Dear sir,
i have purchased samsung syncmaster 794mg monitor in 2010
it works so nise
but pink colour is coming on display,so please help me sir

HI Tahir,

It could be the vga cable one of the pin have bend, one of the wire in the cable broken, dry joints in the crt board or even one of the color transistor or the video preamp ic or the crt driver ic have problem. You need to check all these.

Jestine

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HI Boling,

Thanks a lot for sharing with me about selling components.

No problem.

I bought this power board from a computer store, the LG authorized service shop didn’t want to troubleshoot the board, so it is of no use. I saw only the big power capacitor bulged. After replacing the 100uf 450V ecap, and powered it on, I got 13.3 ( stable ) V for 12V marked pin, but for 5V marked pin I got 4.7V to 5.1V up and down ( not stable ). These measurements are taken with no load condition, as I don’t have the load to test with.

Do you think the 5V supply have any problem? What is causing this voltage unstable?

Difficult to say because some power supplies the voltage will fluctuate under no load condition. You need to connect to a load an retest. Try connect to a 12 volt automobile lamp.

Jestine

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Hello Jestine,
I am sorry to bother you this time.
Please I have a monitor which I bought which I bought 5 years ago as a
second hand product. Since then it has been working alright but the
brightness is very low as compared to other one I have at home. Sent
it to technician sometime ago and I was told it could be a flyback
problem but never tried to repair it for me. It is

Gateway Monitor

HI Aboagye,

If all the voltages in the CRT board are good then suspect a bad pc tube. Make sure the heater voltage is 6.3 vdc, g2 voltage is 250 to 300vdc and G1 at least -20 to -70 volt.

Jestine

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Thank you for getting back to me so soon. I do have a two channel Tektronix scope. How would you go about applying voltage to the input pin if the boards are out of the unit. I am working on a 50″ Pioneer PDP 502 MX monitor that was given to me. I can’t hardly wait to get it up and running, it’ll be so easy to read for these old eyes. Again thank you so much for the help. Someday I hope we’ll meet on the other side of life.  Don

HI Don,

Usually I will repair the no power symptom using normal meters first before using the scope. That means, if the complaint is no power, we will perform the voltage testing on the primary side like checking the supply voltage to the power ic and make sure the filter cap have 155vdc (if you are from USA) . If there is missing voltage then i will trace it backward to see at where the voltage had gone missing. Or i will solder all the components in the power supply side and check. If all check to be good then i wil directly replace the power ic and retest.

Jestine

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HI Boling,

Once an old samsung 15″ CRT monitor brought in ( manufactured in 2000 ) which has a very dim display and heater voltage is normal; G1 has -34V, G2 has 602 V but its flyback doesn’t have screen pot. Is this the picture tube problem? How can I lower G2 voltage since it has a centre spot when being switched off?

Center spot could be due to no grounding at the CRT board or the tube life span may come to an end. Chances is very high the tube have problem. Trace where the G2 voltage from and check the resistors usually in high ohm. YOU can also play around with resistor value when connecting a 2 watt resistor between the G2 and ground. Try with a 1 meg resistor and then use a lower ohm resistor till you get the right voltage. But in your case, if the tube already have problem then there is no point in lowering the voltage.

When repairing a CRT monitor, which points voltages are dangerous to our meter, besides the voltages that are higher than our meter capability? Sometimes I feel hesitate whether I could take voltage measurement on that point or not.

The collector of HOT.

Do you also use a soldering station? Is this a must tool to have？Do I need to buy one?

No i do not have and it is not necessary to buy one unless you are repairing lots of the mainboards. The temperature can be controlled so that it will not spoil the ic you want to solder.

Jestine