Wednesday, July 16, 2014

Android Phone tablet no audio after factory data reset

After installing a certain application to my phone tablet, I noticed it has become too slow and sometimes not responding to touch and therefore I decided to do "Factory Data Reset".

 Everything went as expected and it was successful as you can see on the picture below.

I re-installed the application from the backup file and I was now ready to resume normal services.

After doing several test I was happy to note that the tablet is now faster and works like new.

Before long I received a phone call and noticed that there was no ring tone and so I went straight to audio profiles, to my amazement I noticed it was not set to silent mode and thought maybe it the volume which was low.

So I slide it all the way up and still nothing happened, no sound, I tried to play video and again no sound. That is when I realized I have a problem here.

I started playing around with the gadget to find where I have muted the audio without success.

The next move is to Google to see if there is someone out there who might have encountered such a problem and indeed I noticed it is a BIG issue to many folks out here.

I followed many advices given and nothing worked, one thing I was sure of is that this problem has nothing to do with hardware since it happened after the Factory data reset.

I became too busy trying to figure out where the master reset audio is and again I was not lucky, so I decided to just reset the tablet using the reset key at the side of the tablet as the last resort.

After resetting the tablet by inserting a pin on the small hole at the side of this tablet solved the audio problem.

Kindly note that this hole is not same as the mike slot; in most cases it is labeled RESET.

Thanks you guys
Humphrey Kimathi

Wednesday, June 18, 2014

CRT Television secondary output supply query

Hi Humphrey,
I just bought your book several days ago and right now i was reading it. Can you please help me; there are things i can not understand in chapter 6 specially the B1 to B6.

 I cant find them in the schematic diagram. Do you have schematic that has a label B1 until B6 for chapter 6?

I am so excited about this book, you see, i took a lesson from a technical school But I already forgot.

With this book, I will have something to refer to anytime I Want. After this book, i plan to also buy book from you like LCD and Plasma TV

Thanks a lot.

Edu Vejano


Hi Edu,

Thanks for your feedback and glad to hear from you,

Back to your question, as you have noticed in this chapter I am explaining about the secondary outputs in s.m.p.s.

All switch mode power supplies usually has a number of outputs which varies depending on the model but the minimum is two.

When the outputs are two, one will be high voltage over 100Volts and the other is low voltage around 20 volts.

In this case you can assume the high voltage is the B+ (B1) and the lower voltage is B2.

This I used just for education purposes and therefore it is not labeled but in some models they label the B+ voltage which supplies the fly- back transformer.

In absence of a circuit diagram you can figure out the B+ voltage by considering the working voltage of the capacitor used to filter that line which is usually rated 160Volts.

See the diagram below for more info.

Kind regards

Humphrey Kimathi

Friday, May 2, 2014

Multi-component tester review

Recently I bought this components tester from eBay and here is my personal review, first the tester does not come with user manual and the menu is written in Chinese.

After playing around with the available keys I was able to note the following.

 Not sure what the other keys not labeled are used for.

One more thing I noted is that you cannot use it for in-circuit testing even for capacitor ESR but you can solder out one leg of the capacitor and test for better results.

When assembling the meter probes consider the three socket as 1-2-3 as labeled in the picture above
Battery use: the tester automatically power off after a few seconds and therefore very good at saving battery power.

Finally it can detect NPN, PNP bipolar transistors, N -channel and P -channel MOS FET, JFET , diodes , two diodes, thyristors small power unidirectional and bidirectional thyristor including pin arrangement identification Automatically.

This is a BIG plus for technicians who have issues of indentifying which pin is which especially for small transistors, you need not go to the net to get the specs to indentify the pin arrangement.

I bought the tester from this link but seem the listing has ended, I think if you want one you can still search from ebay for the same item.


This is my personal review and I have no relation with the seller and therefore if you commit yourself to buy this item should be by your own choice, I disclaim any liability, loss or risk taken by individual who directly or indirectly act on the information contained herein.

Here is the actual tester at work

Tuesday, April 22, 2014


Goodluck from Nigeria send in this ESR meter project

Good morning sir,
I am glad that I have finally arrived. Challenges and experience is the best way of learning. I have to think and rethink over the entire circuit again and again when I do not see your reply mail.

 I have to make more research and get the same circuit but different designed on the net. And compare it just to know where my problem is.

I also download YouTube video of the same circuit which I watch.

Finally I am now successfully done.
 Here is my Finished Project attachment

Circuit diagram from the net



Template transferred to pcb

  Final products

Testing the new esr meter