Heatbed Relay Melted

For the last couple of prints I noticed a strange burning smell from my printer. The printer was functioning fine so I wrote it off as the filament I was using. However this morning I started a print and the smell was stronger. I looked all around and noticed the heatbed relay had melted and there was a small amount of smoke coming from it. The printer was still functioning fine.

I turned off the printer immediately.

Anyway, I was wondering if I can just throw a new headbed relay in there which is relatively inexpensive... Or was this caused by a bigger problem? Here are some pictures.

Attachment 3810
Attachment 3811

Q1. How many amps does your power supply put out?
Q2. How long was the printer operating for when it was doing "the last couple of prints"?
Q3. What was the room temperature at the time?

Have a look at Contact Data in the spec sheet for the relay:

http://www.components.omron.com/components/web/pdflib.nsf/0/7270ED3CFB55EBFF85257201007DD4FF/$file/G8QN_G8QW_0607.pdf

Could you have exceeded its max carry current?


Old Man Emu

Having had a look at the build instructions, relay specs and all, my answer is that the red wires, which have overheated and melted the connector, are too small for the current that they need to carry. If you look at the build instructions you will see that the wires from the PSU to the relay and from the relay to the heated bed are very thick. They have to be to carry the full current. What you have are thin wires which resist the current and heat up, melting your connection. Here is a picture of my relay set up on my i8 printer:

Attachment 3818

See how thick those wires are? I used speaker wire from a car doof doof music amplifier.

Read this: http://3dprintboard.com/showthread.p...how-to-connect

Buy a new relay and wire it in using the thick wire. Problem solved!

Old Man Emu