electronics repair made easy

LED TV PANEL TROUBLESHOOTING & REPAIR

2026-01-08T19:38:00.001+03:00

New ebook launch.

🎯 WHO THIS BOOK IS FOR

This book is designed for:

Beginner technicians with basic electronics knowledge
Workshop trainees and apprentices
Practicing TV repairers seeking advanced panel diagnostics
Technical instructors and training centers
Self-taught technicians wanting structured, professional guidance

⚠️ This book is not for casual hobbyists.
It is written for those who want to work confidently in real repair workshops.

📑 TABLE OF CONTENTS

Introduction to LED TV Panels
Panel Structure and Working Principles
Common LED TV Panel Fault Symptoms
Safety Rules and Essential Tools
Signal Flow and Panel Fault Diagnosis
Backlight System Troubleshooting
T-Con Board and Panel Interface Faults
TAB / COF Bonding Failures
Repair vs Scrap Decision Making
Advanced Backlight and Panel Techniques
Customer Communication and Pricing
Forced Recovery Mode and Firmware Repair
Common Mistakes, Safety, and Workshop Guidelines

✅ CONCLUSION OF THE EBOOK

By completing this eBook:

Students will confidently diagnose LED TV panel faults
Avoid unnecessary replacements
Make professional repair-or-scrap decisions
Communicate effectively and safely with customers
Operate efficiently in a real electronics repair workshop

Stop guessing. Start diagnosing like a professional.

Learn how to correctly identify panel, T-Con, and main board faults using real workshop methods.

👉 Click here to get the full LED TV Panel Troubleshooting & Repair eBook

Kenwood Electric Pressure Cooker – Dead on Arrival, Back to Life!

2025-08-11T21:06:00.003+03:00

A customer who sells electric Pressure cookers brought me a “return” unit for after-sales service. It had been sent back by a buyer because it was completely dead.

Upon opening the cooker, I immediately noticed seriously burnt components on the power board. One Zener diode, which I marked with an arrow for reference, was completely shorted. I suspect this fault was the starting point that led to the damage.

At first, the extent of the burn almost discouraged me. But since the customer had brought two identical cookers, I decided to use the second one as a reference for the missing and damaged parts.

The faulty components were:

12V Zener diode
47Ω 2W resistor
1MΩ resistor

Luckily, I had all of them readily available in my shop.

After replacing the three components, I powered the cooker through my series current-limiter bulb. The bulb stayed dim — a good sign that there were no other major shorts. Then, I heard a reassuring click from the relay, and the display lit up.

That was my moment of victory — the Kenwood cooker was alive again!

Visit our Nairobi office here or contact us on +254 733 475 040

VON 2.1 Channel woofer works a few minutes then stops

2025-06-11T12:14:00.010+03:00

A customer called me concerning a woofer that she wanted checked by a technician. She told me that the woofer was dead. I was in a hurry, so I did not have time to confirm the customer's complaint, which is very important.

I picked up the woofer on my way to my shop. upon reaching my shop, I applied the power, and the woofer was up and running. So I just kept it aside to do other things.

Later, I called her and told her the woofer is working, she then told me that it stops working after a few minutes.

From experience, I know that these symptoms are usually caused by failed capacitors, so my first assignment was to check all capacitors using an ESR meter.

To my surprise, there was no culprit, and all capacitors were found okay.

I decided to use the next card I use in troubleshooting woofers by using touch.

So I powered the woofer and placed my fingers on the audio ics, and whichever is getting very hot is usually the culprit.

Using the above method, I found the IC below TDA 2030 marked with X was getting too hot for my fingers and hence decided to replace it directly.

After replacing it, I did the touch test again and noted the ic was still getting very hot, I guesed maybe there was a capacitor I never picked and I decided to re-check all the capacitors around that ic which are very few and all of the passed the test with flying colors, so what next.

I kept the woofer aside, very frustrated man, later I decided to check for dry joints on the entire board using a magnifying glass, and to my supprise I noted a capacitor on pin1 of TDA 2030, which was getting hot, has a serious dry joint which could not have been picked using naked eyes.

I re-soldered the capacitor and tested the woofer and noted the ic is no longer getting hot.

Later, I decided to do a postmortem of what caused the IC 2030 to overheat.

So I decided to get the circuit diagram of IC TDA2030, and this is what I got. Pin1 is the input signal, and capacitor C1 is used to block DC and pass the AC signal. Since the capacitor had dry joints, this led to a poor signal to the IC and hence overheating.

I tested the woofer the whole day, and still, the machine was running cool. I called the owner and informed her, and she was very happy. So was the tech.

Visit our Nairobi office here or Contact us on +254 733 475 040

🔧 Want to take your electronics repair skills to the next level?
Grab your copy of Woofer repair – a practical, easy-to-follow guide packed with real solutions, pro tips, and step-by-step fixes.
📘 Tap the cover to order now and start repairing like a pro!

NordicTrack Treadmill Motor Controller model MC2100ELS, Control Board Power Supply dead now repaired.

2024-10-07T17:25:00.005+03:00

I received a phone call from a client who wanted his treadmill control board checked by a technician.

I scheduled him the following day since I was busy at the time.

The following day I visited the company where he works, the treadmill was used as the worker's gym facility.

On arrival, I found the board was already taken out of the treadmill and in his office.

I did some initial tests and found IGBT (K50DDTP), an Insulated-gate bipolar transistor dead short.

I tested other components and all looked good according to my meter, Customer pointed out that the main circuit breaker tripped when the treadmill was powered.

Here is the transistor K50DDTP which was a dead short collector-emitter junction.

I could not get this part and I therefore ordered it online from AliExpress.com. It took 8 days to ship to Kenya since I used expedited shipping.

Once I got the part I went back to the customer who was very happy to see me back with the important part.

I replaced the part and was taken to the gym room to do the testing. I re-installed the board slowly and carefully and now was time to test.

I realized the power board is not powering on and noted the plug fuse was also gone. I replaced it and after applied the power I saw smoke and a ball of fire from the board I had just installed.

I was pretty sure the transistor has gone again but I had imported 5 pieces so I was not very worried though I was concerned about the component which triggered this.

I tested the same transistor in circuit and sure I heard a beef, I took the board out again and testing the board out of the system realized the part survived and 2A fuse died a painful dead(blackened).

So what caused the big short which caused this fuse to blow? I decided to replace the 2A fuse and re-install the board but leave the treadmill DC motor out as you can see below.

I applied the power to the treadmill and this time no issue was detected, I was also able to log in and the display was okay.

This led me to conclude the motor is shorted and needs replacement.

Again, this part is not readily available in my local market, and I am still searching from second-hand shops.

Thank you guys

See you in the next class

Ramtons inductor cooker model RM381 came in dead, now repaired.

2024-09-01T21:10:00.002+03:00

I received the above inductor cooker in my shop for repair, dead on arrival.

I opened It and did some scanning on the power board, coil, and display circuit and all looked in good shape.

Since the unit was dead I began by checking the state of the main fuse and found it open, whenever you find the main fuse open expect a heavy short ahead.

So, don’t be in a hurry to replace the fuse unless you want to keep the fuse manufacturing company in business.

I continued troubleshooting looking for a shorted component since only a shorted component can cause the fuse to open. Main suspects being diodes, transistors and ics.

Components on this supply are few and therefore testing from the bottom side of the pcb noted a beep on transistor which was attached to heavy metal heatsink.

Cross-section view of the same

I removed the heatsink to access the transistor and noted it was H20PR5, an IGBT, tested dead short both in and out of the circuit.

Unfortunately, I could not get this component in our local market, i ordered it online from AliExpress, which took 8 days to ship to Kenya.

I finally received the part this morning and after replacing, the machine came up smiling.

Thank you guys

See you in the next class

LG 49-inch LED television model 49LH549V has no picture but sound was okay.

2024-07-04T09:08:00.009+03:00

I received a phone call from a client who wanted his television checked by a technician.

The client told me he suspected backlight failure, so I proceeded to the site armed with all equipment for any scenario.

I arrived at his place hassle-free since he gave directions, the name of the court plus the house number very well.

On arrival, I was shown the television which was still mounted. I unmounted it and placed it on the table.

I placed the television with the back cover up, applied the power, and noted the backlights were ON.

With that, I realized the issue was not backlights like the owner had hinted and therefore had to do more detective work to diagnose the problem.

I also noted the screen has a blueish background. This means that the TV is working well but missing the data.

In this case, the main suspects are TCON, LVDS cables, COF, and motherboard.

I decided to begin checking the TCON, the best place to begin is by testing if the TCON is getting the 12Volts from the motherboard.

The best place to test this voltage is across the fuse as shown below.

Kindly be sure to test this voltage on both sides of the fuse, this will help you to know if the fuse is open or not.

I tested and found the voltage on both ends of this fuse, this means the 12 voltage from the motherboard is present and stable.

Next, I checked the VGL voltage and got zero, this voltage is usually negative. Tested across the two coils and one has 12 volts and the other one has near zero volts again.

I suspected the TCON was faulty and before making the conclusion I decided to remove the LVDS cables one by one.

After removing this side, I re-tested the voltages again and now I was able to get VGL voltage at -5Volts.

I turned the television on the screen side and this is what I saw.

This made me conclude that the issue is on the small circuits connected to the panel as you can see here below.

Since they are two and identical I decided to test the few components there for shorts since the only thing that can bring down voltage is short on the power line.

When testing my meter set to continuity, I found these two capacitors buzz indicating shorts. I removed them one by one and still the buzz remain, this means the short is elsewhere. I re-soldered both and continued with my troubleshooting.

I noted this other capacitor at the far end which also tested shorted with my meter.

I removed it out of the circuit and the short was gone completely.

I applied the power to the television and the television came up beautifully.

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Sony Home theater model HBD-DZ650 changing function automatically now repaired.

2024-04-15T16:51:00.007+03:00

I received the above home theater in my shop for repair, complaint from the customer was changing function automatically.

Since I was busy I requested him to leave his contact so that I can let him know when ready. Later I opened the machine.

I scanned around and noted two capacitors with top slightly bulged out on power supply board(S.M.P.S), I used my ESR meter and picked several capacitors too with ESR value out of the range.

I replaced the bulged-out capacitors and others I was not happy with, after testing I noted the problem was now solved.

I notified the owner about the progress and was happy to hear his machine is now working.

🔧 Want to take your electronics repair skills to the next level?
Grab your copy of Hometheater repair guide – a practical, easy-to-follow guide packed with real solutions, pro tips, and step-by-step fixes.
📘 Tap the cover to order now and start repairing like a pro!

Cool steamer producer is repaired

2024-02-04T16:58:00.001+03:00

I received this machine on my bench,With commercial name of EMSIG made in china.

like most of these kind of machine does not producing cool steam the red led on the face machine is on this means that the power is coming inside but something or things does not let machine to produce the steam the machine consist of two pcb board one as psu smps another one is the oscillation board that generates the frequencies around 890k hertz TRANSISTOR BU 406 is agent that by help of cap and a coil make oscillation frequencies and signal frequencies directly goes to the membrane of piezo electric and start to vibrate in this frequencies the water break in small pieces and by help of a fan blow the pieces of water to the up and outside of machine

HOW does a piezo Atomizer work?

Piezo atomizers work by applying an alternating electrical current to a piezoelectric transducer which causes it to vibrate ultrasonic frequencies this vibration is then transferred to a liquid which breaks up into a fine mist of droplets. the size of droplets can be controlled by the holes sizes on mesh and by adjusting the frequency and amplitude of the vibration

After opening the machine faced with too much Dirt caused by sediment of water. the user said never used lite water for this machine and this much of sediment was just cos of use of heavy water. Psu of this machine produce to kind of voltages one 32 volt Dc just for oscillator board and12 volts for fan of machine both where good and within tolerances so far so good then I disconnect the wires that attached to piezo then by help of frequency meter of vtom i measured the frequencies that going to piezo my meter read about 896 kilo hertz then something must wrong it inside the piezo.

I opened the metal cap of piezo what you guess yes,The red wire from the body of piezo was disconnected the previous repairer on this machine tried to resoldred the red wire to the body of piezo but the soldering was incomplete and was broken eventually the best thing to do was to replace the piezo with same size I and cleaned all the inside of machine with lite HCL with a tooth brash this job.

Old lady was satisfy from this job since she has problem when breathing the dry air.

This article was brought to you by Mr Beh.

Location:Tehran

Country:Iran

Why electronic protector talking long to activate protection mode.

2023-11-14T22:00:00.000+03:00

The problem of this AC line surge protector was not starting to give protected AC before 6 minute, something must be wrong inside the machine since there was no diagram for this circuit as general services first I re-solder all the joints then the most problematics part are e -capacitors I had three on the board.

10 microfarad @50 volts

220 microfarad@25 volts

22 microfarad @ 16 volts

The value of 220 microfarad cap was changed to 200 micro and ESR 148 ohm that was not good two others were not bad enough by replacing the cap machine start to give voltages after 2 minute

Article brought to you by Mr.Beh. based in Tehran City-Iran.OP AMP DBL 324

Ramtons Microwave oven model RM/320 with “no heating symptoms” now repaired,

2023-09-20T14:25:00.004+03:00

I received a microwave from a customer who wanted it checked by a technician,

The complaints were the microwave was working well in terms of setting time and everything but after going through the process, It could not heat the food.

This problem from my experience it is used caused by failure in one or more components of the high voltage circuit.

These incudes, magnetron, high voltage capacitor, high voltage diode, High voltage fuse or high voltage transformer.

After dis-connecting the microwave from the wall outlet, I begin to test these components one by one.

I noted the high voltage diode has a reading on diode test of my digital meter which it should not in a normal working condition.

I disconnected one leg of the diode and still got a reading, I removed it out of circuit and still got the same reading as you can see below.

After replacing the diode, the machine was up and running again, customer was happy, so was the technician.

LG home theater model HT302 came in with low audio output now repaired

2023-03-07T07:58:00.003+03:00

I received this home theater from a customer who wanted it checked by a technician.

Complains was low audio output, I inquired from him a brief history of the machine and told me that he bought the machine in 2007 and never taken it to a technician until last week it was working well but developed low output for the last few days.

I opened the machine and did a thorough scanning of the power supply board and mainboard and noted two capacitors with top part swollen.

I replaced them expecting it to solve the problem one touch but I was wrong, after changing the two capacitors there was still no change.

Since the customer hinted the machine was bought in the year 2007, means the machine has been working for the last 16 years failthfuly, therefore I decided to do more test on capacitors which from my experience they age faster than other components.

I did test all capacitors on the power board using an ESR meter and got several culprits as you can see below which according to my ESR meter they were way far from the normal capacitors.

I replaced all of them and now was time to test and see if there is improvement.

I loaded it with my USB flash disk and the results were awesome!

Thank you, guys,

See you in the next class

ARMCO Microwave oven came in dead now repaired!

2022-10-08T14:48:00.002+03:00

I received this microwave from a client who wanted it checked by a technician.

Initial test indicated the machine was totally dead, I opened it and tested the power supply fuse and found it okay.

Next, I checked the control panel and found inductor L101 was open, I followed that line and noted it was feeding IC100(NK364PN) and therefore suspected it could be shorted.

The best test for I.Cs is direct replacement and hence went to the shop looking for one but I was not lucky.

Next option is to import, I got it from Ali.Express, took two weeks to ship to Kenya.

I informed the client and said he has no problem with that and hence I placed the order.

For the inductor I bought is locally and therefore waiting was for only the I.C.

I received the I.C in my hands after two weeks and did the replacement and after applying the power I was happy with the results.

I informed the client and was very happy, just when he wanted to come to pick it I noted something very strange.

The machine was getting very hot, around the magnetron side of the out cover.

I opened the machine and noted the fan was not rotating and therefore needed some tests.

I tested across the fan connectors and got open circuit, I removed it out the machine for further scrutiny and noted one side coil wire was broken out of the circuit.(hanging loose)

I did the re-soldering slowly and carefully and now the reading was 405 ohms.

I re-installed the fan and after testing I was happy with the results.

Thank you guys

See you in the next class

LG HOME THEATER MODEL DH3140S COME DEAD NOW REPAIRED.

2022-09-10T10:48:00.003+03:00

I received this home theater from a client who wanted it checked by a tech, I applied the power and noted there was no sign of life.

I opened up the machine and proceeded to scan the whole system, beginning with the power board and later motherboard.

I noted two capacitors with top part slightly swollen on the power supply section, usually if you get a capacitor with top part swollen it is advisable to replace it directly with testing.

I proceeded to the mother board and found two capacitors with outer cover ripped off and one with top part slightly swollen as you can see below.

I decided to replace all capacitors with the same capacitance value but higher voltage rating to avoid come back.

After replacing the capacitors I applied power and the machine came up smiling.

Hometheater repair ebook by Humphrey, click the book cover for more detail

Visit our Nairobi office here or Contact us on +254 733 475 040

Thank you guys

See you in the next class

32 inch Vitron Television picture upside down after motherboard replacement now fixed

2022-07-07T13:21:00.004+03:00

I received this television from a customer who wanted it checked by a technician.

She told me that she suspect a loose cable and hence minor problem.

I checked the voltage and found they are present even on the secondary side of the power supply.

I also noted some components were getting too hot on the secondary side (Never torch components on the primary side unless if you power off and remove the power cable from the outlet) and since the power On led was off means the microprocessor was also not getting power.

I decided to do new motherboard replacement, getting these boards in my market is quite easy.

I visited the shop and I was back with one which was exactly the same and therefore I expected easy fix, plug and play.

And yes the television fired on beautifully from the back I could see backlights are on.

Turning to the screen I noted the picture/image were upside down like you can see below.

I did some Google search about this issue and realized it is quite common.

The solution was to use remote control to access the factory setting.

In my case I had no remote control and the way out was to change the memory ic. From the old board to the new board.

Memory ic on the old board

After replacing the new memory ic with the old one from the old board the problem was solved as you can below.

21 Inch CRT Sanyo Television (model CM21YS2S) came in dead now repaired

2022-07-01T11:52:00.009+03:00

I received this television from a customer who wanted it checked.

CRT television are getting phased out here in Kenya very fast but still am getting a few from customers like the one before us.

I asked the customer a brief history of the problem even before opening.

He told me that it started to take time to power up, 1 hour, 2 hours, 3 hours 9 hours, one day and eventually never powered again.

With that I concluded the problem is capacitor related and therefore when I opened it I first did scanning the whole board and noted one capacitor with top part slightly swollen on the vertical circuit.

I replace the capacitor hoping for the best but after powering on I noted the TV was still not powering on but at least this time the red led is on but blinking.

I pulled my ESR meter and started testing all capacitors on the board especially the secondary side and noted most capacitors were faulty, I changed all of them but I could not solve the blinking led.

Since time was not on my side I decided to keep it aside and work on it later.

Later in the evening I decided to continue troubleshooting the board and this time I decided to test capacitors on the power supply section, usually there are few capacitors on this section and therefore I started with the one which filter the startup voltage to the control IC STR W6754.

The first capacitor passed the test with flying colors but was not happy with the second one as you can below.

The capacitor was rated 47uF/35V, here I was expecting ESR reading of less 1Ω but here I was getting 0.15K Ω, multiply by 1000 you get 150 Ω, This ESR reading can even bring a fighter jet down and therefore the television was justified not to power up.

I changed the capacitor and now it was time to test for any improvements.

After applying the power I noted the red lights was now stable and that put a smile on my face.

I later re-assembled the board back to the tube and everything worked well.

Thank you guys

See you in the next class

Epson projector model EB-S02 with “Error in Auto Iris” now repaired.

2022-06-21T17:53:00.006+03:00

This projector was brought by a friend who needed it checked, I powered the machine and this is what I saw on the screen.

A technician is more or less like a medical doctor but medical doctors have added advantage since human being can talk and explain how they are feeling.

In electronics we rely on symptoms and error codes if generated, in the case at hand we have “Auto iris error” code.

From the above error code, I did some research and noted the error is usually caused by problem with Auto Iris Assy.

To access this module you need to open up the machine below,Epson projector model EB-S02

After removing the cover

Motherboard now removed

Remove the optical engine Ass.

Auto Iris assembly is part of optical engine.

In human being,”The function of the iris in the eye is to control the amount of light that reaches the retina. It does this by changing the size of the pupil, the transparent window that allows light into the eye's interior.

The same case applies to projector auto Iris and therefore if there is an error on this assembly the Auto iris error will presents.

After accessing this module I scanned it and noted one of the blades was loose and hence not closing well and hence the error.

I tightened the small bolts and re-installed it back to the optical engine assembly and after powering it up the error was gone.

Thank up guys

See you in the next class.

40 inch Samsung LED television model UA40J5000AK dead now repaired!

2022-04-04T12:57:00.007+03:00

I received a call from a client who wanted his television checked by a technician.

It was within the estate, so using the direction he gave I was able to locate the place effortlessly.

Upon reaching the place, I was shown the television, applied the power and indeed the television was dead, even the power ON led was off.

I opened the television and did scanning on both power and main board and could not see any suspect’s area or component.

I pulled my meter and tested the main fuse and to my surprise I found it okay.

With that I now decided to do proper troubleshooting, first let me point out here that dead symptoms in television(LCD-LED) can be caused by power supply failure or main board failure.

From my analysis I concluded the problem was on the power board and therefore begin doing sample testing on components especially for short.

Since the fuse was intact I could not suspect shorted component on the primary side since shorted component on the primary side will lead to instant blow to the main fuse.

So I begin testing output component like diodes and transistors which failure rate is quite high.

Testing for shorted components in circuit is okay but if you find a beep, it is always important to solder one pin out of the circuit to confirm the actual culprit.

As I continued testing secondary output components I got a beep across a diode and I wanted to be sure if indeed it’s a beep on just low capacitor resistance reading before charging.

In my case the beep continued and this put a smile on my face, this could be the culprit.

I soldered the two diodes that had beep out of the circuit and found one was dead short.

Since I was working on site I had to go back to my shop because I did not have this diode (FR) with me.

This time I decided to carry with me the whole board for further testing once I replace the faulty diode.

Back in the shop I salvaged the diode from a junk board which had same specs with the one which was faulty, after replacement I tested the board and noted the standby voltage was present and stable.

I went back to the client place hoping for the best and after re-installing the power board, I applied the power and I noted the backlights were on since the television was placed back up.

This put a smile on my face, this is the final results.

14 inch JVC CRT television model AV-14FMG3B hit by power surge now repaired.

2022-03-24T12:47:00.002+03:00

I was visiting a client, who wanted her television checked by a technician; she has left a message to her neighbor who has a shop on the same block to direct me to her house.

Once I reached the shop, I introduced myself and my mission there, while talking to the lady another client of mine whom I have repaired his television previously passed by and as we greeted each he mentioned that I really helped him to revive his dead television.

The shop owner heard the conversation and was interested to see if I can revive her television which was hit by power surge and decided to keep it in the store.

I proceeded to my mission and while coming back I found the lady has already picked the television from the store waiting for me.

I opened the television and since it was hit by power surge I was much interested on the power supply which always super heavy casualties once hit by power surge.

First I checked the state of the main capacitor and found its top part lightly swollen.

With this I concluded indeed this was power surge, sorry I did not take a photo before removal from the board.

Next I checked the health of other safety components and found the fuse was okay to my surprise, checked the surge limiter and found its open which means it succumbed before the fuse.

I tested the bridge diode using my digital meter and found its okay, after changing these two components I decided to apply the power using the series current limiter and noted the bulb was shinning like the sun even after one minute, with this I concluded there is a still a shorted(s) component on the power supply.

I tested the voltage across the bridge diode middle pins (ac pins) and found the voltage was quite low.

I decided to replace the diode bridge directly and see if it was failing under load since I had already tested it using the meter and tested good.

After replacing the bridge diode I noted the voltage is now normal and the voltage on the secondary side was also present, the B+ voltage was also present and stable, but the TV could not fire, No High voltage.

The power on Led was also blinking and this leads me to conclude I am not out of the wood.

I pulled my ESR meter and begin testing the secondary output filter capacitors starting with the lines which I noted the voltage was dancing a lot for lack of better word.

I bumped on capacitor C945 rated 1000uF/25 volts which in circuit ESR reading was around 3 ohms, I decided to remove it out of circuit and test again using multi-components tester and this is what I got.

ESR of 14 ohms and capacitance has dropped by half not forgetting the V-losses.

I replaced this capacitor and again tested the effects of that and I was happy with what I saw.

The TV is now up and running

Thank you guys

See you on the next class

Von Hotpoint microwave model HMG-202DB with “no heating problem” now repaired.

2022-03-11T10:11:00.006+03:00

I received this microwave from my neighbor who wanted it checked by a technician.

The owner told me that there was a loud bang and since that time they set it aside (store) and were planning to buy another one since they considered the issue as beyond repair.

I took it with me to my shop and once I applied the power I noted it was powering on well, I placed a glass full of water and hit express button and after 30 seconds I checked the water and found it was still cold.

I then decided to open up the machine and do some troubleshooting.

I begin testing the H.V fuse and found its okay, next I checked the H.V diode and found it dead short.

Next I checked H.V capacitor with my multicomponent tester and found it okay as you can see the results below.

I replaced the HV diode which was found faulty and tested again with a glass of water and after 30 seconds, I found the water was a little warm.

I decided to check the H.V diode again and found it once again shorted.

Before replacing the diode again, I decided to replace the magnetron directly.

I replaced the two components and after testing again with a glass of water, I found the microwave was now working like new.

Thank you guys

See you in the next class

Von hotpoint 2.0 Channel Surround speakers model HA160200 inputs not responding(stuck) now repaired

2022-01-31T14:48:00.005+03:00

I received this machine from my neighbor who wanted it checked by a technician.

The complaints was machine has no response from the inputs keys, Non was working.

I took the machine with me to the workshop and upon opening it I scanned the board and I could not see any area which looked suspects in terms of stress or blackened as you can see below.

I did some voltage testing and everything looked good.

I decided check the small circuit board which control the inputs.

Accessing this circuit was not easy since the manufacturer decided not to make it accessible easily, no screws or hooks, just used the hot melt glue to fix the thing together.

Very unfortunate considering the customers has invested quite substantial amount of money but the quality was poor as you can see below.

Once the small input module was out of the machine I again did some scanning and I noted a resistor with one leg broken right at the resistor body and therefore soldering it back together was not possible.

So I replaced it with another resistor with the same value which I got from my resistor repair kit.

More scanning revealed break on the pcb track and I sorted the broken track with a wire jumper as you see below.

After replacing the resistor and fixing the broken track, I decided to apply the power and to my surprise the problem was shorted.

Big problem, simple solution.

43 inch Hisense television hit by power surge now repaired

2021-12-07T14:49:00.004+03:00

I was sitting in my shop working when I heard a loud bang and then power in my shop went off.

I went outside and noted some people near my shop pointing where the bang came from, Power transformer has blown.

Being a weekend the power was not restored until Monday, coming back to my shop I passed by a shop nearby and the shopkeeper told me the power was restored back but most of his items were dead.

Among them was power supply for his kerosene pump, I went to my shop and did some testing, luckily only my laptop was plugged to power outlet by the time of power purge.

I checked it out and noted it was dead as dodo, that a story for another day.

A few minutes later I received a phone call from my landlord, complaints was that his TV has not worked since the day of the power surge.

Being month end and I had to pay bills including rent, I decided to treat this as urgent, I went to his house, picked up the television and brought it to the workshop for repairs.

Upon opening the television I went straight to the safety components starting with the main fuse which as you can below it was open.

The black mark across the fuse pins indicates the fuse died a painful dead and therefore expected a heavy short ahead.

Next I checked the status of the switching Mosfet(TK14G65W) and was found okay, this brought a smile on my face since getting this fet in my market it’s not easy, I usually import and therefore take 3 to 4 weeks.

Since the switching fet was found okay, we can safely assume the control ic is also okay, from my experience, when this fet short, does not go alone, usually cause the control ic to short also.

I continued scanning and noted the main filter capacitor has its top silvery part swollen, this is an indication of effect of high voltage surge, the capacitor was rated 100uF/450v, here in Kenya we use 240 Vac and therefore we should expect around 320 to 339 volts DC at the main capacitor.

I decided to replace the two components, fuse and the main capacitor and see the effect of that, I decided to use the series current bulb current limiter and I noted the bulb was very bright even after one minute.

I decided to continue with troubleshooting and noted the voltage at the main capacitor was very low.

I switched off the power and tested the rectifier diode and found two are dead short.

I replaced all the four diode and again applied the power using the series bulb, this time the bulb came up brightly and then dim.

With that I concluded that no more shorted component and therefore I can apply the power without the current limiter bulb.

I did the same and the machine came up beautifully

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Clubox woofer producing Humming Noise now repaired!

2021-11-08T14:05:00.006+03:00

I received this woofer from a customer who wanted it checked by a technician.

He hinted that the woofer was from another technician who was not able to repair it.

Items from other technician are tricky to repair especially if the tech had limited knowledge on how circuit works, they ends up making so much experiments and guess works and therefore chances of repair is quite low.

Nonetheless I decided to have a try and see if I can help this customer who seemed desperate to see his machine back to normal status.

After opening the set I found the main filter capacitor rated 470uF/25V has its top part swollen.

From the symptoms at hand the failure of this capacitor fits so well and I was very confident this was one of the easy fix.

I pulled a replacement capacitor from my capacitor kit quickly and decided to do test and the machine came up beautifully.

I decided to continue listening the soothing music from the machine as I continued with other repairs.

After about 30 minutes, the humming sound was back, I decided to open the set and see if the same capacitor has failed again.

I noted the capacitor was still holding strong, no signs of stress and decided to use touch method to pick up any component which may be overheating.

I started with the audio I.C and found it extremely hot, I suspected it instantly but continued with my touching method and placing my finger on top of the main filter capacitor which I have just replaced also found it very hot, touched the bridge rectifier and also found it un usually hot.

I decided to change the Audio I.C directly but before that I decided to power the woofer one more using the DC power supply since the woofer was using due power(AC and DC).

I run the machine for nearly one hour and this time that machine was running cool, all components.

This made me rule out all the suspected components, Looking closely at the transformer connector I noted it has some burnt marks and was not happy with this, I suspected the transformer is failing under load and to confirm this I decided to run the machine again for 30 minutes and feel the state of this transformer, after running the machine for 30 minutes, I touched the transformer and found it un usually hot.

I decided to do direct replacement but since I did not have this part in my workshop I decided to go buy one in town.

I replaced the transformer with a new one and again run the machine for one hour and the machine was still working well.

I again did the touching process and all components were running cool.

TLS woofer came in with low audio output now repaired

2021-09-14T08:19:00.005+03:00

I received this woofer from a client who wanted it checked by a technician.

According to her the woofer no base but the rest is working well.

I did the test to confirm what she said and noted the woofer symptoms were different from what she gave. The actual symptom was low audio output.

I opened the woofer and this is what I saw.

Once opening the woofer and did some scanning, I noted an area with dark burnt marks, in electronics dark area on the board are signs of stress.

Turned the both the other side and noted a resistor has been fixed across the burn marks, this is a low value resistor and therefore was acting as a fuse.

Next I followed that line and lead me to the amplifier i.c. Tda7379.

I tested the voltage on one pin of this resistor and noted it was fluctuating, I removed one pin from the circuit and the voltage went up, this lead me to conclude that the amplifier ic has some internal injuries and needed replacement.

I went to town looking for this part and got the part effortlessly.

I replaced the i.c and after applying the power, I noted the machine was restored back to normal.

49 inch LG led television model (49UJ634V) with backlight problem now repaired.

2021-08-25T17:58:00.004+03:00

I received a whatsups message from a neighbor with the following image taken from his television screen and wanted me to advice him about the issue.

As you can see from the image the top part is dark, from the screen shot I suspected backlight failure but was to confirm since from experience if one backlight fails for branded television like LG I expect the protection circuit to kick in and shut down the television.

The following day I went to the site and was shown the television and I decided to open it up and confirm my hypothesis.

After opening so many screws I was able to access the inside of the television as you can see below.

I pulled my led backlight tester and tested the two pins of led connector and noted the voltage was very low, with that I concluded backlight failure and the next move is to remove the screen (panel) in order to access the backlight.

Accessing led backlight is a delicate affair, I am not going into details since I have done that in my book LED repair case history volume1, where I have given a step by step guide on how to replace led backlight like a professional without breaking the panel.

After removing the panel/screen, I was now able to access the diffusers as you can see below.

Next is the reflector as you can see below.

And finally the backlights, I tested each strip and only one strip was working out of four strips, kindly note that for the 49 inch LG each strip has two strip left and right and therefore total number of strips in this television is eight pieces.

With the sample led strip I went to the shop and bought the whole sets of eight pieces including the one which was working since as you know leds used in backlight have life span which is usually 4 to 5 years.

According to the owner the television was already over 5 years and therefore changing all backlight at the same time was prudent idea to avoid call back.

49 inch KONKA Led television came in with power related problem now repaired.

2021-08-12T14:08:00.008+03:00

I received a phone call from a client who wanted his television checked by a technician.

The symptoms were, Television is powering on then shutting down after 20 to 30 minutes.

When the television shut down, the audio remains but no picture.

Since I could not figure out the real cause of this symptom from the description given on phone, I requested him to bring the television to the shop for further testing.

Within one hour he was at my shop credits to Google map which does great job in directing customers to my shop.

Once on my work bench I decided not to test what the customer said since I figured out taking a whole 20 minutes waiting for the symptoms to present is waste of time.

I opened the television and after removing the cover my eyes caught the attention of one capacitor which had its top silver part slightly swollen as you can see below.

The capacitor was rated 33uF/200V

Looking at the capacitor you will see that it is located on the LED backlight drive circuit and this can cause the television to behave as the customer complaints were.

I decided to replace the capacitor with 33uF/400 Volts instead of 33uF/200 volts since the symptoms presented by this capacitor was failure due to high voltage.

I replaced the capacitor and the television came up beautifully.

I tested it for two hours non stop and the issue of shutting down never presented again and this lead me to conclude the television has now been restored back to factory setting.