Hardware Information


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-repair-articles.htm


MORE RESOURCES:
This RSS feed URL is deprecated, please update. New URLs can be found in the footers at https://news.google.com/news


Fossbytes

Intel Adding 'Hardware Lock' To Prevent ME Chip Hacking In Future
Fossbytes
Current, Intel ME chips have software-based implementations to prevent firmware downgrade. Now, Intel has taken hardware-based measures to prevent such incidents from happening. According to a confidential Technical Advisory posted on GitHub, the ...



Wired.co.uk

Google is getting serious about hardware, but it won't win easily
Wired.co.uk
But since the release of the Google Chromecast, the search giant has gone big on hardware. Now it produces its own laptops, smartphones, home assistants and products in a handful of other categories. In early 2018, Google expects to complete a $1.1 ...

and more »


Billings Gazette

Avoid a heart attack: Shovels sold in Billings-area hardware stores warn about symptoms
Billings Gazette
Kierra Knox, Chest Pain Clinic coordinator at the Billings Clinic, right, and King's Ace Hardware store manager Don Korf stand inside the store on Friday holding shovels with a sticker warning about the signs and symptoms of heart attacks. CASEY PAGE ...



Florida Hospital Nicholson Center launches mobile broadcast hardware for advanced surgical training
News-Medical.net
The Florida Hospital Nicholson Center, one of the leading robotic training centers in the country, today announces the launch of the B-Hive, an adaptable mobile broadcast hardware that allows for a unique and customized learning experience. The B-Hive ...



PGH City Paper

New Local Release: Bindley Hardware Co.'s Ever Satisfactory
PGH City Paper
On Ever Satisfactory, Bindley Hardware Co. thoughtfully plays with genre boundaries to create a crossover-appealing record that uses rock, folk, Americana and country in a compelling mixture. Songs like “The Good Ones” lean more into the traditional ...



Upgrading PLA hardware and 'heartware' in the Xi Jinping Era
East Asia Forum
In the period leading up to the recently concluded 19th Chinese Communist Party (CCP) congress, civil–military relations in post-reform China had been viewed under the lens of Party–army relations. But more recently, following Xi Jinping's ...



Tulsa World

High school football: Why state titles mean more than hardware for two schools in Oklahoma City
Tulsa World
High school football: Why state titles mean more than hardware for two schools in Oklahoma City. By Jenni Carlson The Oklahoman; 6 hrs ago; 0 · Facebook · Twitter · Email. OKC John Marshall 3A championship newsok. The John Marshall Bears celebrate with ...



Cruden simplifies hardware driving simulator design
Electronics Weekly
As an example, Cruden installed a driver simulator merged with a dSPACE HIL set-up at the Ostfalia University of Applied Sciences in Germany, where students can integrate hardware into the driving simulator. HIL set-ups, for testing sensors ...



Forbes

New Samsung Details 'Confirm' Radical New Hardware
Forbes
Although all the focus on Samsung's new display technology has been around the presumptively named Galaxy X and its folding display, a recently filed patent shows the South Korean company taking the idea of a bendable display in completely the opposite ...

and more »


HARDWARE STORE
STLtoday.com
Schneider's True Value is located on Main Street in St. Peters. The hardware stores provides a wide variety of services including blade sharpening, carpet cleaner rental, chain saw sharpening, glass cutting, key cutting, lamp repair, pipe cutting and ...


Google News

home | site map
© 2007