Mega's AMS 1117 5V Getting Hot with RAMPS 1.6

I have placed RAMPS 1.6 on my Arduino Mega Clone. When I feed RAMPS 1.6 with 12V 2A, the AMS 1117 component is getting hot. For testing, I have placed Adafruit Motor Shield on my Arduino Mega Clone and fed it with 12V 2A, the same component did not get hot.

  • Does this show that something is wrong with my RAMPS 1.6?
  • What do you think can be the problem?
    I have a multimeter, which components should I test for discovering the damaged component?

I have figured out the problem. It happenes when the RepRapDiscount FULL GRAPHIC Smart Controller is plugged.

What was the problem?

I have now determined the problem correctly. When I connect the EXP2 cable of Reprap Discount Full Graphic Smart Controller to RAMPS 1.6 and power it up with 12V 2A, Mega's A1117 (which is the 5V Regulator component) over heats. This does not happen when the kit (Mega+RAMPS 1.6+128*64 LCD+4xTMC2208) is supplied with the USB of the computer.

Did you read the WARNING?
https://reprap.org/wiki/RAMPS_1.6

I have purchased RAMPS 1.4 and it is doing the same heating up issue as soon as I connect EXP2 and 12V 2A additional power supply. Strongly probable that I have something wrong with the Reprap Discount Full Graphic Smart Controller.

That's a whole different problem from the mega 1117 getting hot

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Okay, it seems that I have the issue mentioned in the following link.

https://reprap.org/wiki/Arduino_Mega_Pololu_Shield#Known_issues_and_limitations

Workarounds include
(a) Removing D1 on the RAMPS and providing external 5V power to the Arduino/RAMPS,
(b) Driving the backlight of the graphical LCD from 12V through a series resistor instead of from 5V (a 120 ohm 1W resistor is about right for 12864-type displays),
(c) Using an Arduino variant with a more powerful voltage regulator (e.g. Taurino),
(d) Replacing D1 by 3 or 4 diodes connected in series.

I have tried (a), i.e., I unsoldered D1 diode and it worked. But this time I need to power Mega from USB port with 5V and RAMPS from Power port with 12V 2A. When power Mega from Power port, the screen fades out and does not update but the encoder and the buzzer work.

I want to power both Mega and RAMPS from Power ports 5V and 12V, respectively.

Therefore, I want to solder D1 back in to its position, and apply (b) or (d) but I need some information about these workouts.
How can I apply (b)? How can I find which pin corresponds to the backlight of the 12864 LCD?
For (d), I do understand what should I do but where can I find the details of D1 diode?

Thank you.

Post a schematic showing what you plan on changing.

Regarding my post #8, I searched the internet. But I still have no idea for (b).
Bur for (d), I figured out that D1 diode is 1N4004.

  1. Which details of 1N4004 should I take into account (voltage or ampere)?
  2. What happens when I use 3x (or 4x) 1N4004 in series?
  3. I could find 1N4007 in a store here, can I use 1N4007 instead of 2.5x 1N4004? If so, I want to use 1x 1N4004 and 1x 1N4007 in series.

The 1N4004 is a 400V diode and the 1N4007 is a 1000V diode but since you are only dealing with 12V it doesn't matter which you use. The important thing is the current rating, both are 1A.

I would use 4 in series, you can mix them up, in this application it doesn't matter.
Two 1N4004s and two 1N4007s in series or any combination thereof would be OK

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Each diode has a voltage drop across it, usually around 0.7V at low current, as much as 1.0V at 1amp for the 1N400x type diodes. The string of four diodes lowers the voltage going into the regulator on the Mega, lowering the amount of power that the regulator needs to dissipate. The total power being dissipated into heat is not changing, it is being spread across the voltage regulator and the diodes.

Using a buck converter to convert the 12V to 5V, then powering the Mega from the 5V pin, would be another way to implement option (a) without needing an additional external power supply.

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After applying (a), I had to power Mega front the USB port. Using the barrel jack on Mega was not useful to make the 12864 LCD work properly (the screen was not refreshing and the back light was dimmed). Thus, I believe, I will have the problem as long as RAMPS have a power link to Mega, when I use 12vā†’5v buck converter to power up Mega.

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