Wednesday, December 30, 2009

We are a Google favorite place!

Just wanted to share that we got our letter in the mail the other day and I'm proud to say Preher-Tech is a Google favorite place. Check us out on Google today. Click on the photo below.

Friday, December 25, 2009

Ripple Rejection Ratio

Have you ever wondered what Ripple Rejection Ratio is?
Ripple Rejection Ratio or Power Supply Rejection Ratio (PSRR) is a measure of
how well a circuit, component or Power Supply rejects ripple coming from it's input
at various frequencies and is very critical in
many RF and wireless applications. In the case of an LDO(Low Drop Out Regulator),
it is a measure of the output ripple compared to the input
ripple over a wide frequency range (10 Hz to 10 MHz is
common) and is expressed in decibels (dB).

Read more by checking out this PDF file. Or click on the photo below.



Power Factor Correction

I have a friend that is a fellow TV repair man and he was having some trouble understanding power factor and power factor correction. I suggested he read the "Power Factor Correction Handbook" by ON Semiconductor and I also wanted to share it with you guys as well. These guides are great and by reading this book you should have a general understanding of power factor correction. Click on the picture below to download this great book for free.




Wednesday, December 23, 2009

Power Supply Repair Guide

If you are an electronics repair specialist or just an electronics hobbyist interested in learning more about SMPS repair you must get this e-book. "Troubleshooting & Repairing Switch Mode Power Supplies" is the latest edition to Jestine Yong's series of excellent electronics repair books and I have to say this one is my favorite so far, It explains all the major circuits of the SMPS, how to identify all the major components, troubleshooting and testing methods plus so much more! This is the essential reference to anyone interested in learning SMPS repair. If you are a professional in the field of electronic repair like myself, then this book will help you big time, because as you know a large percentage of electronics equipment failures are related to the power supply and a large majority of electronics devices today use an SMPS. Don't hesitate check out this great book today, I highly recommend it.




Wednesday, December 16, 2009

Electronic Repair News Letter

If you missed the Preher-Tech News Letter in 2009, then now is the time to subscribe and get all our great electronics repair tips for 2010. Join now and receive 12 free electronic repair articles, one each month for the year of 2010.

Tuesday, December 8, 2009

LCD TV Repair

I went out on a service call today for a Hyundai LC-23Y18, TV had standby light and when you tried to power the unit on the standby light would start flashing. As usual I checked all the Electrolytic capacitors in the SMPS first thing and sure enough like usual I found a capacitor with a high ESR. It was a 470uF capacitor on the secondary side of the standby switching transformer. The capacitor had an ESR of 7. After replacing the capacitor the TV worked like new. You can see I am very often replacing electrolytic capacitors in these LCD TVs and that is why I always check the Electrolytic capacitors in the SMPS first thing because so many problems can occur when these fail. That is why it is so important to have a good ESR meter if you want to do electronic repair, electrolytic capacitors are everywhere not just in the SMPS circuits.

Sunday, December 6, 2009

LCD Monitor Repair

A customer dropped off a Samsung SyncMaster 204T monitor for repair earlier this week, the display flickered and then went dim. He was told by his "computer guy" that the monitor needed a new CCFL. I told the customer I would look at it and that I thought it was more likely to be an inverter circuit issue. After opening the monitor as usual the first thing I did was look for loose connection and bad electrolytic capacitors on the SMPS board(bad electrolytics cause all sorts aof problems and are often the cause of failure), in this case the SMPS and inverter are integrated into one board. Right away I found that 2 secondary filter capacitors in the SMPS that had an ESR of 6 ohms and had changed value from 820uF to 10uF. Both capacitors had a max working voltage of 25V. After looking over the rest of the monitors circuits and checking the components in the inverter circuit I found no other problems. I re-soldered the HV transformers and MOSFET ICs in the inverter circuit as there was a few pins on the ICs with ring cracks as well as the HV transformer pins. I replaced the 820uF 25V capacitors and put the monitor back together. After setting it up and turning it on it was as good as new.I called the customer and told him he could come pick up his monitor. The customer was very pleased and the service charge was only $60. Hope this helps some of you they may come across one of these monitors with the same problem.



Monday, November 23, 2009

LCD TV Repair Video Tutorial

We have started a video tutorial on LCD TV repair, we will do one video every 1-2 weeks. Here is the first video which is an overview of all the major circuits within the LCD TV.





Friday, November 20, 2009

LCD Monitor Repair

I have spoke of this book before, but I wanted to mention it again as it is such a great e-book. If you would like to learn LCD monitor repair than you need to take a look at this book. The author is Jestine Yong a great friend of mine and a master at electronics repair. Take a look at LCD Monitor Repair today.

Click here.



More titles by Jestine Yong, How To Find Burnt Resistor Value and Testing Electronic Components.


Monday, November 16, 2009

Preher-Tech Tools and Tips

Have you seen the Preher-Tech Tools and Tips page? If not check it out today, here are a few of the great links you will find there.

Understanding Switch Mode Power Supplies
Identifying Television SMPS Problems
Algebra Course
Understanding The TV Horizontal Output Stage
Soldering 101
Practical Transformer Handbook
Capacitor Tutorial
Understanding Transistors

Got to the tools and tips page by clicking here.



The Personal Computer

A personal computer (PC) is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator. This is in contrast to the batch processing or time-sharing models which allowed large expensive mainframe systems to be used by many people, usually at the same time, or large data processing systems which required a full-time staff to operate efficiently.
Click here to read more.


'Universal' Programmable ....

....Two-Qubit Quantum Processor Created.

Science Daily (Nov. 16, 2009) — Physicists at the National Institute of Standards and Technology (NIST) have demonstrated the first "universal" programmable quantum information processor able to run any program allowed by quantum mechanics --
Click here to read more.



Thursday, October 29, 2009

Computer Certifications

Here are some more certifications, all of these are related to computers. Take a look maybe one of these will be one you can take and help boost your resume.


Computer Technician Test

Computer Skills Test

DOS Test

Microsoft Office Access 2007 Test

Click Here to see more.


Wednesday, October 28, 2009

Electronics Certification

Getting an electronics certification not only makes you feel great about all you have learned and accomplished, but it also let's employers, friends and family see that you really have what it takes to be professional in the electronics field. It will give you a great sense of pride that will motivate you to do better at your job and to continue learning and achieving even more certifications.

Here is a great place to get some electronics certifications. These are not easy tests and I suggest you study before trying to take one.

Basic Electronics Test

Integrated Circuits Test

Amplifiers And Filters Test

Analog Electronics Test

See all tests and pricing by clicking here


Also the C.E.T.G. offers electronics technician courses and certification.

C.E.T.G.

Apprentice Test

Journeyman Test

Master Technician Test

Thursday, October 22, 2009

Fix your video game console

Here are a few cool links for people who need help repairing or modifying their game console, enjoy.


Video Game Console Repair

Wii Repair


Xbox 360 repair


PSP repair


Wii Mods


Xbox 360 Mods



Watch TV From Your PC

I love this!! I hate paying monthly bills for TV, although I never do because I always watch TV on my computer anyways, but now this will allow me to watch all my normal programming plus more when I want to instead of waiting for it to release on a website. I think this is an awesome deal for only a small one time payment. I urge you to check it out and start watching TV on your PC today. Click here to learn more about this great deal.


















Wednesday, October 14, 2009

Jack O Lantern Light/Flasher

Hello again from the office of Preher-Tech. It is getting pretty cold here in Medford Oregon, time to stop drinking the iced caramel mocha's...LOL. Halloween is coming soon, so I thought we should do a Halloween project. Here is my Jack O Lantern Light/Flasher. The video doesn't perfectly capture the way the LED's flash but you get the idea. Hope you enjoy and if anyone wants the schematic just email me john@preher-tech.com.



Tuesday, October 13, 2009

Shop Jimmy

This is an awesome place to get parts. I have used this company in the past and have had nothing but great results. Take a look at Shop Jimmy today by clicking this link. Also read this article at "the star tribune" about the owner Jimmy Vosika and also a look into how things are done over at Shop Jimmy.






Shop Jimmy is going to give away a FREE refurbished flat screen TV, as soon as they hit 1,000 followers on there Twitter account, so follow Shop Jimmy today and tell everyone you know to follow them as well.


Tuesday, September 22, 2009

Project Page Updated.

We have recently added some new projects to the project page on our website. Click here to go to the project page now. You will see the new 3 LED flasher/blinker and a PIC 12F629 LED chaser. Check it out today!!


Friday, September 18, 2009

Series Regulator

Here is some good info on making a better linear voltage regulator then the shunt type Zener Diode regulator in the last post ,with the addition of a NPN BJT the circuit becomes a much more efficient series regulator. Click here to read more.

Thursday, September 3, 2009

Making A Zener Diode/Resistor Voltage Regulator

Here is a cool article on using a zener diode and resistor to make a simple voltage regulator. This is a basic shunt regulator. Click here to read the full article.


Power Supplies

Every electronics technician definitely needs to understand how power supplies work. Many times failures with electronics equipment will be in the power supply circuits and you need to understand the circuits well to be able to trouble shoot them properly.Click here to read an introduction into power supplies.

Friday, August 28, 2009

Transistors Tutorial

Here is lots of great info on transistors. If you want an in depth look into transitors this tutorial is a must read. Click here to read the entire tutorial.

Monday, August 17, 2009

Electronic Toy Organ


Check out our latest project an electronic toy organ. click here to see the schematic and the parts list at our website on the project page. Hope you enjoy and build one for yourself, my kids really enjoy playing with this toy.

Thursday, August 13, 2009

August 2009 Nuts and Volts Magazine

I really like this magazine every month it contains lots of good information on electronics and cool project ideas. This month in the article "Properly Selecting Electronic Components, part 2" there was a lot of good information on components, tools and good electronic theory info including formulas for construction of your own capacitors and inductor's, plus other classic electronic formulas and facts. This is a really good magazine that everyone can enjoy and learn from.Thanks Nuts and Volt's and I hope you continue to put out awesome magazines every month for years to come. Click here to find out more about this great magazine or click on the photo below.

Tuesday, August 11, 2009

Updated Tools And Tips Page

The Preher-Tech tools and tips page has recently been updated and lots of new info has been added and we will be adding a lot more shortly. Click here to go to the tools and tips page now and start reading all the recently added articles. All this info is specially picked out for those in the electronics repair field or those just wanting to learn more about electronic theory. Enjoy.


Transformers

This is an important topic, all good technicians not only need to know what a transformer is and what they look like but also need to understand the theory behind how they work. It is also good to understand the different types of construction and there applications. There is a lot more to transformers than you may realize.



A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors — the transformer's coils. A varying current in the first or primary winding creates a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in the "secondary" winding. This effect is called mutual induction.
If a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (VS) is in proportion to the primary voltage (VP), and is given by the ratio of the number of turns in the secondary (NS) to the number of turns in the primary (NP). To read more click here and here.


Wednesday, August 5, 2009

News Letter Delay

Just wanted to inform all my news letter subscribers that this months news letter is delayed until the 14th. I apologize but repair work has been very good , I keep getting influxes of LCD repairs. I want to make sure my book is ready before releasing the news letter and did not have enough time to finish the book yet. Thanks for understanding. I will be updating the Blog with lots of good info until then though so stay tuned.

Tuesday, August 4, 2009

New ESR Meter

Here is the ESR-micro v3.1 I had told you was being sent to me in a past blog. Well it is here now and I have done a review on my website.To see the review click here or click on the photo below. I have to say I really love this meter as it is so small, well made and also it checks capacitance and has a large range too 1uF-60mF(60,000uF). This meter will be getting a lot of use from me and we will see how it stands the test of time.



Thursday, July 30, 2009

Preher TV Online Store

We just launched our online store, please visit today by clicking here, or by clicking on the photo below. We will be adding more fun stuff soon and also would love suggestions, please email me at john@preher-tech.com with your ideas. Thanks and have a great day.


Tuesday, July 28, 2009

Testing MOSFET(Metal Oxide Semiconductor Field Effect Transistor)

Here is some good info on testing MOSFET transistors, one link uses a DMM and the other link is from my friend Jestine Yong, he shows you how to test a MOSFET using an analogue meter and I must say I really prefer Jestines testing methods. Click here for link 1 and Click here for link 2, also click on the photo below for another great link on testing MOSFETs.

How to test BJT(Bi-polar Junction Transistors)

Recently one of my news letter subscribers wrote me looking for some information on testing BJTs, so I thought this would be a good topic for the Blog. Here are 2 links to some good information on testing a BJT , click here for link 1 and click here for link 2 you can also click on the photo below.

August News Letter

Don't forget to sign up for our FREE monthly electronics news letter, if you have not already signed up do it now by clicking here. Every month Preher TV will send out a news letter packed with electronics information and August's news letter will also be the release of my new book on electronics repair including LCD TV repair. Don't miss out, again if you are not a subscriber start today by clicking here or by clicking the photo below.

Saturday, July 25, 2009

Making Electrical Measurements Part 3:

The third part on making electrical measurements. Click here to read part 3. These three articles just touch the surface, to learn much more about making measurements and testing electronic components you must read a good book on the subject, like "Testing Electronic Components" or "Electronic And Electrical Servicing", these are great books and by reading them not only will you have gained great amounts of knowledge but you will also have completed the first 2 necessary steps towards getting a CETG apprentice certification.




Making Electrical Measurements Part 2: Loading

Second part of Making electrical measurements.Click here to read more.

Making Electrical Measurements Part 1

Here is part one of a good article for taking electrical measurements, this is something you should feel very comfortable doing if you want to be an electronics repair technician, if you want to feel comfortable it is essential you know what you are doing..Click here to read more.

Wednesday, July 22, 2009

Lot's of work!!!


Sorry I have taken so long to update the blog lately, but I have been very busy the last week. LCD TV repairs are increasing constantly and the demand for qualified technicians to do warranty TV repairs is greatly increasing. This is great news for me as I can make some good money. Also I have been working hard on my book so that coupled with the extra work lately has made it hard for me to get online and blog. I now think I am organized enough that I can start updating regularly. Today I will catch the blog up by posting multiple times today, Have a great day.

Beware B.I.C. (blue star international components)

Beware of blue star international components, I have used them in the past with no problems, but I usually don't because they are over priced. This time I made an order because my normal distributor did not have the part I needed in stock and I needed it fast. Well guess what? These guys sent me a used refurbished convergence IC, it looked like it was pulled from a junk pile!!! it had rust on the back even!!! And guess what, it didn't work, I had to order another one from some where else to fix this customers set, and refund the customer the express shipping on that used part.I have emailed blue star international components asking them how they will resolve this and why they would send me this horrible used part when I was purchasing a new one, they have failed to respond and chose to ignore me. Oh well my business will never use this horrible company again, and I urge any of you that use this company to be aware they are using bad and illegal business practices. Be careful of anywhere you buy parts and stick with your trusted distributors.

Don't use these guys they do bad business, BEWARE!!!!
http://www.bluestar-online.com/


(Edit 7/30/09)
Well I have to say that although I have never received a response from Bluestar , I did notice today that they refunded me the money for the IC, when checking my bank account. I'm glad they refunded my money but it really does not excuse selling that "rebuilt" STK393-110.

Wednesday, July 15, 2009

Tools And Test Equipment

Pro'sKit is a company I like to by some of my tools from. They are very nice for the price. Pro'sKit also offers a variety of test equipment.Check them out today by clicking here or by clicking the photo below.

Monday, July 13, 2009

Schematic And Parts List(astable DJ)

Here is the Schematic and the parts list for the "Astable DJ" circuit featured on our project page recently.Visit the project page by clicking the photo below.


Parts List:

R1,R2 = 330 Ohm resistor
VR1,VR2 = 22k Ohm variable resistor
D1 = red 3mm LED
D2 = green 3mm LED
D3 = P6KE24A
C1,C2 = 10uF @ 16 volts capacitor
Q1 = D600K NPN
Q2 = C3228 NPN
SW1 = any SPST switch


Please note, these are just parts I pulled off an old board to put this circuit together.The components I used are definitely not the only or best choices, please play around with the parts you have laying around and see what works best.

Friday, July 10, 2009

Mitsubishi - Blinking Green Light

Here is some info on a very common repair for mitsubishi projection TVs.I myself have done a few of these DM module repairs.Hope this might help some of you that have seen this problem and not found a solution.Click here and also click on both photos below to get alot of info on this common repair.
.

Simple DC to DC converter

Here is a simple circuit for converting a DC voltage to another DC voltage, I thought this was a pretty cool little circuit that might be useful in a project sometime.Click here or click on the photo below to read more about this circuit and some of it's possible applications.

Electronics Website

Electro-Tech-Online is a cool forum I have been going to lately.I enjoy reading the threads and posts.There are many knowledgeable people on this site and it is also nice to help out when you can.Check out the website by clicking here or by clicking the photo below.



Wednesday, July 8, 2009

New Project,LED Flasher

Here is our latest recycling project, using broken electronic devices from around the shop.This is a simple astable mutivibrator using variable resistors for an adjustable time constant.The parts list and schematic will be available soon on our project page, click here to visit the project page.Enjoy the video clip.


Sunday, July 5, 2009

Nuts And Volts Magazine

I think everyone involved in electronics should get a subscription to a good electronics magazine.It's good for refreshing the mind and keeping up with new advancements as well.I personally subscribe to Nuts And Volts, This months issue included "build the transistor clock" which was a really great article and looks like a fun project.The article also included some info on Flip flops, Decoders and Counters. Nuts And Volts also includes many cool advertisements for the electronics enthusiast along with all the great articles to read.To Check out Nuts And Volts magazine today click here or click on the photo below.

Friday, July 3, 2009

Email Support For CETG

Our certification program CETG(Consumer Electronics Technicians Group) is now offering email support to help with the course part of the certification program.We will help you with any questions or concerns you have while reading the study material and getting ready for the test.We will be available for you as an instructor 24 hours a day to help with your course, and we will assist you all the way to certification.The email support program is a great deal at only $40.00 USD.And remember CETG certification is available to anyone in the world who speaks and reads english, you will be able to test at a local testing center, by phone or online your choice.Click here to find out more about the email support program or click here to get more information on the CETG.Or you can click on one of the photos below.