Training manuals for beginners

[7th_gear]

Such a very informative article you posted moon !

We really appreciate your advanced explanation but you see our topic is for beginners. You may opt to start a thread for advanced thinkers based on this beginner guides that lucascape started in here.

Mr. beginner is very hard to deal with, you have to explain as short as you can, any longer explanation would make them stop reading, unlike Mr. wizard whom you would be adressing at which is willing to read and learn more.

Thank you very much for letting us know that in the future, when we are ready for your advanced teaching and knowledge, you are here and is willing to help us


Salam & BR

[1amigo]

Originally Posted by shanchai

Such a very informative article you posted moon !

We really appreciate your advanced explanation but you see our topic is for beginners. You may opt to start a thread for advanced thinkers based on this beginner guides that lucascape started in here.

Mr. beginner is very hard to deal with, you have to explain as short as you can, any longer explanation would make them stop reading, unlike Mr. wizard whom you would be adressing at which is willing to read and learn more.

Thank you very much for letting us know that in the future, when we are ready for your advanced teaching and knowledge, you are here and is willing to help us


Salam & BR

I am in TOTAL agreement with you, Mr.Shanchai. We need to understand the needs of Beginners here and need to keep things much simple and easy to understand and teach them things only which are likely to find digestible and interesting enough.
Even in my lessions, which i have posted here, i now feel that i might have made the subject little too deep and might have made it little boring or "frustrating" as one of our Beginner has aptly told me in my private messages. I thank the person who has given me this feedback and I shall now be preparing the lessions little more realistic for mobile phone repairers and little more interesting also for all who read them. I thank lfc_fan for drawing my attention.
Please bear with me dear beginners, I am working with this intent on the next lessions.
I mean no disrespect to "moon mobiles", but like Mr.Shanchai i would also like him to start a new thread for advanced learners. We would be thankful to him if he does it soon please, because we may also learn many advanced aspects from him in theory to increase our knowledge.

[raufsagar]

Hi Lucascape!

Its Great To See Your New Lecture About GSM Operations!
But Please Regularly Post Your Lessons And Try To Avoid Long Disappearance......
Thanks

Rauf

[1amigo]

Surface Mount Technology

Surface Mount Devices(SMDs), PCBs, assembly systems, assembly processes and consumables grouped together are termed as Surface Mount Technology(SMT).
SMDs are mounted onto PCBs and soldered by high speed equipment using surface mount technology. This method is used to achieve the large volumes of production required by international companies whose end product is sold all over the world.
Soldering SMDs manually requires patience, skill and practice.

Surface Mount Devices

Surface Mount Devices(SMDs) are high performance miniature components that are directly soldered on to the lands(pads) of the PCB.
SMDs are available in both leaded and lead less versions. A majority of normal components that were available as through hole components (components that have leads or pins which are long enough to pass thro’ the holes in the PCB) are available in SMD version covering integrated circuits, discrete semiconductors, resistors, multilayer ceramic capacitors, electrolytic capacitors, plastic film capacitors, tantalum capacitors, inductors, presets, trimpots, fuses, etc.
SMDs are suited to almost every application. They have proved to be better than conventional components in terms of ruggedness, reliability and size.
SMDs are packed in tape and reel, tubes, trays, or bulk for convenience of feeding automatic placement machines.

Advantages of SMDs The miniature size of the PCB pads and tracks populated by tiny SMDs results in a reduction of inter-track capacitance. Self-inductance is virtually eliminated because of the very short leads or total absence of leads. These two factors are ideal for high frequency circuits especially in the RF range. In digital circuits propagation delays are reduced and clocking rates become higher.
In SMT the components and tracks are on the same side of the board making it very easy to trace connections and access test points on assembled boards. This tremendous advantage will be appreciated when one thinks of the problematic through hole PCB which one has to keep turning over and over trying to remember component location on one side and remembering at which point to test the circuit on the other side.
SMDs generally cost more than through-hole components. The difference, however, is not great enough to worry hobbyists.
The miniature nature of SMD assemblies is found interesting to hobbyists who are into miniaturist activities, such as model railways, military modelling, and doll’s house furnishing. An imaginative hobbyist will find numerous applications for these tiny circuits. In fact, many through-hole projects can be converted to SMD by model-makers to add realism to their models.

[1amigo]

RESISTORS
Surface Mount resistors are manufactured in many standard sizes. The size code describes the dimensions of the resistor. A 1206 resistor is 0.12 inch long and 0.06 inch wide.
Normal Non-SMD Resistor looks as below :

This is a picture of a 10Kohms ordinary Non-SMD resistor:
(DOWNLOAD THE DOC FILE FOR VIEWING THE PICTURE)
Surface Mount Resistors or Chip Resistors look like :
(DOWNLOAD THE DOC FILE FOR VIEWING THE PICTURE)
Surface Mount resistors are marked with a three digit code for ± 5% tolerance devices and a four digit code for ± 1% or ± 2% devices. In the case of three digit codes the first two digits specify the first two digits of the resistance and the third digit is a multiplier (number of zeroes). Resistor marked 102 in the above figure is 1000 ohms or 1Kohms, and the resistor marked 100 is a 10 ohms resistor.
In the case of four digit codes the first three digits specify the first three digits of the resistance and the fourth digit is a multiplier (number of zeroes). The figure arrived at is the resistance in Ohms. Resistors of less than 10W are marked with an R in place of the decimal point e.g. 6.8W is marked 6R8.

[1amigo]

CAPACITORS
Traditional Capacitors, how they look like:
(YOU CAN VIEW THE PICTURE BY DOWNLOADING THE ATTACHED ZIP FILE AND OPENING IT)
When we talk of Surface Mount Capacitors, Multilayer ceramic chip capacitors are used in most applications. They come in similar sizes as chip resistors. They are usually unmarked so special care must be taken while handling . The standard values are from 0.47pF to 100uF in a range of 16 to 50 volts.
And this how they look like :
(YOU CAN VIEW THE PICTURE BY DOWNLOADING THE ATTACHED ZIP FILE AND OPENING IT)
They are much similar to chip resistors in size and shape but the middle area in Chip Resistors is Black whereas it is a light ash brown color in Chip Capacitors.
Tantalum chip capacitors are produced in a range of values and voltages. A typical tantalum with a capacitance of 10m F and voltage 16 measures about 5.8mm by 4.5mm. It is enclosed in a plastic package with terminals at each end. The package is directly marked with the capacitance and voltage; polarity is indicated by a band at the positive end.
INDUCTORS
SMT has many important applications in the field of radio communication that has led to the availability of a wide variety of inductors. Their package construction is similar to that of the tantalum chip capacitors.

[1amigo]

SEMICONDUCTORS
The most popular package used for transistors, diodes, zeners, and LEDs is the SOT23. The pinout for transistors is generally standard for all manufacturers with very rare exceptions. Pinouts for diodes vary, as many packages contain two diodes, connected either in common-anode or common-cathode mode or as two separate diodes. With a single diode, terminal 2 is usually the anode and terminal 3 is the cathode, with no connection to terminal 1.
(YOU CAN VIEW THE PICTURE BY DOWNLOADING THE ATTACHED ZIP FILE AND OPENING IT)

PRESETS
Variable cermet resistors are available in the usual range of values. Their size is about 3 to 4mm square.

[1amigo]

INTEGRATED CIRCUITS
Operational amplifiers, comparators, audio amplifiers, timers, CMOS logic, 74HC logic, RAMs, optocouplers, voltage references, voltage regulators, etc., are available in SMD form. All these ICs are usually given their original type numbers with a suffix, most often ‘D’, to indicate that they are SMD. Packages are termed SO (small outline) followed by an indication of the number of pins. SO14 is a 14-pin IC. SMD ICs have the same specifications and pin-outs as their through-hole versions. Pin number ‘1’ is indicated either by a dot or bar. Another indicator is the bevelled top edge of the package along the pin number ‘1’ side.
A Normal Non_SMD IC looks like in the picture below:
(YOU CAN VIEW THIS PICTURE BY DOWNLOADING THE ATTACHED ZIP FILE AND OPENING THE EXTRACTED DOC FILE)
And a SMD IC looks like :
(YOU CAN VIEW THIS PICTURE BY DOWNLOADING THE ATTACHED ZIP FILE AND OPENING THE EXTRACTED DOC FILE)

[1amigo]

And a more advanced form of SMD IC called a micro BGA chip looks like in the pictures below :
(YOU CAN VIEW THIS PICTURE BY DOWNLOADING THE ATTACHED ZIP FILE AND OPENING THE EXTRACTED DOC FILE)
And a more complicated or multi-point BGA that you will mainly see in a Mobile Phone will look like this :
(YOU CAN VIEW THIS PICTURE BY DOWNLOADING THE ATTACHED ZIP FILE AND OPENING THE EXTRACTED DOC FILE)

[lfc_fan]

Vast amount of lessons posted by our friend 1amigo today, please keep it up as regular postings will keep everyone interested and keep the thread going.

Thank you.

[1amigo]

CHARGEABLE BATTERIES USED IN MOBILE PHONES :

As is well known the batteries can be mainly of two kinds : (1) Rechargeable & (2) Non-rechargeable
Wherever a continuour prolonged and more frequent use of the batteries is required as in Mobile Phones, the Non-chargeable Batteries are not useful and so the Rechargeable Batteries are the only kind which are used in Mobile Phones.
In the earlier models of Mobile Phones, just about 6-7 years ago, the batteries that were used were of the Ni-Cd types of batteries. The name Ni-Cd is derived from the material used to make this batteries viz.Nickel and Cadmium. This batteries had been replaced by the next generation of Ni-Mh batteries (Nickel MetalHydride) mainly because the Ni-Cd batteries were (1) Very Big in Size (2) Very Heavy in Weight and (3) had a shorter life span because of a phenomena called “memory effect”. All these 3 disadvantages were overcome to a great extent in Ni-Mh batteries. The Ni-Mh batteries were smaller in size, lighter in weight and had a longer life span because of very less of “memory effect”.

To understand what this “memory effect” is, let us know the working pattern or the life pattern of all chargeable batteries. The capacity of a battery is expressed in mAH units. What is this mAH? It is the short form of milliAmpereHour. To make it simple, it is the result obtained by multiplying the current drawn from it in milliamp units and the number of Hours for which it can supply that current, after which time it will either be able to supply less or no current.
So, mAH = mA x Hours (Current x Time in Hours)
If the battery is rated at 600mAH, it will be able to supply a current of 600mAmp for 1 Hour. If less current is drawn from it, it will be able to supply this less current for more time, because mAH is fixed. What I mean to say that if only 300mAmp is drawn, it will be able supply this for 2 Hours because 600mAH is a constant rating of the Battery and
600 = 300 x ? will give the result as 300 x 2Hours, correct?

or if 200mA is drawn from it, it will last for 3 Hours and if 60mA is drawn it will last for 10 hours and so on.

When we say that Ni-Mh batteries were smaller or lighter than the earlier kind of Ni-Cd batteries, we mean that a Ni-Mh battery required to supply say 600mAH of current will be smaller and lighter than a Ni-Cd battery required to supply the same 600mAH of current capacity.

The Basic of all chargeable batteries is that all Chargeable Batteries have a life span of a certain number, say 400 cycles of Charging (when connected to charger) and Discharging (when in use). Now given this fixed limit, we should apply our intellectual to make maximum use of this fixed life cycles of our battery, right? How should we do it then? SIMPLE, once you keep it in charging don’t stop the charging until it is complete and the Battery reaches a stage of FULL charge. And next more important point, is that do not again put it for charging until it is fully discharged. If you can take care of this two points while handling any kind of chargeable battery, then your battery will last for a much longer time. This fact is true for all kinds of batteries like Ni-Cd, Ni-Mh, Li Ion, Li Polymer etc. etc.

However, what happens in practical life is that either people are not told about this characteristic requirements of the Mobile Phone Batteries or the circumstances don’t always allow them to follow the above 2 rules strictly. Just out of the fear of getting stranded by the shutting down of the mobile phone because of the battery getting fully discharged, people just keep on putting the Mobile phone for charging every now and then and so what they are doing, you know?
First of all, you are aware that every time you put the phone for charging, you are reducing your available count of cycles from the given 400 cycles by 1, correct?
Secondly, assuming that the fully charged battery was to last for say 72 hours and you started to charge it only after say 36 hours and you are more likely to be doing it every time out of your sheer habit, correct?
So what is the total time usage you achieved out of using this battery for it’s whole life span? Simple to calculate it, see
36Hours x 400 times = 14,400 hours
And if you had been wise enough to charge it only after it was getting fully discharged by the normal working or usage, it’s life would have been
72Hours x 400 times = 28.800 hours

So now it should be clear to you why it is advised to let the battery be used up almost fully till it shuts down the phone, as far as possible.
Because, it shortens the life span of the battery in number of hours or days or months eventually, correct?

Now in addition to this shortening of life in Ni-Cd batteries, one more problem occurs is that because of such frequent charging of the Battery (handset), the Ni-Cd batteries start getting fully charged up very fast!! and you may say that what is wrong if it gets fully charged up very fast? Right? It is wrong because it also get discharged very fast!!!!!!!!!! Wondering why it happens?

To make you understand it easily, we know that a 3.6V battery is made up of 3 cells of 1.2V each, and let us assume that each of this 1.2V cell is made up of smaller cells stacked inside itself (inside each cell). Now when these small cells are getting charged up they get charged up from the bottom-most cells to the upper most cell and when they are in use they start getting discharged from the topmost cells first to the bottom-most cell last. So when the battery is half discharged, the top half of the cells are discharged and the bottom half are still in charged state and we start applying the charging again. So everytime only a few cells on the top side are getting a chance to be put to use and to get recharged whereas the bottom most cells neither get a chance to be put to use and so never get a fresh charge also for themselves. Over a period of time, this bottom cells become practically dead because of this thing happening almost every time and eventually they end up reducing the capacity of the battery in terms of less talk time and less standby time. This effect is called “memory effect” in Ni-Cd batteries.
This disadvantage was overcome to a very great extent in Ni-Mh batteries in addition to smaller size and lower weight of the Ni-Mh batteries. Similarly, the next generation of Li Ion batteries were superior to Ni-Mh batteries in all respects on the same 3 counts and so are in wide use at present. Soon we shall see even this Li Ion batteries getting replaced by Li Polymer batteries and may be further down the lane we may be able to witness very very small and tiny batteries, who knows!!!!!!!!!!

[ashraf123]

Helo All Friends Please Urgently My Help I Have A Nokia 6600 I Open Set And Wash Pc Board And Dry Hot Air And Compleat Fitting Set On Ok But Not Search Signal Please Help

[1amigo]

Originally Posted by ashraf123

Helo All Friends Please Urgently My Help I Have A Nokia 6600 I Open Set And Wash Pc Board And Dry Hot Air And Compleat Fitting Set On Ok But Not Search Signal Please Help

What was the problem before you did all this work on it?
Please go for manual searching and report what response you get there, does it show any networks?

[shahzad11]

These all words are courtacy of
www.ambtechniques.com


Charging Faults

Dear friends here we will discuss about what kind of functions a typical mobile phone has so let us start our new lesson. while starting i would like to say all of you that you please keep in touch with me by our contact us page and please don't feel any hesitation to ask me any question if you have about these lessons. these lessons will make you learn good repairing skills so keep reading these lectures.

First of all we will discuss how many main functions a mobile phone often has irrespectively of mobile brands.

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GSM Links GSM repairing GSM forums GSM flashers


charging faults are mainly of three types

No charging
Not charging
Auto charging
No charging:

in this fault a mobile phone does not charge at all when charging pin is inserted nothing happens it is always due to damaged fuse. or broken charging supply track if we repair fuse or jumper broken tracks we can set this fault off.

but on the first step I am telling you how to check no charging fault.

Check Your battery if it is not connected properly no charging fault occurs.
check continuity between charging pins it should be nor full nor high resistance.
if it is showing full continuity then there may be some problem in your charging IC may it is totally short you can re hot /replace this IC.
if there is no continuity in charging pins 90% fuse is damaged. you can replace fuse or jumper it. if a fuse shows full continuity in multi meter then it is working correctly if it is not so it is damaged.
if fuse is not damaged you can check tracks if broken.
if fuse, battery and tracks are ok then charging IC would be damaged.




Not charging:

in this fault a mobile phone shows a message "Not charging" on the screen when ever it is connected with charging pins. this type of fault is not a mere hardware fault it is 90% software fault. this fault is present only in nokia and I personally experienced a problem with a nokia 3100 it was showing "Not charging" i tried hardware solutions but totally in vain so I upgraded my software now every thing was ok. . and this is the same case in many types of nokia brands you can check this up.

Only nokia 1100 when "Not charging" fault comes it is very hard to remove this fault in nokia 1100 I only repaired a little number of nokia 1100 displaying this message there was a problem in charge connector diode next to charging fuse. but often it can be solved by repairing software or upgrading it.

Auto Charging:

In auto charging a phone continues showing charging despite of removing charging pin from phone.

in this type of fault the "BSI" pin of mobile phone is very important because it is used to tell the phone what is the state of mobile phone charging now so if this pin is not ok this fault occurs.
there are some cases in wich a mobile phone battery is ok but auto charging is present you can check transistors if used in charging section and if faulty replace it because this transistor is used in some mobilephones to cut off charging from phone automatically. in
In some cases a resistance in charging section is responsible for that which is marked as "R22" in charging section so you can check "+" supply connection with this

[shahzad11]

Hi guys i hope you will have appriciated this post i ll try in the future to post such material to share knowledge with all of you and I hope that everyone will share there repairing tricks also with me