banding issue on Agfa 8800MKIII with Eclipse plates

[Phanx11]

Hi everyone

Client has old Agfa 8800MKIII that had tons of issue. Previous owner used machine for 12 years straight. After fixing both LD driver boards, power supplies, cleaning all optics and calibrating all motors etc... Machine works and prints well on positive plates (Agfa Elite pro, chinese clones...)
But client got negative Agfa Eclipse plates and here is where problems begin.

For 1, i never worked with these plates and neither did guys i know from Heidelberg and Agfa it's self. All the feedback i can get for the plates from them is they are horrible and it's more marketing then truth. Fountain solution is now green instead of blue and rollers are as dirty as they were, no real change.

There seems to be banding problem related to zoom. I can play with zoom, focus, drum speed and exposure and i get either black on white or white on black banding. And if i find best settings and change them, then go back to them i see result is different. But on positive plates this doesn't happen and no banding.

Also struggling to calibrate on these plates as you can't see anything with protective coating. Drum speed too high/exposure high = washes away photopolymer layer with protective layer. Drum speed low or lower exposure and protective layer is too hard to remove. (which already sounds counter intuitive)

Any thoughts/experience with these plates or machine settings?

 

[maxon]

I didn't have any major problems setting up Eclipse on Avalon / PTR platesetters including GLV machines, they do require more energy though. Bear in mind these are negative working plates i.e. laser writes the image. You are not supposed to see any banding in non printing areas as there's no exposure so a fresh unexposed plate out of the box should wash out evenly and completely. Btw you can use a sponge soaked in fountain solution or just about any mild detergent to scrub the plate by hand on a small area, "processing" a wedge or test image on plate without going on press - and it does clean up beautifully, so you can put a magnifier or microscope and inspect the result in the prepress room. If that particular platesetter had issues in the past it might struggle to calibrate... check the GLV profile and parameters. Keep rpm low.

 

[Phanx11]

I didn't have any major problems setting up Eclipse on Avalon / PTR platesetters including GLV machines, they do require more energy though. Bear in mind these are negative working plates i.e. laser writes the image. You are not supposed to see any banding in non printing areas as there's no exposure so a fresh unexposed plate out of the box should wash out evenly and completely. Btw you can use a sponge soaked in fountain solution or just about any mild detergent to scrub the plate by hand on a small area, "processing" a wedge or test image on plate without going on press - and it does clean up beautifully, so you can put a magnifier or microscope and inspect the result in the prepress room. If that particular platesetter had issues in the past it might struggle to calibrate... check the GLV profile and parameters. Keep rpm low.

Found the zoom motor's gears are worm down, motor has enough backlash/free move that's equivalent to 200 pulses. From service zoom position manually, minimum allowed 210 pulses, backlash is same.

See video:

Ordered new zoom motor from Agfa, not to mention new turbofan. Old one had burned winding. Not sure how, motor has feedback on all phases, so much for that.

Anyway, while waiting for part still experimenting with machine.

Can someone explain to me why the zoom/focus test STD patters on negative plates come out looking like this:

https://www.upload.ee/image/15355548/IMG_20230619_161525.jpg

While the same pattern/test carried out on positive plate is normal:

https://www.upload.ee/image/15355561/2023-06-07_16.36.38.jpg

Problem with zoom looks like this. Although if you see video on motor backlash, it makes sense why this can be. Zoom lens must be so said glued in place when motor not working.

https://www.upload.ee/image/15355569/2023-06-01_16.42.21.jpg

https://www.upload.ee/image/15355571/2023-06-07_16.28.11.jpg

 

[maxon]

Zoom motor may be ok. Wrt to test patterns recheck the media type set as nega.

 

[Phanx11]

Zoom motor may be ok. Wrt to test patterns recheck the media type set as nega.

It's NOT ok. Zoom must hold, just like on your camera lens it must be tight seal, not self wondering back and forth. Gear are worn in gearbox not motor it self. That's why there is backlash.

You know i doubt we'd face so much trouble for month if we forgot to set media type to nega. But yes believe me, it's set to nega. Already made many more profiles, hopping it's memory error or media slot glitch or conflict and none help.