Bed Input Power  

RE: Bed Input Power

Posted by: @gorillamotors

I have had my Prusa MK3 for over 3 years now and I have things crop up that needed to be fixed. This is the second time in 1 month that my Bed Input Power (red positive wire) that has been fried and needed to be replaced. I had one occur with the original einsy control board and one with the new one. What is happening??

 Bed-input-power-1.jpg

 Bed-input-power-2.jpg

Gorilla Rocket Motors?  I have had this happen.  I would guess you had a short or loose connection.  I have to keep checking screws monthly to ensure they are secure.  

RE: Bed Input Power

Posted by: @cwbullet

 

Gorilla Rocket Motors?  

That's me

RE: Bed Input Power

I am the same cwbullet from TRF.  I miss your motors.  Great stuff.  

RE: Bed Input Power

Posted by: @cwbullet

I am the same cwbullet from TRF.  I miss your motors.  Great stuff.  

Thanks. We are trying to get the new president here set up and running of GRM. Hopefully soon.

RE: Bed Input Power

@gorillamotors

If it is close to FL and they want to hit some fields to push their wares, I am still the Prefect in SC.  

RE: Bed Input Power

@cwbullet

I will let him know.

RE: Bed Input Power

Hot joints resulting from poor crimp terminations are a major cause. Loose terminals are also a factor as heat cycling causes screws to walk out.

Some people overtighten the screws and strip the threads. Either way, whether it is screws that are loose from walking out or from stripped threads, a lose terminal is also a hot joint

A couple of ways to combat it:

Don't use the factory cables. They suck - period. The cable gauge is borderline and the factory crimping sucks.

Make your own from high temp silicone insulated wire with a conductor cross sectional area of 2.5mm2 (14 AWG in numpty speak). Easy to get from electrical wholesalers, etc or electronics hobby stores.

After crimping the terminals on, you can seal and backfill them with solder, but be sure to make sure the solder is drawn back into the crimp. Putting a blob over the end achieves nothing.

Using this larger CSA wire will reduce impedance, which will reduce or eliminate the heat at the terminals. It's still advisable to check the screw tension now and then.

RE: Bed Input Power

Posted by: @morphias

Hot joints resulting from poor crimp terminations are a major cause. Loose terminals are also a factor as heat cycling causes screws to walk out.

 

Some people overtighten the screws and strip the threads. Either way, whether it is screws that are loose from walking out or from stripped threads, a lose terminal is also a hot joint

 

A couple of ways to combat it:

 

Don't use the factory cables. They suck - period. The cable gauge is borderline and the factory crimping sucks.

 

Make your own from high temp silicone insulated wire with a conductor cross sectional area of 2.5mm2 (14 AWG in numpty speak). Easy to get from electrical wholesalers, etc or electronics hobby stores.

After crimping the terminals on, you can seal and backfill them with solder, but be sure to make sure the solder is drawn back into the crimp. Putting a blob over the end achieves nothing.

 

Using this larger CSA wire will reduce impedance, which will reduce or eliminate the heat at the terminals. It's still advisable to check the screw tension now and then.

I am not sure they suck.  I have 7 of 8 MK3S printers working for 2 years on their initial wires.  I think they require that we do regular maintenance and you should do that even with “superior” wiring harnesses.  It is a matter of safety.