Connecteur Heatbed surchauffe
Bonjour !
je venais de changer le connecteur (molex), car il avait légèrement chauffé et le courant passait mal. J’ai pris un original sur le site de prusa. J’ai fait une demie douzaine de print sans pb (dont un benchy avec le prusament petg black mat, d’une grande finesse). Et à l’instant j’ai senti une ordeur pas normale.
Le connecteur + le fil allant à la thermistance étaient en train de surchauffer.
On voit meme en arrière plan la grille du boîtier qui a fondue au contact du cable !
Une idée du problème ?
Merci pour vos conseils et avis.
J’adore ma MK2S, elle fait des prints impeccables, pas envie d’en changer meme si la MK4 me fait de l’oeil !
RE: Connecteur Heatbed surchauffe
Mon francais et mal, so I answer in English.
To me it looks you have a shorted-circuit. Get yourself a multimeter and measure the resistance, untill you find where the short is.
Maybe inside the connector? Anyway it is a process of measuring, getting things apart untill you find the error.
Regards, Eef
RE: Connecteur Heatbed surchauffe
Thx Eef (english bellow)
Hélas, je ne sais pas trop quoi tester avec un multimètre. A l'exception de ce "problème", le plateau chauffait normalement (j'étais sur un print en PETG, plateau à 90°c) et tout le reste de l'imprimante fonctionne parfaitement.
Est-ce que le plateau de chauffe pourrait être un "consommable" ? Après plusieurs années, il doit être changé, car il nécessiterait trop de puissance pour chauffer ?
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But unfortunatly, i'm not sure to what I have to test.
I'm wordering if the heatbed can be a part of the problem ? is it a piece that should be changed after couple of years of printing ?
RE: Connecteur Heatbed surchauffe
What and how to test:
- You want the heat in the heatbed and not elsewhere (like in the connector in the wires what lead to the heatbed).
Why is the heatbed hot and (normally) not the wires? This is because in the heatbed the resistance of the wires is much greater. This resistances makes that amperage is transformed to heat (nice formula: Power transformed to heat = I x I xR (so amperage x amperage x resistance).
- If not only the heatbed is heated but also other places (in the wire), then there are two possibilities (often in combination):
1. The amperage is higher then it should be. This happens if there is a shortcut. The two wires (+ and -) touch (or almost touch) before the heatbed. That will give a higher amperage and (see formula) give extra heat . If the amperage would be very high, the control unit would probably not be able to deliver the amperage and shuts itself off (or goes up in smoke).
2. If there is extra resistance on other places, then the heatbed, in the wires. That would create a hotspot. (the amperage will be the same, but the higher resistance will cause the extra heat. Example: Yesterday I had a heater connected to a 12 volt PSU. The wire was too short, so I took another wire, what was lying on the bench. This wire was much thinner. And yes, you guess what happened. The wire got hot and the plastic insulator melted (before the heater was hot!).
Looking at the picture, around the connector (or the connector itself) gives probably extra resistance (then the connection is bad) and/or there could be a (partly) shortcut on that spot.
If you have no mulimeter to check the resistance/voltages, etc, then I would do this:
1. Check the connector, maybe reassemble it, so you are sure the connection is very good.
2. If it is soldered, then resolder it, use enough resin so the solder nicely flows.
3. Check if the insulation is OK and the two wires do not touch or almost touch.
4. Also check if the wires could touch metal parts of the enclosure.
Maybe this helps. Regards, Eef
RE: Connecteur Heatbed surchauffe
PS:
Looking at the picture I also see a sharp kink in the cable. Could be a bad point too.
So check the wires not only close to the connector, but also al the wire untill the heatbed.