Hi,
To explain my problem, we have a cnc production machine in my shop that was overheating and the machine had no way to tell us except shutdowning for the time it was cooling itself. So i made a module that have a ds18b20 digital sensor connected directly in the hydrolic system that tell me the temperature in real time, and set off an alarm when a programmed temp is reach. Its perfect to prevent loss of production, but i have a problem with it. The lcd1602 that i use to output data is blowing every couple month. The first time it was my fault, i put no limiting resistor on the backlight. The second time, no sign of overheating except for the main chip on the lcd. Changed it again. This time, when the lcd died, i noted that the lcd was hot during the machine on time, and when i shutdown it to close the shop, the lcd was cold. So i took my multimeter and tried to seek any unwanted voltage, and i found that there is a 3,2V AC current coming from the case (stainless steel case). I removed the mounting and put a layer of rubber behind it and mounted it with plastic bolt to isolate it from the machine. But i still have a 2.4V AC coming from the machine, probably by some sort of induction from a motor inside. So my plan is to try to ground this AC to protect the module.
Now you have the background (which may help you find something i missed), i'm wondering if i can ground the case by connecting a wire from the Negative side of the wall wart, before the voltage regulator that power the module on the case. Will the ac go to the neutral of the shop electrical system ( that is connected to the earth ) ???. I dont know exactly how those wall wart do their jobs so i dont know if i can do it that way.
So thanks in advance for helping me with this situation. I'm getting tired if wiring new lcd to this module.
Mikael Lavoie
To explain my problem, we have a cnc production machine in my shop that was overheating and the machine had no way to tell us except shutdowning for the time it was cooling itself. So i made a module that have a ds18b20 digital sensor connected directly in the hydrolic system that tell me the temperature in real time, and set off an alarm when a programmed temp is reach. Its perfect to prevent loss of production, but i have a problem with it. The lcd1602 that i use to output data is blowing every couple month. The first time it was my fault, i put no limiting resistor on the backlight. The second time, no sign of overheating except for the main chip on the lcd. Changed it again. This time, when the lcd died, i noted that the lcd was hot during the machine on time, and when i shutdown it to close the shop, the lcd was cold. So i took my multimeter and tried to seek any unwanted voltage, and i found that there is a 3,2V AC current coming from the case (stainless steel case). I removed the mounting and put a layer of rubber behind it and mounted it with plastic bolt to isolate it from the machine. But i still have a 2.4V AC coming from the machine, probably by some sort of induction from a motor inside. So my plan is to try to ground this AC to protect the module.
Now you have the background (which may help you find something i missed), i'm wondering if i can ground the case by connecting a wire from the Negative side of the wall wart, before the voltage regulator that power the module on the case. Will the ac go to the neutral of the shop electrical system ( that is connected to the earth ) ???. I dont know exactly how those wall wart do their jobs so i dont know if i can do it that way.
So thanks in advance for helping me with this situation. I'm getting tired if wiring new lcd to this module.
Mikael Lavoie