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Electronics Repair Questions/Answers and Testimonials -Part 45

By Jestine Yong on April 30, 2013

Dear Justine,

Your SMPS Repair e-book thus reveal and boost my troubleshooting on LCD TV power supplies. I personally want to thank you on the tremendous effort and unselfishness in sharing your ideas in troubleshooting PSU. Its really cut down my troubleshooting and repairing time as most appliance are power supplies related failure, plus the 2 meters just ordered from you – Blue ESR and Blue Ring Tester really fascinate me in troubleshooting more on any type of machine brought in with PSU faulty. I do repairing after Government working hours and weekends.

Tauala K

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Hi Jestine!

I have a defective DC drive that controls a DC motor. I found a 39 ohm (1/2W) resistor increased to 44 ohm.

Do you think that a variation of 10% could cause a problem? Perhaps the problem lies on the track of that resistor?

Regards,

Bruno

HI Bruno,

It can be a yes or no. It depends on how sensitive is the circuit. You may have to try it out.

Jestine

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Hello Jestine

I have a question about a particular computer failure I’m facing. I
know you don’t work on desktop motherboard but I supposed one of your
readers may help.

Here is the failure: As soon as I plug in the unit, it automacaly tuns
on with fan on top of cpu speening but no post , no display nothing
all. Pressing on power button for about 30s,it is off. Unplug it,
plug it again , same scenario

Hi,

Have you check/replace the power supply? Sometimes a missing power good signal could cause such problem.

Jestine

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what are the faults of the atx power supply?what tools u use in ur repairing?

thanks

Hi Marius,

No power, low output power, intermittent no power, power shutdown and etc. I used blue ESR meter, blue ring tester, analog/digital multimeterf and digital capacitance meter. You may need a the atx power supply tester.

Jestine

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Hi Jestine,
Pls. can you check these transistors, 5N60C and 13003BR from your DATA book if there is another Part Number as their replacement part. They are not available here in my local electronic shop even in the city of Manila I’ve tried already but in vain.These transistors are came from power supply of DVD Players, Pensonic and Promac respectively. Thanks again.
Romeo

Hi Romeo,

My data book does not have this part number. The 5N60 C is in the link below:

http://pdf1.alldatasheet.com/datasheet-pdf/view/84506/FAIRCHILD/FQPF5N60C.html

You can look for the same or higher spec.

13003br could be MJE13003 and my databook suggested BUX84, BUX85, 2SC3352 as replacement.

Jestine

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Hi Jestine,

My Television only shows a vertical line in the middle of the screen.

What could be the problem?

Hi Martin,

Vertical line from top to bottom could mean the horizontal yoke coil open or surrounding components have problem. It can be dry joints too.

Jestine

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Dear Mr. Jestine,

I need your help regarding repairing of power supply, I have one computer in our company, the brand/model is Acer Power S285, if all the cables are connected such as VGA, keyboard, mouse, LAN and power. When I push the power button it will not power ON but when I disconnect the LAN it will automatically turn ON. I suspected that the power supply have a problem because all the parts inside the computer including the mainboard is ok. I tried to used another power supply and its turn ON without removing the LAN.

Now, I opened the power supply, inside the power supply I did not see any bloatted e-caps, did you have any idea what’s the problem with the psu or this not psu related?

Thank you very much!

Dexter

HI Dexter,

I suggest that you check/replace the ecaps because not all ecaps will bulge. This is the reason why an ESR meter is useful in detecting bad caps that have good appearance outside but fail inside.

Jestine

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I have a problem with a LOGIK lcd of model : LLPM-50.It goes on ,then shuts down in around 3 secs.I opened set ,did some voltage checks, 5V STB ,12V, and 24V ,but they were OK.

Next I checked the inveter-ON signal , it was present(OK) to both inveter boards.Now I am suggesting that , its either bulbs or inveter board.It uses BD9897FS as the driver IC. I downloaded the datasheet for the IC.Now my problem is ,I am failing to temporarily bypass inveter-shut down on this IC.The block diagram has shown that this IC has 4 inputs under PROTECT-BLOCK (comp 1,comp2 ,CP ,and SRT).I am kindly asking for help , on how to fully diagnose my TV.

Thank you ,Good day.

Best Regards

Hi Happymore

It is either the backlight or one of the transformer have problem. Just use another good backlight to confim it. Compare the resistance reading of the top and bottom transformer. If there are different in the resistance reading then the transformer have problem.

Jestine
http://www.JestineYong.com

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I have a carpet cleaner (electrical operated steamer).
As soon as it is switched on the house Consumer Unit trips.
I checked all the wiring inside the machne and all OK.
On the inside a 2 x 3 inches circuit board (photos attached), the lower part was
covered by foam.
I managed to remove 90% of this foam which was sticky and glue covering both the
capacitor and diode leads.
Could this be the cause of a short?
After all I noticed that in most electronic equipment this foam is frequently
used.
Thanks for your help.
Joe

HI Joe,

There is a possibility. Try clean the board with thinner and see how it goes. Keep me update on this. Before that you can use your analog meter set to x 10 k and measure between live and ground and neutral and ground. Both should not have low resistance.

Hope this helps.

Jestine

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Jestine

Just thought I would make the comment that I bought one of these about a year ago and I find it extremely useful. In particular I have had 5v rails going out of tolerance which although the power supply is still running, can cause many intermittent issues with the Main board in particular. Even if a technician does not repair power supplies, I still believe this is a must for the toolkit.

Have a nice day.

Regards

Laurie C

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

Jestine,
First of all, thanks for all the great info you provide. I’ve purchases several of your on-line books.
I recently worked on a Seiki 32″ Class LCD display (LED backlighting). My friend said it was dropped. It did appear that the LCD display itself was at fault. I found a replacement after doing some searching on ebay. Yesterday, I decided to completely dismantle the TV. What I discovered is when the TV was dropped a small corner of the LCD display was broken. It appeared nothing in the actual display area was broken, but some traces on the edge of the LCD matrix were missing because of the broken piece at the far corner of the display unit. Was wondering if you knew if anyone actually repairs the display, and if that small missing corner could be replaced to fix the missing traces in the matrix?
Thanks for any input!

Best regards,

Mike

Hi Mike,

You are welcome. In your case, sorry I do not know of anyone that can actually repair the LCD display. Try ask shopjimmy.com or even encompassparts.com to see if they have any info on this or not.

Jestine

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Hi Yestine,

I’m using the same atx power supply tester for nearly a year now and I’m very satisfied about this one. Former I used a “homemade” one with only LED’s but that did not satisfy me.
Only 1 point of comment: sometimes, if a (faulty) PSU will not start, you have to connect a HD or CD-player to generate a “startup-load”.

I’m using this tester mostly for service “on site” and it gives a very quick answer of the state of the computers PSU.
For protection I use an old leather photocamera bag.

Dear Yestine, thanks for your extended review and have a nice day,

Albert
Holland.

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

HI Paul,

1)if i replaced a resistor with a fusible one by accident would that be ok,i know i can replace a fusible one with a normal one for test purposes only but what if i accidently did it the other way around,

I have not done that before but I believe it is ok as long as the current draw is lesser than what the resistor can handle.

2)if the 100w bulb does not light at all(nothing) when using as a load does this confirm problem with power supply,as this is what was the result when i started on this supply,only after i replaced the open 1R 2W metal oxide resistor and 56v zener i got the bulb to light bright and stay bright,because im hoping when i replace the O.27R 2W resistor and Shunt regulator the bulb will light bright and then go dim/off,

It depends on the type of power supply. In LCD Monitor power supply a good power supply usually will not cause the bulb to light up even at the initial stage of turning it on. But to other type of power supplies, the bulb will light up first before going dim and off.

Hope this helps.

Jestine

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Hi jestine, i have a problem solving a colour stain(i dont know the terms used for it) of a CRT SONY TRINITRON(KV-28 FX65U). I tried using a magnet to correct the colour on the screen and also check the degaussing area it seems to be ok.
Pls, guide me on what to do to remedy the situation.
Thanks.

Hi Daniel,
If the color patches can’t be removed with the help of a demagnetizer then the problem is a bad CRT Tube.

Jestine

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Hi Sir,

These are the part number of schottky diode. I’m using WHEELER analog tester model number W-375. I’m using new test probe that comes from SANWA tester. Sir if I’m going to use other analog tester and if the result is the-same in reverse test with slight movement of needle or high resistance in x1 ohm, it means that all these diode are defective is that right Sir?

1pc –    SB140
1pc –    SB530
2pcs –   IN5822
4pcs –   IN5819
10pcs – IN5817

Respectfully yours,

Jerry

Hi Jerry,

From my Sunwa tester at x1 ohm these schottky diodes should not have reading when the black probe at cathode and red probe to anode. If have reading means the diode is not good. It could only have reading when under x 10 K ohm test.

Jestine

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Hi Paul,

yes it does help thankyou,i need to ask you another question please,if i cant find metal oxide resistors,is it okay to replace with metal film to the same specification instead,

You can try because not all circuit design are that sensitive. I do came across out of 100 units only 1 or 2 units that need the original type of resistor.

i truly appreciate all your help and advice i dont know how you find the time to answer everyone as you are such a busy person,thanks

You are welcome.

Jestine

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Dear Jestine

I have a problem in samsung LED monitor.The problem is computer input is not found.
When I turn on the monitor a message show “no cable found” & when I plug in the VGA cable the message is gone and nothing to display.
Please give me a solution .

For your kind information , I am an Engineer, I complete My Diploma-in-Electronic Engineering & I also complete B.sc. in EEE.

Thanks
Ratul

Hi Ratul,
It could be the cable have internal wires broken or there is leaky components in between the vga connector to the MCU ic.

Jestine

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Hi Mr Jestine Yong

My name is Trevor from Seychelles I’ve been trying to repair an lcd monitor.The symptom with that screen is that it shows some white horizontal lines on it after about ten minutes the monitor is switched on.those white lines keep moving vertically up and down the display.i WISH YOU CAN HELP ME AND TELL ME WHERE YOU THINK THE PROBLEM MIGHT BE.

I TRIED SENDING THIS QUESTION ON YOUR PERSONAL WEBSITE BUT THE MESSAGE DIDN’T GO.

the SCREEN MODEL IS: ACER P205H.

THANK YOU

Kind Regards

Trevor

Hi Trevor,

Try check if there is any bulged e-caps and make sure the output voltages from the power supply are stable. if all the voltages are good I’m afraid the lcd panel could have problem with the dry contact in the tab bonding which is very hard to repair.

jestine

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Hello Jestine.

I have a monitor Samsung SyncMaster SA 100 when I turn it on I have to move the VGA conector in order to see whats going on the screen, besides everything is in green, could you please help me with this.

Martin

Hi Martin,

This could mean some of the wire lines in the vga cable have problem.You may need to cut the vga cable and fabricate another new connecter. This is not an easy job.You need to have patience to do it.

Jestine

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HI Sylvester,

i think i found your information very useful,thank you.

You are welcome!

but before i
start i need to ask few questions: which dmm do you prefer(autorange
or manual)?

Autorange because it is faster and accurate.

do i have to always replace every component with a new
one?

Not exactly because I do use those components from junk board.

if i dont wana give up on an appliance before i fix it,help me
know how to encourange myself that the appliance will come back to
life.

You just have to open up and check it. By looking at it would not know if it can be brought back to life or not.

Jestine

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22 Comments

Austin onweaba

November 24, 2013 at 5:27 am

jestine please help me my tv set have problem of standby b+ is ok where should i check?

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Reply
- Jestine Yong
  
  November 25, 2013 at 10:14 am
  
  Hi Austin,
  
  Standby could mean the CPU IC, EEPROM or the main power supply could have problem. Have you check for shorted secondary diodes in the main power supply. Check also to see if the standby power supply is 5 volt or not.
  
  Jestine
  
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Austin onweaba

December 1, 2013 at 5:39 pm

helo jestine, thanks for reply to me, but please what is the full meaning of CPU IC and it located at which side in panel?

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Reply
- Jestine Yong
  
  December 3, 2013 at 6:29 pm
  
  Hi Austin,
  
  It is located in the mainboard and usually the largest ic. Some call it as CPU and to some is MCU. CPU means central processing unit and MCU is microcontroller unit.
  
  Jestine
  
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Austin onweaba

December 3, 2013 at 10:19 pm

helo jestine yong thank you very much for your help to me. I have another problem with one of my tv set it dots colors at screen so please what are those things that can cause such problem?

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Reply
- Jestine Yong
  
  December 4, 2013 at 10:53 am
  
  HI Austin,
  Please send the photo to jestineyong(at)electronicrepairguide.com
  
  Jestine
  
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Austin onweaba

December 5, 2013 at 8:09 pm

helo jestine there is one of DVD player i'm try to repair the problem it have is that when plug power cord in socket it will come on and open by itself then pressed close button both in remont it will close and write loading for some seconds it will stop loading then the drawer come out again by itself. I have check power supply it seem to be ok. So what is the cause?

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Reply
- Jestine Yong
  
  December 6, 2013 at 11:08 am
  
  Hi Austin,
  
  It looks like the mainboard have problem with this weird symptom. Please makes sure the mainboard is getting the right supply dc voltages.
  
  Jestine
  
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Austin onweaba

December 9, 2013 at 1:37 am

helo jestine good day my tv set shuntdown when it try to start, the i check b+ it seem to be ok i also check horizontal transistor,flyback and replace them but the symptom still present so please help me for the fault.

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Reply
- Jestine Yong
  
  December 9, 2013 at 7:44 pm
  
  HI Austin,
  
  Did you the see the picture and then shutdown? What is the B+ dc supply voltage and how many inches TV?
  
  Jestine
  
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Austin onweaba

December 9, 2013 at 10:29 pm

it dose not show picture before it shutdown,the b+ volt is 110 and it is 15 inch tv.

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Reply
- Jestine Yong
  
  December 10, 2013 at 10:54 am
  
  HI Austin,
  
  Noted. This could mean the flyback or the safety cap could have problem.
  
  Jestine
  
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Austin onweaba

December 10, 2013 at 10:42 pm

safety is which capacitor? Which side it located in mainboard?

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Reply
- Jestine Yong
  
  December 11, 2013 at 4:06 pm
  
  Hi Austin,
  
  Nearby flyback usually rated from 1600v to 2000v.
  
  Jestine
  
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Austin onweaba

December 14, 2013 at 6:48 pm

helo jestine i hope you are alright, please help me, my tv set have problem of cracking picture, sound is ok. what is the cause?

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Reply
- Jestine Yong
  
  December 14, 2013 at 11:23 pm
  
  HI Austin,
  
  Could you send the picture to my email because I don't get what do you mean by cracking picture.
  
  Jestine
  
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Austin onweaba

December 15, 2013 at 6:02 pm

okay, i will send you the picture later. I have question to you the question is that how can i connect CRT tube that contain double focus with CRT board that contain one focus socket?

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Reply
- Jestine Yong
  
  December 16, 2013 at 9:39 pm
  
  Hi Austin,
  
  I have not connect it before thus I can'tr give you advice on this.
  
  Jestine
  
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Austin onweaba

January 9, 2014 at 9:00 am

helo jestine,happy new year. Sir please tell me the functions of those transistors:-NPN transistor, PNP transistor and examples of them.

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Reply
- Jestine Yong
  
  January 9, 2014 at 8:33 pm
  
  HI Austin,
  
  You can type in Google or search wikipedia as they have full explanation of such components and other components as well.
  
  Jestine
  
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Austin onweaba

January 11, 2014 at 6:12 am

helo jestine, please help me and ask audience those things that makes tv set to shutdown when it try to start,when showing picture before shuting down and when it dosen't show picture.

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Austin onweaba

January 12, 2014 at 1:00 pm

helo jestine, please tell me those things that can cause tv set to shutdown when it try to start,whether showing picture first or not before shutingdown.

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