Hi,

Sir jestine i have a question i got a faulty diode and i wanna get a new one but i’m comfuse for the substitute parts… the faulty diode is MUR460 and at the botton is say 937….  i wanna know whats 937 stand for?

Look for only mur460. The 937 could be the manufacturer own coding for their own reference. You can refer to this link:

http://pdf1.alldatasheet.net/datasheet-pdf/view/59215/DIODES/MUR460.html

i found the faulty diode in the primary power supply of the LCD tv,  and i check online for the diode MUR460 but they have a different number at the botton… MUR460 432 600V… my concerned Sir jestine is can i subtitutes Diode MUR460 432 to MUR460 937!!!

Yes you can just use MUR460 and you will be fine.

SIr jestine one more question how can i know how much voltage that diode can handle, its not show to the PCB board! thanks you so much hope you can help me…. take care!

The diode can withstand up to 600v according to the spec.

Jestine

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Hi Jestine, I purchase your E-Book on how to Find Burnt Resistor Value and I found it fascinating, I had several components that had burnt resistors that I could not repair and return it back to the client, but know I know how to find these value. Thank you for your knowledge and sharing them through your books. I look forward in buying more new books from you. Thanks again.

Best Regards,

Andre

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HI Sarang,

Surprised to see your quick reply. Thanks a lot.

You are welcome!

my Q. is
I have 17 ” Samsung Syncmaster CRT monitor. 5 years old…Home used..(not used too much)
Suddenly there was some burnt smell and small suuuu sound from back of the monitor,
when it was on.
If we face the monitor as we sit infront of the computer, the smell was from our right
side and little middle of the back of the monitor.
I offed it immediately…waited for some time and again tried to on it with caution.
Again smell was there, but display is there…little disturbed.

SO Q. is =  Can it be repaired ? what part is burnt ? Capacitor or Transformer ? or what else ?
I do not want to throw it as scarp for simple reason.
I want to get it done.

You need to opne it up and check. it could dry joints causing spark that produced the smell or it can be components that have burnt. If you do not have experience in dealing with electricity i suggest that you send it to a professional repairer because monitor have high voltage .

Jestine

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Hi Ibraheem,

My flat screen Monitor is not working properly.The problem is that no screen when powered i.e the power button will be On while it will display nothing.someone told me that it is the module.How can I fix this problem. note that the Maker of the Monitor is BenQ 17 inch flat screen.

thank your for attention while looking forward to your quik response

If there is no supply voltage to the inverter ic and the mainboard have good supply voltage then most probably the MCU is the fault. You need to reprogram the MCU or get a new part for it that have the programs inside.

Jestine

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HI Vikrant,

Hi jestine hope you are doing well…

I’m fine thanks.

Thanks for you news letter.I have a otherboard and it has some power problem i have checked all transistors But they are seemed to like ok.but i know,have to check out of board but sir some transistors are in very consisted area of board i an’t easily even touch soldring gun to remove them and i don’t have SMD REWORK STATION, PLZ tell me how to remove them by techinics and test tem.

Without rework station it will be difficult to remove it. or you can try apply solder to all the transistors 3 legs and once the solder have melted then pull out the transistor. You can try search youtube.com on how to remove smd components. SMD transistor are difficult to check because most of it has internal resistor that made the meter reading not accurate. you can check it through comparison with another working unit.

Jestine

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HI Peter,

How good of you to take the time to reply with a bit of help.

No problem

I understand your point about a faulty Schottky checked with a DMM; but surely an analogue meter would suffer the same problem?

Analogue meter have higher output voltage as compare to DMM thus checking diodes are much more accurate.

In this case, as in so many, the component is so small that reading the marking 31 was something I could do with confidence only when I used a X45 illuminated magnifier (BTW these are dirt cheap on the internet & very useful in such situations).

I did put the device into my 3VDC led drive circuit, & confirmed that current would pass only in one direction.

I also measured a 0.7 VDC drop which I think establishes that it’s some kind of diode, possibly Schottky, maybe a Zener ?????

Schottky have 0.2 VDC drop.

I have spent so many hours searching & downloading datasheets to compare package size & style.

Finally I think its a: 1 N4148 fast switching diode, available in glass DO-34 & DO-34 package.

The DO-35 seems the only one readily available so I have ordered some & hope the package size will not matter; I am fairly sure I can get it on the board.

Lately i found lots of manufacturer did not label the diode as 1N4148, they labelled it as 48 only and you may think it is a 48 volt zener diode. Look at the board marking and the marking will be “D”

Your suggestion (31-DF6 or DF8) is a good one & frankly somehow I did not consider these possibilities.

But the package size is way too big at about 5 mm Diam x 9/10 mm long.

First i thought yours was the bigger diode because it is very common to see big schottky diode that have the part number 31DF 6 and etc.

Jestine

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Dear Jestine
I am fine here and wht abt u. I have some problem in my canon LBP 1210 printer. when ever i give a command to print there is a error message Check Toner Cartiage even there is a cartiage inside a printer. To detect a cartiage i have to open and close a printer cover several times. plz tell me that should i do.

HI Sumit,

If the printer can’t print after sending the signal the formatter board have problem (assuming it can print under self test).

Jestine

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Hi Jestine, I have a question… If you have an IC that has been damage and you cannot recognize the part number, is there any way you can get a replacement or tell the part Number?

Hi Andre,

No it is hard to tell. You need to refer to schematic, compare with other equipment, call up your repair friend to check on the same equipment in their workshops or through your own experience. For example, if you always deal with a power supply that use UC3842 ic (8 pins) and one day you saw a power supply with missing power ic or burnt  power ic. Since the bad ic have 8 pins then most like the power ic part number is UC3842.

Jestine

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Dear Jestine

I would just like to thank you for all the information made available by you to me via your lcd monitor e repair book.I find it very valuable and understandable, keep up your good work.

I just manage to repair my very first lcd tv. It were the power inveter board that was faulty and believe me without your info I would never fix it.Thanks again and have a lovely day.

Kind Regards

Dana

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Hello Jestine,

There is a good news that my multimeter is repaired. I was hopeless and planned to purchase new sanwa yx360tr original meter and also thought that original meter can also be defective if any resistor will open, so it is better to repair this one. Therefore, one day i got sufficient time to repair this meter. I searched its manual in the internet and i got it. From manual i could not get the circuit but got the values of resistances. Thus i trace the faulty range and understand the circuit and also measured all resistor values then i found one 3k resistance was open. After replacing it, the meter came back to life. My advice to other members is that use analog meter instead or digital meter because you can repair this meter yourself but digital meter is very cirtical to repair. I already have two good quality digital meter useless. Previously i prefer to use digital meter but now i experienced analog meter is better than digital. In some specific cases digital meter can be used where analog meter is failure like capacitance checking etc.

Thank you Jestine. I have got lot of inspiration and knowledge from you.

Regards

Gopal

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Hi Sir Yong, I’ve download the ebooks. Those books are great and self explanatry. Infact am happy with you at the first place…With you ebook, I’ve detected a shorted optoisolator and also a faulty resistor in one of my spare battery charger.. Though am still reading the books. Thank God for person like you. Best Regard
Iheanyichukwu. Imo State, Nigeria.

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Sir, how was day,i hope everything is going ok. Sir I come across the problem with this crt tv which is first time to me to saw this types of problem, as I am hobby in electronic repair I have spend only four to five years in this field,so you see I am the most one to get assistant from you professional. Sir as you see I attach the picture of the problem of this tv I want you to put me on the right way on where to focus to solve this problem. Thanks you very much.

HI Mukthar,

The problem is one horizontal line and you need to check on the vertical putput ic. Check for dry joints and make sure the supply voltage to the vertical output ic is sufficient.

Jestine

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good day sir,

I read about the pc diagnostic card to determine fast where and what is the problem on the motherboard…do you have any DIY or can you recommend where to buy this diagnostic repair card?

Hi lito,

Sorry i do not have any DIY. You could find lots of places that sell this card from the internet and one of the websites is:

http://www.pc-diagnostics.com/pc_diagnostics_tools/flippost_isa_pci_bus.shtml

Jestine

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Dear Jestine,

TQ for the reply.

2. Yes, there is light at end of tube.

3.  When switch off, there seem to be a small,white, &  bright light small dot size of a pin head in the center of the screen which will gradually disappear.

Regards,

(Ting)

Hi Ting,

Then you need to check if the crt tube yoke coils is properly connected or not. If not connected or the corresponding components have problem, there will be a dot in the center. Make sure also the crt tube ground is properly grounded.

Jestine

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Sir, a friend brought his laptop power pack for me to repair. In it, i notice a burnt varistor. I dont know how to take the reading of a good or bad one. Please asist me. Also what do you think would be the cause of this…?

Hi Iheanyi,

A good varistor under x10 k ohm should not have any reading both way. If there is reading means it is shorted. In your case, you need to check all components in the power side . Make sure also the secondary output diode not shorted. If the fuse and varistor blow then most like only these particular components have problem. To be in the safe side check all the components in the power supply.

Jestine

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Hi Jestine,

I read you book is a awsome book i didnot know anything about electronic compnent but now i know much better so please can u help me what i have to buy for testing electronic compnent lik which maltimeter,and etc. and from where i have to buy

Shailesh

Hi Shailesh,

You can buy common tools and meter from your local electronic shop. For meter you need:

1) Sunwa 360tre analogue meter that have the x10k range.
2) Digital capacitance meter (preferably made in Taiwan brand like TES).

If you have extra budget you can get:
1) Blue ESR meter
2) Blue Ring Tester and even
3) Oscilloscope (if you know how to use it).

Have a good day!

Jestine

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HI Siebo,

how are you? I have some questions.

I replaced 2 startup resistors to smps Vin pin. But there is 200vdc on the Vin pin of ic.

I don`t understand, I expected 12-16 volt dc, because 2 resistors (2x 750k) have voltage drop?

what can be wrong here?

The power IC could have open circuit or the e-cap have problem. Try replace the ic and retest.

Is there a (quick) way to test (mos)fets onboard (Without soldering them out) ?

Since mosfet need to be triggered thus the best have to test off board.

Jestine