Heated bed LED  

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malcinator
(@malcinator)
Trusted Member

Hi,

I have just finished putting together my MK2 and I'm working my way through the Calibration. I have noticed though that the LED on the heated bed does not light. The bed does heat up and the temperature readings on the LCD rise and fall but there is no LED.

My kit didn't arrive with the printed book for the build so I'm not sure if the LED should illuminate when it has power or not? If someone could let me know if this is a fault, or I have connected it incorrectly or the LED function is no longer used I'd really appreciate it?

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Posted : 15/10/2016 4:06 pm
david.t2
(@david-t2)
Noble Member

Heatbed should come with connector already mounted on its cable. It is possible that some mistake happened during connector assembly causing reversed polarity on heatbed. It would behave exactly this way - heatbed works, but LED doesn't.
Check polarity of heatbed cable in its connector.

Posted : 15/10/2016 4:35 pm
malcinator
(@malcinator)
Trusted Member

Hey,

I was beginning to think that I must have connected something round the wrong way.

But... The connector that comes pre-assembled on the heated bed will only fit into the socket on the RAMBO board one way? Anyway I will take a closer look.

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Posted : 15/10/2016 4:39 pm
david.t2
(@david-t2)
Noble Member

The connector that comes pre-assembled on the heated bed will only fit into the socket on the RAMBO board one way?
Yes, but it contains two screw terminals, where the wires could be swapped. Look here to find out how the polarity is oriented on outputs.

Posted : 15/10/2016 5:02 pm
JohnOCFII
(@johnocfii)
Estimable Member

I have noticed though that the LED on the heated bed does not light. The bed does heat up and the temperature readings on the LCD rise and fall but there is no LED.

The LED should illuminate when the bed is heating. It may be solid, or it may blink, depending on whether it is warming, or just holding temperature.

Take a close look at the solder pads and the LED connection. It is a surface mount LED, so you will probably need a magnifying glass. If the trace is cracked, you may wish to contact Prusa Research support via Chat to discuss.

Take a look the image included in step 13:

http://manual.prusa3d.com/Guide/7.+PSU+%26+Heatbed+assembly/109

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Posted : 15/10/2016 11:34 pm
malcinator
(@malcinator)
Trusted Member

So it turns out the wires were the wrong way around in the terminal block. I swapped them around and now the LED functions.

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Posted : 16/10/2016 3:00 am
JohnOCFII
(@johnocfii)
Estimable Member

So it turns out the wires were the wrong way around in the terminal block. I swapped them around and now the LED functions.

Good job!

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Posted : 16/10/2016 4:37 am
RandyP
(@randyp)
New Member

Do you or does anyone have a pic of this change? I just build my Mk2s and have the same issue. Bed functions properly aside from the LED not working.

Posted : 08/08/2017 9:18 am
JeffJordan
(@jeffjordan)
Member Moderator


Do you or does anyone have a pic of this change? I just build my Mk2s and have the same issue. Bed functions properly aside from the LED not working.

just swap the wires at the connector. as far as I can remember the connector has two screws to fix the ferruled wires.
for heating purposes the polarity for the heatbed is completely irrelevant... but not for the LED.

dem inscheniör is' nix zu schwör......
Posted : 08/08/2017 8:28 pm
RandyP
(@randyp)
New Member

Ok,

So you're saying just swap the heated bed power wires themselves in their connector/socket? Easy enough of course, just looking to clarify.

I'd hate to damage this beautiful tool.

Posted : 08/08/2017 9:01 pm
JeffJordan
(@jeffjordan)
Member Moderator


...
So you're saying just swap the heated bed power wires themselves in their connector/socket? Easy enough of course, just looking to clarify.
...

yes, exactly.
no danger for damaging anything by this procedure.... unless you are very clumsy while messing around with the connector.
a wrong polarity at the heatbed couldn't damage anything.

dem inscheniör is' nix zu schwör......
Posted : 09/08/2017 12:18 am
RandyP
(@randyp)
New Member

Most helpful sir, I appreciate it.

Took less than a minute and worked ace!

Posted : 09/08/2017 12:39 am
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