False reported Overcurrent MMU on new unit  

RE: False reported Overcurrent MMU on new unit

Posted by: @pagomichaelh

I'm on a small island in the middle of the south Pacific.  Air freight to here is ruinous, so I had the unit (kit) shipped to my employer's freight consolidator.

Ordered 21 April, received 27 October!  Needless to say, worked until I ran out of gas last weekend assembling the unit.

Today, I tried to put power to it, and I'm getting a 13310 error overcurrent MMU.  Customer support wasn't of much help, beyond confirming what I already knew (nothing plugged in the MMU jack, couldn't be something else).

Prusa is on the fence whether or not they'll ship a replacement x-buddy board direct, or if I'll have to wait another three months or so of ocean freight.

In the meantime, any ideas of how to get it to ignore the error and continue?  I haven't even gotten to the point of finding out if I made an error of some sort!

TIA,

Michael

 

Ciuld you post photo of connections on the mmu and the printer main board. Is this an mmu3 or mmu2

RE: False reported Overcurrent MMU on new unit

I'll get someone to get some good photo's, but there ISN'T an MMU of any sort, and there isn't anything stuck into the port

RE: False reported Overcurrent MMU on new unit

Got someone with a phone.  The error code doesn't exist, and it forwards you to the prusa3d.com home page.

Thanks for looking at this.

RE: False reported Overcurrent MMU on new unit

Posted by: @pagomichaelh

I'll get someone to get some good photo's, but there ISN'T an MMU of any sort, and there isn't anything stuck into the port

Oh I'm so sorry I miss read the post you mean your getting mmu over current but have no mmu. Try down grade the firmware as it could be a firmware error (although nothing been reported on github)

Download the previous firmware version from https://help.prusa3d.com/tag/mk4

Copy it to the USB drive (make sure it is FAT32)

Insert the drive into the printer (turned off or running)

Turn on or restart the printer, upon the boot double press the knob

Wait for a few seconds, screen informing you about flashing the firmware will appear

Flash the FW.

RE: False reported Overcurrent MMU on new unit

Per the manual, before starting the first time, I upgraded to 5.0.1, then at the suggestion of tech support, downgraded to the version that was originally with the machine, 4.7.2.

I'll go in later today, pull the board, check the back side of the board with a glass looking for flecks of conductive material (not likely, but nothing is impossible), then I'll try firmware 4.6.4

I'll post with the results of all of this.

RE: False reported Overcurrent MMU on new unit

Well, pulled the board, inspected with a glass, and found no stray particles.

Went back to the oldest possible firmware, worked my way up to 5.0.1, no change, still orange screen of death

RE: False reported Overcurrent MMU on new unit

Because I'd like to see if this thing even works, I asked if they can take copy of good code (5.0.1), comment out the function that's called when an overcurrent is detected, and I was told 'no'.

Brainstorming, there has to be a short between a supply voltage, and after the precision shunt resistor before it's routed to the port, for that circuit.  If they (or anyone here, since the board is stuffed) could identify which resistor it is, I can crush it so no current can flow through that network, and no overcurrent can be detected.

I'd still need a proper replacement under warrantee, but it would get me up and running short term

RE: False reported Overcurrent MMU on new unit

Posted by: @pagomichaelh

Because I'd like to see if this thing even works, I asked if they can take copy of good code (5.0.1), comment out the function that's called when an overcurrent is detected, and I was told 'no'.

Brainstorming, there has to be a short between a supply voltage, and after the precision shunt resistor before it's routed to the port, for that circuit.  If they (or anyone here, since the board is stuffed) could identify which resistor it is, I can crush it so no current can flow through that network, and no overcurrent can be detected.

I'd still need a proper replacement under warrantee, but it would get me up and running short term

 

Ok so see if the mmu led is on https://help.prusa3d.com/ja/article/xbuddy-status-leds-mk4_532438

RE: False reported Overcurrent MMU on new unit

Thanks for that piece of info.  I won't be able to verify until this afternoon, but from memory, when power is applied that LED glows red

RE: False reported Overcurrent MMU on new unit

Posted by: @pagomichaelh

Thanks for that piece of info.  I won't be able to verify until this afternoon, but from memory, when power is applied that LED glows red

Ok so if it is on then it is hardware not software. The schematics haven't been released so no way to tell what resistor it's is but that would void warranty anyway. So contact support tell them the LED is on and you want a replacement.

RE: False reported Overcurrent MMU on new unit

I did via the 'chat' on Saturday, "I'll have to talk to my supervisor", crickets since then.  Also sent a 'contact me', and nothing back (so far).

Pity this is leaving such a bad taste in my mouth - pay my money, wait 7 months, DOA, and no support

RE: False reported Overcurrent MMU on new unit

Here's a pic with the over-current LED lit.  I had thought it was the power LED because it comes on as soon as power is applied.  When I was talking to tech support, I was never corrected.

RE: False reported Overcurrent MMU on new unit

Posted by: @pagomichaelh

Here's a pic with the over-current LED lit.  I had thought it was the power LED because it comes on as soon as power is applied.  When I was talking to tech support, I was never corrected.

 01b39715-board-5.jpg

Ok so thr thing I'd suggest is unplug every cable and measure the voltage from psu if it's at a steady 24v then connect only that to the main board. Then switch it on and see if uou still get the light.

RE: False reported Overcurrent MMU on new unit

Bailed the new board out of hock with customs and got it installed.

Heart went into my throat when, during the POST, the light flashed red, but all seems to be OK (at last!).

RE: False reported Overcurrent MMU on new unit

I got the same thing. I tried 3 different firmwares. I had just upgraded my MK3 to MK3.5, everything worked fine. Later when I had my printer set up with Octoprint I got Overcurrent MMU. I remembered that some marlin software/motherboards have sometimes problem with USB power. I simply put a tape strip over 5V pin in the USB cable. There is an article about this at Octoprint search for "Put tape on the 5V pin - Why and how"

RE: False reported Overcurrent MMU on new unit

Here is the link. 

https://community.octoprint.org/t/put-tape-on-the-5v-pin-why-and-how/13574

RE: False reported Overcurrent MMU on new unit

Well... today it started without octoprint. No USB devices connected, printer got an error and crashed. Now it won't boot up with MMU3. Tried flashing FW 6.1.3, 6.1.2 and 6.2.0-alpha2. Nothing helps.