LCD flickering like crazy, any idea why? Makerfarm I3, 8" Ramps 1.4...... My LCD screen is flickering and it's driving me crazy. I've tried 2 different power supplies, the second one had the 2, 4pin connectors and is rated to 20A on the 12v rail. My first one only had 1, 4pin connector, so I had to use one of the other power wires, but either way the LCD flickers with both power supplies. I've contacted Colin and he said he doesn't know what the problem is. https://reprap.org/forum/read.php?151,265124,265124#msg-265124 Thu, 13 Aug 2026 14:55:47 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?151,265124,792772#msg-792772 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,792772#msg-792772
With one caveat - While 99.9% of USB cables have internal wires coloured Black, white, green, red, and there is a colour coding standard where Red = 5V...

DON'T ASSUME that this colour code has been respected inside a random sealed-plug USB cable from Far, Far Away...

I spent a frustrating time debugging an implementation, where the USB cable had 5v=black!!!

The USB cable was otherwise perfectly well made, had I not cut it I would never have known. I have since checked and found a lot of my similar short cheap blue cables that come with Arduino clones have similarly random internal wiring. I am always amazed at how reasonable quality items can be for such low prices, just don't expect standards to be followed anywhere they are not plainly visible!]]> alexgibson3d General Mendel Topics Wed, 18 Oct 2017 09:53:47 -0400 https://reprap.org/forum/read.php?151,265124,719462#msg-719462 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,719462#msg-719462 edgeconsults General Mendel Topics Thu, 03 Nov 2016 12:35:08 -0400 https://reprap.org/forum/read.php?151,265124,325534#msg-325534 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,325534#msg-325534 blumojo General Mendel Topics Sat, 15 Mar 2014 23:51:20 -0400 https://reprap.org/forum/read.php?151,265124,268781#msg-268781 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,268781#msg-268781
I'd clip lead the DVM onto the +5 and ground on the display board. Watch the +5 and see what it's doing when you see the filcker. The DVM may not be fast enough to catch every burp, but it shouuld show something.]]> uncle_bob General Mendel Topics Mon, 18 Nov 2013 11:01:36 -0500 https://reprap.org/forum/read.php?151,265124,268389#msg-268389 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,268389#msg-268389 vetteguy112233 General Mendel Topics Sun, 17 Nov 2013 13:27:55 -0500 https://reprap.org/forum/read.php?151,265124,268378#msg-268378 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,268378#msg-268378 uncle_bob General Mendel Topics Sun, 17 Nov 2013 13:16:02 -0500 https://reprap.org/forum/read.php?151,265124,268375#msg-268375 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,268375#msg-268375 vetteguy112233 General Mendel Topics Sun, 17 Nov 2013 13:12:24 -0500 https://reprap.org/forum/read.php?151,265124,267792#msg-267792 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,267792#msg-267792 uncle_bob General Mendel Topics Fri, 15 Nov 2013 22:17:39 -0500 https://reprap.org/forum/read.php?151,265124,267786#msg-267786 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,267786#msg-267786 vetteguy112233 General Mendel Topics Fri, 15 Nov 2013 21:54:30 -0500 https://reprap.org/forum/read.php?151,265124,267227#msg-267227 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,267227#msg-267227
Quote
vetteguy112233
The only reason it bothers me is because I'm worried either I've hooked something up incorrectly or my power supply isn't doing it's job.

Yup, I went through this phase, and I was right to be worried. Not everything was right with my ramps board, and it was (afaik) delivered to me not right. The LCD, for instance, would not work because a non-zero but insufficient voltage was making it to the LCD. And I've found voltage on a pin where it definitely should not be. I didn't get the LCD functional until I removed D1 and powered the Arduino from my ATX supply's 5V rail. Everything I currently need to work works now. And for what it's worth, my flicker is a just subtle change in brightness.

So don't think of my post as me telling you that everything's ok. It's more like the guy in the support group who is proudly leading a functional life despite his affliction.

That said, I'm replacing my board. $20 to avoid a weekend's frustration is a no-brainer, and then I'll have a board to take greater risks with.]]> Karmavore General Mendel Topics Thu, 14 Nov 2013 23:29:07 -0500 https://reprap.org/forum/read.php?151,265124,267150#msg-267150 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,267150#msg-267150 uncle_bob General Mendel Topics Thu, 14 Nov 2013 17:24:05 -0500 https://reprap.org/forum/read.php?151,265124,267143#msg-267143 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,267143#msg-267143
My previous power supply didn't have the extra 4 pin connector, so I used a regular connector. This newer power supply did have the extra 4 pin power connector, so I used the black and yellow from it to go into the other side of the ramps board.]]> vetteguy112233 General Mendel Topics Thu, 14 Nov 2013 17:08:23 -0500 https://reprap.org/forum/read.php?151,265124,267122#msg-267122 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,267122#msg-267122
That said, if I remember to check the voltages, I'll let you know what I learn.

FWIW, I think the stepper noise is a symptom unrelated to the cause.]]> Karmavore General Mendel Topics Thu, 14 Nov 2013 16:31:31 -0500 https://reprap.org/forum/read.php?151,265124,267026#msg-267026 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,267026#msg-267026 vetteguy112233 General Mendel Topics Thu, 14 Nov 2013 13:58:45 -0500 https://reprap.org/forum/read.php?151,265124,266687#msg-266687 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266687#msg-266687 uncle_bob General Mendel Topics Wed, 13 Nov 2013 21:31:58 -0500 https://reprap.org/forum/read.php?151,265124,266677#msg-266677 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266677#msg-266677 vegasloki General Mendel Topics Wed, 13 Nov 2013 20:16:30 -0500 https://reprap.org/forum/read.php?151,265124,266673#msg-266673 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266673#msg-266673
Simple (because I don't have to do all the work) way to check it - grab a DVM and start monitoring +5 to ground along the path. At some point you will find the +5 bouncing around. What ever is between that point and the regulator is suspect.]]> uncle_bob General Mendel Topics Wed, 13 Nov 2013 20:07:24 -0500 https://reprap.org/forum/read.php?151,265124,266662#msg-266662 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266662#msg-266662 vetteguy112233 General Mendel Topics Wed, 13 Nov 2013 18:58:58 -0500 https://reprap.org/forum/read.php?151,265124,266469#msg-266469 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266469#msg-266469 uncle_bob General Mendel Topics Wed, 13 Nov 2013 12:48:22 -0500 https://reprap.org/forum/read.php?151,265124,266442#msg-266442 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266442#msg-266442
Quote
uncle_bob
I'd dump the PC power supply on most of these printers. An industrial 12V 30A supply is pretty cheap ($44 or less).

Yup, and I'm gonna. In fact, I'm going to give 24V a whirl, but that's a discussion for numerous other threads. I made the choice to go with the power supply when my objective was to minimize cost. In retrospect, that decision cost me a lot more in time than it saved in money, but I learned a lot in the process. I wouldn't recommend the ATX route to anyone but the most price sensitive who already have a suitable one on hand.]]> Karmavore General Mendel Topics Wed, 13 Nov 2013 12:03:00 -0500 https://reprap.org/forum/read.php?151,265124,266323#msg-266323 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266323#msg-266323
As I've mentioned a number of times, I'd dump the PC power supply on most of these printers. An industrial 12V 30A supply is pretty cheap ($44 or less). They are much better suited to this sort of application.]]> uncle_bob General Mendel Topics Wed, 13 Nov 2013 07:42:50 -0500 https://reprap.org/forum/read.php?151,265124,266122#msg-266122 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266122#msg-266122
Rather than ramble on like a crazyperson, I think I'll see if I can make the whole thing moot with a new RAMPS. Troubleshooting this old one is no longer as much fun as it used to be.]]> Karmavore General Mendel Topics Tue, 12 Nov 2013 22:59:59 -0500 https://reprap.org/forum/read.php?151,265124,266109#msg-266109 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266109#msg-266109 uncle_bob General Mendel Topics Tue, 12 Nov 2013 21:33:44 -0500 https://reprap.org/forum/read.php?151,265124,266107#msg-266107 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266107#msg-266107
I'm running off a 420W Antec Earthwatts power supply, and a line from its 5V rail is definitely what is powering the LCD. (ATX 5V --> ramps aux pin --> mega board) I've completely removed the RAMPS D1 diode that would have otherwise been providing the power, and I didn't do so neatly. (I've totally replaced D2, which I fried while checking voltages uncautiosly.) I've got a thread on here somewhere discussing my issues, including false indications of *hotend* MINTEMP when starting the *heated bed*, unless the hotend is already reading about 25C or so. My RAMPS board, I suspect, has always been a little flighty, and I look forward to starting with something new for this next one. This PC power supply might not be particularly well suited for this job, either.

If any of this sounds like a known issue, I'd be happy to listen with the emotional detachment I now consider mandatory for this particular issue. :S:XB)

(Sorry to hijack this, vetteguy. Jump back in here and I promise to do what I can to help.)]]> Karmavore General Mendel Topics Tue, 12 Nov 2013 21:23:28 -0500 https://reprap.org/forum/read.php?151,265124,266048#msg-266048 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,266048#msg-266048 uncle_bob General Mendel Topics Tue, 12 Nov 2013 18:15:00 -0500 https://reprap.org/forum/read.php?151,265124,265983#msg-265983 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,265983#msg-265983 Karmavore General Mendel Topics Tue, 12 Nov 2013 15:03:34 -0500 https://reprap.org/forum/read.php?151,265124,265923#msg-265923 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,265923#msg-265923 uncle_bob General Mendel Topics Tue, 12 Nov 2013 12:16:36 -0500 https://reprap.org/forum/read.php?151,265124,265917#msg-265917 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,265917#msg-265917 RicardoGA General Mendel Topics Tue, 12 Nov 2013 12:00:01 -0500 https://reprap.org/forum/read.php?151,265124,265132#msg-265132 Re: LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,265132#msg-265132
1) Make sure the cables are all intact. Ribbon cable is easier to damage than you might think.
2) Check the solder joints on the board between the Ramps and the cables.
3) Same with the solder joints on the Ramps and on the Mega.

If it's just the backlight (text stays ok) then check:

1) Solder joints on the contrast adjust pot and the pot it's self (adjust it a little and see what happens)
2) The connector between the LCD and the main board

I'd bet 3" of slightly used filament that it's a dirty spot on the pot. :)-D. If the LCD module looses power even for a second the text goes nuts. Same is true if you spark it (it's low humidity ESD season again ..).]]> uncle_bob General Mendel Topics Sun, 10 Nov 2013 21:03:34 -0500 https://reprap.org/forum/read.php?151,265124,265124#msg-265124 LCD flickering like crazy, any idea why? https://reprap.org/forum/read.php?151,265124,265124#msg-265124
My LCD screen is flickering and it's driving me crazy. I've tried 2 different power supplies, the second one had the 2, 4pin connectors and is rated to 20A on the 12v rail. My first one only had 1, 4pin connector, so I had to use one of the other power wires, but either way the LCD flickers with both power supplies.

I've contacted Colin and he said he doesn't know what the problem is.]]> vetteguy112233 General Mendel Topics Sun, 10 Nov 2013 19:51:19 -0500