Bad developer or housing? Or something else?

[vickash]

Hi all,

Just put a new developer housing, filled with new magenta developer into a 7760. The previous one was working fine, but I pulled it to use in another machine a while ago. From the first print with the new developer, magenta is faded toward the back (developer motor side), and fine at the front (supply / waste). I made sure to enter the ATC value on first power up. Drums are pretty new, and swapping them around doesn't shift the problem. No other color has this problem. I removed the ROS and cleaned that. I tried another ROS with no improvement.

I'll try swapping the new housing into another machine to diagnose soon, but swapping developers on these is a pain. I was hoping it would be something else. Is this a symptom of bad developer, a bad housing, or maybe something else?

Thanks in advance.

[Jenks]

Re: Bad developer or housing? Or something else?

Hi there take out the dev unit and reinstall it again it may not be located properly

[vickash]

Re: Bad developer or housing? Or something else?

Hi there take out the dev unit and reinstall it again it may not be located properly

Tried that. I printed a 100% M sheet and stopped it during the print. Low density on the back side of the magenta drum. That should rule out the belt, but I swapped it anyway, same issue. Switching around the developer HVPS cables didn't help either.

I took the developer out and put it into another machine, and same problem. Pretty sure it's either the developer housing or material now. Should I try refilling this, or is it the housing at fault?

[Caffeine]

Re: Bad developer or housing? Or something else?

Assuming this is a genuine and new developer and genuine and proper pouch of developer assembly:

The trim bar may be uneven in the developer assembly... It is the part that, as you manually rotate the gear, limits the developer material coming out on the mag roller to create a (theoretically) perfectly smooth consistent layer of developer/toner mix on the mag roller.

As I recall (it's been years since I've used this model, but Fuji Xerox's designs are all basically the same) the trim bar (some call it doctor bar) is held in by two screws on either end. Carefully unscrew it, don't remove in case there are mylar seals holding it in place. But loosen it, kind of jostle it a bit gently, and make sure there are no obstructions or anything. Then reattach but don't go crazy cranking it down, especially on the end that was faint. See if maybe there is some missing or overly compressed foam under the screw at the end where it was faint. Last, try screwing that side down slightly less than the other side. Not enough for it to be LOOSE, but maybe slightly less tight than the other end.

This can happen with old developer, and OFTEN OFTEN OFTEN happens with GENERIC developer even brand new, but if it has happened with a brand new GENUINE pouch of 7760 developer (or WC73xx) and brand new assembly, my bet would be the trim bar is uneven.

Basically, if this is what it is, it is scraping away and leaving too thin of a layer of material on the mag roll at that end. The development process can "accommodate" quite a bit of variation and still basically be ok, but eventually, the developer/toner material is just too sparse for it to print properly. This is why, even though the trim bar would be gradually high-to-low across the whole length of the mag bar since it is very rigid and doesn't flex you only see it at the one end where it is lowest/thinnest. The development can "make do" across most of the length of the trim bar, but eventually it just can't anymore, and it turns faint.

[vickash]

Re: Bad developer or housing? Or something else?

Assuming this is a genuine and new developer and genuine and proper pouch of developer assembly:

The trim bar may be uneven in the developer assembly... It is the part that, as you manually rotate the gear, limits the developer material coming out on the mag roller to create a (theoretically) perfectly smooth consistent layer of developer/toner mix on the mag roller.

As I recall (it's been years since I've used this model, but Fuji Xerox's designs are all basically the same) the trim bar (some call it doctor bar) is held in by two screws on either end. Carefully unscrew it, don't remove in case there are mylar seals holding it in place. But loosen it, kind of jostle it a bit gently, and make sure there are no obstructions or anything. Then reattach but don't go crazy cranking it down, especially on the end that was faint. See if maybe there is some missing or overly compressed foam under the screw at the end where it was faint. Last, try screwing that side down slightly less than the other side. Not enough for it to be LOOSE, but maybe slightly less tight than the other end.

This can happen with old developer, and OFTEN OFTEN OFTEN happens with GENERIC developer even brand new, but if it has happened with a brand new GENUINE pouch of 7760 developer (or WC73xx) and brand new assembly, my bet would be the trim bar is uneven.

Basically, if this is what it is, it is scraping away and leaving too thin of a layer of material on the mag roll at that end. The development process can "accommodate" quite a bit of variation and still basically be ok, but eventually, the developer/toner material is just too sparse for it to print properly. This is why, even though the trim bar would be gradually high-to-low across the whole length of the mag bar since it is very rigid and doesn't flex you only see it at the one end where it is lowest/thinnest. The development can "make do" across most of the length of the trim bar, but eventually it just can't anymore, and it turns faint.

Thanks. I'll try adjusting the doctor blade. Both of them are OEM, but the material IS old stock, yes.

[Caffeine]

Re: Bad developer or housing? Or something else?

Thanks. I'll try adjusting the doctor blade. Both of them are OEM, but the material IS old stock, yes.

If you tried transposing old material from one developer assembly into a new developer, I would call it right there. I would consider that an absolute red flag for the cause of the problem.

I would never ever try to transpose old material into a new assembly. There's an almost impossibility of getting the right amount and ratio of starter that way.

Almost without question, you probably have too little developer material in the new assembly because of loss form the original. That would absolutely cause the very exact thing you are describing.

[vickash]

Re: Bad developer or housing? Or something else?

If you tried transposing old material from one developer assembly into a new developer, I would call it right there. I would consider that an absolute red flag for the cause of the problem.

I would never ever try to transpose old material into a new assembly. There's an almost impossibility of getting the right amount and ratio of starter that way.

Almost without question, you probably have too little developer material in the new assembly because of loss form the original. That would absolutely cause the very exact thing you are describing.

No, it was from a sealed pouch, but I remember seeing a label on the outer box with a 2013 date on it. Old stock, not used developer.

[Caffeine]

Re: Bad developer or housing? Or something else?

No, it was from a sealed pouch, but I remember seeing a label on the outer box with a 2013 date on it. Old stock, not used developer.

Ooooh, gotcha... Ignore that last message. You should be totally fine as long as the developer didn't get heat damaged. (Which you probably would have noticed when you put it in, since it would have been chunky.)

I've never had problems with "old" developer, as long as it was sealed and not left on the dashboard of a car in Florida in the summer.

[vickash]

Re: Bad developer or housing? Or something else?

Adjusting the doctor blade worked. Thanks so much. I found a piece of card stock that was fitting snugly in the gap of one of the good dev units and used that. It's still a tiny bit lighter at the back, but 10x better than before. Maybe I could open up the back a bit more to compensate. Is there a standard gap for these? I'll get a set of feeler gauges.

If this is also a symptom of old (used up) developer, how do you tell when a housing is bad? The service manual doesn't really make a distinction.

I have one that started banding in the feed direction, and when I pulled the developer unit out, there were darker spots on the roller corresponding to the location of the bands.

But I also have a few that started getting either lighter at the back, or lighter throughout. In those cases I replaced with new housing and material at the same time. Maybe I could try refilling those with new material and adjusting the doctor blades? Refilling has been hit or miss for me with these in the past.

Thanks again!

[Caffeine]

Re: Bad developer or housing? Or something else?

Adjusting the doctor blade worked. Thanks so much. I found a piece of card stock that was fitting snugly in the gap of one of the good dev units and used that. It's still a tiny bit lighter at the back, but 10x better than before. Maybe I could open up the back a bit more to compensate. Is there a standard gap for these? I'll get a set of feeler gauges.

If this is also a symptom of old (used up) developer, how do you tell when a housing is bad? The service manual doesn't really make a distinction.

I have one that started banding in the feed direction, and when I pulled the developer unit out, there were darker spots on the roller corresponding to the location of the bands.

But I also have a few that started getting either lighter at the back, or lighter throughout. In those cases I replaced with new housing and material at the same time. Maybe I could try refilling those with new material and adjusting the doctor blades? Refilling has been hit or miss for me with these in the past.

Thanks again!

When the assembly is old and it does it, it means you'd have to open up the gap too much to compensate, and it would run very dusty and probably contaminate your drums, etc etc. Plus, it also means everything ELSE in the developer assembly is getting old, too.

So the symptom is similar, but they are (kind of sort of) different causes.

There is an "official" gap, but I don't know what it is off hand. I always just use my judgement. The very minimum to achieve even density.

[rockdude]

Re: Bad developer or housing? Or something else?

All of the above suggestions make complete sense and should solve your problem.

However if you really want to start grasping at straws, here is one that comes to mine.

While solving the barber pole affect on a 7760 I has a similar problem occur after re-assembly.

It turned out to be a electrical problem. If the above solutions don't solve your problem let me know and I will look into my notes. (My own personal Eureka)

[Caffeine]

Re: Bad developer or housing? Or something else?

Adjusting the doctor blade worked. Thanks so much. I found a piece of card stock that was fitting snugly in the gap of one of the good dev units and used that. It's still a tiny bit lighter at the back, but 10x better than before. Maybe I could open up the back a bit more to compensate. Is there a standard gap for these? I'll get a set of feeler gauges.

If this is also a symptom of old (used up) developer, how do you tell when a housing is bad? The service manual doesn't really make a distinction.

I have one that started banding in the feed direction, and when I pulled the developer unit out, there were darker spots on the roller corresponding to the location of the bands.

But I also have a few that started getting either lighter at the back, or lighter throughout. In those cases I replaced with new housing and material at the same time. Maybe I could try refilling those with new material and adjusting the doctor blades? Refilling has been hit or miss for me with these in the past.

Thanks again!

As to the second half of your question... I rarely refilled these developer assemblies when I used them. They are so small and "cheap" that I wasn't confident of any absurdly long lifespan anyway. So I did as you do, and typically replaced both at the same time. (It is so much easier to load the developer without needing to clean out the developer assembly, too... Especially if you're OCD like I am and try to get as much of the old out as you can... It just keep coming and coming! haha

[vickash]

Re: Bad developer or housing? Or something else?

When the assembly is old and it does it, it means you'd have to open up the gap too much to compensate, and it would run very dusty and probably contaminate your drums, etc etc. Plus, it also means everything ELSE in the developer assembly is getting old, too.

So the symptom is similar, but they are (kind of sort of) different causes.

There is an "official" gap, but I don't know what it is off hand. I always just use my judgement. The very minimum to achieve even density.

Ah ok, I understand.

All of the above suggestions make complete sense and should solve your problem.

However if you really want to start grasping at straws, here is one that comes to mine.

While solving the barber pole affect on a 7760 I has a similar problem occur after re-assembly.

It turned out to be a electrical problem. If the above solutions don't solve your problem let me know and I will look into my notes. (My own personal Eureka)

I know exactly what you mean by "barber pole effect". I've seen that happen once. Can't remember what I did to resolve it. What was the cause?