DIY copy of festoon cable assembly for Zprinter 650/850 and Projet 660/860

[hanakp]

Short version: I had Zprinter 650 which suddenly started to produce 3011 sequencer errors and 1006 "head temp too high" errors. I tried replacing pogo flex cable (22-50080) and pogo board (22-50019) as recommended by service manual, but that didn't help. Next in the line was festoon cable assembly (part number 22-50108) but it would cost over 1200 EUR. I ran out of budget at that point, so I tried to make my own copy. I was successful and my cable eliminated the sequencer errors. But in the end, it turned out the printer's electronics box was faulty, too. It wasn't ecomomical to repair the printer anymore, so I scrapped it. I know these color powder printers are still used for some niche applications, so I decided to share my findings. Also, I'm offering my festoon cable copy for sale to cover material costs, let's say for 250 EUR. And I think I have enough parts to make yet another copy. Any takers? However, keep in mind my copy is slightly different from original (see below) and may not last as long.

Long version: Making the festoon cable assembly is no rocket science, but you need to use proper materials and right crimping tools, otherwise it won't last very long under load. All cables have to be of high-flex type, which means their copper cores are very finely stranded. And don't skimp on the connectors and crimp pins - I used original Molex Mini-Fit Jr. ones, although there are many cheaper copies out there. Remember: a single unreliable connection will interrupt printing and result in a lot of wasted material. Plus, you have no way to tell which connection actually causes the problem. Unfortunately, original Molex crimping tools are pricey, so making only one cable won't be very economical. You should also have Molex 0011030044 extraction tool on hand. I didn't have this problem though, because I already had all the necessary tools lying around from other projects.

Here is the bill of material, you can get it at popular electronics e-shops like Farnell, Mouser, Digikey, TME etc.:

Amphenol 191-2811-034, 190 cm length, 34-way data cable
Unitronic 0027444, 169 cm length, 7-way stepper motor control cable, 0.34 mm2
Helukabel 22516, 184 cm length, 7-way power cable, 0.75 mm2
Lapp 4560033S, 131 cm length, grounding wire, 1.5 mm2
3M 3414-6634, 34-way IDC receptacle, you can use 3414-7634 if unavailable
Molex 39000060, female pins for power cable (0.75 mm2)
Molex 39000047, female pins for stepper motor cable (0.34 mm2)
Molex 39000048, male pins for stepper motor cable (0.34 mm2)
Molex 39012020, 2-pin receptacle housing
Molex 39012080, 4-pin receptacle housing
Molex 39012140, 14-pin receptacle housing
Molex 39012041, 4-pin plug housing
TE Connectivity 34148, ring terminal for grounding wire
BM Group BM80180, insulated male faston for grounding wire
Panduit CLT75F-C20, corrugated tubing
Heat shrink tubing of various diameters, self-adhesive electrical tape, small cable ties etc.

Unfortunately, you'll have trouble making a copy these days, because the 34-way blue flat data cable isn't manufactured anymore. The original was Amphenol 191-2811-034 and I bought out very last stock from Digikey. Actually, I had to buy two 26-way cables, then tear and combine them accordingly. You can see that in the photos, but it has its own problems, namely that the cables tends to crumple near ends. That may lower their lifespan. I used thick duct tape to stiffen them, but it's not ideal. Note you need to tear them exactly as in the original cable, one "half" must be 16-way and the other "half" 18-way. It's because print data is transmitted over pairs of wires (so-called differential pairs). Moreover, these pairs must have an exact impedance (I measured 150 ohms), otherwise data transfer won't work (due to signal reflections). In practice, it means you can't drop in any random flat cable, high-flex or otherwise. I identified possible replacements, namely 3M 3319/34 (PVC insulation) or HF319/34 (polyofein insulation). But all vendors I could find only sell them at 30 meter multiples. Again, it wouldn't be economical if you wanted to make only one cable.

Be warned those 3M replacements are a shot in the dark. On paper, their pair impedance is different (171 ohms) and I have no idea whether they would work. The best bet here would be to reverse-engineer a newer revision of the festoon cable. 3D Systems has been affected by Amphenol cable's unavailability too, so they had to find a suitable replacement. But I've seen only (10+ years old) revision D cables which still used Amphenol. Maybe someone else on this forum could help with that.

Sourcing the thick power cable was a bit troublesome, too. Original is Lapp Olflex FD 855 P 7Gx0,75, part number 0027549, but again, it's sold only in 50 meter multiples. I replaced it with Helukabel 22516 in my copy, but this cable has significantly stiffer insulation. I have no idea whether that may have some negative impact on the cable's lifespan. Another possible replacement could be Alpha Wire Xtra-Guard Flex 65807, but I haven't tested it.

Once you get all the parts, assembling the cable is rather straightforwad, just try to make all lengths and dimensions as close to the original as you can. Some practical notes:

1. Start from the carriage end, as mutual distances between the connectors are critical here. Conversely, the other end (PC104) is almost inconsequential. Trim the circular cables to the same length, because they are wired to single (14-pin Molex) connector.

2. Tear and fold the data cable exactly as the original (16/18 ways), and don't forget about strain reliefs on its connectors (the cable wraps around under them). Press these large IDC connectors in vise if you don't have the right tool, don't use normal pliers or hammer.

3. In the motor control cable, only 6 wires are used for signals, but its shielding is wired to a connector pin on PC104 side. You need to solder a short piece of wire to the shielding to make the connection.

4. Pay attention to how the cables are bundled together. Notice that the corrugated tubing is taped to the bundle at one end only; that allows the cables to slide freely inside when bent. Also, there are short pieces of shrink tubing on the bundle near ends of the corrugated tube. These serve to soften the transition and to prevent chafing. Again, notice these shrink tubes are relatively loose and the cables can slide over each other. You need to put them on the bundle before you install the IDC connectors on the flat cable (I forgot about that while making my copy). Test them beforehand so they're not too tight.

5. In the middle, the bundle is bound so the flat data cable is a bit shorter than the circular cables, see the photo. This is to lower their mutual friction when they're hanging in the printer, you need to make it the same.

6. Don't use cheap/noname electrical tapes to bind everything together, their glue will degrade into slimy mess in a few years. I've been using 3M Temflex tapes because they're stable.

Keywords: Zprinter 650, Zprinter 850, Projet 660, Projet 860, powder 3D printer, Z Corporation, 3D Systems, festoon cable assembly, 22-50108, replacement, reverse engineering, copy