## Monday, August 15, 2016

### Understanding related components in a circuit

When you open electronics equipment like the television for the first time, one can easily get intimidated by the number of components in there.

This shouldn’t be the case if you have adequate knowledge in basic electronics especially on basic functions of the components and how to read circuit diagram.

Actually in my case if I have a problem with electronics equipment I never rush to open it first, and especially if there is something on the screen.

First I analyze the symptom systematically till I am very sure which circuit block is causing such a symptom.

Then I google that particular model if it is a television and download its circuit diagram and again check out the particular circuit which I suspect to be causing the problem.

On this preliminary investigation I mark out on the actual circuit diagram the most likely culprit components with a highlighter.

After that I open up the set and go straight to the suspected circuit. First I scan with my naked eyes for any signs of stress or burnt area on that particular circuit.

If I am happy with the visual inspection, then i do voltage testing to that circuit to see if they are all okay and within the expected range as per the circuit diagram.

How do I know the related components in a particular circuit like the vertical circuit, audio circuit and horizontal drive and horizontal output stage?

This is where related components rule come in, you know in electronics equipment, components are usually arranged in a very orderly manner and in blocks just like in a house you have a kitchen, table room, dining room and bedroom.

All those rooms require lighting and therefore I don’t expect if the bulb in the kitchen goes off (faulty) you go and change the bulb in the bedroom and think that you have solved the problem, and by the way that is why you should check the power first because if the place is dark then you cannot do anything in the darkness, same with the actual electronics equipment.

If you find no power or power not good just go ahead and restore the power on that block (room) first.

So how will i know what belongs to the kitchen and what belongs to the bedroom, my guess is as good as yours.

Usually kitchen items should be kept in the kitchen and bedroom item should be kept to the bedroom.

In electronics same components are usually used in different blocks and therefore it will be confusing to know if this component belong to audio/vertical/ or even power supply.

For example you will get a capacitor in virtually all circuits, so how do you differentiate a capacitor on the audio circuit and a capacitor on the vertical circuit.

To differentiate all circuit board are labeled on the pcb board and usually related components are grouped together.

Let have a look at this actual picture of an audio circuit of this Jvc television.

In this television you can see the audio block (room) is clearly marked with borders and also labelled Audio, also note that the major component here is the audio ic(I.C651)

So in audio block expect the related components to start with Y6XX, Y refers to component category like C-capacitor, R-resistor, Q-transistor, IC-integrated circuit etc. then 6 is the relationship as in this case we have the audio group and the XX is the component Reference number.

So if we have only two ic in that block we will have I.C651 and I.C652 etc

You can see the same block component side here.
So whenever you suspect audio problem this is where you are to concentrate on.

Below again you can see a section of horizontal circuit block of the same TV and all component are grouped in series Y5XX, so any component with that series belong to horizontal output circuit.

Here is the same block component side.

When I wrote my book CRT Television course I was able to identify eighteen blocks in CRT TV and I have analyzed each block and the most common faults in each block and I think this is why the book has remained the favorites to many students majoring in television repair.

Thanks you guys
See you in the next class
Stay safe

Humphrey Kimathi