Author Topic: 3D Printer problems - Monoprice/Wanhao D6  (Read 370 times)

Offline ddmckee54

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3D Printer problems - Monoprice/Wanhao D6
« on: March 11, 2020, 02:44:41 PM »
I'm posting this on several forums, so for some of you this might be a repeat.

I've got a Monoprice printer that is actually a re-badged Wanhao D6.  I managed to kill my printer last week, I static ZAPPED it  - but that's not the only problem.  As I was plugging in the SD card to load a new G-code file I felt a shock through my finger tips and the LCD screen went dark at the same time.  I remember I said "Oh Fudge", or something like that because those two events occurring at the same time are NEVER a good thing.  I tried cycling the power to the printer but that made no difference.  I tried the turn it off for a few seconds and then turn it back on trick, still no screen.  I tried turning it off for over  a minute and then turning it back on but still no joy.  By this time it was past my bed-time and I'd run out of the expletives that I've learned in the past 65 years,  so I planned on trying it one more time in the morning before I left for work.  The next morning, this was Friday, when I turned on the printer the screen came to life.  I said Praise Jesus, turned off the printer, and went to work.

After I got home from work that evening I tried to actually do something with the printer and discovered that I had no cursor on the screen and apparently no way to control the printer.  At this point I opened up the printer to see if I could find any part numbers to order replacements.  The D6 uses two proprietary PC boards, through my research into these boards I found that they call them the control board and the motherboard.  I think the control board is the one that I ZAPPED.  It has the SD card hardware, the LCD hardware, and the control knob/button hardware and would have been the first in line when the static charge hit.

BUT, and it's a big BUT, I also found reference to a relay problem on the motherboard.  It seems that Wanhao cloned the motherboard from another of their printers and didn't quite do their due diligence in the design.  They used a relay with contacts rated for 10 amps maximum at 30VDC, this is a problem when just the heater load is 12.5 amps.  Having designed industrial control systems for over 30 years, I can assure you that relay is going to fail.  It's not a matter of IF it's going to fail, it's a matter of when.   One of the messages the failure of this relay will generate is a Heater Error message, which I had been getting on rare occasions for several months.

So my motherboard relay was failing, along with a dead control board.  I try to avoid the long shipping delays by buying from suppliers on this side of the pond - no such luck.  The only place that I could find that had the control board in stock was Aliexpress.  Even with UPS Expedited shipping I won't see my parts until the end of the month at the earliest.

I'm pretty sure that the only thing wrong with my motherboard is the relay.  I have not been able to find a relay that meets the power requirements, both coil and contact.  I'm leaning towards using a remote mounted something, either a relay or a DC rated SSR, there's plenty of room available in the base of the printer.  The problem I've got is that I think the existing relay has both a NO (Normally Open) contact, and a NC (Normally Closed) contact.  I'm not sure if Wanhao is using the NC to do anything.  Anybody know if somebody has already gone to the work of figuring out the schematics of the motherboard?  I could eventually get it figured out, but if somebody's already done it, why re-invent the wheel?

Don
Too many irons, not enough fire.

Offline Ben

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #1 on: March 11, 2020, 03:29:08 PM »
Sounds like a common problem, I have a MOSFETS installed for the hot bed and the hot end (search ebay 3d printer MOSFETS) this seems to be the workaround

Offline Brass_Machine

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #2 on: March 11, 2020, 04:08:58 PM »
Hi Don,

I found this link talking about the relay issue:

NewScrewDriver.Com

Dunno if you have read it or not.

Have you looked for an upgraded replacement board? I pulled the stock board of my Ender 3 (I know, different printer) and popped in a 32 Bit board that works soooo much better.

Eric

« Last Edit: March 12, 2020, 08:30:03 AM by Brass_Machine »
Science is fun.

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Offline ddmckee54

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #3 on: March 11, 2020, 05:10:58 PM »
I was thinking about just gutting the proprietary electronics, but there's a couple of problems with that.
1) I print from the SD card.  I use my computer in my living-room as my workhorse computer and I don't want to bog it down any more by running the printer from it.
2)This thing has the SD card, the LCD screen, and the control button all mounted on the front of the printer's base.  Most of the readily available components that I've found so far only have the LCD and control button on the same face.

I'd like to keep the front panel of the printer stock.  Otherwise I'll have to print something for the LCD screen that would give me access to the SD card slot.  I have found a version of Marlin on GitHub that's written for the Wanhao D6.  Which has me wondering if I could swap the motherboard for something more suitable, as in cheaper and easier to get, and keep the control board.  Before I try the mother board swap I'll need to get the pinouts of the flat cables that go to the control board, to see if they would match up.

Don
Too many irons, not enough fire.

Offline mc

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #4 on: March 11, 2020, 07:30:09 PM »
If you want to retrofit with something else, there are lots of options. Most of them run some variant of Marlin ( https://marlinfw.org/ )

I'd probably look at something like the BigTreeTech SKR V1.4 boards ( http://www.bigtree-tech.com/ )
They get good reviews, and I've just ordered their dedicated E3 board to upgrade my Ender 3 Pro, along with a replacement touch screen, as they are drop-in replacements, and they should be here sometime in the next few weeks...

However, Marlin will run on quite a lot of different boards.
This is one area where I think you've just got to pick an option with reasonable reviews and go with it, as you could end up getting stuck down a very big rabbit hole, trying to find out what is the 'best' option.

Offline ddmckee54

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #5 on: March 12, 2020, 03:02:44 PM »
Other than the under-sized relay, there really isn't anything wrong with the motherboard.  I'm only running a single extruder and I'm satisfied with the print quality that I was getting.  If I can fix the relay problem, other than the cost of the factory replacement board, I'd have no problem running the Wanhao motherboard.

I MAY have found a fix tor the relay, too early yet to tell for sure.  I'm talking with a supplier in Texas that has a DC output SSR rated at 15 amps with 5VDC control, at least that's the way the datasheet reads. IF they are available in small quantities, and IF Wanhao only used the NO contact on the existing relay, it should be a functional fit.  Even if it doesn't fit on the PCB.

Don
Too many irons, not enough fire.

Offline mc

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #6 on: March 12, 2020, 08:32:26 PM »
A quick search on eBay has lots of SSRs which will work from a 5V input.

The only issue with using a SSR, is they're far more likely to fail short circuit than a conventional relay.
I can't remember what I was planning on using one for, but a couple people far more knowledgeable about them than me, advised me a contactor would be a better option for anything where short circuits would be bad.

Off course, an SSR will be an easier fit as it'll avoid any issues with increased coil current.

Offline WeldingRod

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #7 on: March 12, 2020, 10:03:56 PM »
Interesting!  Closed loop steppers!?!
Has anyone actually used the bigtreetech hardware?  Price is interesting, and I've been thinking about moving up from pre-old-school hardware...

Sent from my SM-G892A using Tapatalk


Offline mc

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #8 on: March 13, 2020, 05:13:02 AM »
Interesting!  Closed loop steppers!?!
Has anyone actually used the bigtreetech hardware?  Price is interesting, and I've been thinking about moving up from pre-old-school hardware...

Sent from my SM-G892A using Tapatalk

I never noticed the closed loop stepper motors. I had noticed the mention of closed loop on the some of the boards, but never paid any attention to it.
The issue with using magnetic encoders, is they're not likely to increase accuracy. Magnetic encoders have quite a bit of dither, so you're probably not going to gain much improvement over open loop microstepping.
They will however have the benefit of things stopping automatically, should a motor stall for any reason.

I'm waiting for one of BigTreeTechs E3 boards with the embedded stepper drivers to arrive. I did um and arr over getting the DIP version, but the embedded version uses the latest drivers, whereas the DIP version comes with the slightly older driver. From what I've seen the latest drivers have basic stall detection, so you can configure your printer to home without using switches, by just stalling at the end of travel.

The BTT boards seem to get good reviews and lots of recommendations online. I suspect the big reason for that, is they are a good combined unit, and in the case of Ender 3 owners, available as a simple direct swap replacement.

Offline picclock

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Re: 3D Printer problems - Monoprice/Wanhao D6
« Reply #9 on: April 05, 2020, 10:04:05 AM »
@ddmckee54
Is this the relay for the heated bed ? If so it should be fairly easy to replace. Post a picture, relay and board, I may even have one.

I have just scrapped my old prusa printer, which I made from bits and part kit. Basically its too old and worn out. The z axis nuts failed  2 weeks ago, just no threads left and heavily worn threaded rod. Then about a week ago, halfway through printing the magic smoke escaped. Looks like the ramps board failed and took the 2560 board with it. So I have just ordered an ender 3 pro. Which I will then mod up to make it as the prusa.

The heated beds are a pain on all of these, and using high current low voltage is a bad way to go. On my scrap printer I went through heater boards and uneven heating until I decided enough was enough. I scrapped the whole prusa bit and replaced it with a flat sheet of aluminium, and used a mains powered self adhesive silicon pad heater.
The turning off and on was done with a Solid State Relay which is optically isolated. The ramps board then only switches a mA. With resistive loads these last forever, and I suspect that the new machine will have the same
 treatment.

Best Regards

picclock
Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)