Monday, November 25, 2019

Sony Bravia model KDL-32R300B came in dead “red led blinks 6 times” now repaired.

This television came from a friend with the complaints above, I tested it at his place and I confirmed the symptoms.

So I took it with me to the workshop and since I confirmed the symptoms at the owners place I went straight to open the panel and accessed the backlight and after testing with my backlight tester I did not get any fault led and I was frustrated because I expected it to be easy fix.

Monday, November 18, 2019

LCD LED Television training seminar at Airport Gate view hotel Utawala-Kenya

Calling on all LCD LED television repair technician

        Back-light repair seminar

On Saturday 13th December 2019 Hum-tech electronics is going to hold a training seminar at Airport Gate view hotel Utawala.

Time: 10.00 am – 3.00 pm

Participation fees- $30 USA dollars (3000 Kshs)

What you will learn

  • Introduction to LCD-LED television

  • Understanding LCD-LED television backlight(LED/CCFL)

  • How to access LED backlight like a professional without breaking the screen.

  • How to change LED television backlight strip or individual LED.

  • How to order and buy spares parts online safely.

  • How to advertise your business using Facebook.

  • Seminar include theory and practical’s

  • Free snacks

The class will compose of only 10 participants, the eleventh student will be booked in the next class.

BOOKING:whatsup  +254 733 475 040  

Facilitator: Humphrey Kimathi

Wednesday, November 13, 2019


Introducing my latest eBook on LCD/LED television repair case history vol.1

Click on the book cover below to have it on your workbench.

Thursday, October 17, 2019

Sanyo 21 inch CRT television model CM21MS22, No audio, messed up color, and visible white lines across the top part of the screen now repaired.

I received a call from a customer who wanted her television checked by a technician.The complaint was the television had picture but no audio.

Upon reaching her home I decided to power on the television to confirm the symptoms and this is what I saw.

Monday, September 9, 2019

JIEPAK 19 inch Led television dead now repaired

A customer brought in 19 inch Led television for check up, complaint was the television was not able to power up.

It was attempting then shut down in cycles, since it was using power adapter I tested the output from the adapter power supply and I got 12.44 vdc.
This looks okay according to the printed output on the adapter body.

So now I was ready to go the next level, opening the television and do further troubleshooting.

But before that I decided to swap the power adapter with the one I use in the shop for testing television in case the owner forgot to bring it along.

After powering the television I was surprised to see the TV has picked up and now working perfectly.
With this I concluded the problem was on the power adapter, but did I not get 12.44 Vdc?

Friday, August 16, 2019

Troubleshooting dead LCD-LED television

You are sitting in your shop and an LCD/LED television is brought in by the customer, where do you start?
First before the customer leave it is better to connect the television to the power source and confirm what he or she has said.

Also it is important to get a brief history of how the problem developed, this sometimes comes in handy when it comes to diagnosis but please don’t take any advice from the customer when they suggest what they think is the problem They are not professionals and therefore will always lead you to the wrong place.

After you connect the power source, apply the power via the power switch, and observe the power ON led at the front.

1.     Television is dead, Power led is ON.
If the power ON led is red, press the power ON button on the remote control or if you don’t have the remote press the front buttons one by one. One of them will kick start the set if all is well.

If the power ON led is present, this means the television standby voltage is present, the main board is also getting power, and keyboard/IR board is also getting power (3.3 v standby)
3.3Vdc is used to power the system control unit,
 power ON led, and the IR receiver. This means whenever you see power ON led is on means the standby circuit is okay and the 3.3 Vdc regulator is okay and therefore don’t waste time trying to test them and therefore you should concentrate on other outlets
So even without opening the set you can be sure the standby voltage is okay.

If when you press the power ON button from the remote control and the power ON led does not turn blue means there is something blocking other power to start and therefore you can now open the television and continue with your troubleshooting.

Open the television slowly and carefully because LCD-LED television are fragile not like the CRT televisions especially the screen.

Turn it upside down and use a soft cloth under the screen to avoid scratches. After opening the many screws and removing the cover, do a quick scan of the board component wise looking for any suspicious component like I said before, component with bulged tops are considered bad, burnt marks on components and circuits' board are considered as stress and you should pay close attention to them.

Any suspect components should be subjected to further tests but with capacitors like I said once a capacitor top is swollen even slightly it is considered faulty.

This is because a bulged capacitor is usually short and if you check it with an ESR meter it will read very low ohms and as you know low ESR reading means the capacitor is okay and this will not be true since the meter will be seeing low because of the short and not the actual ESR reading.

With those remarks, it is time to pull your meter and do actual voltage testing, Voltage testing is one of the finest troubleshooting methods because sometimes you may find that the components are all okay but the track/PCB is broken and therefore blocking voltage from reaching other components, also this will help pick any open components quite easily.

Also voltage testing can help you narrow the problem to the affected block

To do voltage testing on the primary side of the S.M.P.S use the main capacitor as your ground (HOT) and for the secondary side of the power supply use the COLD ground (Television body is usually cold ground)

Please note the reason we started with the voltage testing is because we had power ON led lit otherwise if it was full dead symptoms, no signs of power whatever we could have started testing any safety components like fuses open on the board.

Once you clip your meter negative probe on the HOT ground which in our case is the main capacitor negative pin, now it is time to probe every point of interest on the primary side.

Thursday, May 23, 2019


A customer brought in this radio and wanted it to be repaired; he estimated the radio to be around 20 years old.

Since the radio was dead the best place to start troubleshooting was the power supply, the radio was using linear transformer to step down the 240 Vac to 9 Vac.