Saturday, January 26, 2013

Review of VC921 Mini Pocket Digital Auto Range Multimeter digital multimeter



I recently bought VC921 mini pocket auto ranging digital multimeter from eBay and here is my personal review of the same.



First take note that this is a mini meter and therefore is best suited if you do a lot of onsite job where you don’t like carrying the bigger sizes.

The meter is approximately 4.5 inches long and 3 inches width and therefore can easily fit into your front shirt pocket comfortably.

It is auto ranging and has basic functions like any other meter. Eg DC Voltage, AC Voltage, Resistance, Capacitance and frequency functions among others.

It is also using the “AAA” size battery (2 pcs) although they have not written it anywhere.

The probes are fixed permanently on the motherboard therefore don’t have probe slot.


Testing AC voltage I got 229.4 VAC, which is okay for my country Kenya where we use 240 VAC .

 

Testing  frequency  I got 50.05 Hz, again this is okay for local outlet(50Hz)


 
Testing capacitance of 4.7uf/25V capacitor, I got 5.087 uF..a bit high for this capacitor .




I bought it at eBay at $11.99 and $3 postage. The item was send from Hong Kong by post which was not registed and it took 25 days to Kenya.


Kindly note that this is my personal view and therefore I take no responsibility for the decision you take upon reading this review. I am also not affiliated to the seller of this item.

Regards Humphrey

Wednesday, January 16, 2013

LG DVD PLAYER MP3 AUX 3 BAND RADIO CASSETTE PLAYER with “No Disc” symptoms repaired

  HI MR KIMATHI I am repairing a LG DVD PLAYER MP3 AUX   3 BAND RADIO CASSETTE PLAYER so and so...

My first problem was the set was completely dead with no life at all. 

I found 5 volt regulator ic that was not working in power supply of the set by changing this ic, The micro started to work and set return to life but not completely. 

The CD.DVD player start to show me on the screen “NO DISC” ok according to the book I check the motors they were not bad.

 I start to clean the lens of the set now no disc error is gone and cd player start to work and say is LOADING but after seconds stop working and remain on this mode...

 If you can help me what to do next I will be thank full of you
regards
beh

Tuesday, January 8, 2013

Sony TV KV-G21Q2 picture ok and no sound.



I meet a friend on my way home and requested me to pass by his house to check on his Television which had a problem.

I agreed to pass by although I had no tools with me, this is because in electronics troubleshooting, there are many tools for troubleshooting, some you must buy them from the shop or do it yourself and others are free.

The free ones include the eyes – this tool is very effective especially if something is on the screen. With experience you can locate the faulty circuit without opening the set or touching the meter by just watching and analyzing the screen behavior.

There are others like sound, smell, touch which are also free but that is a topic for another day. So I entered the house and I was shown the TV and it was already on.

I could see the picture was very clear and no sound at all. I asked his son a little background of the problem, so I switched to the other equally important tool and still free....the ears…after listening to his long story I was more than happy when said to me that sometimes sound comes and disappears.

With that one remark I was able to conclude that the audio ic is okay and this on and off could point to loose connection/ dry joints/ Capacitors failing on the audio circuit.

As if that was not enough he added another observation…sometimes when the audio disappear he push a little at the turner connector at the back of the TV and sometimes this also restore the audio…this again to me was another golden tip…with this I finally concluded that the problem is definitely a dry joint or loose connection and with that I promised him that I will come back the following day with tools to open the Set and I also assured him that it is certain no spare part will be used to restore the problem.

Come the following day I was back with my tool kit and after opening the TV i scanned around the audio circuit for dry joint and I couldn’t see a serious one and therefore I did general re soldering around the audio circuit.

I applied power hoping that I have solved the problem first time but I was very wrong…same problem. Now I decided to use live testing by pressing the main board softly with an insulator.



Yes I can now get audio but the moment I release the board the audio fade away, I realized that the board was very flexible and therefore a small pressure was making the whole board bend and therefore it was hard me for to narrow down to the actual area causing this problem.

So I decided to use my finger to push the few capacitors around that area slightly and when I pushed the one highlighted with the arrow above the sound was restored and I suspected it has dry joint on one of its leg and so I turned the board upside down with power off and I again I was not lucky.

Still the problem persisted and now I had to think outside the box…I decided to apply fresh solder to all the 56pins of the i.c nearby without caring which pin is which because I had no circuit diagram to help identify which pin is which.

After re-soldering all the 56 pins of this i.c tda8366 and re-tested, finally the audio problem was restored back to normal.

I applied pressure again on the board and the sound remained and with this I concluded the audio problem was now fully solved.

Tip: when using this idea of pressing on the board to locate a loose connection or dry joint always bear in mind that a small pressure on one end of the board can have an effect at the far end and therefore you can waste a lot of your time thinking that the problem is where you have applied pressure while the problem is on the other end..Please keep this in mind.

By Humphrey Kimathi
Author CRT Television Repair Course