Dead RAMPS? "Extruder Switched Error"
April 07, 2017 07:34PM
So I've been doing a little digging on this. Though I may have missed a post.

I've been getting weird jumps in my hotend and bed temperature readings(using Octoprint). Which leads to an "Extruder switched Error".

Machine is a Prusa i3, home made(about 4 years ago) and has only minor issues up to this point

Things to Note:
- If the machine is cold, turning both bed and hotend temperature on at the same time will cause switch error.
- If I just turn on the bed while it's cold, I get very choppy temp readings.
- If I turn on just the hotend, I get a smooth normal climb in temp. But once I turn on bed, it goes choppy.
- If the machine is heated up, the bed temp reading will look smother, but gets choppy again when I turn on hotend.
- I'm using a 20 amp power supply.
- I've check all my connections.
- Put an ohm reader on my resistors and got a just a little over a 100k reading on both(from what I understand that's close to what should be expected.)
- If I try to print even if the temperature is holding "ok" I get the "extruder switched error"

Smooth Hotend until I set bed temp



Preheated bed example


Setting hotend and bed temp at same time error


Re: Dead RAMPS? "Extruder Switched Error"
April 08, 2017 02:28AM
Could be a bad data connection. USB cable and plugs can wear out.
Your powersupply can have a problem too. Huge voltage drops may cause false reading of the thermistor values.
Check the routing of the high current wires, they shouldn't be close to the thermistor wires. ( crosstalking )

It is unlikely that both thermistors have bad connections or broken wires.
Re: Dead RAMPS? "Extruder Switched Error"
April 10, 2017 05:42PM
I've been running the exact same set up for ~4 years. So I highly doubt that I'm getting any cross talk. Though I may have to try a new power supply... Also, I don't think it's my USB cable because Octo print doesn't issue the commands to shut down because of temp problems.
Re: Dead RAMPS? "Extruder Switched Error"
April 11, 2017 03:04AM
Power supply wear & tear would be an idea worth to check. Inside switching power supplies there are electrolytic capacitors which loose capacity when getting old and/or hot. 4 out of 5 dead units people bring me (TFTs, sat receivers, PS4, TVs etc.) come alive after checking & replacing elcaps.
So you may try to check for blown capacitors - beware, high voltages - yes, even after pulling the plug - or try a replacement PSU known to work.
Re: Dead RAMPS? "Extruder Switched Error"
April 11, 2017 02:19PM
I'm ordering a new power supply... Currently don't have a replacement lying around.

Though I discovered a little symptom that might tell us more. So I was able to get both bed and hot end up to temp by slowly bring them up individually. Once at full temp I ran the Z motors and I noticed they were louder than normal. When I turn off the heat, they went back to sounding normal.

Not sure this image would tell us anything. The spikes in this image are not correlated to the motors turning on.

Re: Dead RAMPS? "Extruder Switched Error"
April 12, 2017 02:10AM
Can you check the 5V regulator of your controller if there are any hickups whle heating?
With a little trick you can use an unused thermistor-input to show the 5V behaviour in your graph.
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