Has anyone seen a problem like this on the RAMP 1.4 board?

reprap
gplus
(Craig Walker) #1

Has anyone seen a problem like this on the RAMP 1.4 board? As you can see from the photo one of the power supply inputs (positive) has been overheating and caused significant plastic melting.

Any thoughts on potential causes? Wire gauge, poor soldering, wrong voltage? The board didn’t short out- it still works (not that I’m running it anymore.)

I’m about to buy a new one - and I’m wondering if it was a faulty board or something I did.

(James Malenko) #2

[1- you shouldn’t solder on there. 2- the wires should be rated for about 12-15 amps.

If the amperage is more than about 12 amps, that can happen.

(Mark Fuller) #3

Loose screw terminals can also cause overheating

(Viktor Dirks) #4

it’s sometimes caused too by oxidized surfaces of the pins or sockets

(Øystein Krog) #5

If you have a bad connection this will happen.
Unless you know some electronics messing around with this stuff is dangerous, that could easily have turned into a fire:/

It almost looks like you are using solid core cables, that is wrong! It’s also wrong to solder stranded cable.

When using screw terminals it is very important that you use stranded wires of the correct gauge and that you tighten the screw a lot so that the strands are properly clamped/crushed.

(Craig Walker) #6

Thanks everyone.

I measured the diameter of the braided copper wire I used and it’s approx 1mm. If it needs to support 15 amps it should have been thicker then that. Ill upgrade to 12 gauge.

I also recall that the screw on that terminal was a little finicky- so many be it was a loose as well.

Just glad I didn’t burn down my house. :grinning:

(Gary Tolley - Grogyan) #7

Yes, the wire gauge is too small.
Also make sure you don’t solder the wires before inserting them into the screw terminals

(Craig Walker) #8

There was no soldering on the braided wires - picture is mis-leading…

Good advice regardless. Thanks @Gary_Tolley_Grogyan & @Oystein_Krog

(Álvaro Rey Rodríguez) #9

I had the same problem a few years ago. I use a relay in order to conect the heated bed to the PSU and, and activate and desactivate it with the ramps. Using this system you reduce 11-12 amps of currente from the ramps conector

(Viktor Dirks) #10

… I’m avoiding relays for switching high currents fast/repeatedly - had one occasion, where the contacts ‘fused’, so won’t release and the oven run at full power (around 1200 degC) for some hours, melting all the parts he should temper at only 400degC :-/

For the RepRap-style heated beds I’m mostly using AC-SSR’s and separate 12V transformers (gets around 16 Volts from them) … or when it’s capable of, from the line with 230 VAC …

(Gary Tolley - Grogyan) #11

Just use a digital thermostat.

(Patrick Mehner) #12

Relay or external Heating-Bed parts to reduce current on ramps.
https://plus.google.com/+PatrickMehner/posts/T7f66am2CWb

(Viktor Dirks) #13

… this ‘endless heating’ was with an idustrial digital thermostat with relay-outputs - after this I’ve changed the relay for a SSR capable of the needed currents … it’s running without any problems for some 5 years now :wink:

(Duncan Gunn) #14

All that current and too much contact resistance by the looks of it. I just bought a cheap RAMPS and it has the exact same look to yours (except it ain’t toasty yet).

I think I’m going to measure, measure and measure some more… Just to be safe.

(Jasper Janssen) #15

@Viktor_Dirks was that a pottery kiln? Normal ovens in the electronics context aren’t nearly well insulated enough to hit 1200C.

(Viktor Dirks) #16

… no, this was an older ‘industrial’ oven from Leybold with even higher max. possible temp, but we reduced the drawn power to fit our power line :wink:

(Mark Fuller) #17

@Viktor_Dirks Ditto on replacing relays with an appropriately specced SSR. Every industrial oven (and one clothes dryer) I’ve converted is still running. One for over 20 years of continuous use.

(Glenn B) #18

Yes, I see that all the time with screw terms. The screws come loose and cause the connection to over heat.

(Duncan Gunn) #19

It looks like the source of heat was the mating surfaces between connectors. See where the hole is. It’s not around the screw terminal but it is around the fingers.

(Jasper Janssen) #20

Yep. Crappy connectors.