Thanks for great Customer Service !

[Doddy]

Any ideas what I could test, bearing in mind that this fault only shows itself after a few minutes printing ?

It's a bugger.

So, it used to work, but is now intermittent? So something has changed.

Thoughts:

Dry-joint and thermal expansion causing the joint to break when the microcontroller starts to warm up. Reasonably possible - examine the SMD device under magnification; if you're handy with an iron (and have a reasonable good iron) then a splash of flux across the SMD pins and walk a ball of solder over the pins and clean-up with desolder wick/braid then clean the board with IPA etc.

or...

Another person had a problem with a failed crystal - a 16Mhz crystal costs pennies and is a 10 minute job to replace. It could be that it's failing under vibration of the printing.

or...

Power Supply failure?, might be worth scoping/triggering on the supply level dipping a bit. More unlikely than the above, and would need a scope to fault-find. Could be caused by a faulty stepper driver drawing too much current.

(that's a thought - can you drive each axis to see if any one is causing problems?)

Have a look at the caps around the switched-mode PSU - any sign of leakage or bulging - worth replacing (you could be getting spikes on the logic supply).

Other noise?, that micro is likely all configured for I/O with only the supply lines and reset lines likely to cause problems.

Actually, could you swap the drivers around?, see if the problem follows a driver?

You mention conductive crap... possible, and there's nothing wrong with a bit of compressed air (just don't poke it down the buzzer). But definitely worth an inspection under magnification.

AvE (youtube) has a plausible theory that thermal issues account for the majority of problems - have a poke around with a finger whilst the printer is running - anything getting hot?

Basically... lots of things to look at and definitely worth spending 30 minutes really going over the board.It's a low density board, quite workable, but much depends on your dedication to not spending money (I'd have a bloody good go at it before forking out £150)

[cropwell]

Thanks Doddy,

Before I get too involved, I have a couple of things to try. I always print using the SD card and a faulty reader could be the cause, so first I am going to try printing via the USB link. Also I will get a new card reader from Wanhao UK on a return basis. If no difference, it can go back. The same for the mainboard, but I may end up sending that to them to check out in another 4DS machine

Sticking a finger on components is difficult as they are all under the main deck and difficult to access when the machine is running.

I thought about the PSU glitching, it is a 24v SMPS unit, so I might just put some sort of voltage drop detector on it using my little scope, but that would be a pain and so is down the list.

Likely suspect is the card reader or the cable from the reader to the mainboard, I had trouble with it before as it got sh1t in it, so maybe the pins are messed up.

I haven't got £150 to shell out on an off chance anyway, so I would have to be damn sure first.

Cheers,

Rob

[Doddy]

Certainly worth trying the easier things first.

I think yours is similar to mine (a Qidi - looks externally very similar, I've had it apart in the past but can't remember the board) - certainly appreciate it's awkward to get to - but set it on a couple of blocks with the bottom off, you can poke a digit or two.

The SMPS - I was actually looking at the SM regulator on the corner of the card - that'll drop the 24V to 5V for the logic, that's the one I'd scope.

Ironically, my previous 3D printers (a RepRap) - it was the USB that was the weak point with ground loops/noise and the card reader more robust (until I tripped over the cable and yanked the micro USB connector off the main board and replaced with a BlueTooth UART, which solved all the problems).

[cropwell]

I have just ordered a new card reader. I will see if that sorts it out later in the week. Connecting via USB is a PITA, getting the coms driver working is not for the faint hearted.

I think I am going to forget the 3D printer for a day or two and cut some ali on my router. If that doesn't bugger me about !!!