Elevator Motherboard Problem Solved
The problem of this elevator motherboard was not showing the number of each level of building correctly as seen in the below photo:
So I opened up the box of the mother board and with a close inspection I found that there were 8 ICs on the board with same part number 74HC573N. The first question I asked myself was why this motherboard has 8 ICs with the same part number ?
It has 8 level building> and 8 seven segment diode display>each seven segment need one driver IC. I knew that each seven segment LED diode would be drive by one IC and that IC was the 74HC573N. Google confirmed that these ICs are the driver of seven segments diodes. Fortunately the manufacturer of the board had made this a friendly board because the 8 ICs were installed on IC sockets.
Just substitute the suspected IC and see the result. For your information I found six ICs that were causing the problem and two were tested good (level 2 and 3) but I replaced them all for reliability purpose since it was easy to replace with the IC socket installed. The function of the elevator motherboard was back to normal after replacing all the 8 ICs.
Note 1: AFP Co.Ltd is a local manufacturer and producing this kind of motherboard. You may open the following link below and visit the manufacturer website:
Note 2: I also found some cold soldering joint in some of the panels and I resoldered them all.
The cost of this repair was only USD3.00!
This article was prepared for you by Mr Beh, one of our ‘Master Authors’ from Iran.
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