Saturday, February 26, 2011

CRT Television Repair Course Ebook by Humphrey Ready



Learn troubleshooting and repair of CRT television from the technician work bench point of view

Click on the book cover for more info



For a free Preview of this eBook in PDF please feel free to email me at:sales@humphreykimathi.com

Countries where this book has sold includes...


 


Friday, February 25, 2011

Causes of retrace lines on the CRT Television screen


In the last article by Mr Beh, you noticed that when the television came up the first time..Still there were white lines observed on the upper part of the screen.

In electronics one can get a lot of clues on the faulty block if one is keen and understand well how different blocks works and possible symptoms when they fail. The more you understand the basic functions of each block the higher the chances of localizing the circuit causing the trouble faster and hence saving on time.

Let us first start by differentiating between retrace lines and just lines:

A)    Lines on Television screen refers to straight lines across the screen like the ones shown on the picture below. Lines usually cover part of the screen but not whole screen.





B)    Retrace lines on the CRT Television screen refers to horizontal lines which covers the whole screen from top to bottom but they are never straight (sloping).



Usually Lines which covers parts of the screen are mostly caused by a fault on the vertical circuit particularly Capacitors ESR gone high. And for Retrace lines they may be caused by the following:-

A)     Blanking Circuit- As electron beam move across the screen of the television scanning from left to right and back usually causes retrace lines, but this never happens thanks to the little known blanking circuit which erase(Blank) those lines which could have been otherwise visible Very fast. But if this block fails then retrace lines will be visible on the screen.

B)      G2(screen) voltage set too high- The Screen Voltage on the other hand if it is increased a lot will causes retrace lines. So next time you change a fly back transformer and find the television is up but the screen has retrace lines try to adjust the screen knob to lower the screen Voltage. The screen will be too bright also.  Usually if the screen voltage increases alone it could point to fly back failure and therefore should be replaced.

C)      RGB Supply too low –On the other hand if the supply to the RBG amplifier is low also usually causes retrace line on the screen and the screen will also be very bright. If this voltage is low it could point to the filter capacitor for that line being faulty(please confirm or replace it directly)


Wednesday, February 9, 2011

Solving White lines problem in upper part of the screen of SONY TV MODEL KV 2199 PART -2


Solving White lines problem in upper part of the screen of SONY TV MODEL KV 2199 PART -2


In the last Article Part 1 of the above Television repair, Mr Beh promised to come back with part 2 of the same Television and maybe you were wondering what is it for if the machine worked…
This is because even if the television was up and running it was not 100% because if you were keen you could see some white lines across the upper part of the screen.
In this article you are going to see the power of term work and networking at its best in the following case…
By the time that report was being published this conversation was still going on in the background.

Mr Beh: DEAR HUMPHREY thanks you so much of your encouragements. But still this tv has problem with screen i have three big horizontal line in the screen in the top. Also you can see on that picture that i sent you. The picture tube also is suspect. The case is under process i will send you the result as a second report of this tv. Today i will have consultation with another repairer friend about this case. Kind regards beh
Humphrey: Hi Beh, Those horizontal lines point to bad capacitors around the ic...check the esr of those cap first.... Humphrey

Mr Beh: HI HUMPHERY thank you for your suggestions. Yes i check all caps except very small ones less than 1 micro i did not found any thing also i do not have any equipments to check the esr less than 1 micro any way thank you
beh

Humphrey:  sure there is no meter to test cap esr less than 1 micro......i can see your frustration on your face man...
i have been there many times and back....am telling you the experience you are getting is for life time...
finally please see attached file for more info....also be sure to re solder all components around that ic.
Best luck
Humphrey

And with that a little background of the events let join Mr Beh for round two of this Sony television repair...

In the first part of this report I explain repair of the power supply and TV start to work. But the TV was not fixed completely because of white lines in the Upper part of the screen. 


This problem could be of following 

1-the weak picture tube (The solution for this problem is costly the new picture tube is around 65 used). 
 2-another probable problem is in the G1 circuit of picture tube.
3- the defective caps around circuit of the vertical ic LA-7830.

 i concentrate on G1 circuit and I did not found any problem in that section. Mean while I received some information from MR KIMATHI he sent
me the diagram of LA ic and (suggest me to check the cap strongly)


I start to check this Electrolytic cap 100 micro@ 35 volts. I pull it outside the board and I check with ESR meter the meter showed infinity but meter must Show at most 0.5. Also I check the cap by capacitor tester .tester must show something near 100 micro farad but Showed only 0.481 microfarad. I assume that the cap must be culprit .by changing the cap with new one the TV starts to work with no white line in the upper side of screen and white horizontal lines disappeared. Thank you MR KIMATHI for your on time info.


 White lines are disappeared from upper portion of screen.
 
In Conclusion by Humphrey

From this article one can learn two very important principles about life:

Principle 1: Important of giving

 Here giving does not necessarily mean giving money but all kinds of giving may it be time, sharing ideas etc..let take a look at the analogy with a river…A river always flow giving water to other small rivers until it finally give everything into the ocean and see rivers are always fresh and never dry up. On the other hand the ocean only receive water fresh water from rivers but because they don’t give out they remain salty forever…here mr Beh decided to follow the river model and shared his idea to the whole world and in the meantime got refreshed by being given an idea which maybe if he never shared this with us it could have taken him long to know.

Principle 2: Principle of Team work.

Another important one…here let me use another analogy..it is said that the power of 3 men combined is more that each man added together…you ask how can it be mathematically…let me explain with an example…let assume you are driving a car with 3 strong men and all of a sudden the car stop and therefore need a push to start..So the three men get out of the car and the first guy one by one start pushing the car…one man… no stat.  And the second man...No start. And then bring in the third man and there you go the car now starts.

So we can conclude that mathematically the force of the three men is more than the force of each man individually and hence you can see why you should think teamwork in your next assignment.

thank you guys
let meet in the next class...





Monday, February 7, 2011

SONY TV MODEL KV 2199 M5T REPAIR -part 1



This report is brought to you courtesy of Mr Beh...We at humtech electronics take this opportunity to thank him for sharing with others...hope this report will encourage others to share their experiences also.....

…and without wasting much of your time let join Mr Beh in the classroom....


I received this TV from one of my friend to repair. It is 10 years old and No diagram was found.  The problem of TV was no power with pilot lamp on and fuse was not blown.
I used voltage testing method for repair of this set:.



Entrance AC voltage to bridge rectifier (LN4SB60) was good also 320 v dc On two poles of big cap mentioned that the big cap is running well. by assistance of goggle I found out that the vcc For STR (STRS6707)   Must be 15 v DC but the voltage on the ic vcc pin9 was 7.5 v dc and This indicate that STR could be leaking the voltages 



after changing The STR with new one the TV start to work but just for few seconds.(the sound was good ). 


 I check all other parts around second part of SMPS .also big transistor (HOT) of set was not giving good answer under test by volt ohmmeter (D1787). After substitution with (D2025) TV started to work steadily.  But still no picture and only three Horizontal line on screen. This means no vertical deflection I proceed to vertical deflection ic in vertical section of the set it was hot like hell and also a big crack on the face of ic was visible this is (LA7830). 



After changing this ic TV start to work also I got the picture very clear and sharp. 



i want to mention that during the work on this TV I used isolator transformer for more safety


Thursday, February 3, 2011

overview of LCD MONITOR REPAIR...click on this video




...and if you would like to become a professional in LCD monitor repair in your home town consider investing on this e book by Jestine Yong.

Tuesday, February 1, 2011

For an overview of how to fix a LG Plasma Television .. please click on this video.


And for those who would like to advance in Plasma Television repairs...Click here to join Classes today.