OK back to the task at hand -
This 7900 was actually shipped in the middle of fall, not the middle winter. I know because I just read lots of interesting stuff about winter in this Northern Hemisphere. This year's winter solstice (shortest day/middle of winter) started our winter on December 22. On November 25th however, this Epson 7900 was actually en-route to California mid-way across the US, tucked inside a Fedex eighteen-wheeler, inside a 200lb wooden crate lined with multiple layers of cardboard. Ironically this particular fall will likely go down in history as one of the mildest on record. Here is Noas snapshot of the average temperature of the US during the month of November. I am not saying this machine was not exposed to cold, or possibly freezing temps. But strictly in the interest of fueling a more accurate understanding of why this printer doesn't work anymore, I was definitely on Route 80 traveling over the Sierras this December in shorts and a tee shirt. It's been alarmingly warm this year. So while it is possible that the ink froze in the head, I actually doubt it.
I will also add to this head-failing mystery the experiences following the machine's arrival: Packed unbelievably well. Crate alone weighed 200lbs and took an hour to disassemble - and I'm a carpenter.
Very first print was a nozzle check. PK showed the same clog I see today, only not as bad. YW showed the same clog grouping that I see today, only not as bad. These two clogs have haunted this machine since day-one of my possession. Cleaning attempts have only made these clogs gradually get worse. Cleaning solution run through it's lines on these problem channels made absolutely no difference. Removing the head, soaking it's face in solution for 24hrs, then sucking a fresh mix of that same solution up through it's face also made NO DIFFERENCE. Not worse, not better. Exactly the same.
The only difference I have seen on these clogs is them gradually getting worse. That suggests to me that freezing ink damaging these particular nozzles, leading to these particular clogs, is not the most probable cause. I am not saying this is not possible. It just doesn't feel like the answer.
I am, however, suspect of these two carts/colors having such old expiration dates on them (both 2010). The PK and YW carts were both 700ml carts, both about 60% empty. From what Dan told me he also has a 9900, and therefore used this 7900 less often. I don't know, maybe these two carts have been opened far longer than 6 months? Maybe the older ink has more of a tendency to clog.
Finally, considering clogs, I would like to put a request out there to all who know so much more than I do about these heads, and Piezoelectricity
in particular; What happens to these electrically charged crystals if they are kept from "changing their shape" once an electrical field is applied to them? For instance, if I run my circular saw through a wet beam, which results in tremendous resistance and binding of the blade, the saw's motor will burn out. Now I know Piezoelectricity is entirely different than my circular saw's alternating current motor, but can the same laws apply? If you lock up these tiny crystals and charge them with an electrical field which would otherwise cause them to "move" but in this case they cannot, could this cause them to burn out? Because if this is possible, it would then be possible for dried ink to lock up a group of crystals and burn them out.
If this theory holds water then I can understand how a compromised wiper blade, which jammed more "tar" into the head than it cleaned off, could possibly ADD to a clogging problem - which in turn could explain why my clogs in particular have only gotten worse with cleanings - not ever better