RG1R DL Automation For Swing Gates
Hi!
Today I got an automation electronic motherboard (mobo) from a technician who setup swing gates. The mobo has a failure on two relays. The relays wont work, as they are bad and the swing gate motor have trouble to close and open the gate.
So I decide to check what type of electronic it is and how can I repair. Here is the mobo and I made a small description about how this mobo is designed:
The motor controlling section:
In this area there are the main parts are the four relays. They control the gate swinging motor. Under each relay is one protection diode, this diodes could be a reason for a not working relay, but in my case they are fine. In this section you have also a fuse for protecting the circuit from over current flowing if something goes wrong in the motor or the electronic.
Power section:
The power section is a simple stuff build up from two main parts.
1. LM317 adjustable voltage regulator
2. 78L09 smd +9V, 0.1A voltage regulator
This section could cause a major problem because the CPU is powered through this section. If the CPU won’t start then all the I/O section won’t work. Actually the whole thing would be dead.
The I/O area:
This is the section where info goes out to the motor how to manage the gate moving, and info come in from the sensors on the gate. Gate closed, opened, gate blocked etc… Actually, if something would be wrong on this section, the gate could have a strange behavior.
The gate could non-stop open and close or the worst think would be if the control section didn’t got an info does your car is on the half way in or out and the gate would smash into the car.
The command section:
In this section is the major I/O processing stuff. Here you can find the CPU which is programmed to communicate with the motor controlling unit, sensors on the gate, with the remote control unit etc.
Darlington array:
This little IC is nothing else then several darlington transistors put together into one small IC.
This is an ULN2003A type of darlington array with seven NPN darlington pairs.
I use this IC very frequently in my project where I wish to protect the output pins from my CPU or I need a bigger load to supply with juice than CPU output can handle.
This ULN2003A is used in this case to control the relays. The ULN2003A get a power on signal from the CPU on some pin and then the needed relay will start to working. If this part is bad then the relays won’t work.
EEPROM:
This eeprom is used to store some calibration parameters of the gate. Something like of how many signals should be got from the rotary encoder from the motor to full or half open or close the door, there are the codes for the remote control unit stored too etc…
If this part or the content of this IC would be defect then I assume the door would not open/close or the remote control unit wont response etc…
RF section:
This section is for communicating with the remote control unit. It is constructed on the TDA5200 single conversion receiver for receive frequencies bands 868-870 MHz and 433-435 MHz. If this goes bad you probably won’t have the ability to control your gate with your remote control unit.
As the technician told me the two relays were not working I focused on the relays and the ULN2003A ic. After I checked the relays and the protecting diodes which I could not capture because they are under the relays and hard to see them I moved to change the ULN2003A.
I called the technician guy and give him the pcb because I could not check all the operations in my service and told him to give me a feed back. After around 30 min I got a call the mobo is working and the gate is moving again as it should.
Conclusion, always check first if the power section is delivering to the unit, then the I/O section and then go to the parts which are between the control section and I/O section.
In most of case in my career I found the problem in the connection section between the I/O section and the control section. The connection section is that area where it comes to connection between the CPU and the relays in my case above. It could be a step motor driver or a classic DC motor connected on the CPU, there is a connection section too, maybe one heavy transistor or a complex driver unit.
Some friends of mine wasted their time searching for parts around the CPU, the relays, in the power section etc. but the main problem is between the cpu and the I/O board parts.
Sometime customers bring to me their equipment with a “known failure” as somebody checked and told the CPU is bad. To kill the CPU is not a big deal but it is hard if the electronic circuit is designed on a proper way. All I/O pins are protected on the CPU outside and the CPU inside too.
So, it is possible to burn the CPU but hard to do. After this repair, I got another several board for repair with similar problem. All of them had a ULN2003A problem. Why? I never figured out…
I hope you enjoy this tutorial and will save lot of repair time.
This article was prepared for you by Christian Robert Adzic from Novi Knezevac-Serbia.
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Note: You can check his previous post in the below link:
https://www.jestineyong.com/test-pins-from-pc-power-supply/
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11 Comments
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Parasuraman S
May 12, 2016 at 10:29 pm
Vow! The ingenuity with which you handle technical stuff, is really amazing! Looks like, sky is the limit for your talents! Hat's off!
Paris Azis
May 12, 2016 at 10:43 pm
Good job Chris. And I fully agree with your conclusion/proposal paragraph!
Best Regards
Albert van Bemmelen
May 13, 2016 at 1:12 am
Good repair Chris! Thanks. I guess you also copied the serial Eeprom
content in case the Swing Gates Board(s) need a new Eeprom, since it was already on a 8 pins socket?
The ULN2003 you succesfully replaced, are also frequently found on
controller Boards from Washing Machines, Tumble Dryers and Refridgerators. Including the Relays.
But so far only the LNK304, LN305 and some 47 Ohm Resistors needed
replacement. (After the LINKSWITCH chips got short circuited the 47 Ohm
Resister burnt through. These LNK chips are Lowest Component Count,
Energy-Efficient off-Line Switcher ICs).
It is wierd that they still use Relays instead of the Modern Solid State
electronic Opto-Triac components.
Albert van Bemmelen
May 13, 2016 at 8:25 pm
By-the-way: in addition to your previous article concerning using older
parts and tools I yesterday found an interesting use for the modern Pull
Tabs from Beverage Cans. People today are also collecting the Aluminium
Can opener Tabs to make other things with them. But I found them the
perfect tool to open your smart Phone or other Electronics Device with.
So why buy another expensive Smartphone opener Tool Set when you already
have the perfect tool for it right at your home for free!
Robert Calk
May 13, 2016 at 1:46 am
Great job and good advice. Thanks Christian.
Gary Gemmell
May 13, 2016 at 2:12 am
You are a very impressive engineer Chris , its not often I am impressed but all your articles are very interesting and you go beyond most electrical engineers with your knowledge of computing / firmware / car electronics - if I had a business , you would be a valuable employee!
beh
May 13, 2016 at 2:46 pm
Chris
thanks for very Crystal clear article and very good photos.
beh
Yogesh Panchal
May 13, 2016 at 3:28 pm
Christian,
Congratulations! for expanding area of knowledge.
suranga bandara, Suranga Electronics
May 13, 2016 at 4:28 pm
Hi, MR-Christian,
Very Good Article and Very professional Mr-Christian,
Thanks for sharing.!
Humberto
May 13, 2016 at 10:44 pm
Hi Christian, you have shared a professional article, and the quality of the photos is 100%, as usual. Keep up.
Chris
May 16, 2016 at 11:53 pm
Thank all of you for supporting my articles.
I try to post-share repairs which are not repeated so often
but usable all over the word.
I try to make a concept in my articles so the reader can maybe
learn something new from it, and so they can use my descriptions
on other fields of repairing too.
Thank you guys, you give me the power to write articles more
precise and better.
Thank you.