RAMPS 1.4 + 24v = Odd beeping?

Hello all,

I've recently swapped out my 12V power supply with a 24V power supply (and 24V heated bed). I removed D1 as noted in on the RAMPS 1.4 wiki and modified the current going to the hot-end with the "#define PID_MAX 64" setting. Everything is working fine, BUT when I instruct the hot-end to heat up (via prontrface) the RAMPS board starts making an odd beeping/buzzing noise and the hot-end LED indicator flashes.

Oddly, if I also heat the bed at the same time, the beeping may stop - although, the flashing LED continues to flash. I suspect this is a result of my use of the PID_MAX property. But I figured it wouldn't hurt to ask here to make sure I'm not about to fry something!

RAMPS 1.4
Marlin
Prontrface

Thanks,
Bobby

i have a ramps 1.4 but ... i dun have a beeper or buzzer ... how isit that urs come with a beeper?

i think he means an electrical buzzing?

Hey guys,

Yes, "electrical buzzing" is probably a better word. It's loud enough to clearly hear. It buzzes at regular intervals while the hot-end is being heated. I stops when "at temperature", then resumes during a heat-up cycle.

The buzzing may also stop when I use prontrface to move a motor, or click to heat the heated bed. I've been using printrboards, this is my first RAMPS board... so I'm not sure if this is normal or not.

I did several 1+ hour prints last night and everything seemed fine, but it's still nagging at me. If anyone has experienced this before, or can tell me this is normal, it would put my mind at ease!

Thanks,
Bobby

oh haha

ok i guess its a bad electrical contact, nozzle heater u say?

Does it sound like a tune or a buzz? I'm just wondering because I was under the impression that PID uses pulse width modulation which would have a specific frequency like a stepper motor at a specific feed rate.

Hey guys,

Redreprap: Yeah, nozzle heater.

cncjoe: Definitely a buzz. And the buzz always coincides with the LED lighting. I assume that at 12V, the LED would stay on solid until 'at temp'? The blinking is due to my using the PID_MAX. That's all fine, but everytime the LED blinks I hear a buzz. As I said above, the buzzing may stop when I move a motor or heat the bed, but the blinking LED continues to blink.

I did more printing last night and so far it hasn't affected anything, but it is making me concerned as no one else is jumping in saying, "oh yeah, this is normal".

I'll try to get a quick video up on youtube. Maybe I'm making a big deal out of nothing.

Thanks for responding.

Bobby

If you modified the power in the firmware I believe that whenever the hotend is "ON" you are using switching the power on and off really fast to fool the hotend into thinking it is still connected to a lower voltage.
To test this theory change the power the hotend is getting in the firmware and the sound should change pitch. It that is what happens it's fine.

You might want to check what the frequency of the PWM in the firmware is set to. You may find that, for whatever reason, it's in the audio range, and this (along with say a not 100% joint caused by a screw terminal or possibly on the FET output) is what is causing your noise issues.