Saturday, October 18, 2014

Need help in troubleshooting CRT Television problem

Dear Sir,
My Name is Yogesh, I am from INDIA.
I am one of your fans and I regularly visit your Blog for technological update.

Sir recently I came across the CRT TV Problem that there is intermittent fluctuation on the screen and picture shaking vertically (maybe overloading).

I have opened the TV and found China make kit with
Toshiba IC.8893CRNG7D65.

I need your help to troubleshoot the problem sir,
can you help me if possible.

Thanking you-Yogesh

Monday, September 8, 2014

Blog follower from Philippines want to know a few things about CRT television repair

Master,

Good morning, I read your article recently: the Understanding of CRT television critical voltage test points...

I was confused a little bit about the word B+ ...I want to clarify this because as a newbie in the field of electronics, safety first is my goal when rendering my services to others...

My question is this: all transformers “s.m.p.s transformer, drive transformer, and the fly-back” are producing a B+, right?

Transformers do not produce any voltage Alex, they just transform (change)

For example they can step down or step up the voltage/current.

But remember you cannot have the two (current and voltage) being increased or decreased at the same time.

Take for example the transformer used in your radio rated 240VAC to 12VAC.

The 240VAC is stepped down to 12VAC, in this case we will have the voltage decreased but the current will increase and that is why you see the output wires of most step down transformers are thicker than the primary side because of this high current.

For drive transformer this is also step down transformer but in case of drive transformer they are basically used to match impedance.

Here are the list of primary power supply is composed of : 1 Fuse, 1 surge limiter,1 main capacitor,bridge retifier < 4 diode> 1 smps transformer, 2resistors in series ,1 posistor1 ,3 ceramic capacitor, 1 degaussing pin, 1 power pin, many jumper line, 4 signal diode...Secondary output supply is composed of 4
diodes that is carrying a dc voltages taken from smps transformer, filter capacitor ranging to 160v, 100v, 50v,25v,16v and 10v,, right?

Sure Alex, this is a good description of common power supply components found in switch mode power supply (S.M.P.S)

But I have a comment on your remark on the secondary diodes…since the output of any transformer is AC current, that is why we have the secondary output diodes which are used to change(rectify) this AC back to DC current.

The diode only manage to rectify the AC signal into Pulsating Direct Current, this is still not clean enough to be used by the circuits and that is why capacitors comes in handy to smooth this pulsating DC into clean DC ready for use by other circuits.



About horizontal driver series is composed of: 1 driver transformer, 1 driver transistor, driver resistor and the final destination is the HOT Transistor ...Now master my question is where can I find the B+ among the electronics components mentioned above?

The best place get this B+ is at the positive leg of the Capacitor you mentioned earlier rated 160V, whenever you see a capacitor on the circuit and want to guess the voltage on that line it is filtering just consider the working voltage of the capacitor used to filter that line…if it is rated 160V just divide that by 2 and you get 80V…so expect the voltage on the line to be between 80-100, this is just a rough estimate of what to expect thought.

Another good point of getting this B+ is the middle leg (collector) of the HOT transistor.



About R-red, G-green, B-blue cathode pins, at sight , how can we know the RGB cathode pins points? In this regards we need to be accurate pointing pins because the printed layout of all PC board is not the same.

Usually these are labeled like KG, KR, KB and should not be a big issue here Alex.


I am planning to buy a book CRT television repair course thus I am worried1… the pictures you Have shown is not the same with the unit I am repairing...like for example the picture of pins Fly-back transformer, page 6 of understanding the CRT television critical voltage test points, the B+ is away from the fly-back transformer, it should be the pin of fly-back transformer has a B+. How come the two points has a B+...I am confused...Please show to me the B+ points.

In electronics Alex, what is important is to get the basic concept and then you can apply the same to any other TV model which shows up at your workbench.

Having said that let me say that I have written my book from the technician work bench point of view and you can confirm that from testimonies of satisfied customers who bought this book.



Anyway,,,I am worried to buy a book because it did not show the complete details or picture of B+.

Oh! Alex, this means you status in electronics repair will remain stagnant and this is not a very good report unless you want to change your career to something else.

All the best my friend.

Thank you Master.

Alex Ancheta L.I.B
Purchaser

Philippines

Thursday, September 4, 2014

introducing a new ebook on LCD and LED television repair

For those of you who are in LCD and LED Television repair and want to sharpen your skills on the same, this book is definitely a good companion on you workbench.

The eBook is written by a renowned LCD's/LED's expert Mr Kent Liew from Malaysia

For more info about the book click the book cover below.



See you on the other side



Saturday, August 16, 2014

A question on how to identify Surface Mount Component

A customer and a friend of mine Mr.Wilson from Malawi who lives in Pretoria, South Africa wanted to know how to identify Surface Mount Component

Hie Mr. Kimathi,

In the first place I want to appreciate you for extraordinary knowledge I have gained from your CRT TV repair eBook.

It’s so clear that even somebody who doesn’t know anything concerning electronics can manage to at least fix a TV with this book at hand.

The issue now is, I am looking for the book which can help me with the Surface Mounted Components like Diodes, Transistors etc, as I am struggling to identify and test many of components from LCD TVs and monitors that’s why I have decided to ask you about your Basic Electronics Course eBook.

I am ready to purchase it as soon as I get this information from you.

Hope to hear from you soon.

May God Almighty continue to bless you and reveal more to you in Jesus name
Kindly,

Wilson.

  
Hi Wilson,
Thanks for your feedback and glad to hear that you have found my eBook valuable companion at your work bench.God bless you too my brother.

Regarding my basic electronics eBook, I have not written about smd components but when it come to testing, the method is the same only that smd are small in size...

What you require maybe is just how to identify them and you can easily Google “how to identify smd components" and I am sure you will get a lot of info for free on the internet.

Again if you have an android phone, go to Google play and download an application called "electroDroid" this is very good even for other components also

Regards Humphrey

Tuesday, August 5, 2014

Another great way to test for remote control without presence of the appliance

A friend of mine and an electronics repairer from Fiji islands sends me this report on how to test a remote control.



While I was playing with one remote control of my DVD player, I was thinking the sensor is just a LED, but why it cannot light when we press the buttons.

I brought it close to my eyes and was trying to view the lightening of that LED.

Hopefully in some remotes we can see a little blink if LED, but as far as I have seen in remotes which are produced nowadays are hard to view the light of the LED with our naked eyes.

Interpretation:
May be the signal light is so tiny that we cannot see it with our naked eyes.

I thought to use my mobile phone camera to magnify the signal light and see if it is visible.

I was so happy, actually to see the LED lightening while watching it though the camera.

Here are the pictures I took:







It can be perorated that ,if a remote is not working it will not have its LED lightened when you press the buttons.TRY THIS OUT WITH A GOOD REMOTE AT HOME

So all my repairer friends there is a very good tester for remotes, which is always in your pockets (Our mobile phones with cameras).

After reading this article I decided to do the same test using my tablet and the result were the same (positive) as you can see the pictures below



This article is prepared by Atish Chand, a repairer from Fiji Islands



Thursday, July 24, 2014

Small switch mode power supplies modification secrets



A friend of mine Mr.Jestine Yong has just launched a new eBook “Small switch mode power supplies modification secrets”

I have personally gone through the eBook and he has shared incredible secrets on how to sort out those tough dog issues found in small switch mode power supplies.

For more information kindly click on the book cover.


https://www.e-junkie.com/ecom/gb.php?ii=1366560&c=ib&aff=222092&cl=215644" target="ejejcsingle">Click here to view more details</a>


Stay safe

Humphrey Kimathi

Wednesday, July 16, 2014

Android Phone tablet no audio after factory data reset



After installing a certain application to my phone tablet, I noticed it has become too slow and sometimes not responding to touch and therefore I decided to do "Factory Data Reset".


 Everything went as expected and it was successful as you can see on the picture below.

I re-installed the application from the backup file and I was now ready to resume normal services.

After doing several test I was happy to note that the tablet is now faster and works like new.

Before long I received a phone call and noticed that there was no ring tone and so I went straight to audio profiles, to my amazement I noticed it was not set to silent mode and thought maybe it the volume which was low.

So I slide it all the way up and still nothing happened, no sound, I tried to play video and again no sound. That is when I realized I have a problem here.

I started playing around with the gadget to find where I have muted the audio without success.

The next move is to Google to see if there is someone out there who might have encountered such a problem and indeed I noticed it is a BIG issue to many folks out here.

I followed many advices given and nothing worked, one thing I was sure of is that this problem has nothing to do with hardware since it happened after the Factory data reset.

I became too busy trying to figure out where the master reset audio is and again I was not lucky, so I decided to just reset the tablet using the reset key at the side of the tablet as the last resort.

 
After resetting the tablet by inserting a pin on the small hole at the side of this tablet solved the audio problem.

Kindly note that this hole is not same as the mike slot; in most cases it is labeled RESET.

Thanks you guys
Humphrey Kimathi