Hardware Information


Flyback Transformer-How to Locate the ABL Line


Whenever there is a complaint about monitor contrast problem I will check on the flyback transformer ABL (automatic blanking limiter) circuit. Sometimes a weak picture tube might caused contrast problem. If the picture tube is good, I will go straight to the contrast circuit. The question is how do we find where the contrast circuit located? Simple, if you have a datasheet for the video pre- amplifier ic, definitely you can find the contrast pin. For LM1203N video pre-amp ic the contrast pin is located at pin 12. Replace this ic or trace from this circuit to find the cause of the contrast problem.

From experienced, usually capacitors shorted and resistor turned into high ohms were the caused of the problem. A video pre-amplifier can also be defective. To confirm whether is circuit or ic problem, just solder out the contrast pin and switch on the monitor. If the monitor display normal picture (contrast ok) then suspect the abl line circuit. If it remain the same (dim contrast) replace the video pre-amp will usually solve the problem.

The contrast signal came from one of the pin (leg) of a flyback transformer which we called it as abl pin. Many technicians have the difficulty to trace the abl pin because usually a flyback transformer consist of around 10 pins. Some pins are B+, GROUND, AFC, ABL, X-RAY PROTECT, VCC, to HOT, HEATER, horizontal centering and etc. But there is one and simple way that i'm gone to show you how to locate the abl pin. Use two analog multimeters set to x10kohm range. Connect it in series (+ probe to - probe) and measure the flyback transformer from anode (the red cap) to all of the pins under the flyback. You have to desolder all the pin or just remove the flyback from the mainboard in order to get an accurate reading.

If either one of the pin shows a diode reading that is the abl pin. The reason we use two multimeters is because the flyback circuit internally have couple of high voltage diodes connected in series. If you have a schematic diagram or any monitor or television troubleshooting book, you will see that the internal flyback diode are connected in series. By connecting two meters the ouput from the probe is around 24 VOLTS which is enough power to check the flyback internal diodes. After you have determined the abl pin, you can proceed to follow the line and find the bad components that cause the contrast problem.

Television or tv flyback transformer generally have the same design compare to monitor flyback. Whether it is a montblanc flyback transformer, rca, mitsubishi or sony flyback the checking usually is the same.

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:


Forbes

Google Is Finally Getting Serious About Hardware. Here's Why.
Forbes
In early 2014, then-CEO Larry Page said Google didn't want to be in the hardware business after all, and sold off Motorola to Lenovo for $2.9 billion (though it kept Motorola patents worth billions). “The smartphone market is super competitive, and to ...
Surprise! The Pixel 2 is hiding a custom Google SoC for image processingArs Technica
Pixel 2 and 2 XL review: The best Android phone you can buyArs Technica UK

all 321 news articles »


TechCrunch

Nintendo nabs two-thirds of monthly game hardware sales thanks to Switch
TechCrunch
Nintendo has managed to lead the industry in video game hardware sales – by a wide margin – for September, which is a very promising sign going into the holiday shopping season. The Nintendo Switch helped this immensely, leading the industry as the ...
Nintendo: Two-Thirds of September Hardware Sales Were Nintendo SystemsRollingStone.com
Nintendo News: Nintendo Systems Claim Two-Thirds of September Video Game Hardware SalesBusiness Wire (press release)
Nintendo Consoles Made Up Two-Thirds of Hardware Sales in September, Games Performing StrongComicbook.com
GamingBolt -AOTF -Hot Hardware -Nintendo
all 351 news articles »


Akron Hardware Consultants sold to New York private equity firm
Crain's Cleveland Business
A New York private equity firm, High Road Capital Partners, announced it has bought Akron-based Akron Hardware Consultants Inc., a wholesale distributor of commercial and institutional door hardware. Financial terms of the deal were not disclosed.
Akron Hardware Consultants Acquired by Private Equity FirmModern Distribution Management

all 2 news articles »


eWeek

Dell EMC's Azure Stack Hardware Gets PowerEdge Upgrade
eWeek
First unveiled at the inaugural Microsoft Ignite conference in 2015, Azure Stack is a software and converged hardware bundles offered by select server manufacturers. It provides infrastructure and platform as a service functionality, essentially ...

and more »


Student Expelled for Using Hardware Keylogger to Hack School, Change Grades
BleepingComputer
Kansas University (KU) officials have expelled a student for installing a hardware keylogger and using the data acquired from the device to hack into the school's grading system and chang his grades. KU did not release the student's name to the public ...



Forbes

Samsung Confirms Hardware Inside Its Next Galaxy Smartphones
Forbes
Samsung's latest sensor chips will enable even thinner and smaller smartphones to take advantage of the latest camera technologies. Announced last week, the new Fast 2L9 and Slim 2X7 chips join the company's line up of ISOCELL sensors designed for ...



Forbes

AI-Ready Hardware To Deliver Facial Recognition Amid Privacy Concerns
Forbes
Apple's response centered around the presence of secure, embedded AI-ready hardware as a cure-all solution to Franken's consumer privacy and data security concerns. Elsewhere in tech, this embedded-AI privacy cure appears to be driving considerable ...



Gizmodo

Snap's Latest Hardware Is a Dancing Hot Dog Costume
Gizmodo
Last year, Snapchat became a “camera company,” changed its name to Snap, and unveiled its first piece of hardware: camera sunglasses called Spectacles. Today, Snap is evolving yet again. That AR dancing hot dog, the star of its last earnings call, is ...

and more »


The Daily Nonpareil

Peoples True Value Hardware going out of business
The Daily Nonpareil
After more than 20 years of business in Council Bluffs, Peoples True Value Hardware plans to close its doors permanently. The store, located at 2917 West Broadway, has announced a liquidation sale with most of the inventory discounted until enough is ...


Google News

home | site map
© 2007