How the Automatic Garage Door Opener Was Repaired Model: BFT–A40 Made In Italy
MAIN BOARD OF MACHINE
Complete set of door parking opener
This repair article started when remote control failed to open the door. The first suspect for such problem was battery of remote control that was checked and was intact. Then this must be a problem of main board system. The only bad component that was visually detectable on the main board was the blown 1 amp 250 volts
By replacing the fuse with a good one the system started to work again and opened the door of garage. That was an easy repair so far so good. But when I was testing the door during opening and closing period I found out that the door safety sensors are not reacting properly to each other. But what are the door safety sensors?
In normal condition when the doors are closing if some thing or someone placed in between the doors the system must be react to this unless otherwise this will cause accident and or damage the car. To find out which part of the system got problem I start from the IR safety sensors. The machine has two IR SENSORs, one as transmitter and another one as receiver.
Transmitter sensor Receiver sensor
As long as the IR transmitter is sending the IR rays to receiver and the receiver that has photo diode receiving the IR rays via photo diode and main board receives the signals via receiver continuously there is no problem and door closes, but this process is possible because of the relay connecting via wires sending the signal to mother board and micro control feel everything is ok and the door getting closed but when something or someone interrupts the ray signals of transmitter to photo diode and receiver cannot receive the IR rays and relays stop and micro control cannot feel the signals, then it orders to stop closing the doors wherever the doors are. Since the external object or person is removed from the IR rays again micro is receiving the signal from photo diode and orders to doors to be closed.
What is inside the transmitter sensor?
Transmitter sensor has one IR diode. And voltage regulator, one 8 PIN IC smc NE 555 that producing clock signals that are very stable and accurate to drive the transmitter diode. In my case IC NE555 receives the supply voltages but not producing any signal in output. These signals must be detectable on pin 3 of IC by scope.
Other components as well as diode were tested good. The receiver sensor consisted of followings: Photo diode. E-caps. Relay .resistors etc.
All of them passed the test. For testing the photo diode off the board I installed the probe of digital multimeter to pin of photo diode and selector of multimeter must be on millivolts by sending the IR with help of remote control of TV multimeter showed that is working and also Atlas AD 75 verified that photo diode is ok finally I replaced the NE555 with good one and I received output signals on pin 3 . Since to have mother board in my lab was not easy to uninstall from the wall and then install on the table of lab to TEST sensors and check the interaction of them I perform this test without mother board
I turned on the sensors with help of 12 v Dc with external power supply and install a digital scope on output of receiver sensor And installing the sensor on stands in front of each other’s transmitter start to send IR ray to photo diode scope showed the signals out of sensor.
This proved that both transmitter and receiver sensors are working, transmitter is sending and receiver receiving and scope showed this then and signal on the scope getting distorted if I interrupted it with my hand for example.
Conclusion: By replacing the glassy fuse and one SMD IC the machine returned to service again. The cost of repair was few American cents but the price of this Machine in our market is 400 USD.
Note: In this kind of Automatic door opener has two IR safety sensors IR SENSOR= INFRA RED ray SENSORS IR diode is producing frequencies between 940 nm up to 36 kHz depend on the material that diodes are made of and photodiodes frequency range is between 10hz up to 49 Ghz.
Note: (My multimeter read the output of receiver sensor 0.68 mv AC )
This article was prepared for you by Mr Beh from Iran
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Note: You can check his previous article on How I Repaired SONY TV Power Supply Model: T370XW02 Made In Taiwan