Big Al
04-13-2010, 07:24 AM
We keep several HP4000ps and 4020ps printers in the warehouse waiting to be deployed to a disaster situation. To keep the heads from clogging up we leave them turned on all the time so regular head cleaning cycles will automatically occur. Once a month we print something to keep the ink flowing and check the printer. Yesterday I printed a demo rendering and the top 3/4 or so was overlaid with cyan (blue). Subsequent prints had bands or blocks on the page starting at the right side of the paper. Prints from a network drop were the same. Went to Google with a query : HP 4020 + Banding. An HP document came up. It said to clean the contacts on the heads and the ribbon cables. It worked! We tried to figure out why and it seems that the signals coming from the GAMUT board are radio frequency signals. They are sent down the cable, which is actually a transmission line, and the cable is terminated by the resistors in the head. If this connection is faulty then you will have a standing wave on the transmission line. This seems to keep the chip that drives the heads turned on and you get an overlay of that head's color on the paper.
We cleaned the ribbon cable contacts with alcohol. There seemed to be a light coating of oil all over the head. We cleaned the head and its contacts with alcohol then rubbed them briskly with a clean red shop rag to put a shine on the contacts. Several test prints were run and they all looked good. Follow up: the next day it is still working well. UPDATE, 5/3/2010, it is still working well, looks like head #7 was the cause.
Just when you think you have the game won? Further print testing and the first test print was all overlaid with blue ink. Then the printer started complaining about head #7 (cyan head), so we replaced it and now it is working well again. Is it fixed? I'm not sure at this point.
Al
We cleaned the ribbon cable contacts with alcohol. There seemed to be a light coating of oil all over the head. We cleaned the head and its contacts with alcohol then rubbed them briskly with a clean red shop rag to put a shine on the contacts. Several test prints were run and they all looked good. Follow up: the next day it is still working well. UPDATE, 5/3/2010, it is still working well, looks like head #7 was the cause.
Just when you think you have the game won? Further print testing and the first test print was all overlaid with blue ink. Then the printer started complaining about head #7 (cyan head), so we replaced it and now it is working well again. Is it fixed? I'm not sure at this point.
Al