Bed constantly heats up - won't turn off.

[jebeddo]

So my v2 was in storage for 4 years, and I just took it out.
I put on some upgraded arms and plugged it back in and was ready to recalibrate it.

However, the bed heater won't turn off.
The second you flip the power switch the bed heat turns on, the red LED turns on, and the bed just rises in temp.
I set the target bed temp @ 40c, just in case the setting of 0c was messing it up.
No good, heat stays on.

I connected the printer to the laptop and through Repetier I can see that the data from the heat sensors are traveling over and reporting, as the laptop shows the same bed heat temp as the v2 lcd screen. So i don't think it's a sensor issue.
When trying to manually turn the heat off via Repetier, it doesn't work.
When trying to turn the heat off via G-code, it doesn't work.

So I'm a bit stumped.
Also, this is just the bed heat. The nozzle heat works as designed.

Any and all ideas are very welcome, and thank you!

[geneb]

Here's what Andy says:

"The way to know if it is a firmware issue or baord issue would be to wipe the EEPROM to clear out the firmware. Then if the bed stops heating, it was a firmware issue. If it keeps heating, it would be a board issue, or something on the ground side of the bed is shorted since they are constant power and ground triggered. "

g.

[jebeddo]

I did a fresh EPROM swipe and new firmware Repetier install on the RAMBo and it is still constant.
In fact, it was still heating all throughout the wipe and install process, when the board was technically not functioning for that period of time.

Thanks for the info on the ground issue, that makes sense and I'll try and chase it down.
I figured it was something to do with the wiring, but I wasn't sure what it could be.
It was working perfectly......4 years ago when I turned it off.
So probably something happened in storage, movement, etc.

I'll chase it down and thank you!!!!

[geneb]

You're welcome! Good luck.

g.

[jebeddo]

Confirmed wiring issue.
Apparently I had attempted to piggy back power off of that line, thinking it was a fresh line from the PSU (old computer PSU style machine).

Thanks again!

[geneb]

Ah. I'm glad to hear it was a simple fix. I was worried that the heated bed mosfet had died on you.

g.

[jebeddo]

@geneb

I'm upgrading now to a dedicated power supply unit, like a proper one.
Not the old ATX PSU version that I had.

For power leading to the RAMBo connector for the bed heat, the old install used 4 yellow and 4 black wires from my computer PSU.
Can I assume that this was due to the current limitations of 18 gauge wire?
That is to say, on the upgrade install, cant I just run a single wire but of a much higher gauge? Like perhaps 14 or 12 gauge?
As opposed to a 4 count of 18 gauge?

This is just for the heated bed.
The other wires are single count of 18 gauge, so that's easy.

Also, just to confirm on the power upgrade.
Were the old yellow wires V+ or V-
Likewise on the old black wires?
Really don't want to fry my RAMBo.

Thanks a million.

[geneb]

Yes, the wire count was due to current capacity. A single 14ga or 12ga pair of wires from the power supply should be fine.

Yellow is + and black (as usual) is -.

g.