The following text was posted to an HP B9180 user group @ yahoo. Unfortunately I didn’t manage to take photos of the inside of the printer.
My 4y old B9180 started making horrible noises. The noise originated from/near with the motor responsible for switching between the hard- (capping) and soft (spitting) sponges. I took it apart (documenting what I did) but didn’t reach the actual motor as it is hard to reach. I ending up buying a new printer last week.
I found some friends willing to take another shot at repairing the HP B9180, and together we spent another afternoon taking it apart again. This time we got further. We reached roughly the point that ralphfcooke reached (sounds like climbing Mt. Everest).
Conclusions and questions
1. Broken gear.
One of the white plastic gears below the waste tank was damaged. One or two teeth were missing. This explains the gnashing noise. Any suggestions how to fix this??
The gear is about the shape of two coins with slightly different diameter pasted together. Both “coins” (quarter/Euro sized) are gears with somewhat different diameter.
Interim answer: considered taking the Shapeways route (creating a custom gear via 3D printer), but Ralph offered to sell a handful of parts. The should arrive soon.
2. Root cause?
The gear probably failed because something in the drive chain between motor and the rack-and-pinion to move the hard/soft sponge assembly was jammed. Is this credible? We didn’t find the actual jam, but there was ink all over the place – including around the gears. What are the chances of the gears breaking again – now that we cleaned up all ink around the moving parts? Could there be a sensor (that we don’t know about) that failed?
Interim answer: hopefully the jam was caused by ink. There seems to be a sensor (coding disc) at the other end of the motor axle. But it is unlikely that this failed?
3. Discovered a mini vacuum pump
The 4 hard sponges are attached (via 2 silicone tubes and T-junction) to a small pump. This pump causes the loud clickety-click noises heard on healthy machines during capping. The pump is a peristaltic pump that literally pushes out air by squeezing soft silicone tubes. A bit of under-pressure is apparently intended to improve the effectiveness of the soft seal ring around the 4 sponges in the capping station. It serves the same purpose as the cap on a pen: it reduces the chance of the print heads drying out. The vacuum-assist pulls the caps and the heads tighter together (think “suction cups”). Do other printers also do this?
4. Discovered a larger tank for dumping ink
Likely already known to those who have taken their printer apart far enough: the 4 soft sponges can dump their ink downward into a large tank filled with felt. This is probably done when the heads are “capped” as it must take a long time for partially dried ink to trickle down. We removed the felt instead of washing it as the felt is probably only important when you ship/store the printer upside down.
5. Test plans
Once/if the damaged gear is fixed, it might be good to do a (literal) dry run: test if the mechanics sounds ok before allowing the print heads to discharge ink. Reason: if the mechanics fail, the print heads will be discharging ink all over the place. In fact, I have literally seen small puffs of ink mist (being mist consisting of ink droplets!) emerge from the open printer. Probably best not to inhale these – although resin-encapsulated pigments don’t sound too toxic. To do a dry run we are considering re-assembly with the flex-foil (wiring to the print head) disconnected. Any thoughts?
6. Waste tank design?!?
Just out of curiosity: what was HP thinking when they created a hardly serviceable waste tank deeply embedded inside the device. When is this serviced and by whom?
Interim answer: say you can dump 200 ml in the tank (half evaporates?). If 90% of the ink gets onto paper, and 10% of the ink is needed for maintenance (sneezing, coughing to clear the print heads), it should last about 75 ink cartridges (@ 27 ml each). So arguably the ink tank lasts the economic life of the printer.
Again my thanks to Ralf Cooke’s recipe on taking the printer apart. We seem to have a slightly different problem ( no “sheared gear axis”) but the problem is pretty close.