RAMPS's D8 dead. Question about reliability.

It is a bit funny that I ask two questions in a row, one for heatsink for D8 and another one about D8 dead Yes, they are related
Anyway, my D8 mosfet is dead. This is a second time, and the question is: how reliable are RAMPS (China). Is it NORMAL to kill two in a year, and if not, what am I doing wrong?
Also, it is, probably, not overheating anyway, as it worked fine, and then simply refused to turn on... No lights on RAMPS, everything else is working but hotbed.
So, how often your electronic components die?

Well they are very cheap right? That only means poor quality. That said it easy to fix using an SSR dc to dc. That way your mosfet only activate the relay and don't need to handle the current from the bed.

You need to check the wiring and amperage pulled by the bed, thin wires, poor soldering and the cheap connectors used by the ramps board are usually the mayor factors for dead mosfets.

No failures on my ramps yet, but I guess I'm only a bit over a year in.

Any schematics for SSR dc to dc that you can recommend?
I thought that if the R of the hotbed is within 2-4 Ohms, it is fine. What do you mean by amperage? I mean, voltage is fixed, resistance is fixed, what can go wrong with amperage?
Also, what can poor connectors do? Do you mean wires from D8 to bed?

Quote
ggherbaz
Well they are very cheap right? That only means poor quality. That said it easy to fix using an SSR dc to dc. That way your mosfet only activate the relay and don't need to handle the current from the bed.

You need to check the wiring and amperage pulled by the bed, thin wires, poor soldering and the cheap connectors used by the ramps board are usually the mayor factors for dead mosfets.

As noted in your other thread - replace the MOSFET with a IRLB8743PBF. I always do this on the cheap China RAMPs. I don't even bother to see if the original MOSFET will work.
The other option is to use a RAMPs from Static Boards - more $$$ but I have been running one of theirs for 2 years on my printer with no issues.
[www.tindie.com]

Steve

---

My updated Instructable on our Prusa i3 Build
[www.instructables.com]

Thank you.