Don't Miss

How the Automatic Garage Door Opener Was Repaired Model: BFT–A40 Made In Italy

By on July 1, 2023
garage door repair

mainboard of garage door


garage door opener diagram

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

bad fuse

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 and receiver module

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.

gate receiver sensor

gate transmitter sensor

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.

garage door transmitter and receiver checking

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

waveform of transmitter and receiver

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.

transmitter and receiver signal

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.

waveform of output receiver

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 )

Beh from IRAN

This article was prepared for you by Mr Beh from Iran

P.S- Do you know of any your friends who would benefit from this content that you are reading now? If so, forward this website to your friends or you can invite your friends to subscribe to my newsletter for free in this Link.

Note: You can check his previous article on How I Repaired SONY TV Power Supply Model: T370XW02 Made In Taiwan



  1. Mark

    July 1, 2023 at 10:25 am

    Well done Beh.

    • Beh

      July 1, 2023 at 6:49 pm

      Hi Mark
      Thank you so much.

  2. Parasuraman S

    July 1, 2023 at 10:40 am

    Excellent article packed with a lot of information and details! Many, many thanks for passing on the experience! May God bless you!

    • Beh

      July 1, 2023 at 6:51 pm

      Dear Parasurman thank you so much.

  3. Tayo

    July 1, 2023 at 11:10 am

    Excellent repair and information.

    This is the power of an oscilloscope and expertise.

    • Beh

      July 1, 2023 at 6:53 pm

      Yes Tayo Scope is really a precious tool in our repair job and thanks

  4. Waleed Rishmawi

    July 1, 2023 at 1:56 pm

    thanks for sharing your success on this repair. a lot of good information provided and shared and I thank you for that. have a blessed day

    • Beh

      July 2, 2023 at 12:16 am

      Hi waleed
      I am happy you like this article and find it useful and thanks

  5. Albert van Bemmelen

    July 1, 2023 at 2:01 pm

    Excellent and well diagnosed repair Beh! It showed that the famous and very cheap NE555 was used to prevent the doors from causing expensive damage.
    Why use an exotic complex circuit that only would increase failure rate if a small and simple chip handles it all very well too!
    And the garage door opener sensors were very professionally tested in your electronics lab without leaving open any doubts!

    • Beh

      July 2, 2023 at 8:38 am

      Hi Albert
      I am happy you found this article
      intersting and thanks

  6. Mendis

    July 1, 2023 at 11:15 pm

    Excellent your information .Thank you God bless.

  7. Beh

    July 2, 2023 at 4:47 pm

    You are welcome Mendis.

  8. Kiran patel

    July 3, 2023 at 8:57 am

    Thank you Dear

    • Beh

      July 4, 2023 at 12:51 am

      You are welcome

  9. Lad

    July 5, 2023 at 4:24 am

    Thank you for your repair story.
    A present I have a similar problem with my gate opener.
    Transmitter and/or receiver do not work.
    Can you pleae answer my questions?
    As soon as the transmitter starts sending ( as long as there is 12V as input),
    must I measure voltage ( impulses) on output of receiver?
    My gateway is about 3m wide. How much well must transmitter be directed to the receiver so that high enough voltage is generated?

  10. Yogesh Panchal

    July 5, 2023 at 11:44 pm

    Excellent! Repair Beh.

  11. Beh

    July 6, 2023 at 12:20 am

    Hi Lad
    When the door start to closing both
    Transmiter and reciever reaching the voltages in was 12 volt and transmiter start to tranmite and reviever do the job and youcan mesuer it. forsecond question i have to say 1 meter from ground for both of them is good .measure it by meters both must be the same hight
    And thanks for questions


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.