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

In The News:

pen paper and inkwell


cat break through


What Tablet PCs Can Do for You

Tablet PCs are great. If you are a mobile person,... Read More

Pixel Disruption To Cause Nausea From User of Computer Screen

As we study the issues associated with teaching kids in... Read More

War of the Disks: A Close-in Analysis of the Hard Disk Drive vs. the Solid State Disk

Much has been written about solid state disks (SSDs) becoming... Read More

Power and Your PC

The power coming into a computer is the most critical... Read More

Basics of RAID

A couple of the recent Tech Tips from www.geeks.com have... Read More

Where does technology come from?

Ever wonder where all the cool gadgets come from? Ever... Read More

5 Ways To Backup Your Data...

The data on your hard drive is the most critical... Read More

High Definition DVD

High definition DVD, also known as HD-DVD (which actually stands... Read More

How to Choose The Right Laptop Accessories?

The notebook computer is coming of age. For the first... Read More

Your Business versus Mother Nature

Business Consultants earn hundreds of thousands of dollars every year... Read More

At War With The Internet

When it comes to sales of technology products over the... Read More

An Introduction to Tape Backup

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

Blu-ray: A Primer

Blu-ray is an optical disc format which is set to... Read More

The Importance of Ergonomic Products

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

Ergonomic Products 101

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

Computer Network Installation

Computer network installation has become an essential prerequisite for any... Read More

DVD Media

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

Would You Like An Extended Warranty With That?

Should you buy an extended warranty with your laptop? You... Read More

Lock Workstation Fast

When you work in an office, it's important to lock... Read More

A Review of Refurbished HP Laptops

HP refurbished laptops can be found on their website hpshopping.com.... Read More

Purchasing Laser Toner Refills

Laser toner refills can be expensive. Over the life of... Read More

Got The Message that You Need New Ink Cartridges?

We all know what it is like when that message... Read More

Using System Restore to Save Yourself from Formatting Your Hard Drive

It is the most annoying thing when one day you... Read More

Be Free with Wireless Speakers

Are you tired of laying wires through your house, creeping... Read More

Intel Celeron vs Pentium

The Celeron and Pentium Processors are two of Intel's best... Read More

Toner Cartridges - How They Work

In the past computers and their accompanying printers were huge.... Read More

Thumb Drives - Great New Technology!

The ability to easily move data from PC to PC... Read More

Best DVDs for Your Personal DVD Player

When bought personal DVD player, the very next thing to... Read More

You Can Prevent Computer Slowdowns & Issues

Most people understand preventive maintenance like changing the oil in... Read More

3 Easy Step To Locate A Real Bargain On Laptop Batteries

Looking for a real bargain on laptop batteries? How do... Read More

Learn to Find Cheap Laptop Computers on the Internet

Cheap laptop computers are coming to a store near you.... Read More

How to Check Your IP

So you need to check your IP address, for whatever... Read More

How To Take Care Of Your Laptop Computer

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