WHY DO REPAIR TECHNICIANS NEED ESR

Dear repair friends,

Once again i am coming back to you to introduce the term ESR (Equivalent series resistance) 

Looking above statement many questions in mind

1) Why do we need this ESR??

2) And again why it is so important for Repair /Trouble shoot work?

3) What is the instruments used to find ESR?

Generally there is a term"The rate of failure is proportional to Number of electrolytic Capacitors present in an Electronic equipment"

Yes, Based on my experiences 70% of electronic equipment failure due to capacitors. Then How to find defective caps?

Methods 

1)Using Analog Multimeter:-There was the day the method taught my father by using Analogue multimeter the pointer needle that goes to end & coming back to zero for good capacitors but this is not 100% correct.Because i failed to trouble shoot defective caps in many equipment.

2)Using Capacitor Meters:-With the introduction of expencive Capacitence meter i felt very happy so that this capacitor meter is the best Detective meter for electrolytic capacitor, Even this meter also not 100% correct. I failed to trouble shoots even in this method

3) Physical appeariance:-Mostly capacitors Bulges on defective it is Easy to identify. Some of the capacitors dry’s an electrolyte & increases their internal resistance without any physical changes. This kind of electrolyte is very difficult to identify even a capacitance meter measures correct but it fails to identify its internal ESR value. 

Most of the technicians based on their expierance replaces the caps if they get doubt while trouble shooting because of its cheap cost.

Then how to identify exactly faulty caps in an electronic circuit?? The answer is ESR meter

Yes, this meter is my favourite meter i will call this meter as capacitor police because within a fraction of minute it can catch the culprit.

Good & Defective capacitor samples

 

 
 

In above pic one is defective & another is good but no any physical change in appearance

After testing with ESR we can easily locate the faulty capacitor.

Pls go through below one of my Repair case History  to understand the effectiveness of this Instruments.

The first Repair success story with this instrument

We received a compliant from Onida crt TV for repair

the unit dead with standby LED ON

After opening the chassis found dual SMPS in this model

1) SMPS 1 used  for driving Audio section & micro-controller standby

2) SMPS 2 used to power up the rest of the sections through relay driving

As on trouble shooting i did not found 300V DC in main filter capacitor @ SMPS 2 back word trouble shooted

Relay is not activated checked the relay circuit found ok.

Now found relay driving voltage abnormal coming via micro-controller  now suspected on VCC line on micro

Found abnormal showing 5.5Volts DC instead of 8v DC the culprit is 8V filter capacitor 100mfd/25Volts.

When i checked with above ESR it is shown open. All this activity taken only 5 to 6 Minutes

Once again thanks to this great instrument I almost saved 90% of my repair time.

TV pcb with Culprit innocent Capacitor marked

Then ESR Meter how it looks? pls go through below  ESR Models which is very important ,Every Repair Technician Must have this instrument to save his precious time.

            

Blue ESR Meter                              Common ESR Meter  

   

 

Analogue ESR Meter      

Pls go through there details through Google internet for there operations & Specifications .Depending up on your Budget one can choose the instrument.

In an up coming article i will let you know its principle of operation & how to use ESR effectively in trouble shooting work

That’s the end of this article see you in the next Topic.

With Best Regards

Basavaraj:BM
basavarajradiotech @gmail. Com

AHUJA Amplifer PA SYSTEMS repaired

Hi,
Wel-come to the wonder ful world of ELECTRONICS Repair articles.Once you know the basic in an electronic every thing is possible.let me take you today in repairing PA Sounds.AHUJA Amplifer PA SYSTEMS.Below is the one came to repair in my service center.

                                            

Came to repair with AUX Picking compliant

                

                                               

                        

Amp Inside look

Ahuja is one of the Indian brand having its name in quality.Many people trust & prefer this in Temples,schools,collages & even orchestra team own this brand.Since from my child wood i have seen many models starting from in-built casset player like single wheel machenisum to latest USB player model.I have repaired many models since from those days.   

Simply speaking amplifiers are simple circuits. I think you are studied in your basic diploma or engineering course. Same circuit is commercially applied here in this model. Any how once if you receive this kind of equipment's for repair one can charge more depending up on the the wattage. Now let us discuss how I repair this model and what  was the complaint. When I received amp with new costumer he told me that he is having aux compliant I mean it's not picking aux input I think every one understood that what was the complaint no further explanation. When I removed the front panel I noticed it is having one-one input composed with NPN C1815 transistor works as a pre-amplifier which is used to boost the incoming signals.

Since this amplifier related aux complaint my concentration is on aux related circuits only. Before touching active component I checked the aux control knob for its working found OK. Now I checked the transistor found OK. Also checked preamp vcc found normal. Now myself totally fed up when every thing is OK then what could be the problem??. I need to know what is happening to this signal feeding to aux input. Finally I pulled up my oscilloscope to see the the conditions. When I placed the probe to test point to my surprise signal is dropping low at the preamp input due to transistor leaky. As I discussed in my earlier articles defective or leaky transistors are looking good even when tested on good meters.

  Back Good transistor soldered for checking purpose


 Based on this concept directly replaced aux preamp transistor NPN C1815 . Again when I tested it was success. I got good visual signals in my scope. Re-assembled the panel and turned on the equipment. Very happy to listen the melody song when I played via my mobile. This is how I repaired AHUJA amplifier. That's an end of the story. Let us meet in the next session.
Regards
Basavaraj BM
basavarajradiotech @gmail. Com

WIPRO LCD MONITOR NO DISIPLAY NOW SOLVED

Hi friends
 welcome back.After a long time again i am writing this artical revealing how i solved this Wipro monitor no disiplay complent.Before start pls look in to the photo snaps one came to my service center for repair.

Above is the one came for repair

                                                 Back view after removing back cover

Let us know what is happened to this  machine.When i opened the chassie as useal i observed the filter caps bulged as a common case .see below for your reference.

After looking this really i felt very happy so that i can easily solve this problem.Confidently i replaced this filters and switched on the equipment to know the results.There is no any sign of light inside the monitor panel.Now i need to know & go for further investigations .
Further i glanced the circuit for any physical damage /crack on components/etc
Now my next step is to go for voltage test methods to catch the culpirt.Since the problem related to back light my doubt is to check the voltages in inverter pcb.

While testing with my multimeter test prob taken me to the fuse input which is showing open.This is blocking the DC12 Volts reaching further circuits inverter pcb.

After replacing fuse again getting open further investigated the reason to cause this. The main culprit is one of the inverter transformer.Replaced the inverter transformer which is removed from the junk board for  same type, Now Monitor started working  in very good condition.Happy to see this from customer end.This is the repair success story of wipro monitor.

                                                   Assembling the unit after repair

                                       Happy to see the result after caps/fuse/inv transformer replacement


Thanking you let us meet in the next session with one more intersting sucess stories
take care with best regards.
Basavaraj:BM
basavarajradiotech @gmail. Com