Preher-Tech Blog

Switching Power Supply Design Videos

2013-05-01T23:20:00.001-07:00

Dr. Ray Ridley of Ridley Engineering has started uploading some videos on switching power converter design to the Ridley TV channel on youtube. Below is Switching Power Supply Primer Part 1,

Click here to visit the Ridley TV Channel and view more videos from Dr. Ray Ridley.

I also recommend visiting ridleyengineering.com and registering to gain access to the design center where you will find a good amount of wonderful articles on switching converter design and theory and also some free software. Click here to visit the design center.

LCD Monitor Repair Online Course and Certificate

2013-04-14T16:46:00.001-07:00

We are excited to announce that the highly recognized LCD Monitor Repair Certification from Noahtech Electronics Training is now available online.

The LCD Monitor Repair Certification is an excellent way for you to prove your proficiency in electronics repair to employers or potential customers.

Upon passing the 25 question online test a high quality hard copy certificate will be shipped to you from Noahtech within 1-2 weeks. Delivery may take 3-4 weeks depending on your country of residence.

The details of your test score will also be posted on the graduates page of noahtechelectronicstraining.com for easy verification of certification and test score.

The cost of this excellent certification is only $69.00

The following study material is required to study for the test and easily attain a high score.

LCD Monitor Repair by Jestine Yong. Click here for more information.

Testing Electronics Components by Jestine Yong. Click here for more information.

The LCD Monitor Repair Online Certification test was developed by Jestine Yong and William Hor Co-founders of Noahtech.

Remember to visit preher-tech.com

Power Supply Repair Guide

2013-04-11T18:53:00.004-07:00

Troubleshooting and Repairing Switch Mode Power Supplies is a great guide for technicians who are interested in learning more about switching power converters also known as SMPS(Switch Mode Power Supplies), common SMPS failures and how to troubleshoot and repair them. This 271 page guide was written by Jestine Yong.

This book is written in a way that is very easy to understand for beginners but also has plenty of repair tips and information that will be appreciated by experienced technicians as well. Click here to get more information about this ebook on repairing SMPS.

LCD Monitor Repair Guide

2013-04-11T18:36:00.005-07:00

This amazing guide written by Jesting Yong is a definite must have for anyone interested in LCD monitor repair.

Jingyan MESR-100 ESR/low ohm meter review

2013-03-27T01:13:00.000-07:00

I recently purchased a new ESR meter from a seller on E-bay called mib_instruments, their ebay store can be seen by clicking here and their website is www.mib-tech.com, where you read more about the company and see more of the test equipment they offer.

The meter I purchased from this company was the Jingyan MESR-100 ESR/low ohm meter. The total cost was $59.99 including shipping. It took 12 days total for the unit to be delivered to me in the USA after being shipped from China, really quick I thought. The unit was shipped and I received tracking within 48 hours of purchase. The meter was very nicely packaged as you can see in the photos below.

This unit is really well made and is the best ESR meter I have seen in this price range. It has features I like from the other ESR meters together in one unit, toggle on off switch, banana jacks, battery compartment and a nice back lit LCD.

Click here to see the full specifications and features on MIB instruments website.

I will be using this meter daily to see how it holds up on the bench and out in the field with daily use and I will post an update in the next few months. Over all I really like this ESR meter so far and I would definitely recommend it.

Please email any questions to contactus@preher-tech.com and also remember to vistit www.preher-tech.com.

LCD Monitor Repair Case Histories Volume 2

2013-02-23T21:53:00.003-08:00

"10 True Repair Case Histories of LCD Monitors Volume 2" is the latest repair guide from Jestine Yong. As usual Jestine does a wonderful job of walking the reader through common faults with LCD monitors, familiarizing you with common circuits and components while guiding you to a successful repair. From the case histories presented in this book you will easily acquire the necessary knowledge to repair common faults in many different brands of LCD monitors.

Included in this guide:

1. No Display in Acer AL1717A LCD Monitor

2. No Power and Power Blink in Benq 19” G900WD LCD Monitor

3. Display Shutdown In Few Seconds In Samsung 740N 17” LCD Monitor (Backlight Modification Tip)

4. No Power in BenQ G900WD 19” LCD Monitor

5. Display Shutdown in Few Seconds in Samsung 22” 2233SW LCD Monitor

6. No Power in E177FPb 17” LCD Monitor

7. No Power in HP 19" HP L1908W LCD Monitor

8. Dim Display and Intermittent Can’t Power On In Samsung 732N 17” LCD Monitor

9. Display Shutdown After Few Seconds in Samsung 19” LCD Monitor 931BW (Another different backlight modification tip)

10. Reddish Colour in Samsung 943NWX Soft Touch Control 19” LCD Monitor

To read more about this new guide "10 True Repair Case Histories of LCD Monitors Volume 2" click here.

Remember to visit www.preher-tech.com

LCD TV Repair Tips V2.0

2013-01-25T18:54:00.001-08:00

A Collection of LCD Television Repair Tips V2.0 is the title for the latest repair guide from Kent Liew.

This e-book contains information on the following types of failures:

No Power, Dead

No Display with blue or green color LED light lit

No Display but Back light working and sound OK

No Display on TV mode but working on AV mode

No Display with red or orange color LED light flashing

No Start up or Slow start-up, Stuck in Standby Mode

Display Shutdown after a while

Display Distortion

Double Images on screen

Negative Picture on Screen

Solarisation Image

Hum, Buzz or Hissing Noise inside the LCD TV

Sound / Audio Problem

Erratic Functions or Intermittent Problem

Display Darkness, Backlight Failure or Inverter Problem

Display Colour Problem

Horizontal or Vertical Lines & Bars in the screen

Solve LCD TV Under Protection Mode

EEPROM dumps corrupt symtoms, Firmware Issues

Product Details:

E-book Format: PDF file

Pages: 67 pages + 38 pages (Bonuses)

Language: English

Bonus: Included Email Support & 3 Bonuses of LCD TV Repair Case Histories!

Compatible with: PC, Laptop & MAC Computer

Price: $13.95 USD

Click here for more information on this LCD TV repair guide.

Samsung power supply repair

2012-10-02T15:14:00.003-07:00

Preher-Tech offers mail in repair service on the following Samsung power supplies,

Samsung HPT42
Samsung HPT4234X/XAA
Samsung HPT4234X/XAC
Samsung HPT4254
Samsung HPT4254W
Samsung HPT4254X
Samsung HPT4254X/XAA
Samsung HPT4254X/XAC
Samsung HPT4254X/XAP
Samsung HPT4264X/XAA
Samsung HPT4264X/XAC
Samsung PL42C71HDPX/XAX
Samsung PL42C71HPX/XAX
Samsung PL42C91HPX/RCL
Samsung PL42C91HPX/STR
Samsung PL42C91HPX/XAP
Samsung PL42C91HPX/XAX
Samsung PL42Q91HDPX/XAX
Samsung PL42Q91HPX/XAO
Samsung HPT5034X/XAA
Samsung HPT5034X/XAC
Samsung HPT5044
Samsung HPT5044X
Samsung HPT5044X/XAA
Samsung HPT5054X/XAA
Samsung HPT5064X/XAA

Repairs typically run $50-$70 plus shipping and handling. We also sell a repair kit for all of the listed models for $50 including shipping and handling.

If sending your power supply, TV should have one of the following failure symptoms:

-Clicking
-shuts down
-goes on/off by itself
-won't come on-dead

Please visit our mail in repair service page for more information. You can also email us at contactus@preher-tech.com for more information as well.

New LCD TV and Monitor repair books

2012-10-02T14:38:00.000-07:00

"Collection of LCD TV Television Repair Tips" , By: Kent Liew
The "LCD Television Repair Tips" guide is easy to use and straight to the point.
Click here for more information.

"10 True Repair Case Histories of LCD Monitors: Volume 1", By: Jestine Yong
This guide is a compilation of 10 actual repair cases of LCD Monitors.
Click here for more information.

Also don't forget to check out this best selling 195 page guide on LCD TV repair,

"Troubleshooting and Repairing LCD TVs", By: John Preher
Click here for more information.

www.preher-tech.com

LCD TV Repair Guide

2012-06-29T15:18:00.000-07:00

If you are interested in learning how to repair LCD TVs check out this best selling e-book, Troubleshooting and Repairing LCD TVs by John Preher. This is an in depth 195 page e-book and has been recently revised. Only $25.00, if you are interested please click here to take a look at the sales page for more information.

Don't forget to visit preher-tech.com

Viewsonic VG1930WM no power, repaired

2011-07-24T23:19:00.000-07:00

I just finished repairing a Viewsonic VG1930WM that had no power, no standby LED, completely dead. I opened up the monitor and checked the output voltages from the power supply and both were present and stable. I verified that the 5V was still present at the main board. Next I checked the output from the 3.3V and 1.8V linear voltage regulator ICs on the main board and the 3.3V regulator's output was considerably low around 2.2V, the output from the 1.8V regulator was also very low but it gets its input from the 3.3V regulator so it makes sense that the 1.8V regulators voltage was low. I replaced the 3.3V regulator after verifying it was faulty and the monitor was still dead when I plugged it in to check voltages again, the 3.3V regulator's output was now within tolerance so I again checked the output from the 1.8V regulator and it was still low about 1.2V, so I then replaced the 1.8V regulator and when I plugged the monitor in to check the output from the 1.8V regulator I saw the standby light turn on, the voltage output from the 1.8V regulator was now within tolerance and the monitor turned on and functioned flawlessly.

Professional Repair: If you are interested in having your power supply board repaired professionally then you may be interested in our mail in repair services. We can do the repair on this particular power supply for $50 plus the cost of return shipping and handling. Click here to see our mail in repair service page. You can also email contactus@preher-tech.com for more information.

Also don't forget to visit http://www.preher-tech.com

Viewsonic VX910 no power, repaired

2011-07-24T23:00:00.000-07:00

Recently did a repair on a Viewsonic VX910 that had no power, no standby LED, totally dead. Upon opening the monitor I could see that someone had already replaced all the electrolytic capacitors in the output filter circuitry, but for this type of failure I normally don't suspect the filter capacitors anyways. I plugged the monitor in to check for any output voltages from the PSU and I could here a faint chirping coming from the power supply, this is always a good indication of a shorted output diode or faulty components in the feedback circuitry, the power supply is continually trying to start up and then shutting down,over and over. As I suspected there was no output from the power supply. I pulled the power supply and the first thing I checked was the dual schotttky diode D660 and one of the diodes in the dual package was shorted. The original diode was a MBR10100CT dual schottky diode, I replaced it with a B20100G dual schottky diode. After replacing the dual diode the monitor powered on and worked once again.

Professional Repair: If you are interested in having your power supply board repaired professionally then you may be interested in our mail in repair services. We can do the repair on this particular power supply for $50 plus the cost of return shipping and handling. Click here to see our mail in repair service page. You can also email contactus@preher-tech.com for more information.

Also don't forget to visit http://www.preher-tech.com

Philips 37MF321D/37, 37MF331D/37, 715T2056-1 Power Supply Repair

2011-06-20T23:35:00.000-07:00

We have been receiving quite a few 715T2056-1 power supplies for repair from Philips 37MF321D/37 and 37MF331D/37 LCD TVs. The failure symptom is typically that the green standby/power indicator led blinks constantly and the TV will not turn on. The most common reason this particular power suppy fails is the 2200uF 25V capacitor at location 2074 has puffed and vented or has a significantly high ESR, some of the other electrolytic filter capacitors on the secondary side of the power supply may have a high ESR as well. The 9.1V 0.5W zener diode(BZX79C9V1 is used for replacement) at location 6079 is commonly shorted, but may also be open as well. The SMD 2.2 ohm 0.125W resistor at location 3045 has opened and is usually burned often damaging the copper trace on the bottom of the PCB. Parts are available from http://www.mouser.com/. If you have any questions regarding this repair or any other electronics related questions please feel free to email me john@preher-tech.com.

Professional Repair: If you are interested in having your power supply board repaired professionally then you may be interested in our mail in repair services. We can do the repair on this particular power supply for $50 plus the cost of return shipping and handling. Click here to see our mail in repair service page. You can also email contactus@preher-tech.com for more information.

Remember to visit http://www.preher-tech.com

HPT4234, HPT4254,HPT4264, No power, Clicking, Repaired

2011-06-19T22:53:00.000-07:00

If you have a Samsung HPT4234, HPT4254 or HPT4264 that does not turn on and only clicks or intermittently shuts down and starts clicking and you are looking for information on how to repair the power supply, see our post on how to repair the HPT4254 power supply which also applies to the HPT4234 and HPT4264 power supplies by clicking here.

Professional Repair:If you are interested in having your power supply board repaired professionally then you may be interested in our mail in repair services. We can do the repair on this particular power supply for $50 plus the cost of return shipping and handling. Click here to see our mail in repair service page.

Take care and remember to visit http://www.preher-tech.com

Samsung HPT5044 (HPT5044X/XAA) no power, clicking, repaired.

2011-06-08T16:54:00.000-07:00

Samsung HPT5044 (HPT5044X/XAA) no power, clicking, repaired.This repair was basically a very similar repair to one we often do on the HPT4244 power supplies, but we wanted to give this one it's own post so that people searching for info on the HPT5044 with the failure of no power only clicking when attempting to turn the TV on or also intermittent power and clicking, would be able to easily find this info when searching online. The HPT4244 power supplies that we have been receiving for repair come in with an open fuse at location F803, shorted MOSFETs at locations QS801 and QS802 and open SMD dual package diodes at locations DS801 and DS802. QS801 and QS802 are both AV218N50 MOSFETs, but we substitute with FDA18N50 MOSFETs. F803 is an 8A 250V time delay/slow blow fuse. DS801 and DS802 are both 1SS184T5LFT, UFR dual package common cathode SMD diodes. All parts are available from http://www.mouser.com/.

Click here to read the repair info on the power supply from the HPT4254 which is extremely similar. There is some good info in this post including other components you will want to test if MOSFETs QS801 and QS802 are not shored or F803 is not open as these boards have multiple failures that can happen.

Professional Repair:If you are interested in having this board repaired professionally then you may be interested in our mail in repair services. We can do the repair on this particular power supply for $50 plus the cost of return shipping and handling. Click here to see our mail in repair service page.

Remember to visit http://www.preher-tech.com.

Testing HV transformers in LCD TV inverter circuits

2011-05-25T12:02:00.000-07:00

This article is from the Preher-Tech May 2011 newsletter. In this article I show you how easy it is to test LCD TV inverter transformers.

Click here to download the article "Testing HV Transformers in LCD TVs"

Don't forger to visit http://www.preher-tech.com

The BLUE Ring Tester

2011-05-13T10:25:00.000-07:00

Preher-Tech is now selling the BLUE ring tester fully assembled by us and in kit form as well.

Click here to visit our sales page and get more info.

The BLUE ESR Meter

2011-04-12T19:15:00.000-07:00

Preher-Tech is now selling the BLUE ESR Meter fully assembled by us and in kit form as well.

Click here to visit our sales page and get more info.

Sharp Aquos LC32D43U no power

2011-04-12T11:46:00.000-07:00

Here is an article from this month's newsletter about a repair we did on a Sharp Aquos LC32D43U that had no power or standby light, totally dead. Click here to download the article "Sharp Aquos LC32D43U No Power"

Professional Repair:
If you are interested in having this board repaired professionally then you may be interested in our mail in repair services. We can do the repair on this particular power supply for $50 plus the cost of return shipping and handling. Click here to see our mail in repair service page.

Repair Kit:We also have a repair kit for the power supply available for $35.00 which the parts necessary for this repair and includes USPS priority shipping within the contiguous United States. Click here to visit our repair kits page and purchase this kit.

Remember to visit http://www.preher-tech.com

Electronics repair training videos

2011-03-16T23:34:00.000-07:00

Click here to visit Randy Fromm's YouTube page and see more of his great videos.

Also click here to see Randy Fromm's Arcade Schools training programs.

Randy Fromm's Arcade School offers a wide range of video training programs, from beginning electronics to advanced microprocessor repair.

Randy Fromm's Electronics Repair Guides

2011-03-16T21:42:00.000-07:00

Here is a great website to purchase some really good electronics repair guides by Randy Fromm, http://randyfromm.com/shopping/

Randy Fromm's Arcade School offers a wide range of video training programs, from beginning electronics to advanced microprocessor repair.

Here is a list if some of the available programs:

-Randy Fromm's Big Blue Book of Really Great Technical Information
-Randy Fromm's Big Green Book of Monitor Schematics
-All-You-Need Beginning Electronics for Operators and Mechanics
-Basic Videogame Troubleshooting
-Diodes, Transistors & Other Semiconductors
-Switching Regulator Power Supplies (Peter Chou type)
-Conventional Power Supplies
-Videogame Monitor Repair Made Simple
-Using a Digital Multimeter
-Using an Oscilloscope
-Introduction to Digital Electronics
-Troubleshooting Microprocessor Based Systems

Click here for more information and to visit the sales page.

Typical electrolytic capacitor ESR values

2011-03-05T18:25:00.000-08:00

Here is a chart showing typical ESR values for good electrolytic capacitors. For many of the capacitor values listed the ESR will typically have a value 10X the value on this chart before it starts to cause problems in most circuits. This is the same ESR chart found on the original Dick Smith ESR meter and the also EVB ESR meter.

Click here to download the ESR chart.

Remember to visit http://www.preher-tech.com and if you have any questions you can email me john@preher-tech.com

LCD TV Display Failure Symptoms and Possible Causes.

2011-02-13T21:15:00.000-08:00

This is a 6 page guide that shows LCD TV display failure symptoms such as vertical bars and lines or noise/distorsion in display etc and what the possible cause of failure may be.

Click here to download PDF file of LCD TV Display Failure Symptoms and Possible Causes.

You may also be interested in our LCD TV Repair Guide. Click here to read more.

Don't forget to visit http://www.preher-tech.com

Oscilloscope Tutorial

2011-02-12T21:54:00.000-08:00

Thought all my readers would enjoy this, it;s from nutsvolts.com the online home of Nuts & Volts Magazine.

Afrotechmods shows us what an Oscilloscope is and how to use it… An oscilloscope is the most important piece of electronic test equipment you can buy after a multimeter. They allow you to see, in great detail, what is going on with all the voltages in your circuit. If you ever work with audio circuits, timers, micro controllers or radios etc... an oscilloscope will help you get the job done.

Click here for the full article and videos.

How to repair LCD TVs

2011-01-11T12:46:00.000-08:00

"Troubleshooting and Repairing LCD TVs"
If you are interested in repairing LCD TVs then click here to check out the top selling LCD TV Repair Guide.
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You may also be interested in Kent Liew's LCD TV Repair Membership Site. This is a great place to get training manuals, service manuals, schematics and more. Click here to read more.

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Remember to visit http://www.preher-tech.com/