Friday, February 17, 2017

Simple test for Cathode ray tube (CRT) bad or not.

To do this test, be sure you have the screen voltage presence and the heater is lighted and HV is present.



Friday, February 3, 2017

China TV (La76931) No raster, picture or sound

Clifford May Johannesburg South Africa
Hi Humphrey,
I've got a problem with this TV as you will see on the schematic I've got all voltage except 5volt on n552. 12v is ok on n551 but no 5volt coming out of n552. It gives me 1.2volt. I also changed transistor n552 but still the same. I desperately need your help please. Thanks in advance.
Kind Regards
Clifford



Monday, January 23, 2017

M-TECH DVB-T2 decoder dead now repaired

A friend of mine called me to pass-by his place to check out his Decoder which was faulty, I passed by and the decoder was dead as dodo.

Usually in electronics dead symptoms are mostly caused by power supply, therefore I suspected problem with the power supply.

I did not have my tools with me and therefore I did not open the decoder on site, back to my workshop I opened it and the first thing I did was scanning for any sign of stress (blackened area or burnt components).

Everything looked good and I was about to pull my digital meter to do some voltage testing when I noted a capacitor on the secondary side of the power supply which had it top slightly swollen.

As I said previously and I repeat again, any capacitor with swollen top is usually faulty, this usually happens when the working voltage of the capacitor is exceeded.


Wednesday, January 18, 2017

MK-328 Multi component tester (Transistors NPN PNP MOS, Capacitor ESR, Inductance, Resistor, diodes)

This meter is an intelligent semiconductor device analyzer, it can measure most of the diodes, bipolar
Transistors, Junction/MOS FETs and low power thyristors. It automatically identifies the type of devices and Pinouts, measures the current gain HFE, gate threshold and FET junction capacitance, a typical application is to pair two transistors or identify an unknown SMD device.
Test clips can be connected any way round, the
Pinout can be identified and displayed on screen vs. test clip numbers. Beside the semiconductor device analyzer, this meter can also work as a RLC/ESR meter, the RLC/ESR accuracy may not be able to compete with the professional one, but it definitely meets the needs for most of the applications. A 9V battery (part number 6F22) is used for this meter.




Friday, January 13, 2017

14 inch China Television sound OK but no picture

I got this phone call from a client who wanted his television checked by a technician, I passed by and I found the TV was ON but there was no picture on the screen (dark screen) but audio was present and very clear.

I opened the TV on site and the board was covered with one inch thick layer of dust and therefore decided not to disturb it lest it cause havoc in the customer house.

But I did some scanning using my set of natural tools in the name of eyes and I was able to see two big capacitor with top slightly swollen.



Friday, January 6, 2017

Ramtons toaster model RM/195 dead, now working

I received a phone call from one of my neighbor who wanted to know if I repair bread toaster, he was right because toaster repair is not my area of specialization.


This is because I decided from the word go I will not be a jack of all trade but master of none and therefore my area of specialization is TVs, Monitors,DVDs, SMPS.

Being my neighbor I decided to see if I can be able to help bring his toaster back to life and I requested him to drop it at my place so that I can check it in the evening as I usually have another full time job.

Came evening I found the toaster already waiting for me, I applied power, pressed down the push down plunger and nothing happen.


Tuesday, December 13, 2016

Customer support-Mangala from Sri Lanka

Mangala Wijetilake from Sri Lanka

Hi Humphrey,
On these days I am reading your E-book on Troubleshooting of TVs.  It is very interesting and several questions have arisen in my mind when reading.
It is very much appreciated if you could reply to following questions.

1. There were some tests which have been carried out by dummy load (250 V bulb). How do i decide the wattage of the bulb. Does it depend on the wattage of the TV set?

No really Mangala, you can even use 40 watts, usually it is not wise to dis-connect the B+ line and test it without the load but if you don’t have the load in place then you can test briefly to check the presence of voltage once the B+ load is isolated.

If you isolate the load and apply power and find the B+ has voltage and stable then you can conclude that the primary side is okay and no need of checking it.

Suffice to say here that this is done when you tested the B+ voltage and find it missing and when you dis-connect it you find the B+ voltage now re-appears.
  


Wednesday, December 7, 2016

14” inch China Television with high output voltage now repaired

This television was brought in for repair by my neighbor, upon opening the television I started troubleshooting using the free tools of the trade (my eyes)

I scanned around the whole circuit looking for any swollen capacitor or burnt areas which is usually suspect or signs of stress in electronics gadget.

I noticed a swollen capacitor on the secondary side of the S.M.P.S (C562). Swollen capacitors are usually caused by high voltage on that line and therefore I wanted to find out which line is the capacitor filtering.




Friday, November 25, 2016

Thursday, November 24, 2016

MK-328 Transistor Tester Capacitor ESR Inductance Resistor Meter LCR NPN PNP MOS

 Multi component tester now available!










About this meter.
This meter is an intelligent semiconductor device analyzer, it can measure most of the diodes, bipolar Transistors, Junction/MOS FETs and low power thyristors. It automatically identifies the type of devices and pinouts, measures the current gain HFE, gate threshold and FET junction capacitance, a typical application is to pair two transistors or identify an unknown SMD device. The test clips can be connected any way round, the pinout can be identified and displayed on screen vs. test clip numbers. Beside the semiconductor device analyzer, this meter can also work as a RLC/ESR meter


1pc Transistor Tester
  
Now available and ship worldwide free shipping!

Sunday, November 13, 2016

21 Inch CRT Television dead now repaired


First let me point out this television belong to my youngest sister, she called me to pass by her place but due my busy schedule I was not able  to make in time.

Therefore she decided to ask for assistance from the nearest technician near her home town.

Of course this I came to learn later otherwise according to her the television never left the house.

I passed by her place and after a small briefing about how the problem started, I was told that there was power brown out in the estate when the problem started.

For those who don’t know what is power brownout- electrically speaking is a drop in voltage in an electrical power supply,so named because it typically causes lights to dim.

21 Inch CRT Television dead now repaired

First let me point out this television belong to my yongest sister, she called me to pass by her place but due my busy schedule I was not able  to make in time.

Therefore she decided to ask for assistance from the nearest technician near her home town.

Ofcourse this I came to learn later otherwise according to her the television never left the house.

I passed by her place and after a small briefing about how the problem started, I was told that there was power brown out in the estate when the problem started.

For those who don’t know what is power blownout- electrically speaking is a drop in voltage in an electrical power supply,so named because it typically causes lights to dim.