Well it's official, I killed the printer. When I fired it up Friday night it booted up normally, the screen came to life and was on the proper screen for having completed its' boot up. What I didn't have was a cursor, or any way of controlling the printer.
I started tearing the printer down to get to the electronics and found out that like most 3D printers that use the flavor of the RAMPS board, this printer also the electronics divided into 2 sections, the control board and the motherboard. This printer is a Monoprice which is a rebadged Wanhao D6 by the way, but more on that later. However unlike the vast majority of printers, Wanhao uses proprietary boards. What they call the control board contains the SD card hardware, the LCD screen hardware and the control knob/button hardware. I think this is probably the board that I ZAPPED since the SD card plugs into it. I was trying to find a supplier on this side of the pond that had a control board, no such luck. The one place that did list it was out of stock.
The Wanhao D6 motherboard, where to start? This thing is flippin' expensive, I found one on Ebay for $185 USD, the Wanhao 3D printer parts site wanted about $250 USD. I also found that this board has a built in flaw, a 2 buck relay that controls the 24VDC to the printer. That relay's contacts are rated at 10A for 30VDC, when both heaters are on at the same time the load is 12.5 amps - just for the heaters. These relays are known to fail, but they do warn you they are failing, they display one of several different error messages. I would periodically get a heater failure message that would require me to reboot the printer - this message was on the list of error messages caused by the failing relay.
Aliexpress was the ONLY place I could find both the control board and the motherboard. the cost was about 1/2 to 2/3 of the cost anywhere else, but I won't see my parts until 3/31 with UPS Expedited shipping. I could have paid twice as much for DHL shipping, but it only saved me 2 days so it wasn't worth it.
So bottom line, I've definitely got a busted control board, and I've got a motherboard that's most likely failing. With repair parts 3+ weeks away, in order to keep from going into 3D printing withdrawal, I fired up the old printer which has been sitting and gathering dust since I got the Monoprice - almost 2 years now. Other than having to re-level the bed, not uncommon with that printer, it took right off with no problems.
I printed out the front fenders using the Prusa Clone, and after a couple of modifications and reprints they actually looked pretty good and fit in their desired location. Ummmm… yeah, make that they fit - not so much. The fit problem showed up when I put the turret on the frame and swung it around to check clearances. It didn't quite clear, the turret would interfere with the top of the fenders. One more re-design to lower the fenders by 2mm and I should be good to go.
What lies ahead for the D6 clone - not sure. I'd like to get rid of the expensive proprietary boards but with the way the control board is laid out, in particular the slot location for the SD card, I don't think that's likely to happen. I found a version of Marlin on GitHub that's specifically for the Wanhao D6 motherboard, I think that is definitely in the future for the D6. (I got used to Marlin on my Prusa clone.) I never did like Wanhao's proprietary menus, and their info screen leaves a lot to be desired. Small things, like useful information. The Wanhao info screen basically is just an estimated time to print completion - in hours at first, then minutes when the remaining time is under an hour. If I keep the proprietary motherboard I will still have to deal with the relay problem, but there's plenty of room in the base of the printer to wire in a remotely mounted 5VDC relay with contacts that are actually rated for the real load.
Don