Ormerod 2 continuity test on the "Heated bed shield"

Hello all,

I've almost built my first Ormerod 2 (528.4) and I am performing the continuity test on the "Heated bed shield" section on the wiring page.

When I'm doing this with red on the shield/cable and black on the terminals and I have my multimeter in the same position as that image, I get a reading of 78 on both terminals and a beep. (with black on the shield/cable and red on the terminal I get nothing after a second or two)
If I move it to the 200 ohms setting, I'm reading 60 ohms resistance on both terminals as per this diagram

This also happens with the shielded cable removed and the red multimeter terminal touching the case.

I have disassembled , removing all wires except the PSU to 5V regulator connection) ,and checked the duet solder is not touching the case (and there is kapton on the metal base there as instructed) and I still get the same reading.

Once I remove the PSU to 5V regulator connection, the reading stops.

So I'm not sure if there is a problem here as I'm not electonically inclined. The the first reading and the beep makes me think there might be problem, but it is only when the PSU is connected, so the ohm reading makes me think that there is just a little bit of current passing through the PSU and all is OK. But I'm not an expert my any stretch, just confused now.

What's happening please, is this simply a bad test due to the PSU being connected?
Should I be worried, should I perform any other tests, or should I carry on and commission?

my guess is that the shield is touching the connections at the bottom of the heated bed. You can put some Kapton tape on both sides of heated bed to insolate the connections. I personaly didnt bother with the Sheilding ,RepRapPro has to supply it in order to pass the CE certification in order to sell the product. I found most of the shielding didnt really fit(atleast the ones i got). My advice is dont bother with the shielding. But i invite evryone else to contribute their thoughts ofc!

Edited 1 time(s). Last edit at 09/30/2015 01:40PM by Darathy.

Darathy, firstly I appreciate the input!

Not sure what you mean about the heating bed, because of this (perhaps badly worded, sentence)

"I have disassembled , removing all wires except the PSU to 5V regulator connection) ,and checked the duet solder is not touching the case (and there is kapton on the metal base there as instructed) and I still get the same reading."

What I mean is that I get this reading with the everything bar the PSU connecting to the 5V regulator (i.e. the heating bed, and all motors and sensors) disconnected from the Duet.

(and it is Kapton'ed up anyway, thank you)

ah ,another guess could be you have short between the duet and the Duet case. I have put Kapton on that aswell:

Just put it on the top surface in this picture:


If that does not solve it, try contacting Support ,might be a foulty duet....

Sorry i have read it quickly and didnt notice that you removed evrything.

Edited 2 time(s). Last edit at 09/30/2015 04:23PM by Darathy.

Hey Darathy,

Thanks again.
Yeah, I also should have mentioned that I followed the documention and was very careful about solder touching (checking and clipping off ends) as well as putting Kapton on the bottom of the shield.


I've put the Duet on USB power (I figured I'd carry on following the commissioning instructions until it said turn on PSU) and it all seems OK so far....

In the absence of any response from #reprappro on IRC and ReprapPro technical support email (and noone else here), I may just take the plunge (and report back as to whether magic smoke has escaped from my Duet)

Edited 1 time(s). Last edit at 09/30/2015 05:12PM by cheeseandham.

Or if anything, since the connectivity test is passing via the PSU, a faulty PSU is a possibility?

The amusing thing is, the ReprapPro office is 20 minutes drive from me, I'm tempted just to turn up on their doorstep with it if they don't answer my email

Due to the lack of reply from here and RepRapPro support,.and the fact I thought it was simply passing throught the PSU via the 5V regulator. I took the plunge anyway and carried on commissioning.

It worked, and I updated RepRapPro support, and received this email later on.

Quote
Ian - RepRapPro tech support
Sorry for the slow reply. We've been getting ready for, and attending (on Wednesday and Thursday) the TCT 3D printing show at Birmingham NEC, which has put us a little behind answering emails.

I think you've posted on the forum, too? Here: forums.reprap.org/read.php?340,564553

And I've also seen your later email, where you said you carried on, and everything seems okay! It took me a little while to work out what you were saying, and where you were reading a resistance. I think you're right; what you were actually reading was the resistance through the PSU (more likely than the 5V regulator board), rather than a fault with the bed and shield. I expect if you had removed one of the wires from the 12V input screw terminals, you would have read no resistance (or, maybe, some capacitive resistance, tending towards infinite resistance). But you took the plunge anyway, and it worked out okay! We tend not to bother putting the bed shield on; it tends to just get in the way, and it's rather difficult to fit without shorting out the contacts..

It does look like I have a fault with the Duet board anyway though, as the Ethernet network connection isn't lighting up when connected! I'm not looking forward to having dismantle all of this

Quote
cheeseandham
It does look like I have a fault with the Duet board anyway though, as the Ethernet network connection isn't lighting up when connected! I'm not looking forward to having dismantle all of this

Remove the Ethernet connector from the Duet and plug it into a PC (or other device that has a LAN connection). If the PC has Ethernet connectivity but neither of the Duet Ethernet LEDs light when the same connector is plugged into the Duet (obviously with the Duet powered up), then it is almost certainly a fault on the Duet. A common issue used to be that the Ethernet connector pins were not soldered on the Duet - I don't know if that is still a common manufacturing fault.

Dave

My background is computer networking and I'd done many tests. There were no Ethernet LED's lighting up when the Duet was connected on any device (switches, routers or PC's) with any of the many cables I own. I could also see there was no traffic on the static IP I'd assigned (or DHCP lease when I put it on DHCP) so this was the one part of all this that I was fairly confident with my "faulty" diagnosis.

I took it to RepRapPro - as they are down the road (interesting place to visit by the way!) - and Ian in support tested it,confirmed and replaced it on the spot (he was great to have a conversation with too whilst this was all going on! Very pleased with the service!)

Hello There,

I am having the same sort of issue. How did things pan out in the end for you when you finally used the power supply as opposed the the usb power.

Regards,

desertwalker66.

Quote
cheeseandham on October 03, 2015 04:58AM
Due to the lack of reply from here and RepRapPro support,.and the fact I thought it was simply passing throught the PSU via the 5V regulator. I took the plunge anyway and carried on commissioning.

It worked.

fault with the Duet board anyway though, as the Ethernet network connection isn't lighting up when connected

Not sure if related to this or anything, but the replacement boa (which was fitted by Ian at RepRapPro, not me) burst into flame within a month while doing ABS prints
I've been wary of doing any ABS since... (however I am getting gorgeous prints from it now on PLA)