Changing WiFi access point How to re-Configure
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Wrapping the wifi antenna in metal foil (taking care not to short anything)
Very good idea! Haven't tried yet but thanks!
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Still having most problems with the wifi connection.
The connection is unstable and unreliable even though the wifi signal strength is excellent.
Already reformatted the micro sd and even tried another one. No improvement.Firmware Electronics: Duet WiFi 1.0
Firmware Version: 1.16 (2016-11-08)
WiFi Server Version: 1.03 (ch fork)
Web Interface Version: 1.13PS: While trying some things out the bed and hot end heating stopped working. CPU temperature rises to 100°C immediately after startup with only the power supply connected. The diag led lights red all the time.
I think I have just destroyed my board… I am thankful for any tip I can try out...
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It's normal for the diag led to be illuminated if you have selected Z probe type 1 in your M558 command because it shares a pin with the Z probe command signal. Pl
With USB power only applied, does the board still present a port to an attached PC?
If the CPU really is at 100C then it is most likely fried. How are you measuring the CPU temperature? The on-chip temperature reported in some versions of DWC is not accurate until it has been calibrated.
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Thanks for your reply.
I still can communicate via serial with Pronterface. Even the Duet Web Control is accessible. That's where I get the high temperature reading from. Furthermore I can feel the heat rising with a finger on the CPU. It takes just 10 seconds to get really hot even on usb power only.The only mistake I remember was not turning the printer off while reattaching the effector pcb (T3P3 Kossel Mini)
Doing this I must have shorted some pins.How can I be sure it's the CPU?
What's the best technique repairing it? I can buy some ATSAM4E8E-AU or -AUR… for 16€ each.What other components may I check for damage?
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I suggest you check the voltage of the output from the 3.3V regulator. If it is about 3.3V and the processor is getting too hot to touch, then most likely the processor is damaged.
Replacing the mcu is tricky. One possible technique is:
1. Put the board on a temperature-controlled hotplate and heat the hotplate to 100-125C. This makes it easier to desolder and resolder the microcontroller
2. Use a hot air desoldering tool to melt the solder on all the pins simultaneously and lift the processor off using a vacuum pen. Caution: if the solder isn't fully melted all the way round, you may lift some PCB traces. Take care not to disturb the surrounding components, because the solder on them will have melted too.
3. Apply no-clean flux to the pads and/or to the bottom of the pins of the new mcu (taking anti-static precautions)
4. Drop the new processor on in the correct orientation using the vacuum pen, align it with the pads, and use the hot air tool to heat the pins all the way round simultaneously. Take care not to overheat the new mcu.
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The 3.3V regulator input voltage is 4.2V and the output voltage is 3.2V.
Or maybe I will order a ATSAM4E8EA-ANRCT-ND from digikey for 11€.
It's a pity because parts of the MCU are still working apparently.
Seems like desoldering the chip without removing other surrounding components is the hardest part isn't it?
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The hardest part is desoldering the chip without lifting traces. As long as you don't jog the board when the solder is molten, the surrounding components shouldn't move. You definitely need a vacuum pickup tool, which is available very cheaply on eBay. and a good hot air desoldering tool with a square nozzle the right size for the chip,
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Okay thanks for the information. I have two more questions:
- Can the heat applied by the hot air desoldering tool be destructive to the traces or are the traces just sensitive for mechanical loads (if the solder is not fully molten?
4. Drop the new processor on in the correct orientation using the vacuum pen, align it with the pads, and use the hot air tool to heat the pins all the way round simultaneously. Take care not to overheat the new mcu.
- So there is no additional solder necessary?
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The problem is that heat softens the adhesive that holds the copper to the substrate. So if you pull the chip off when the solder between some of the legs and the traces isn't molten, you may lift the trace.
You shouldn't normally need any additional solder, provided you melt the solder on all the pads at once. If you do apply additional solder then you will most likely bridge some pins or pads. You can remove solder bridges using solder wick.
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I found someone who successfully replaced the mcu. On usb power it seems to work fine. I can access the DuetWebControl.
However with the 24V power supply only the blue VIN led is on.
I think another part is also damaged.Maybe because of the "12-24V Input, 5V 2A Output PWM Buck Converter" on page 3?
https://github.com/T3P3/Duet/blob/master/DuetWifiv1.0/DuetWifi_Schematic.pdfIt would help me a lot if you can have a guess what part to check.
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Is the 5V_EN jumper fitted?
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Sorry, I really forgot the jumpers…
Thank you very much! -
I just solder-bridged the blown 0603 size 125mA fuse F1.
It didn't protect the mcu, why not? -
It's impossible to protect the MCU completely against all the types of external short that can occur. The fuse does quite a good job, as evidenced by the fact that several users have blown the fuse but the microcontroller has survived. But we're always looking for things we can do to make the Duet WiFi even more robust, and in the most recent PCB revision we made another change to help the fuse do its job even better.
A solder bridge won't protect the board the way a fuse will. Better to fit another fuse, or even a resistor of a few ohms.
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That fuse is too expensive to get (shipping) and at the moment I don't need any other electronic components. Using a wider available fuse and a fuse holder like some people suggested is not a solution for me.
I searched for information about using a resistor. It's not that nice but it could probably protect more components if it's a high current short.
Does any resistor <10 ohms work better than nothing?
A new mcu is only 11€. So why not change it again if a short destroys it? -
The fuse not only protects the MCU, it also protects the VSSA trace and via on the PCB from burning out if you short VSSA to +12V or +24V. Such shorts seem to be surprisingly common, probably because of shorts in the hor end wring and/or faulty cartridge heaters that develop a short between the element and the case.
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If PCB traces burn out, they stop being conductive, so you can throw away the whole board?
Do you have experience in using resistors as fuses?
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@nokian:
Do you have experience in using resistors as fuses?
No, which is why we are using a genuine fuse even though it costs much more.
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I tried covering the WIFI adapter with Aluminium foil but it was too sensitive for me and I only managed to get from -61db to -79db. So had to switch off router. to change access point. (I think part of problem might have been having too many access points with the same SSID - I am no longer doing that).
ps I went from a v old Duet - second production batch to this and it has been great - I actually just get on with printing. -
The new DuetWiFiServer will take the access point ssid and password from a file on the SD card, so this will no longer be an issue. Currently, you need to either get out of range of your router or temporarily turn off wifi on the router.
