14 Gauge Wire to the Heated Bed = Fried Mosfets?

[JohnStack]

I burned a heated bed and board last week. I'm wondering if it isn't that I used 14 gauge wire from the board to the heated bed.

Thoughts? Seems to me that it might in some cases. I'll never know if I heated up the board too much while soldering or if it was the wire.
In any case, 18 gauge is recommended...so I thought I would ask.

I sure wish the fuses on the Rambo actually protected everything related to heat.....

[Jimustanguitar]

Using larger wire (lower gauge number) is never detrimental. Especially on a heated bed circuit. Unless you're intentionally trying to heat the wire itself or to use it as a resistor, bigger is always better.

In what way do you think that the heat from soldering hurt the bed? Can you inspect what's left? Which end burned up?

I'd be much more suspicious of a loose connection at the green captive screw connector on the Rambo. Resistance there will cause burning and melting without overdrawing the fuse.



Sorry for your luck You might contact SeeMeCNC to see if they can accomodate a better price for you on a new board. I don't know if they get a special price or not since they don't actually manufacture the Rambo, but it's worth a shot.

[JohnStack]

Thanks for the feedback. I thought there might be increased draw but all in all, even though I checked for continuity, I heard a pop...

[Edit] The solder points at the thermistor lifted.

I have never cared for those small green block connectors...geneb's suggestion about a separate connector (a daughter?) is so much better.

I'm good with SeeMeCNC. Already ordered up and should be here today. I truly hate building a new one to be stuck and even worse than that, have it be while I'm in another continent!!! LOL Compounding it further is bench testing on my personal machine only to have it blow too! Wow.

There was this joke I heard somewhere about a priest and a donkey. I can't remember the joke well but it was something like the only command the donkey understood to go forward was "Patience." The person riding the donkey was at the top of the steep cliff and both the rider and the donkey were scared. Making a mistake, the rider said "Patience Jackass, Patience."

[Eaglezsoar]

Thanks for the feedback. I thought there might be increased draw but all in all, even though I checked for continuity, I heard a pop...

[Edit] The solder points at the thermistor lifted.

I have never cared for those small green block connectors...geneb's suggestion about a separate connector (a daughter?) is so much better.

I'm good with SeeMeCNC. Already ordered up and should be here today. I truly hate building a new one to be stuck and even worse than that, have it be while I'm in another continent!!! LOL Compounding it further is bench testing on my personal machine only to have it blow too! Wow.

There was this joke I heard somewhere about a priest and a donkey. I can't remember the joke well but it was something like the only command the donkey understood to go forward was "Patience." The person riding the donkey was at the top of the steep cliff and both the rider and the donkey were scared. Making a mistake, the rider said "Patience Jackass, Patience."

John, I have a hard time understanding how a 14 gauge wire has anything to do with the solder points at the thermistor lifting. I am not knocking your
craftsmanship because I know you well enough to know that you know what you are doing but it certainly sounds as though there was a problem with
the solder connections on the Onyx. Stuff happens I hope that your Onyx is still usable. Jim is right, it usually is problems with the captive screw on the
connector. These need to be tight and checked once in a while to maintain tightness. We have all seen the pictures of the melted connectors. Best of luck
to you John.

[Jimustanguitar]

The pads on the Onyx require a lot of heat to solder to. Most low wattage irons can't do it quickly and you end up with a lot of stray heat that can melt other things... MCM usually has 50+ watt temperature controlled stations for sale or on model-end clearance. Look for the Tenma brand if you're in the market for a first 'real' soldering iron.

If I were to redesign the Onyx, it would have an ear on it that stuck out beyond the round build plate with drilled holes to solder on connector blocks.

[Captain Starfish]

I used 14G on my Max bed and found no problems with the soldering.

Where I DID have an issue was at the other end on the RAMBO, my wires would not fit into the screw terminals. I had to shave off quite a few strands to get the bundle to fit in there and there was a disturbing number of stray strands kicking around the first time I attempted this. Second time I managed to get it all under control.

Sounds like you had a short somehow - either the thermistor leads shorting the bed or possibly at the connector on the other end. If you have a multimeter it's worth checking the resistance at the screw terminals.