Hi, i just got my RAMPS 1.4 kit and am soldering it up now. I came to the point were the diode is put in and realized i'm missing the 1n4004 in my kit. Don't know if it was missing from the supplier, but anyway... I went through my boxes of scrap and found some SY320/8 diodes. I'd like to use these so i don't have to go shopping for a measly diode. A quick google tells me they're rated for 1040 V, 2A which should be plenty, but i'm not sure what the function of D2 is in the circuit. I think these should be way overspec, but they have a larger voltage drop 1,2 V instead of the 1,0 V of the 1N4004. Will this cause problems in the circuit? I'm only going to use D2 for now, I'll se later if I'll need to power the arduino via the RAMPS and have to use D1 as well. PS: Data for SY 320/8 found here... Regards Andreas https://reprap.org/forum/read.php?219,115614,115614#msg-115614 Tue, 13 Oct 2026 06:23:32 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?219,115614,115713#msg-115713 https://reprap.org/forum/read.php?219,115614,115713#msg-115713
I did a bit of googling last night and came to the same conclusion. If anything, the "bigger" diode should be more resilient if the polarities actually are reversed, since it can handle a bit more current and will fail later if the fuse doesn't blow quickly enough.

As a bonus I learnt to check the protection diode(s) in case a fuse blows, since they may have taken a beating. If they fail open circuit, they're no longer any good for protecting the circuit, but will seem to operate normally. If they fail short circuit, they will continue to blow fuses which is more obvious of course.

The voltage drop should be of negligable importance, since it's not in series with the supply (and even then 0,2 V extra would probably not be anything to worry about).

Regards
Andreas]]> anwe79 RAMPS Electronics Thu, 26 Jan 2012 06:15:18 -0500 https://reprap.org/forum/read.php?219,115614,115662#msg-115662 https://reprap.org/forum/read.php?219,115614,115662#msg-115662
If you are certain that you will not connect the 12 volt power supply backwards then you can safely leave D2 out of the circuit without any ill effects.

Based on the information you have provided about the SY 320/8, it should be a workable substitute for the 1N4004.]]> madscifi RAMPS Electronics Wed, 25 Jan 2012 22:58:56 -0500 https://reprap.org/forum/read.php?219,115614,115614#msg-115614 https://reprap.org/forum/read.php?219,115614,115614#msg-115614
I went through my boxes of scrap and found some SY320/8 diodes. I'd like to use these so i don't have to go shopping for a measly diode.

A quick google tells me they're rated for 1040 V, 2A which should be plenty, but i'm not sure what the function of D2 is in the circuit. I think these should be way overspec, but they have a larger voltage drop 1,2 V instead of the 1,0 V of the 1N4004.

Will this cause problems in the circuit?

I'm only going to use D2 for now, I'll se later if I'll need to power the arduino via the RAMPS and have to use D1 as well.

PS: Data for SY 320/8 found here...

Regards
Andreas]]> anwe79 RAMPS Electronics Wed, 25 Jan 2012 12:28:42 -0500