Saturday, May 27, 2017

21 INCH LG SUPER SLIM CRT TELEVISION DEAD NOW REPAIRED

This television was from a customer I had repaired another television and was happy with my service and therefore when this other one developed a problem he requested me to fix it if it was possible.

Most customers fear dead symptom equipment but from experience dead equipment are easily repairable with main cause of dead television/equipment is power related.

Therefore I passed by his place and picked it so that I can do repair on my workbench.Upon reaching my workbench I applied the power even before opening and indeed the television was dead and no sign of life.

Friday, May 19, 2017

MK-328 Multi component intelligent semiconductor device analyzer video

Here is the video of amazing MK-328 multi component tester at work!


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Saturday, May 6, 2017

How to troubleshoot CRT Television with Power supply is dead but voltage at the main capacitor but nothing at the secondary side.

First find out the IC used in the supply and Google its datasheet and find out which pin is V.C.C

This is commonly called start up voltage, if this voltage is absent the I.C not work and therefore the supply will appear dead.

In the example given here the V.C.C pin is 3 and require 18.3 Volts to start. If this V.CC is missing then trace back looking for open resistors (e R802 or R801 and also diode D804 or even PCB broken.



Thursday, April 13, 2017

LG MODEL CF-14K50E DEAD NOW REPAIRED

I got a phone call from a client who wanted her television checked by a technician. I passed by her place and I was shown the TV which needed checking.

I pressed the power button and no sign of life was noted on the television, therefore I opened the set and with the Television back cover removed, I applied the power once again and this time I could hear some noise (chi…chi… chi) near the fly-back transformer.

I powered the TV off and removed the power cable from the outlet and decided to do resistance and since there was no visible component broken or darkened area, I decided to test the H.OT transistor.
I tested across the middle leg (collector) and the emitter and got a beep, I reversed the probe and again I got a beep (This test was done while the HOT was still in-circuit)

Saturday, March 25, 2017

Sony DVD model DAV-TZ200 Home theatre system “no disc” symptoms repaired.

A friend of mine brought to me his home theatre to me to check it out, the initial complaint was that it was not able to read disc.
Upon receiving it on my workbench I pressed the power button and it came up well...




Friday, March 10, 2017

Understanding the CRT television regulation control circuit

Sometimes I get question from my customers where they complain the B+ of the CRT television is higher than expected.

In those cases I always refer them to the feedback circuits. In this article I am going to highlight a few things about this circuit.

First let me point out that all switch mode supply (S.M.P.S) tend to increase more and more after startup.

Therefore engineers decided to come up with a solution and that is when they introduced the regulation circuit.

Below you can see components involved in regulation in the circuit diagram below.


Monday, February 27, 2017

Connecting speakers in series and in parallel

When connecting an amplifier to a speaker it is important to match the impedance of the amplifier to the speaker for maximum power transfer:

On the circuit below we have an 8 ohm amplifier connected to two 4 ohms speaker in series to get 8 ohms (4+4) and therefore the amplifier impedance is equal to the speaker impedance.

If you don’t observe this principle then you will overload the amplifier and eventually it will blow.