hi jestine

thanks for  the reminders i have been to one or more of those sites get what i need and quite then later try finding the sites but all usually in vain,now jestine i have a sony ctv model 2197m3s that has all red colouring from raster to showing images i have checked the c2611 trnsistors and the corresponding resistors but they look ok so im staarting to doubt the tda8375a before i go further anyadvise would be most apreciared

HI James,

I suggest that you compare the Green and blue transistor at the CRT board for voltage and signal (waveform) with Red circuit. Any difference in voltage or the signal is the clue for you to start troubleshoot at that particular section.

Jestine

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

Jestine, one more question from me.
I have been using the ring test method on smps with great success. My question is: when ringing the primary of smps transformer, will it be able to pickup leaky sec diode or only a shorted sec diode?
Regards
Riaan

HI Riaan,

Only complete shorted diode and not leaky diodes.

Jestine

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

HI John,

Sorry for the late reply as i am in the automotive industry and will like to repair automotive vehicle computer boxes.

No problem and nice to know that you are in the automotive industry.

 

Can the leak seeker be used to only test certain components or find shrots in all componets,as i will assume the ecu`s are high density boards.Will this help me in for automotive ecu`s fault finding.

This test is meant for only finding shorted components in the DC ground line. This mean if an IC or a capacitor shorted to ground and cause the whole board to malfunction and the power supply could not start up then this leakseeker is helpful. If the cap or the IC only slighlty leaky then this tester can’t detect it.

While googling for a short locator I found this equipment- http://www.testecvw.com/ Try email the owner to see if it will help in your repair work. I will post this in my blog too.

 

Also do you sell information on how to use a logic pulser to test or send signals into ic`s and see the out come via a logic probe.

Sorry i do not have such information.

Also do you sell test equiptment for component level testing like esr meter ect…..If yes,let me know the cost.

Yes I do sell Blue ESR meter and Blue Ring Tester. Since you are in the automotive line I’m not sure if this ebook can be a help to you.

Jestine

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

How are you sir? am measuring 96v from there b+ and hear a loud
cracking sound from fbt,is it a sign of a faulty fbt?

I guess yes because 96 volt is consider normal. Before that check to see if any of the safety cap around the flyback have open circuit or not.

Jestine

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

Hi Sir sorry to bother u i have a question, i’m repairing an LCD tv whitewesting house model no.TLD 32W4 HDC. the trouble is no display but the stand by is on. when i check on it i found the open resistor 0.1 ohms then i put a good one. after that i plug it in to check if it gonna work, but the resistor burn right away then i found out that the FEt P20NM50FP is shorted, and then i put a new FET again, the resistor didn’t burn but i have the same trouble it still no display but the stand by is on! And my other tv is SAnyo the FET is shorted and open resistor, i already put a new part on it but it didn’t work, the stand by is turn on for 10 second and after that its off! Sir Jestine hope you can help me with my problem! thanks you so much Sir Jestine i really appriciated all of your info you share to me! have a good night ang take care!

I suggest that if you found any bad components you need to check all the corresponding components. If all check to be good then you may need to direct replace the power ic and retest.

Jestine

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

Hi Mr. Jestine,

I have a problem in Compaq monitor (CRT 15″). The problem was, monitor light is vibrating (small and big) twice in a second. I have checkd that booster output voltage is also vibrating but output of smps is stable 46v. After boosting hardly 5 volt increasing though filter capacitor 0.68mf is ok. Oscillator section is using TL494 IC by which boosting MOSFET works. When i opened the boosting mosfet, light became stable but small. Again after connecting , When i touched the meter prob at pin 1 of TL494 then voltage became very high and blasting sound is heard (like capacitor burst), but capacitors are ok, now there is no light, it appears that video section IC became faulty. EHT is working as because i have got the screen voltage. How should i troubleshoot this boosting problem. I had tried by replacing the TL494 ic. Driver transistor of MOSFET is ok. Please provide me, the circuit diagram if you have. Please reply a.s.a.p.

Regards

Gopal Sharma

Hi Gopal,

Sorry i do not keep schematic diagram. For any schematic you need to search from eserviceinfo.com After removed the B+ fet if everything works fine and could see the small picture (you need to adjust the screen voltage) then the problem could be link to bad gate drive waveform or B+ coil could be shorted internally and can only be tested by ring tester.  Sometimes a bad horizontal driver transistor also could cause such problem.

Jestine

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

HI Sothea,

– Can we notice more clear between Normal Diode and Schottky Diode.

No you can’t you have to search for the diode part number to get the datasheet then only you will know it belongs to which type.

– Can we use Analog Meter to read to Voltage & Ampere of Diodes.

No you can’t you need to search for the diode datasheet. Try
alldatasheet.com

Jestine

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

Hi Jestine ,

 

Can i replace diode 1N5822 with 1N5408 and transistor K3469 with K2645 , thanks

Hi Chong,

No you can’t because 1N5822 is a schottky diode. YOU need to replace with UF5404.

The k3469 have 12 amp but k2645 is only 9 amp thus it is not suitable for replacemen.

Jestine

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

HI: I have two westinhgouse 42 inches lcd tv’s model number vr-4225. The boards inside are in good condition.
the tv’s power up and shut down after a few minutes. The power supply is corporated with the inverter circuit that connect to the light. It look likes bad transfromers or backlights. What you think could be the problem. Please, reply. Thanks

 

Hi Stevenson,

Yes it could be either the high voltage transformer or one of the backlight have problem. Compare the high voltage transformer resistance winding and if the primary and the secondary value are good then suspect the backlight have problem.

Jestine

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

 

Hi Sir sorry to bother u i have a question, i’m repairing an LCD tv whitewesting house model no.TLD 32W4 HDC. the trouble is no display but the stand by is on. when i check on it i found the open resistor 0.1 ohms then i put a good one. after that i plug it in to check if it gonna work, but the resistor burn right away then i found out that the FEt P20NM50FP is shorted, and then i put a new FET again, the resistor didn’t burn but i have the same trouble it still no display but the stand by is on! And my other tv is SAnyo the FET is shorted and open resistor, i already put a new part on it but it didn’t work, the stand by is turn on for 10 second and after that its off! Sir Jestine hope you can help me with my problem! thanks you so much Sir Jestine i really appriciated all of your info you share to me! have a good night ang take care!

I suggest that if you found any bad components you need to check all the corresponding components. If all check to be good then you may need to direct replace the power ic and retest.

Jestine

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

HI Victor,

Hi jestine,thanks alot these days for assistance.i still have these questions. 1.If the 5v or 12v is not seen at the secondary output diodes,list for me various things that can be wrong.

It can be anything like blown fuse, shorted power fet and ic, open start up resistor and even bad e-caps. Different model have different problems and solutions

2.you said if the power fet is shorted,usually the pwr ic is gone.pls kindly list other components that is usually gone if power fet is gone.

You need to check as there are thousands of model in the market. You have to know that there is no straight answer because of too many model and design in the market. There is no short cut in troubleshooting. That means you have to troubleshoot yourself and find out the answer.

3.mention the most important component components in the primary and secondary power to check voltage during power failure troubleshooting.

Primary side check the supply voltage to power ic. Secondary side check the output diodes voltage.

4.which of the pins in primary power transformer is the drain pin?

Look at the center pin of power fet and you will know which one is drain pin because it has a circuit path from drain pin of power fet to the transformer pin.

how many are they and how can i know the drain pin?

There is only one and please refer to the above answer.

5.you told me how to test the primary winding voltage with meter,how is the secondary winding of pwr transforme tested for voltage?

Secondary winding ac high pulse voltage can’t be tested by our normal meter. If after the secondary diode output and you get voltages this means common sense that the secondary windings have output AC.

6.what can cause one to start voltage testing in lcd monitors?

When there is no power or power blinking problem.

7.i have one 15 inches dell.the problem is that the led is
blinking and no display.i didnt see any bad capacitor at the secondary power.what should i do to revive this monitor?

First make sure the output voltages are good and stable. If not good then check the power side. if it is good then check the voltage regulator of the mainboard. If all check to be good and the power led still blinks then the problem is in the MCU.

Jestine

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

Hello Sir,
hope you are you are doing well. sir ihave problem on a itt nokia crt television the raster is very dark and went turning the g2 voltage the retrace line will appair on the screen if you reduce g2 voltage the raster come normal but its very dark. Sir what are the componet to be suspected.Thanks for your concern.

Hi Mukthar,

It could be the tube have become weak or the heater voltage have problem. Try this link:

http://www.repairfaq.org/samnew/tvfaq/tvbrightcrt.htm
to see if it will brighten the tube.

Jestine

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

Sir,

What do you think failed because when i turn on my benq lcd the contrast menu appears always and adjust automatically downwards from 50 to 0.

Thank you and more power,

Vic

HI Vic,

It could be the eeprom data or the MCU data have corrupted. Before that make sure all the push buttons are working and the voltage at the mainboard are between 1.8, 2.5 and 3.3 volt.

Jestine

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

Good Day Sir Jestine,

Am so glad that you continuously help people like us who are very interested in electronics and are still need your support.
How I wished that I could find a word that could give a gratitude more than THANK YOU. Thank you so much Sir Jestine. You’re
so kind… Hope you will accept my gratitude for now. But I promise to also share with you whatever i can have and earned from my experience that in some way or another can be beneficial  in your advocacy of helping others in the field of electronics.
Once again THANK YOU so much… More power to you and GOD Bless you…

Truly yours,
Romeo

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

Hello Jestine, I hope you are doing good. I am writing this message to just fankly know your opinion.

I realized that, on your ebooks and articles, you never mentionned the octopus or the XY troubleshooting method . For your information, the octopus method on which Huntron instruments are based provides the XY curve on an oscilloscope or a tracker CRT. That is the curves is in fact Voltage versus Current. Personally, I prefer this method over the classic multitester because it is safe and fast. Anyway, what do you think about it? What are its disadvantages if any?

Sincerely

Hi Adam,

Good question. In fact I have the Huntron tracker where it uses analog signature analysis to track down the circuit problem. I personally have used this tester on some basic components and found that it was not accurate as compare when you test a component with analog multimeter. This meter is good for comparison purpose and this tester is expensive I did not mention it in my ebook but I do mention it in my blog. Besides Huntron there are Polar Instrument, ABI and many others that use the same technique for troubleshooting.

Jestine
http://www.JestineYong.com

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About

Jestine Yong works as an Electronics Repair Lecturer in Kuala Lumpur Malaysia and his training website is http://www.NoahtechElectronicsTraining.com. You can check out his repair blog at http://www.JestineYong.com