FIXED POWER SUPPLY.

 

·         AHome

·         Blog

·         CRT TV Repair

·         SMPS Repair

·         PCB Repair

·         Fan Repair

·         Test Components

·         General Electronics Repair

·         DVD Repair

·         LCD Monitor Repair

·         CRT Monitor Repair

·         Electronics Repair Questions & Answers

 

Two Shorted Diodes But Four Replaced

A super market owner across the street came running to my shop and asked for a 1.5 amp fuse. He explained that the electronic scale that they have at the shop went dead. He said he will replace the fuse and let me know. Soon enough I found out that the fuse he installed gone open again which confirms my fear that the power supply in that device was shorted and needed repair.

The scale is too big to fit in one shot so this is the display of the scale and the next photo is the rest of the

 scale.

It was not the best clean electronic scale that I ever worked on; it was dirty and needed a lot of cleaning. The repair is my job and the cleaning is the owner part.

 

So let us repair the power supply inside this device

It is a 24 volt power supply with 3 amps rating. I was not thinking of repairing it when I first opened the power supply. I thought of ordering a new power supply. The owner did not want to wait for the new part to come so he told me to go ahead and get it fixed.

If you look closely to the fuse, you would see or think it was intact but in fact when testing with the multi meter, the fuse was open. Since the fuse was open, the logic and common sense is to check first of all the bridge rectifier.

As expected, one of the diodes was reading a dead short and the other diode was giving me reading both ways. Four of the diodes of the bridge rectifier were replaced.

I saw this burnt mark on the metal holding the power supply board but discovered later on after testing the Mosfet that this burnt mark was old and other technician replaced the shorted Mosfet with a new one.

After checking all the parts on that power supply board, I determined to use the light bulb trick to find out if there is still shorted part that I may have missed while testing

It was confirmed that the power supply board is free of any shorted component and this is the time to put the fuse back and get the machine working again

 

 

 

 

 

 

13007 Power Transistor, Faulty Diodes and a Capacitor Found in Self Made LED Porch Light

This is a generally available Power Supply that can take around 2A load usually used for LED Serial Lights. I had bought one along with a ready made strip of LED lights for use in my Car Porch. This has been working fine for the last two years. But suddenly went dead, tripping the MCB. So removed it and checked what went wrong, after thorough cleaning. I had provided grill to prevent any gecko doing any exploration. Though the grill was having very small pores, the unit was almost packed with very small dead insects, which find its way through.

On opening and checking the components on the board, I could see that the fuse was cracked; all the four rectifier diodes were short along with the 13007 transistor. The tank capacitor, 33/450V was showing zero ESR and on removing it, I could see that it was rusted and corroded at one pin, due to leakage. These were indications of high voltage surge and moisture formation. Replaced the defective components and checked for any more defects and could not find any.

Since exact size of fuse was not available, used a slightly large one, covering it with a protective sleeve and marking its value on top of it. Powered the PS through a series bulb and found it to be working. So assembled it back and retested it.

Plugged it back on the car porch and checked it again.

These are the defective components:

 

PS3 REPAIRED

 

 

 

 

 

 

PS3 With Red Light And Beeping Sound Repaired

An American friend of mine brought me this PS3 for repair. It belongs to his two kids and recently, the machine was not working the way it should. The moment it was powered on, it is supposed to change from red light into green but instead, it was only getting red light flashing and a beeping sound then shuts off.

This is a self check at start up and seems like something inside this machine

causing the self check to find something wrong there.

It is an old PS3 but taking it apart is very easy and as seen in the photo just take this parts off and I will be able to see the main board.

The parts were off and I am getting closer to the main board which I think it is the main cause of the problem here.

Very dusty board and if you look closely to the bottom left side of the board I could see something spilled on board and I was not happy to see that.

It looks and smells like coffee spilled here.

More spilled stuff here as well and the more I see of this the more I get nervous and the chance of getting this fixed is very slim.

That looks very bad and seems like someone tried to clean it up but instead made it worse since the thermal past is spread all over the board and it is not supposed to be like that.

I started to clean the board and making sure all the thermal paste is off these parts and after all this cleaning was done, I decide to reflow the main two IC’s because I checked online about his fault and everyone recommended to do this process.

To my surprise, after all the cleaning, reflowing the main two IC’s, adding the fresh thermal paste and then putting all back together it actually worked.

Yes, it worked but my question is how long it is going to last? I informed the customer and he was ok with whatever it happens because he is planning to get a new PS4 or PS5 for his children.

 

 

                               ELETRICALS AND ELECTRONICS:

                                             SERVICES BEING OFFERED

 

                                                     [1] MAINTAINANCE:

                                                    [ 2] REPAIRES:

                                                    [3] TROUBLESHOOTING

                                                    [4] INSTALLATIONS:

                                                    [5] SCHEMITIC DIAGRAMS INTERPRETATIONS

                                                    [6] DESIGNING CIRCUITS

                                                    [ 7] TESTING COMPONENTS

 

                                 MANDATORIES:

                                                    [1] THIORIES:

                                                    [2] PRACTICALS:

                                TOPICS:

                               CIRCUITS ANALYSIS

                                                     [ 1] RESISTANCE

                                                     [ 2] VOLTAGE

                                                     [3] CURRENT

                                             CIRCUITS COMPONETS

                                                   [ 1]   RESISTORS

                                                    [ 2]   TRANSISTORS

                                                   [ 3]   INDUCTORS

                                                  [4]      DIODES

Introduction and Basics of Electronic Circuit Design                                          

Designing an electronic circuit begins on the breadboard (protoboard). The bed board is a thin plastic rectangular construction base to which electronic components are soldered. The soldered connections are not permanent and can be removed and placed again and again within reason. The construction of a breadboard subsequently turns it into what is known as a PCB, often used in computations, signal amplification, and data transfer.

The interconnections on a PCB connect the soldered components. Charge flows from the positive terminal throughout the interconnection loops to the negative terminal.

Note, Q3 and Q4 in the figure below are complementary, NPN and PNP respectively. This circuit works well for moderate power audio amplifiers. For an explanation of this circuit see “Directly coupled complementary-pair,” 

Ch. 4.

REFRIGERATOR NOT COOLING REPAIRED

 

To those who wish and interested to practice the electrical and electronics, servicing and repairs I request them to join us and gain knowledge and skills in troubleshooting repairs and servicing the  electronics equipment.

 

  TROUBLESHOOTING,REPAIR AND SERVICING

TVS

WASHING MACHINE

REFRIDGERATOR

HOME THEATRES SYSTERM

RADIOS

PROJETORS

DESTOPS

CCV SECURITY SYSTEM

ELECTRIC DRYERS

ELECTRIC OVENS

MICROWAVES

ELECTRICAL WORKS, INSTALLATIONS

 

a. Refrigerator not cooling

The refrigerator not cooling but all function are working normal including the compressor are also running as well.  You also may find a refrigerator cooling at freezer point but in fridge not generating cold at all. But first I will deal with not cooling issues.

 

The refrigerators comprise: the compressor

                                                               Condensers

                                                               Evaporators

                                                              Expansion valve

 

 

 

Lets me starts explaining how did I done to reinstall the refrigerator back to working normal.

The following are the images of the compressor inside the refrigerator

The work of the compressor is to circulates the refrigerant throughout the system and adds push air to the warm of a circuits. The compressor is the heart of the refrigerator and it plays a very huge role in the refrigerators system. This is how it look.

Checking everything and found are good condition then weld pipe on charging line and prepare the refrigerant. You should identify the appropriate refrigerant type of required for your refrigerators…. refrigerants R-134a and R-600a.

 

 

Recharged then tested and it was fine. Conclusions fixing the refrigerators is very easy job. 

 

 

                                                                                

 

 

                        BLOG: electronicsrepairtech.blogspot.com

                        EMAIL: dicksonmuchoki@gmail.com