Hello Jestine I hope you are doing well.

I am working on a samsung 242mps   Lcd Monitor.

http://www.samsung.com/uk/business/b2b/pdfs/products/displays/desktops/sm242mp.pdf   .


I came to me DEAD no lights no standby power lihgt or anything.

I took it apart and got down to the power supply.

I test a few things and all looked good.

I tested the stand by voltage and it was at 5 volts.

But no other voltage is present just the stand by 5 volts. So I followed it on the main board to the power switch.

there is 3.5v on the power switch. I all so check the switch and it is working .

Have you run into this type of problem ?

Is there a way to start the power supply by itself with out being hooked up to the main board so I can check for the other voltages are presant?


Thanks for your time.


Grant Fullen

HI Grant,

The standby voltage need to be fed to the MCU so that it can send a signal to turn on the main power supply. If you are getting supply voltage to the MCU and there is no power led then I’m afraid the MCU may have problem because the power LED signal is coming from the MCU. Make sure the MCU crystal have sinewave and the VGA cable is connected.  Please update me on this status.



Hi Jestine,

This monitor’s problem is the display turns yellowish and flickering after using for about 3.5 hours. It had been repaired by some repairmen, and now I still don’t know which section to concentrate.

Attached are the photos of the board and the display after 3.5 hours ( should be white )



HI Boling,

After using 3.5 hour then only have problem? If yes then this kind of problem need to use the coolant to troubleshoot it by spraying at the lcd panel or the mainboard ICs.



Hello Jestin,

Thanks for the information, always very helpful as usual.

May I ask you another advise on this problem that I have with my personal CRT Sanyo Monitor. The problem is the picture became dim/whitish and also white lines appeared on pic.

Attached I am sending you a photo of the monitor, the lines are quit visible on the pic.

Thanks in advance for you time.

All the best


Hi Clayton,

It can be the g2 setting too high or missing voltage to the CRT board. Make sure the RGB cathode have about 40 to 60vdc and the G1 voltage should not have 0 volt.




Hello..Jestine cuba you tengok gambar TV yang saya send ni..pada pendapat you apakah kerosakannya?
Saya telah menukar vertical ic yang baru tapi masalahnya tetap sama.

Harap..you dapat berikan sedikit tips.

Terima kasih.


HI Nooriskandar,

Voltan tak cukup sampai kat vertical ic, ataupun ada kerosakan komponen di sekitar vertical ic.



hello Mr. J. Yong….i need your help. this time i want to focus on trouble shooting on TV. i got her TOSHIBA 14″ 110V, it happened  that my brother he plug it directly to 220V….what do i expect geehhh a smoke white coming from the TV. what the first step should i do…kindly send some step by step on how to repair this TOSHIBA..this was for my from a gift of my sister…my mom so lonely… i said don’t worry mom i fixed this for the help of Mr. J. Yong….hope to hear you soon…thanks sir!

b’ regards,

Ricky of Philippines

HI Ricky,

I suggest that you check all components in the primary side. Pay special attention on the fuse, bridge rectifier and also big filter cap. The smoe could be from the big filter cap.



goodday Jestine,


Question 1>Colour tv brand sony 25 inch ,the problem is at horizontal.after check found that mylar cap 1500v were broken,horiz transistor were shorted too.after change both of it,sometimes afew minute having apicture,after afew minute become horiz line and it goes to standby mode.what is the actual problem?




Hi Fuzi,

Did you replace with the same part number of cap? Horizontal line is due to bad vertical section so please check for any dry joints in the vertical output ic and make sure the supply to verticaln ic is good and stable.



Dear Mr.Jestine Yong,

I have an LCD Monitor with external power supply,and after I checked
the psu has a problem.
It has 0 volt,but it has 12V everytime I touched one pin of the
transformer using a multimeter.
but when I turn off, it is back to 0V when turned on.And try to touch
other pin of transformer,it back on.
I already try to resolder all the component,but still the same.
The transformer has a high pitch sound when the psu has 12V output.
Can you help me solved this kind of problem?
Thanks in advance.

Best Regards,

HI Julianto,

I suggest that you check all the components in the power pack especially the filter cap in the primary and secondary side using esr meter. If you do not have this meter i suggest that you directly replace those caps and retest.



HI Boling,

Yes, but unfortunately I don’t have any coolant because it is hard to buy locally and the overseas merchants don’t ship to Indonesia also. If I continue burning in after 3.5 hours, the display may come back to normal, but no longer the problem would come again.

Try use a usb fan to blow on the mainboard and lcd panel board to see the problem will still exist after 3.5 hours. If yes, then most likely it is not due to heat and could be the problem with the MCU programs. I’m a bit curious too as the problem only appear after 3.5 hours.

when the problem comes, I have checked all the supply voltages are still OK, but the supply to panel always be 4.89 V whether it is working normally or having problem. The 5V pin on the power supply board measures 4.98 V.

Some board design will work on supply that is slightly lesser than it supposed to be.



TV panasonic 21 inc flat screen problem when adjust screen at flyback or adjust brightness/contrast at menu program, picture drop at horizontal side. when adjust to maximum tv automatic turn off. need your help …


Make surer all the output voltages are good and stable regardless whether you adjust or do not adjust the screen. If not stable then i guess the e-cap may have problem.


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