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Electronic Repair QuestionsAnswers & Testimonials Part 5

By Jestine Yong on July 15, 2008

Hello Sir,

All the while i’ve seen and read all your messages regarding repairs and have help me a lot gathering the right information and tools . you have been very kind and appreciate very much your work in helping others achieved their goal in electronic repair. I personally think that you are a very kind man and generous. We may be different in religion but i thank God for a wonderful person like you.

Thanks very much

Z.L

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Mr. Yong,
I just bought your repair books (LCD Monitor Repair) this week and find them very helpful. Thank you!

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Hi Mr L,
Thanks for reading my blog! Here are your questions and answers:

I have taken the panel apart and examined the power inverter board and I was surprised that this inverter board does not use the p-channel Mosfet C5707, eventhough the circuit board has 4 blank spaces for them?.

For your information C5707 is not a p-channel FET. It is a normal type of NPN transistor.

There are no bulging capacitors, found the 2A 250V pico fuse burned and one of the Bridge Rectifiers faulty. Replaced the fuse, bridge rectifier and 0.22uf 275V capacitors but still could not get it working.

You must first fix the SMPS so that it will produce outputs at the secondary side of SMPS. Once you got the voltages i’m sure the Monitor will be working again. Since the fuse and the bridge rectifier have problem, this could also mean that the components in the primary section may have problem too. It could be a defective power IC and etc.

Could it be the problem with the TL1451 IC?

TL1451 IC is an inverter IC and it will not cause no power symptom unless it is totally shorted which is very rare.

Do you have any experience with this LCD type of monitor before?

Generally LCD Monitors problems are shutdown, no power, dim display, reddish, lines and etc. Once you know the principles you will know the rest on how to solve different types or brands of LCD Monitors.

Appreciate if you can share the schematics for this model of inverter board.

Sorry, i do not have schematics for this model of inverter board.

Jestine

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After struggling to repair the fax machine, I’ve managed to repair it, I just change the leaky e-caps which all have high ESR, but I don’t know how long after reapir it will last. Most of the original e-caps rating voltage was 35V, but considering I have to buy the 105 degree C, I must replace them with 50V because I can’t find the exact rating voltage here. Is it okay to change with higher working voltage e-caps ( the same capacitance ) in any electronic circuit?

Yes but not a too high voltage rating

Another interesting point is that when I repair it I saw some components like diode but with no marking on its body and the marking on the PCB is something like BEA101, do you know what is the function of it. When I measure with ohmmeter, it shows low ohm on both ways.

It could be a small bead (small coil)

Also, could you explain the function of Varistor?

Please visit https://www.jestineyong.com/?p=206

It is only after I browse the fastrepairguide that I see another e-book of yours named How to find burnt resistor value and I’d bought it yesterday. I believe it will enhance my skill in repairing.

Thanks again for your support!

When you are teaching students to repair the monitor, do you use the isolation transformer? When repairing using it, is it still significant to distinguish the hot and cold ground?

Yes i do use it for the protection of my students. Yes, in order for your meter to register a correct reading.

Are you also running parts supplier shop? How is the business?

No, my main business is in the monitor and printer repairing and also the repair courses. My repair business and the repair courses are doing well.

Reading your article about the interview with Steve French, I found many brand propriety website like sony, samsung, etc which ask for username and password. Are they exclusively for their employee or we could register as a member by paying fee?

I guess it is meant for their employees and their authorize service providers.

Do you think a newbie like me ( amateur ) is possible to attend factory training locally, what are the requirements?

I’m not sure about this but a phone call to the factory could answer your question. Generally the factory will need at least a certificate or diploma in electronic engineering.

Lastly, I saw from the article that many years ago you were running computer repairs, may I know why didn’t you go on to run the business.

Do you mean loading software, sell new computers and technical support? Sometimes we need concentration in order to excel in our work, i just can’t do so many things at one time go. I will lose concentration and eventually i will be “Jack of all trade and Master of none”.
Focus is my priority.

Thanks for all of your supporting effort. May God bless you and the family.
Same to you and family.

Jestine

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hi there my friend. hope all is well. i have this question for you. I have this charger for a horse hair clipper. the internal step down transformer is blowing a fuse all the time. is there a way to find out the out put of this transformer. the input is 120 volts. the highest value of the capacitors is 16 and the lowest one is 12. any ideas to find out.

I’m fine thank you. In your case for the 16 v output line the ac output line should be about 9Vac and the 12vdc output the output ac line should be about 6 Vac.

Hi Jestine,

Thanks for your response. I got it, it worked like a charm.

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Hi Abraham,
Here are your questions and answers
This monitors are those i coud not able to repair need tip from you,the following is their symptoms:

no.1- Aopen monitor Model no. A50S this monitor has no desplay.I replaced horizontal output transistor with similiar it seems high voltage is ok.

Please check the heater and the G2 voltage. Since it already has high voltage then make sure the heater has 6.3 vdc and the g2 voltage have about 200 to 300 Vdc

no.2- CTX monitor model no. VL950S this monitor is showing one vertical line at the center plus no desplay and relay clicks tick..tick…

Concentrate on the horizontal yoke coil area. It could have dry joints and aslo please visit this website http://www.electronicrepairguide.com/testing-flyback-transformer.html to test the fllyback internal capacitor for any short circuit since the relay have click-click and tick-tick sound

no3- SIEMENS NIXDORF monior model no. MCM 1503 this monitor relay clicks tick…tick..and no high voltage(B+), power seem ok.

Visit this website http://www.electronicrepairguide.com/testing-flyback-transformer.html

no4.-AMAZING monitor model no.CM-8489GX this monitor shows display is multiplied in to 5, what i mean is when you turn on the pc windows opens at this time instead displays one full windows screen, it is multiplied in to 5.

Try replace the horizontal and vertical oscillator IC and also check the corresponding components in the S-correction circuit especially the non-polar capacitor. The capacitor value may be out.

Hope this helps!

Best regards,
Jestine Yong

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Hi, Jestine Yong,How are you ?

Thanks for the nice Book. I fixed 2 LCD Gateway 21 inches monitors. The capacitors were bad, high temperature.

R.V

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Hi B,

Here is your questions and answers:

The tv monitor went off automatically after operating for few years; never came back on when powered on. When power is switched on, power led (RED) would come on and go off quickly.I found several dry joints on the board and soldered them. When powered on the tv, monitor able to light up but gave single horizontal bar/line in the middle. I replaced two of the filter capacitors for the vertical deflection circuit on the board. this time monitor able to light up. however, there are several bars/lines on the top of the monitor which after some minutes would disappear to the top of the monitor. Of course when the monitor is first switch on the monitor lights up, the display would look abnormal as if its stretching from the bottom and top outward. later the stretching would return to normal. then monitor would go off by itself!

I timed the monitor from lighting up till it shut down and it was 7 minutes to that extent. when the monitor shuts down, it could not be powered up again. it would stay for around 30 minutes then when power on would come on. again it would shut down after 7 minutes of running. this timing was taken after the same test was repeated. For this automatic shut down, i do not know which component is faulty and is causing this shut down.

Could you help me solve this problem, Jestine?

I would be very happy when this tv come back to life coz it’s been sitting there for years and was about to be disposed. I checked the circuit diagram of this tv model on the internet and its similar to the model 2165XR 2 DEO of Toshiba brand.
First you need to separate the circuit as which of the circuit is causing the shutdown problem. In order to do that you need a 100 watt bulb to connect across the B+ line as shown from this website :

http://www.scribd.com/doc/2957819/TT204-Identifying-television-SMPS-problems

Sometimes a slowly rising voltage could cause the display to stretch and then shutdown. If all the voltages checks to be okay then concentrate on the secondary circuit section like the vertical area and etc. If the output voltages are abnormal then put full concentration on the power supply section. Check all e-caps with ESR meter as capacitance meter can’t really tells you if the e-caps are in good or bad condition. Follow the test from the website and please let me know how it goes.

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I have read some of your articles & opinions,and find that some is new and useful to me especially the ESR meter,since I have never used such meter to check capacitor before.Yes I agree that a faulty capacitor can not be 100% checked by normal meter,that’s why the ESR meter comes into the picture.My repair tools are just digital multimeter & oscilloscope,I even seldom use an analogue meter to check components.How much is the ESR meter in ringgit?

Whenever i do electronic repair work i have to use ESR meter to speed up the job. The price in RM for a kitset is RM320.00 and for a fully assembled kitset would be RM420.00

I have been in repairing UPS(uninterrutible power supply ) area for almost 10years, my mains duty is to repair faulty PCB boards at components level, modify & design simple circuits.

Nice to hear about your background. I have a friend who has worked for Amp and Volts in Cheras for many years and now on his own in repairing Monitors and UPS too.

Sorry to trouble you since you are busy.
No problem.

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Dear Sir:

I got a copy of your LCD Monitor Repair as i go over it, i found this ebook very informative and easy to follow.

By the way I am attaching a picture (Samsung Model 540N S) i dont know what makes the my lcd screen look like this, there is a line on the bottom part of the screen. What possible area of the board (Samsung Model 540N S) am going to check?

thank you.

Hi R,
Thanks for the support on my ebook. The problem most probably in the LCD panel as if the bottom lcd driver have problem the whole bottom area would be affected. You need to replace the panel to solve the problem as there is no way we can change the lcd driver ic. By the way thansk for the photos-it helps a lot! If you have other questions please do email me again. Have a good day!

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4 Comments

baby_hupchao

July 19, 2008 at 12:39 am

Dear jestine
I like read your exprience for repair monitor.
I'm repairing a Samsung CRt monitor.The Display turn to left 10cm.I adjust button to max but not ok.
what part i have to test now for repair ?
Thanks a lots.
Have a good day.

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admin

July 21, 2008 at 4:03 pm

Hi,
This is the horizontal size/pincushion problem and you need to check on the pincushion transistor area. The number could be D2058 or etc and it is attach to the heatsink nearby flyback. Sometimes it could be a shorted modulation diode too. Hope this helps!

Best regards,
Jestine Yong

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saputro adi

July 17, 2009 at 9:10 pm

Dear Mr jestine
I like read your exprience for repair Lcd
I,m repairing a Samsung LCD 17" Silver Black.The Display OSD on. I Coneting Kabel Data to CPU but not ok (Cpu is Good)
what part i have to test now for repair ?
Thank a lots.
Have a good day

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admin

July 19, 2009 at 11:33 pm

Hi Saputro,

May i know what is the problem with the LCD Monitor? No display, display dim etc?

Jestine

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