Confusing purge page and nozzle test results

4900

#1

I was given a 4900 by an owner who no longer needed it. When I received it, it was loaded with piezoflush in an attempt to clear out several clogged channels. I have made progress getting the head cleaned. The latest effort involved removing the selector assembly and flushing that with piezoflush - it still had old ink in it.

After doing this and running an ink charge, I now have all ten channels printing. If I print a ten-color print page, I get six colors in nice dark piezoflush pink and four colors in light piezoflush pink. There isn’t any obvious banding on the 10-color print page. What explains the difference in the darkness of the four light pink channels? (I am assuming that all of the colors should print piezoflush in an even pink.)

Also, I am only getting three colors to print with a nozzle check: Y, LM and LC. LC is one of the colors that prints light pink yet it prints a perfect nozzle check. M, OR and GR print dark pink on the 10-color purge page but do not print at all on a nozzle check. Is there any obvious explanation for this?


#2

You still have pigment in your lines in the channels that are printing dark.

There may be more crud to get purged and this may be blocking the single nozzles from appearing the check but this is first I’ve heard of an entire channel not appearing on the check but printing in the actual print.

cheers,
Walker


#3

That could be. I believe the printer was used for Cone Pieziography before I got it. That’s six channels, is it not? The carts are labeled from their use in Pieziography but the dark channels don’t align 100% with the carts that had black pigment ink. Things may have been moved around, though. Also, I was only getting three “dark” channels before I ran a #3 cleaning. Afterwards I stated getting six “dark” channels. I scanned a printed page and attached it. How is Cone Piezioflush supposed to look? Are the light channels normal or are the dark channels normal?


#4

[QUOTE=Remo Nonaz;10863]Also, I am only getting three colors to print with a nozzle check: Y, LM and LC. LC is one of the colors that prints light pink yet it prints a perfect nozzle check. M, OR and GR print dark pink on the 10-color purge page but do not print at all on a nozzle check. Is there any obvious explanation for this?[/QUOTE]

Was the purge pattern printed in QTR calibration mode? See here and here. If not then the purge patterns will likely be a combination of channels, which would explain the differences you observed.


#5

The purge pattern was printed directly from Photoshop using the standard printer driver. Likewise, nozzle checks are done with the printer driver or from the printer menu. However, there is a very good chance that the printer was used with QTR as it was used for black and white piezography. Is there a setting deep in the printer’s menus that would limit which channels print in a nozzle check? I have not run across such an option, but it would explain exactly what I am seeing with that issue.

Your suggestion is useful - I could run QTR (I have it) to print both the purge page and a nozzle check and see how it compares. Probably not today though. I’ve promised people I will I do something other than screw around with an old printer today! :wink:


#6

The nozzle checks will show the state of the nozzles in each individual channel. But not so the purge pattern, at least not the way that you printed it. That way of printing will mean that each bar in the purge pattern will be a combination of channels. I can explain why in detail if you like (printer is CMYK but presents to the OS as RGB), but it’s going to be simpler if you just trust me on this.

The only way to have each bar in the purge pattern represent one ink channel is to follow the instructions in those two links. Both involve printing using QTR in what is known as “calibration mode” - you [B]cannot[/B] do this using the Epson driver, or by playing with the printer’s settings. The first link explains how to print the ink separation page in calibration mode. The second is doing essentially the same thing, only using larger versions of the ink separation page, some of which target single channels.

The ink separation page and these special purge patterns may look really strange and it’s not obvious how they work, but believe me when I say that when printed using QTR in calibration mode, then each bar or column will be the result of printing with a single ink channel.

In short - read the links.


#7

Bryan:

I followed the links and printed the QTR calibration mode print. It is exactly as you would have expected it based on your analysis; channels 4, 5, and 6 are printed in pink, all others are missing. I assume these are the yellow, light magenta and light cyan channels, the ones that print in the nozzle check. I can’t tell from the page because with no black printing there is no lettering.

This puts me back to square one. When I first fired up this machine these were the only three channels working. As I got it cleaned up, the other channels appeared to be coming on line, but this was an illusion. I know the head is capable of passing ink on all channels from purging it outside of the machine. It may be a dead head or it could be something further back upstream from the head. Any ideas on how to pursue this? I’m getting out of my depth.


#8

It could be an actual dead head but it’s hard to say. Most likely a combination of a funky damper assembly and an old cleaning assembly (total about $500 in parts at compassmicro.com but they keep them in stock for this reason).

I’ve reconditioned about 5 epson 4900s by purging head manually (outside of printer), replacing the damper/cleaning and doing Piezoflush initfill. But I had 2 other 49s with actual dead channels . . . so there is a risk there of a true head-failure in my experience.

regards,
Walker


#9

I haven’t taken a hard look at the selector assembly. Is it safe to assume that the dampers can be moved around? That might be a good way to figure out what is working and what is not. Also, I have a second head but it passes fluids less well than the head that is in the machine. I will install that and see what difference it makes. Even if channels are badly blocked up, if channels that did not work before begin to print anything, it would be an indication that the problem is in my current head, not upstream. If I only get the same channels functioning (at any quality), wouldn’t that indicate that there [U]are [/U]problems upstream?


#10

Yes! You are on the path. This is how I handled previous 4900s (by testing a good head in what I thought was a bad printer to validate if it was somewhere else in printer or in the head.)


#11

OK! Thanks for the support. I found taking the head off is really simple and I can get it done in a half hour. Alas, the charging and cleaning takes forever! I should be able to get a shot at it sometime this week, especially if the weather stays cold and rainy.


#12

I swapped the head today but after finishing up the printer will not turn on. I checked the power cord - it’s OK. I tried turning the unit on in serviceman mode and that does not work either. Is it possible the power supply has just failed on me or are there other interlocks I might have screwed up? All the head wiring is back on and the two plugs from the selector assembly are connected. I did leave the head cover off but it is 100% plastic so I don’t see how that could interfere with powering up.

Update: I got advise that putting the old head back in might correct the power supply issue. Seemed unlikely but it worked. So the PS is not dead but now I have a head that is printing NO colors despite a charge and #3 cleaning. Sigh.


#13

The printer should be able to power on regardless if it even has a head in or not!

Walker


#14

Well that’s what I figured. How can the machine do the low-power technical stuff, like read the print head, if the main power is not on? Apparently there is some kind of linkage, because with the ‘new’ head it would not power on at all. Put the old head back in and presto - powered right up.

So now I am really worried about doing this again and doing it right. The head code should be entered before installing the head. If I enter this and install the ‘new’ head and it won’t power up, with the new code in, will it power up with the old head put back in? I can’t change the code unless the machine is on. If this goes badly, I’ll kill it.


#15

You may have a bad second head. If there is a power surge detected from the head, this could keep the printer from actually booting . . . If the head isn’t there, no power surge. You’ll get a ton of maint-errors but the printer would still boot . . .

It’s worth it to mention at this point that the ribbon cable and wires in these heads are like 100% fragile.

Maint repair procedures recommend new ribbon cables every time you replace a head.

best,
Walker