I missed the part about the 5mm green connectors only handling 12 amps when I built my printer. It ran well for about a month, maybe more, but the other day it cooked the connector that was feeding power to the big mosfet pair. The connectors on each side of that one were also damaged. One of the mosfets was driving my heated bed (11 amps) and the other was driving my hot end heater (2 amps). The board may be slightly damaged where the input was, but the outputs are fine, and the board is working to control things that didn’t get broken.
I was thinking I would use the jumpers that can provide an alternate source of power to the big mosfets and then replace one of the output connectors and run my hot end heater from that. The heater uses 2 amps, which should be fine since when running off the jumpers those big mosfets can support 4 amps.
Can I use the big mosfet in the mixed mosfet pair to drive my heated bed? The docs say big mosfets can handle 20 amps, but I want to be sure I’m getting everything correct such that I won’t have issues like this again.
If there’s a better way to rebuild than what I’ve come up with, feel free to let me know too. Thanks.
Imported from wikidot
This is working fine. I was initially concerned that the main connector would now have 13 amps flowing through it, but on the side of that connector is a “15A” so I think it’ll be good.
The main ( VBB ) connector is also limited to 12.5A, so what you are doing is likely not safe. It may work for now, and fail later ( which already happened to you if I understand correctly ).
I strongly advise you use a SSR for your heated bed instead of a mosfet, and make sure you do not go over the connectors’ ratings for all of the rest.
If you need any help don’t hesitate to ask.
I shall look into that then. Maybe my connector with 15A on the side came from something else, as I just have a bunch of them in a bag.
The example in the 3d printer guide has the reader use the 2 outputs from the big mosfets for their heater and hot end. Perhaps that example should be re-worked to maybe just have the heater there and the small mosfets, or mixed mosfets used for the hot end. Less chance of someone following the example like I did and overloading the connectors.
Here’s the relevant part (look to the Example heading). httpCOLON//smoothiewareDOTorg/3d-printer-guide#toc11
I’m willing to update it, just not sure what the suggested changes should be.