No heat, blown fuse?

Glacian22 · Post by **Glacian22** » Fri Sep 11, 2015 3:40 am

Yesterday I was running a print only to have it die unexpectedly from with the thermal runaway message - your hotend is heating up slower than expected, thermistor may be decoupled, or whatever the actual wording is. I reset the printer and heated it back up only to have the same thing happen during heatup, it never even got to the print. Now it won't heat up at all, neither the hotend nor bed. I've checked with a multimeter, there's no power going to either one, but the printer itself is still powered.

If it were a problem with the power supply, I'd have expected nothing to get power at all, and if it were a blown fuse on the Rambo, I'd thought that it would happen all at once, not over the course of a couple hours with the heat coming and going. Does anyone know what this could be? Thanks.

Glacian22 · Post by **Glacian22** » Fri Sep 11, 2015 5:11 pm

No ideas?

bubbasnow · Post by **bubbasnow** » Fri Sep 11, 2015 5:31 pm

what temps are your thermistors reading?

Glacian22 · Post by **Glacian22** » Mon Sep 14, 2015 5:10 pm

Both the hotend and bed are reading at room temp, so I don't think it's a thermistor issue.

mhackney · Post by **mhackney** » Mon Sep 14, 2015 5:12 pm

What controller board and hot end are you using? It does sound like a fuse on RAMBo. The big blue one likely. Pull it and see if its blown.

Glacian22 · Post by **Glacian22** » Mon Sep 14, 2015 5:47 pm

RAMBo and Prometheus. I'll check that fuse, thanks!

Glacian22 · Post by **Glacian22** » Mon Sep 14, 2015 5:50 pm

Looks like it's still intact. :/ Do any of the smaller ones deal with hotend and bed power?

Glacian22 · Post by **Glacian22** » Thu Sep 17, 2015 11:51 pm

I tried changing firmware just in case there was a bug, but going back to repetier .91 didn't help. Guys I am lost here...there's just no power flowing to the hotend or bed, but everything else is fine.

Earthbound · Post by **Earthbound** » Fri Sep 18, 2015 2:48 pm

Glacian22,

Need to know what board version your RAMBo is. There are differences in how various subsystems (logic, motors, fans, etc.) get their power, so troubleshooting fuses by symptom is version specific.

In the meantime, I'd check the following:

Continuity of each fuse (I'll suggest removing from fuse holders for most honest result).
Voltage from power supply (check at input to RAMBo, and check all three pairs of terminals).
Does LCD display work when USB cable is unplugged?

Welcome to the SeeMeCNC Community

No heat, blown fuse?

No heat, blown fuse?

Re: No heat, blown fuse?

Re: No heat, blown fuse?

Re: No heat, blown fuse?

Re: No heat, blown fuse?

Re: No heat, blown fuse?

Re: No heat, blown fuse?

Re: No heat, blown fuse?

Re: No heat, blown fuse?