Fix to prevent heat bed cutting out using relay switch

Just to add another datapoint - I don't any significant drop in bed temperature when my print fan comes on. My basement is around 18C or so. I have the new MOSFET and 14A Polyfuse installed. The printer can keep the bed (at least the thermistor underneath) at 114C. It might drop to 111C at the most. I do have sheet of metal partially blocking the rear from cross breezes. My print fan does have a simple squished conical duct on it. Perhaps that helps to keep the airflow away from the right side where the thermistor is mounted.

 

x16 gf1400
But my fuse on the power switch is what keeps blowing

 

the heat bed on mine isnt the problem....getting it to turn on without immediately blowing the fuse on the power switch is my problem.

 

on both my printers it reads the same on f2
but on the one that keeps blowing the fuse f1 says

B
R500
30125

 

Mark, sorry but I am confused by your last two posts. You said the power switch fuse is blowing on turn on. Then you say f1 (the smaller polyfuse) is triggering. Are they both going off?

If the power switch fuse is blowing it sounds like a big problem like a short somewhere or a bad power supply. You should closely check your wiring for shorts. Especially look at the screw terminals for any stray wire strands that are bridging. That fuse is probably doing what it is supposed to do and preventing a fire.

 

One of the robo3d admins was asking if anyone had any variations of what the f1 and f2 said on them so thats why i posted that part..
Basically what happened is i just finished a print and my robo 3d r1 just gave out on me...no noise no pop no smells just lost power of the led lights and everything else.....it looked like the bed temp was still registering on matter control tho.....i hit the forums and read some posts and checked my fuse and it was blown... i checked under the bottom and it looked like the wires going to D8 were kinda black(the red wire) and not screwed in so i screwed it back in both red and black but it blew another fuse. I ordered new fuses today and ive went thru about 7 of them looking for a fix and trouble shooting.

 

I'm still waiting on fuses and a replacement fan....I took the fan off and spliced it to my other R1....I have an e3d coming and needed to print the mount for the fan....I waited until someone gave me the go ahead but no one ever did so I just made a decision to go 4 it....could you send me another power supply please? Here are how both my machines came underneath.

 

All replacement parts are handled through the replacement part request form.

 

I just got my R1 this last Monday. I've come across this very problem with my unit, it can reach 84*C before it shuts down. My solution is the same as they do in robotics. I've ordered a Solid state relay, this will basically use the ramps pulse as a control signal for the 25 amp SSR( more than enough for the heated bed) without the worry of mechanical cycling wearing it out.
Another thing I noticed is when the bed shut down so did the extruder, so is the extruder on the same fuse as the bed?
Also when this problem occurs does anyone else have the software stop responding to axis commands, or is this an arduino/ramps firmware protocol to protect the system?

 

ok, how do I fix this?

 

In the firmware config.h or configuration.h file you can set the max temp and flash it to the printer.

Adjust at your own risk of course.

 

OK I have an R1 with bed leveling. I've got the 8mm smooth rods.

 

Can't you just edit the current firmware using those values?

 

As long as you have a Ribbon cable for the Y axis you'll be fine. If you have a connector you should remove it to go above 85C safely.