

Make sure the modulation diode located near flyback not shorted. Check the pincushion transistor (attached to a heatsink) not shorted too.

The problem in the second monitor – LG studiworks 575N is that when I plug it into the outlet, it starts 'ticking' and won't turn on. There is no light on the power indicator and no reaction to the power button, it just keeps ticking. After inspecting the board I also found one blown capacitor for 200v 47Uf . The whole area around it on the board is dark and has a bit of charring . I've replaced this component and again it didn't help. The monitor's still ticking and has no response to buttons.

Try visit this link:

http://www.electronicrepairguide.com/testing-flyback-transformer.html

Jestine
http://www.JestineYong.com

===============================================

HELLO SIR !

HOW CAN FIND THE VALUE OF SOLID TYPE CAPACITOR. I HAVE A CAPACITOR WHICH HAVE FOLLOWING DIGIT ON IT AS 5N 680 4J

WHAT IS MEAN BY THIS. 

ON REGULAR CAPACITOR VALUE WILL BE GIVEN AS   1000 UF 6.3V. 

Hi Jitendra,

Try check out the link:

https://www.jestineyong.com/understanding-smd-electrolytic-capacitor-coding/

Yours could be a 680uf with 6.3 volt- J means 6.3 volts according to the table in the link.

Jestine

===============================================

Hi John,
Just need to ask you why half of my TV screen is almost black and sometimes it becomes clear.
My TV is Sony LD flat screen
Thank you so much,
Sam

Hi John,

If your tv is crt flat type then it could be the vertical output ic area problem. Make sure no dry joints in the ic and the supply voltage is good.

Jestine

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Hi Mr Yong,

 i have question regarding the Haier LCD tv 32" and want to know what is the exact voltage output for the regulator labeled 17-33L and 1117L  i search in the internet but i can't find it, so please help me. 

thanks,

dong faller

Hi Dong,

The 1117L comes with few version like -33, -25, -18.   33 means 3.3 volt output, 25 means 2.5 volt output and 18 means 1.8 volt output

Jestine

=================================================

HI,

my question is about P-channel Mosfet .

 when i charged it red probe still touch the pin 2 (Drain) then i use my finger to touch both gate pin 1 ) & pin 2 ( drain) then black probe touch with pin 3 (source). i got result is low resistance. after that i release my finger no touch pin 1 & pin 2 , the black probe still touch the pin 3 (source) their result become drain energy means result start drop to hign result resistance is this is normal or just this mosfet are faulty ???

This is normal as some fet would not hold the charge.

 then i touch pin 3 (source) again their result is high resistance  no low resistance but i still no discharged it.

If your black probe touch on pin 3 and finger touching pin 1 and 2 the needle should go back to low resistance again but then again it will drop.
 

 

    but if i test with N-channel Mosfet the result is diffrerent their result still is in middle low resistance after i release my finger to touch pin 1 & pin 2.

Different mosfet have different characteristic- some will hold the charge and some will just drop regardless if it is a N or P channel FET.

Jestine

=========================================

 Compliment of the season sir. How is your business and your family. I appreciate all the help you've rendered to me throughout this year, and most especially your monthly newsletters. Kudos to you sir. Please i have a 14"tv with proper sound and picture, but it draws some tiny horizontal line across the screen. The picture i.c and the components around it are all working fine. What could have being the cause. Could it have been the line(fly back transformer). I'll be glad to hear from you as fast as possible. Thanks for your unending advice. Wish you a happy new year in advance. 

Hi Olabanji,

Thanks. It could be blanking circuit problem or the tube already weak. Blanking circuit is located at the vertical output ic area. Try check the tda1675 ic datasheet and you will see the pin "blanking". This is just an idea at where you should locate the blanking circuit.

Jestine

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Hey its me robert I just got a blue esr today, but when i checked a cap good with my digital cap meter 9.60 for a 10uf cap 25volt. I got a reading of 2.2 on the blue esr so is it bad or do i have a bad blue esr I got your chart off your web site and it said 1.5 was high for this cap. is it possible that the blue esr is testing on a level that my reg digital meter set on cap is not seeing ? please help

HI Robert,
 

According to the chart in the below link the cap that you are testing seems to be out and need replacement:

https://www.jestineyong.com/esr-meter-table/

The chart values mean for any cap that you are testing the value that you are getting should be lowered than the chart and not more than that. If you are got 2.2 esr ohm and the chart is 1.5 esr ohm then you need to replace the cap. 

Jestine

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Hello again Mr Yong and a happy new year

I need your advice on a problem I have with an ATX PSU

It’s an OCZ 700Watt StealthXstream 

The PSU doesn’t light up at all

When I put a PSU tester (Thermaltake’s A2358) the 3.3v 5v and 12v light up and instantly go off (the psu shuts down)

I’ve looked for leaky or bulged capacitors but no luck (I don’t have an ESR meter yet)

Tested the fuse OK

Tested power transistor, Bridge rectifier and Diodes with an analog MultiMeter  all OK

Inspect the PCB and didn’t find anything burnt

Is there something else that I could look?

Thanks for your time 

Best regards

Hi Aggelos,

Thanks. Shutting down can be caused by few factors like bad esr in e-caps, bad components in the surrounding secondary PWM or opto ic, no actual load and etc. If the pwm ic or the opto ic and tl431 ic bad could also shutdown the power supply.

Jestine

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sir,HAPPY NEW YEAR 2013 TO you and your family and the electronics world.i have an lg tv with the horizontal # c6093 shorted. i am not able to find that part number anywhere . i have a same board that uses d2627 as horizontal but the flyback transf on the two boards are different. but same circuit with parts same. i wonder if i could use the D2627 as substitute to the c6093. or do you have any substitute numbers for c6093?please advise. Thanks

Hi Corriete,
Thanks. As for using D2627 to substitute the C6093 I can't give advice on this because I do not have the C6093 spec. I suggest that you test out the tv and if the transistor runs warm (not hot) after few hours then you can use it. If it turns hot very fast then you may need to look for another number.

Jestine

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Dear Jestine,

 

Sometimes I come across a problem when checking the output of car chargers which suppose to be 12v, when I check the output with a voltmeter sometimes i found the voltage 16v and sometimes 10v, what could be the problem?? These voltages are on different chargers 

Thanks

Stephen

Hi Stephen,

Some charger could produce higher output but when connected to a load it will drop. If it is 10 volt then it could cause by bad e-caps.

Jestine

==================================

Hi, Jestine, happy New Year to you and your family.

Many thanks for  sending me your electronicrepairguide its really a big help for me.

right now I'm repairing LCD TV. Model 37D800.  brought by the customer.

when i open the cover i found a blown fuse. i replaced the fuse and blown again.

i read from one of your LCD repair guide, stating, "once you replaced the fuse and blew again.

suspect one diode of the bridge rectifier broken. and you're right. when i checked the rectifier

one diode is shorted.

the problem now, i already checked almost all electronics store here in manila and i can't find

the rectifier No. "KBU 1006".

best regards/boy

Hi Boy,

If one diode shorted I recommend you put in 1N5408. Replace all the 4 diodes together if found one have problem.

Jestine

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I'm restoring a 1965 Sony videocorder. In searching for replacement transistors I don't know the meaning of the last digit after the dash in this part number: 2SC401-6. A 2SC4016 also exists. Could this be the same transistor with a different marking system? Is this last number significant from a rating standpoint? These transistors are used in the servo control circuit. I have found a substitute for 2SC401 listed as 2N3710 using the cross reference at http://english.electronica-pt.com/db/cross-reference.php. I have found no transistors with a dash in the part number. I hope you can help. Thank you very much, Rick

Hi Rick,

2SC401 is more acceptable because during 1965 the 2SC4016 have not been manufactured yet. Try the substitute number and if it works fine (not hot) then you can proceed to use it.

Hope this helps!

Jestine
http://www.JestineYong.com

==================================

Hi yong, I have encountered one problem in our production pcba's…. We are getting vcc and gnd short issue while testing it in a in circuit tester…. Can you plz help me to resolve this? If yes I will send you the necessary details about this problem……

Regards,
Prashanth

Hi Prashanth,

You can try use a short circuit finder to locate such problem. Please visit this link below:

https://www.jestineyong.com/short-circuit-finder/

Jestine

==================================

Jestine,

 

The problem was an open backlight ccfl.  Since I have not replaced these before and I received this monitor for free, I decided to just use it for parts.  So I opened it up to see how it is put together.  I must say that replacing the ccfl is not an easy task.  I just hope I am successful on the next one.  Any tips doing this would be helpful.

Thanks!

Duane

HI Duanne,

Yes you are right replacing the backlight can be very tough. A slight mistake could break the tcp package causing vertical bar across the screen. However there are some design where you can pull out the lamp easily. As for the tough one, one just has to becareful and slowly remove all the blocking parts. There is no short cut and need patience to do it. 

Jestine

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HI Massimo,

hi jestine i have a resistor colour:blue,gray,silver,gold,black in that order. i can't seem to find the right value for this resistor anywere. i have tried resistor calculator internet,but only one has silver as third digit and the value i get form internet resistor calculator is 0.68 ohms,but what is the black band for and what is the silver and gold value as a digit.the resistor comes from a bush tv (btv185dvd). it would be great help if you can give me some advice on this resistor please. thank you.

Ignore the black and the value should be 0.68 ohm. Some resistor have white color behind and it has to be ignored too.

By the way I will ship your meter on Monday using FEDEX.

Thanks for the support!

Jestine

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Thanks alot for your info

I have another question 

I need to know if u know on a ABS pump on a vehicle and alot off other controllers , if u open it then there is a sticky gel that covers everything and makes it diff to work on pc board

 

I have seen a movie on you tube that they use some solvant sulotion that the dip it in for a while , but they dont tell what they use and after they have work on board they throw that gel kompound on board again

If u can help

Thanks

HI Walter,

I suggest that you check out my blog post and read the comments. 

https://www.jestineyong.com/how-to-remove-the-silicone-in-the-circuit-board/

Some replies suggested a solvent to solve the problem.

Jestine

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Dear Jestine,
I have come across so many LCD TV HDMI problem that they said there HDMI is not working.
Do you think you could send me some information on how to fix with these problem? Thank you!

Hi John,

If all other input jack is working except hdmi then you may trace and troubleshoot the hdmi area for shorted components or even open circuit track. Sometimes the problem can be caused by firmware where you need to upload the new software from the factory in order to solve it.

Jestine

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Dear Jestine

Happy New Year to you and very many thanks for the latest news letter January 2013!!

I got it and I have read it more than three times now. Its a very good article and is going to help me, and others I believe, in understanding LCD TVs, this will lead me and others as well to be better repairers of this type of TVs.

I really appreciate for this article and many others that I have been receiving from you, keep it up please.

Thanks a lot 

 Best New year's regards!!

Luciano

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2 Comments

  1. Austin

    November 16, 2013 at 6:47 pm

    jestine good morning please i have problem with my tv set it have problem of vertical line in middle of screen what is the cause?

    Likes(0)Dislikes(0)
    • Jestine Yong

      November 16, 2013 at 10:17 pm

      HI Austin,

      Check horizontal yoke coil area for dry joints and open horizontal yoke coil winding.

      Jestine

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