<p>The problem was that one of the pins on the Ramps board power supply header was not soldered. The manufacturer had omitted to solder one of the pins, so there was no power to D8. Fixed by soldering the pin in place.</p>

CC BY-SA 4.0
2018-12-20T21:08:06.297Z
2018-12-20T21:53:16.807Z
2018-12-20T21:53:16.807Z
Lemmy
<p>Without testing the board(s) completely, by probing each component, it would be a bit hard to tell precisely. Your best bet might be to try it and see if it works ok, and if not, you'll see exactly what doesn't work... if that makes sense. Whilst not exactly the same issue, <a href="https://3dprinting.stackexchange.com/questions/3417/how-drastic-is-reversing-the-polarity-of-the-power-supply-to-a-ramps-board/6909#6909">this answer</a>, to the question <a href="https://3dprinting.stackexchange.com/questions/3417/how-drastic-is-reversing-the-polarity-of-the-power-supply-to-a-ramps-board">How drastic is reversing the polarity of the power supply to a RAMPS board?</a>, <em>might</em> help.</p>

<p>Now, after having correctly read your question (:-D), I see that you've already done the above, that I mentioned. Maybe these links will help: </p>

<ul>
<li><a href="https://reprap.org/forum/read.php?1,295757" rel="nofollow noreferrer">No power to heatbed, how to test ramps for problem??</a>, and;</li>
<li><a href="https://reprap.org/forum/read.php?415,728107" rel="nofollow noreferrer">(RAMPS)Hotend change pin from D8 to D10</a>. </li>
</ul>

<p>There are other similar links on the RepRap Wiki. You might need to check the power MOSFET and/or the fuse. The problem is knowing whether the Arduino Mega is damaged, or the RAMPS board, or both.</p>

<p>However, perform some of the relatively simple checks, listed below, for the:</p>

<ul>
<li>Outputs;</li>
<li>MOSFETs - in particular <strong>Q3</strong> which is switched by <code>D8</code>, and;</li>
<li>Fuses - in particular, <strong>F2</strong> (<code>MFR1100</code> - refer to <a href="https://i.sstatic.net/CNVhe.png" rel="nofollow noreferrer" title="RAMPS Schematic">schematic</a> below) as it is this fuse <em>alone</em> which provides <code>12V2</code> which, in turn, is used by <code>D8</code>/<strong>Q3</strong> for the heated bed. It should be noted that there are <em>two</em> 12&nbsp;V supply lines and it is the latter which concerns the heated bed:

<ul>
<li><code>12V</code>, and;</li>
<li><code>12V2</code></li>
</ul></li>
</ul>

<hr>

<h3>Salient points from <a href="https://reprap.org/forum/read.php?415,728107" rel="nofollow noreferrer">(RAMPS)Hotend change pin from D8 to D10</a></h3>

<blockquote>
  <p>Also... There is something else to be aware of. Depending on what you claim you are attaching to the RAMPS board, the pins move around. You have 3 High Power MOS-FET's. You can use the RAMPS board to drive some combination of heat bed, fan and 2 extruders. Depending on what you claim you have on your printer, the pin numbers for things move around.</p>
  
  <p>I kind of doubt that is what is causing you problems... But it might be...</p>
</blockquote>

<p>and check the config (bit of a long shot)</p>

<blockquote>
  <p>Have you checked that you don't have any error condition (such as <code>MAXTEMP</code> or <code>MINTEMP</code>) which prevents the hotend from being switched on?</p>
</blockquote>

<p>Be wary of randomly switching outputs for high current draw devices (such as the heated bed)</p>

<blockquote>
  <p>Your topic says "D8 to D10" but if this is your heated bed, you can't
  do this. D8 is on the 11amp circuit. plugging the heated bed into D9
  or D10 goes threw the 5amp fuse and it will blow. </p>
</blockquote>

<p>To test the outputs:</p>

<blockquote>
  <p>But basically test the io ports</p>
  
  <p>Remove the ramps</p>
  
  <p>Setup a led and resistor in the D port you which to use (make sure led
  is the correct polarity) </p>
  
  <p>load up the blink demo program, change the port it uses to the port
  you testing.  Upload firmware (this will overwrite you current
  firmware) Does it blink? yes the IO pin is ok, no, The IO pin is dead.</p>
  
  <p>repeat for all io pins you which to test</p>
  
  <p>See <a href="https://learn.adafruit.com/adafruit-arduino-lesson-1-blink/loading-the-blink-example" rel="nofollow noreferrer">learn.adafruit.com</a> for more information</p>
</blockquote>

<h3>Salient points from <a href="https://reprap.org/forum/read.php?1,295757" rel="nofollow noreferrer">No power to heatbed, how to test ramps for problem??</a>:</h3>

<p>Check the fuses</p>

<blockquote>
  <p>Check the fuse (the big yellow thing). Connect you meter to ground and both sides of the fuse in turn. You should get about 12v on both.</p>
</blockquote>

<p>Continuity check</p>

<blockquote>
  <p>continuity test the heated bed with it not plugged in. is it possible you have an open in your circuit?</p>
</blockquote>

<p>and </p>

<blockquote>
  <p>Have you checked the cables? Also is the led coming on for D8?</p>
</blockquote>

<p>The next section of the thread deals with an overheated (50&nbsp;A?) MOSFET. Check the condition of that:</p>

<blockquote>
  <p>ok think i found the culprit, any ideas why that blew?</p>
</blockquote>

<p><a href="https://i.sstatic.net/hho7Q.jpg" rel="nofollow noreferrer" title="Burnt MOSFET"><img src="https://i.sstatic.net/hho7Q.jpg" alt="Burnt MOSFET" title="Burnt MOSFET"></a></p>

<p>A couple of good points</p>

<blockquote>
  <p>With the bed I found there are 2 issues at play here.</p>
  
  <ol>
  <li><p>The standard MOSFET that is typically found in theese kits have an RDS that creates a fair amount of heat at 10A and at this level the
  datasheet says stick a heatsink on. Screwing a piece of metal to the
  MOSFET cures the issue I use an aluminium bracket because thats what I
  had laying around, thermal compound helps too if you have that laying
  around from a PC. </p></li>
  <li><p>A lot of heat beds state that they are 1.2ohms but aren't ( just a variance in manufacturing prehaps? ) sticking a cheap multimeter
  across it says this but in practice it may not be reading correctly. I
  found this out because my bed kept tripping a 11A polyfuse but was
  fine with a 12A meaning its somewhere around 1.1ohms. good news is it
  means my bed heats up slightly faster!</p></li>
  </ol>
  
  <p>but seeming as your transistor blew I imagine the polyfuse is ok,
  watch out though you may find it slowly does kick in when the MOSFET
  works properly because if its near its tripping point it can gently
  heat up and stop the current.</p>
</blockquote>

<p>A good test procedure - <strong>this is probably the most relevant check for your case</strong></p>

<blockquote>
  <p>That's not the way it's wired. Check the <a href="http://reprap.org/mediawiki/images/f/f6/RAMPS1.4schematic.png" rel="nofollow noreferrer">schematic</a>.</p>
  
  <p>12V input on RAMPS -- fuse -- (PS1) + output to BED</p>
  
  <p>GND -- Source[MOSFET]Drain -- (PS2) - output to BED D8
  ---------------- Gate</p>
  
  <p>As you can see, the MOSFET is switching the GND connection to the bed.
  There will always be +12V on the + bed terminal whenever power is on
  as long as the fuse is good. There's an LED across the + and - BED
  terminal on RAMPS to indicate voltage. If that LED is turning on when
  you turn the heated bed on from the host software, then the MOSFET is
  good. If it's not coming on, they you might have a bad MOSFET or your
  +12V supply is bad. Verify using a voltmeter across the bed terminals and across the 12V bed supply input in RAMPS.</p>
  
  <p>The Prusa heated bed PCB should have a resistance around 1.1 ohm.</p>
</blockquote>

<p><a href="https://i.sstatic.net/CNVhe.png" rel="nofollow noreferrer" title="RAMPS Schematic"><img src="https://i.sstatic.net/CNVhe.png" alt="RAMPS Schematic" title="RAMPS Schematic"></a></p>

<p>Then there are some tests for the fuses. Looking at fuse <strong>F2</strong> (the main culprit, which protects the <code>12V2</code> circuit):</p>

<blockquote>
  <p>You haven't mentioned checking the fuse yet. You should make sure that
  it's not blown. If RAMPS is still wired to the 12V power supply for
  the bed, you can check this easily witn a voltmeter between the + bed
  terminal and the ground wire from your power supply (any of the -
  terminal between the power supply and RAMPS). You should read 12V if
  the fuse is still good. If not, then the fuse is probably blown. If
  the fuse is good, then it's a problem with the MOSFET.</p>
  
  <p>You should visually check the solder pads for the MOSFET to make sure
  that all the 3 pins are still soldered well. The chip can get hot
  enough to melt the solder resulting in broken connection. Then with
  the power on, turn on the bed heater in the host software and measure
  the voltage going into the gate pin of the MOSFET. That should be the
  outside pin on the same side of the MOSFET as the + D8 terminal. You
  should see TTL voltage there (probably close to 5V). If you do, then
  it confirms that the MOSFET is bad.</p>
  
  <p>BTW, 1.5 ohm is probably too high for the bed resistance. You need to
  subtract the resistance that you measure when you touch your
  multimeter leads together. There could easily be 0.4 ohms there.</p>
</blockquote>

<p>and</p>

<blockquote>
  <p>As far as checking the fuse, another way would be to turn off all the 12V power to RAMPS and check for continuity between the + bed power supply input and the + bed output on RAMPS. If the fuse is still good, this should be a short (near 0 ohms). If you disconnect the + lead to the bed, then this would be more accurate.</p>
</blockquote>

<p>For fuse <strong>F1</strong>, you can do the following, although it is extremely unlikely that this has blown as the rest of the circuit is working from the <code>12V</code> circuit: </p>

<blockquote>
  <p>There's also a separate fuse for the other 12V supply input to RAMPS that powers the rest of the controller, including the AT Mega. You should check that too in a similar way. With all the power off, measure the resistance between the leads of F1 on RAMPS. You can also double check the resistance on F2 (bed 12V fuse) right next to it.</p>
</blockquote>

<hr>

<p>That should give you something to get started on. Without knowing more details, it's hard to be more precise.</p>

CC BY-SA 4.0
2018-12-16T16:59:07.163Z
2018-12-16T17:57:32.270Z
2018-12-16T17:57:32.270Z
Greenonline
<p>I'm setting up my first 3D Printer, a Prusa i3 MK2 clone. 
When I try to heat the bed, nothing happens. Then Marlin throws this error after a while:  </p>

<pre><code>Bed Heating Failed
PRINTER HALTED
Please reset
</code></pre>

<p>In Pronterface I see this in the console:</p>

<pre><code>Error:Heating failed, system stopped! Heater_ID: bed
[ERROR] Error:Heating failed, system stopped! Heater_ID: bed

Error:Printer halted. kill() called!
[ERROR] Error:Printer halted. kill() called!
</code></pre>

<p>There is 0 voltage across D8 on the Ramps board, where it is connected. When I heat up the hotend, on the other hand, which is connected to D10, I see 12V across the board's D10 terminals.</p>

<p>The bed is MK42 type.</p>

<p>My axes, extruder hotend and fans are working OK. </p>

<p>I previously burned out the 5&nbsp;V regulator on my Arduino Mega by misconnecting one of the end stops. I replaced the regulator on the board and the 5&nbsp;V supply seems to be working OK again. However I wondered if I might have damaged the board in some other respect? Or is there a config setting in Marlin I should change?</p>

<prusa-i3><heated-bed><ramps-1.4><troubleshooting>
RAMPS board - no power to heatbed
Lemmy
# RAMPS board - no power to heatbed

(Asked by: username_0 on 2018-12-16)

I'm setting up my first 3D Printer, a Prusa i3 MK2 clone. 
When I try to heat the bed, nothing happens. Then Marlin throws this error after a while:  
Bed Heating Failed
PRINTER HALTED
Please reset

In Pronterface I see this in the console:
Error:Heating failed, system stopped! Heater_ID: bed
[ERROR] Error:Heating failed, system stopped! Heater_ID: bed

Error:Printer halted. kill() called!
[ERROR] Error:Printer halted. kill() called!

There is 0 voltage across D8 on the Ramps board, where it is connected. When I heat up the hotend, on the other hand, which is connected to D10, I see 12V across the board's D10 terminals.
The bed is MK42 type.
My axes, extruder hotend and fans are working OK. 
I previously burned out the 5 V regulator on my Arduino Mega by misconnecting one of the end stops. I replaced the regulator on the board and the 5 V supply seems to be working OK again. However I wondered if I might have damaged the board in some other respect? Or is there a config setting in Marlin I should change?

**Tags:** prusa-i3, heated-bed, ramps-1.4, troubleshooting

---

## 2 answers

### Answer by username_0 on 2018-12-20. Score: 2 | Accepted answer

The problem was that one of the pins on the Ramps board power supply header was not soldered. The manufacturer had omitted to solder one of the pins, so there was no power to D8. Fixed by soldering the pin in place.


---

### Answer by username_1 on 2018-12-16. Score: 2

Without testing the board(s) completely, by probing each component, it would be a bit hard to tell precisely. Your best bet might be to try it and see if it works ok, and if not, you'll see exactly what doesn't work... if that makes sense. Whilst not exactly the same issue, [this answer](https://3dprinting.stackexchange.com/questions/3417/how-drastic-is-reversing-the-polarity-of-the-power-supply-to-a-ramps-board/6909#6909), to the question [How drastic is reversing the polarity of the power supply to a RAMPS board?](https://3dprinting.stackexchange.com/questions/3417/how-drastic-is-reversing-the-polarity-of-the-power-supply-to-a-ramps-board), *might* help.

Now, after having correctly read your question (:-D), I see that you've already done the above, that I mentioned. Maybe these links will help:

* [No power to heatbed, how to test ramps for problem??](https://reprap.org/forum/read.php?1,295757), and;
* [(RAMPS)Hotend change pin from D8 to D10](https://reprap.org/forum/read.php?415,728107).

There are other similar links on the RepRap Wiki. You might need to check the power MOSFET and/or the fuse. The problem is knowing whether the Arduino Mega is damaged, or the RAMPS board, or both.

However, perform some of the relatively simple checks, listed below, for the:

* Outputs;
* MOSFETs - in particular **Q3** which is switched by `D8`, and;
* Fuses - in particular, **F2** (`MFR1100` - refer to [schematic](https://i.sstatic.net/CNVhe.png "RAMPS Schematic") below) as it is this fuse *alone* which provides `12V2` which, in turn, is used by `D8`/**Q3** for the heated bed. It should be noted that there are *two* 12 V supply lines and it is the latter which concerns the heated bed:
  + `12V`, and;
  + `12V2`

---

### Salient points from [(RAMPS)Hotend change pin from D8 to D10](https://reprap.org/forum/read.php?415,728107)

> Also... There is something else to be aware of. Depending on what you claim you are attaching to the RAMPS board, the pins move around. You have 3 High Power MOS-FET's. You can use the RAMPS board to drive some combination of heat bed, fan and 2 extruders. Depending on what you claim you have on your printer, the pin numbers for things move around.
>
> I kind of doubt that is what is causing you problems... But it might be...

and check the config (bit of a long shot)

> Have you checked that you don't have any error condition (such as `MAXTEMP` or `MINTEMP`) which prevents the hotend from being switched on?

Be wary of randomly switching outputs for high current draw devices (such as the heated bed)

> Your topic says "D8 to D10" but if this is your heated bed, you can't
> do this. D8 is on the 11amp circuit. plugging the heated bed into D9
> or D10 goes threw the 5amp fuse and it will blow.

To test the outputs:

> But basically test the io ports
>
> Remove the ramps
>
> Setup a led and resistor in the D port you which to use (make sure led
> is the correct polarity)
>
> load up the blink demo program, change the port it uses to the port
> you testing. Upload firmware (this will overwrite you current
> firmware) Does it blink? yes the IO pin is ok, no, The IO pin is dead.
>
> repeat for all io pins you which to test
>
> See [learn.adafruit.com](https://learn.adafruit.com/adafruit-arduino-lesson-1-blink/loading-the-blink-example) for more information

### Salient points from [No power to heatbed, how to test ramps for problem??](https://reprap.org/forum/read.php?1,295757):

Check the fuses

> Check the fuse (the big yellow thing). Connect you meter to ground and both sides of the fuse in turn. You should get about 12v on both.

Continuity check

> continuity test the heated bed with it not plugged in. is it possible you have an open in your circuit?

and

> Have you checked the cables? Also is the led coming on for D8?

The next section of the thread deals with an overheated (50 A?) MOSFET. Check the condition of that:

> ok think i found the culprit, any ideas why that blew?

[![Burnt MOSFET](https://i.sstatic.net/hho7Q.jpg "Burnt MOSFET")](https://i.sstatic.net/hho7Q.jpg "Burnt MOSFET")

A couple of good points

> With the bed I found there are 2 issues at play here.
>
> 1. The standard MOSFET that is typically found in theese kits have an RDS that creates a fair amount of heat at 10A and at this level the
>    datasheet says stick a heatsink on. Screwing a piece of metal to the
>    MOSFET cures the issue I use an aluminium bracket because thats what I
>    had laying around, thermal compound helps too if you have that laying
>    around from a PC.
> 2. A lot of heat beds state that they are 1.2ohms but aren't ( just a variance in manufacturing prehaps? ) sticking a cheap multimeter
>    across it says this but in practice it may not be reading correctly. I
>    found this out because my bed kept tripping a 11A polyfuse but was
>    fine with a 12A meaning its somewhere around 1.1ohms. good news is it
>    means my bed heats up slightly faster!
>
> but seeming as your transistor blew I imagine the polyfuse is ok,
> watch out though you may find it slowly does kick in when the MOSFET
> works properly because if its near its tripping point it can gently
> heat up and stop the current.

A good test procedure - **this is probably the most relevant check for your case**

> That's not the way it's wired. Check the [schematic](http://reprap.org/mediawiki/images/f/f6/RAMPS1.4schematic.png).
>
> 12V input on RAMPS -- fuse -- (PS1) + output to BED
>
> GND -- Source[MOSFET]Drain -- (PS2) - output to BED D8
> ---------------- Gate
>
> As you can see, the MOSFET is switching the GND connection to the bed.
> There will always be +12V on the + bed terminal whenever power is on
> as long as the fuse is good. There's an LED across the + and - BED
> terminal on RAMPS to indicate voltage. If that LED is turning on when
> you turn the heated bed on from the host software, then the MOSFET is
> good. If it's not coming on, they you might have a bad MOSFET or your
> +12V supply is bad. Verify using a voltmeter across the bed terminals and across the 12V bed supply input in RAMPS.
>
> The Prusa heated bed PCB should have a resistance around 1.1 ohm.

[![RAMPS Schematic](https://i.sstatic.net/CNVhe.png "RAMPS Schematic")](https://i.sstatic.net/CNVhe.png "RAMPS Schematic")

Then there are some tests for the fuses. Looking at fuse **F2** (the main culprit, which protects the `12V2` circuit):

> You haven't mentioned checking the fuse yet. You should make sure that
> it's not blown. If RAMPS is still wired to the 12V power supply for
> the bed, you can check this easily witn a voltmeter between the + bed
> terminal and the ground wire from your power supply (any of the -
> terminal between the power supply and RAMPS). You should read 12V if
> the fuse is still good. If not, then the fuse is probably blown. If
> the fuse is good, then it's a problem with the MOSFET.
>
> You should visually check the solder pads for the MOSFET to make sure
> that all the 3 pins are still soldered well. The chip can get hot
> enough to melt the solder resulting in broken connection. Then with
> the power on, turn on the bed heater in the host software and measure
> the voltage going into the gate pin of the MOSFET. That should be the
> outside pin on the same side of the MOSFET as the + D8 terminal. You
> should see TTL voltage there (probably close to 5V). If you do, then
> it confirms that the MOSFET is bad.
>
> BTW, 1.5 ohm is probably too high for the bed resistance. You need to
> subtract the resistance that you measure when you touch your
> multimeter leads together. There could easily be 0.4 ohms there.

and

> As far as checking the fuse, another way would be to turn off all the 12V power to RAMPS and check for continuity between the + bed power supply input and the + bed output on RAMPS. If the fuse is still good, this should be a short (near 0 ohms). If you disconnect the + lead to the bed, then this would be more accurate.

For fuse **F1**, you can do the following, although it is extremely unlikely that this has blown as the rest of the circuit is working from the `12V` circuit:

> There's also a separate fuse for the other 12V supply input to RAMPS that powers the rest of the controller, including the AT Mega. You should check that too in a similar way. With all the power off, measure the resistance between the leads of F1 on RAMPS. You can also double check the resistance on F2 (bed 12V fuse) right next to it.

---

That should give you something to get started on. Without knowing more details, it's hard to be more precise.


---

