G,Evening.Mr.Justine.

Yes Bro,I mean ,I have reflow to nvidia chip 3 to 4 times,but problem still the same,that s hard disk have been not detect.Kindly ,tell me pls ,How can I solve this problem.

Thank you.

Tariq

HI Tariq,

The NVIDIA is for video and you need to check on the north/southbridge ic.

Jestine

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HI Waleed,

I am working on a view sonic lcd screen. there is a problem in the power supply. I found a Zenner diode blown (SMD) plown in the power supply area. it connects the ground of the main capacitor to one of the Mos n fet legs. I am trying to find out the rating on this zener and sad to say that there is no writing on the body of the zenner. is there a way to find out and from experience, what would be ther power rating for it. please help. thanks

I suggest that you try 18 volt with 1 watt since it is hard to find a smd zener diode. It may not work but you have to try.

Jestine

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Good day;

Dear Mr Jestine,

I had check the PC power supply that has no output voltage. visual check, all the component are good. check all the ESR capacitor also good. resistor and diode good. i had touch up all the component. but still no output. check the IC supply is 5V. other passive component also good.

ic type: SG6105 and DM311.

this is very simple power supply, but i can’t solve it. why?

HI Rahimah,

Perhaps the power transformer (shorted winding) or secondary side have problem.

Jestine

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

Thanks for your regular newsletter, however, I am having problem with replacing faulty FET power transistors on my transmitter power module. How do I go about it in view of Electrostatic effect on the transistor which usually destroys them.

HI Iji,

You need a wrist strap to drain off any static from your body. You can this wrist strap from any electronics shop. May i know your question ” how can i set up a workbench to achieve this” to achieve what-could you elaborate?

Jestine

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Hello Jestine,

I would like to take the opportunity to thank you again for the articles you send to me every month, keep up the good work.

I am writing this E-mail to ask if you have any article about IR remote control repair or explaining in details the full function of the components found inside it.

Wish you and your family All The Best

Clayton

HI Clayton,

Thanks for your email but sorry i do not have such article. Try check these link as i found it to be very good:

http://www.repairfaq.org/sam/irrfaq.htm

http://en.wikipedia.org/wiki/Remote_control

Jestine

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

Dear Jestine Yong

I am  thank you  very much about your information you periodicly  send  on lcd and plasma tv .

I need your help on my own plasma tv type  lg 50pq30 there is a problem a line appear on the screen  vertically in the mid of the screen with a one pixel width the red and the blue color connected together if any one a appear the other appear to with out brightness control always in the max but if the green appear only no any of them appear with it.

Please if its possible to send me the service manual of 50pq30 and how to fix this problem

please note that  I am an electronic engineer with long experience in electronics I can understand the diagrams and the diagnoses tree ..etc.

I am very appreciated any help to fix this problem .

and thanks in advance.

Engineer

Ali

Hi Ali,

Please check the x buffer board for any dry joints or burn ic. Sorry i do not have the schematic diagram.

Jestine

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Hi Gopal,
Congratulations for developing your new website. May god bless you.

Thanks.

I have one question that if there is no circuit diagram and SMPS output voltage is not mentioned in Monitor then how do we know that output voltage is normal, low or high. Is there any tips to guess about the output voltage.

If you get about 6.3 heater voltage then generally all the voltages should be fine. If one output voltage low, usually all will be affected assuming if all the filter cap are in good condition.

In a monitor i am getting 78v for EHT supply without boosting. I connected a new HOT and started the monitor, it displays normal white light when data cable is not connected but as soon as i connect the data cable HOT shorted immediately, What may be the reason. I think supply voltage is more than normal but i am not sure. Please help me.

You can try remove the B+ fet and retry or check all the big non polar cap in the flyback transformer area.

Whether buck or boost MOSFET will work if HOT is not connected.

This may burn the FET if HOT is not connected. The fet circuit cannot run without a load.

In a 15″ ACER monitor there is buck ckt with P channel mosfet. I am getting 114v at Source and Gate but there is no voltage at Drain, HOT is not connected because HOT and MOSFET was short when I have seen first. time.

Gate should not have 114 volt. Gate is getting signal from the h/v oscillator thus the voltage is low. You must completely check this circuit again. Check also for the B+ coil for short circuit.

Whether i should check above faults with series lamp with HOT for safety purpose. what should be the wattage for series lamp.

You can try that but you cannot on for too long otherwise the fet will burn again. The lamp should be around 60 to 100 watt.

Jestine

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