Ceramic Disc Capacitor-How to Accurately Test It

The last article I mentioned about electrolytic capacitor breakdown when under load. In this article I will talk about the high voltage resin coated ceramic disc capacitor. In computer monitor, it is frequent used in the screen voltage (G2) line at the crt board. When it fails, it can cause erratic or intermittently raster bright and dim and sometimes no display.

Adjusting the flyback transformer screen control will not solve this problem. You can isolate the problem as whether if it cause by a defective fly back or G2 line at crt board. Remove the G2 wire from circuit and measure the screen voltage with a digital multimeter- it should have a constant voltage (will not vary). If the voltage is not stable suspect the fly back. If it ok then trace the screen voltage circuit. Usually this circuit consist of only resistors and capacitors. Sometimes a defective crt socket might cause this type of problem also!

Many times a tech can't solve this intermittent or no display problem is because their digital capacitance and ohmmeter measured ok on the capacitors. The capacitors in the screen voltage line are usually rated of 102,103, and 472 1kv to 2kv. A 'missed' in checking this capacitors will caused the technician can't solve the problem, unless he direct replace the capacitor. An intermittent capacitor can pull down the screen voltage causing the display problem.

As mentioned earlier, an ohmmeter with 12v output and a digital capacitance with 3v output are unable to accurately check the capacitor that have the rating of 1-2 kilovolt!

If you have the analog insulation tester or meter, the panel will show a short circuit when certain voltage are pump in to check the high voltage capacitor. The voltages that you can select is depends on the brand or model you buy. Some have the range of 50v to 1000v and some have the range from 100v to 500v. It is optional whether you should have one. If you have one then it would be an added advantage for you. The other option that you have is to direct replace the suspected capacitor. In my country, you can get a new one in less than US150.00 or you may bid a used unit from eBay.

As for me, checking the small blue resin coated ceramic disc capacitor that have the capacitor code of 104 50v, besides using digital capacitance meter to check for the value, i also use an analog meter set to times 10Kohm that have the output of 12v to check this type of capacitor. Many times it will revealed the bad intermittent capacitor. You will be shocked to see the capacitance meter checked ok but show a shorted reading when check with analog multimeter.

In the market there is certain brand of analog multimeter that have the range of 100kohm. If you open up the cover, you can't see the 9v battery in it, what you see only the 2 pieces of 1.5v battery. This type of meter can't accurately detect the short in the capacitor because the output voltage is only 3volt!

For those of you who involved in repairing monitor, you will agree with me that checking the flyback internal capacitance- quite often you get the right value 2.7nf with digital capacitance meter but when you switch on the monitor, you will hear a 'tick-tick' sound from the flyback. This is because the capacitor is breaking down when under load. If you did not do anything with the flyback, gradually the internal capacitance will become shorted and you will need to refurbish the flyback.

Jestine Yong is a electronic repairer and a writer. For more electronic repair information please visit his website at http://www.noahtec.com/electronic-repai r-articles.htm

---

How to Shop for Inkjet Printer Cartridges

Keeping Shipping Costs DownWhen shopping for inkjet printer cartridges online... Read More

Printers

Do you feel overwhelmed when buying a computer or a... Read More

Computer Components for Idiots

There are many fancy add-ons for computers, but the basic... Read More

The Printer Cartridge Wars: Generic or Remanufactured Cartridges Right for You?

OverviewAs "generic", "remanufactured", and "new compatible" inkjet printer cartridges and... Read More

Used Laptop Computer: Your Quick Purchase Inspection Guide ? Part 2

Used laptop computers are everywhere these days. How can you... Read More

Correctional Institution Preventive Maintenance Software

There is a great need for preventive maintenance in correctional... Read More

Types Of Laptop Batteries

Throughout the years there have been many technologies involved with... Read More

Testing Flyback Transformer - How to Test and When to Replace It

Nowadays, more and more monitor comes in with flyback transformers... Read More

What is EEPROM ?

EEPROM stands for Electrical Erasable Programmable Read Only Memory and... Read More

Special Events Recording in DVD Players Age

The proliferation of portable DVD players has dramatically changed the... Read More

Video Display

Video displays are most recent technique used in both outdoor... Read More

Ergonomic Products 101

Human beings are scaling new heights day by day. Markets... Read More

A Technical Introduction to Audio Cables

What is so important about cables anyway?One of the most... Read More

A Review of Refurbished Toshiba Laptops

Toshiba offers a few of their refurbished laptops in the... Read More

Top Three Factors to Consider While Choosing a Data Center for Your Business

Data Centers are the core of the Internet. The computer... Read More

Getting to Know Inkjet Printers

Inkjet printers were born in the 1980s, replacing the popular... Read More

USB Hubs and Ports Explained

The USB standard has become the universal means of connection... Read More

An Introduction to Tape Backup

If you run a small business, chances are you're saving... Read More

How To Take Care Of Your Laptop Computer

As the proud owner of a laptop computer, you'll want... Read More

When Good Color Goes Bad...

Even with the popularity of digital technology, and the availability... Read More

Ten Ways (plus 1) to Save on Printer Ink and Toner Cartridges

Are you getting tired of the high cost of printing?... Read More

The Importance of Ergonomic Products

Interestingly, ergonomics though sounds to be a modern and trendy... Read More

DVD Media

DVD is an optical disc storage media format that can... Read More

Tips To Select Proper Motherboard

Selecting motherboard is really simple. As name suggests "Motherboard" acts... Read More

Where Can I Find The Best Case Mods Online and Save Money?

Are you captivated by the stunning Case Mods you've seen... Read More

Flash Your ATI Video Cards BIOS

Flash your ATI video card BIOS.You will need the following:1.... Read More

Expansion Cards Part 2: AGP

Expansion Cards Part 2: AGPThe first in this series of... Read More

Used Laptop Computer: Your Quick Purchase Inspection Guide ? Part 3

Used laptop computers are everywhere these days. How can you... Read More

The Constantly Changing World of Inkjet Technology

We have finally advanced to a time when technology can... Read More

Laptop Computers and the PVP Effect!

Roll over lumbering desktop computers, the limber laptop is here,... Read More

Buying a Plasma or LCD TV FAQs

This article focuses on frequently asked questions by buyers of... Read More

The Importance Of Current Sense Resistor In Switch Mode Power Supply

Current sense resistor is usually located in the switch mode... Read More

Three Must Have Accessories For Notebook Computers

An Optical MouseNotebooks are normally equipped with touch pads which... Read More