C-2557 caused by a filter

I had a worrying call about a Bizhub 362 that was getting C-2557 errors. A C-2557 error on a Konica Minolta copier is caused by the Toner Concentration Ratio (TCR) sensor in the black developer developer unit reading too high. The TCR sensor reads how much toner is in the developing unit and allows the machine to control the toner level by adding toner. But if the level is too high the copier can't easily remove the toner from the developer mix and so an error is generated. Sometimes the high reading is actually caused by too much toner in the developing unit but usually by old developer mix or a faulty sensor causing a bad reading.
However the machine I am looking at doesn't have any of those things wrong with it. How do I know? Because I changed the developing unit only a month ago. Also the error only occurs during longish print runs (50 pages) and if the machine is allowed to sit for a few minutes and turned off and on again it will work fine until another long print run is started.
I went into the service menu and had a look at the TCR sensor values and they seemed normal and then did an F8 just to be sure. No good.
While waiting for the F8 to finish I went and had a look at the Konica tech bulletins for this model and found an interesting bulletin all about this very problem. The Konica boffins mention that if the ozone filter is blocked it can cause the error. So I pulled the back off the machine and pulled the filter out and sure enough it was full of dust. I vacuumed it out and the other filters while I was in there and put the machine back together. I gave it a test and no more errors!
It seems that the restricted air flow through the filter was causing the imaging unit to overheat during longer prints and then the TCR sensor would start giving higher readings until it failed.
So just because the filters are hard to get to doesn't mean that you should ignore them. Clean your filters!

C-2255 after IU replacememt

I had a slight problem after changing the colour imaging units (IU) in a Bizhub C754e. The 3 IU had reached the end of their lives so I pulled them out and put a new set in. The machine then displayed that an internal error had occurred and rebooted itself twice. Still failing the machine displayed a C-2255 error and gave up. I pulled up my list of trouble codes for these machines on my phone and had a look but this code was not on this list!

Don't panic yet.

I have a list of trouble codes for the C364e on my phone as well and the code is there. Developing unit motor failing to turn. Obviously one of the new imaging units had a problem with its developing unit that was causing the drive to lock up. Not the first time I had seen this so still no need to panic.

I started from the left and pulled the yellow IU and used my pliers to give the developing drive coupling a turn clockwise on the back of the IU. It was jammed.

Sometimes the developing powder in the unit can settle in transport and jam the augers inside the unit. Giving the unit a few taps on the side while turning the coupling quickly freed it up and I stuck the unit back in. I pulled the other two out but they felt ok and went straight back into the machine. I then went through the gradation adjustments without any more problems.

I will point out though that if you have this problem you need to be careful not to shake up or spill any developer out of the new unit as you will not be able to use it and it will need to be replaced. Also be careful not to turn the coupling to hard or it can break. But don't worry if you do as you have a spare on the old imaging unit that you just took out. And always turn the dev unit drive in the correct direction.

Also someone had played around with the date on this copier so now it shows the image unit life counter start dates as being in 2012. Not a problem but may confuse the next tech who comes to look at it and will wonder why the image units were changed 3 years before the machine was even manufactured.

Blank page removal not working

I was given a quick fix for a scanner problem just now that is interesting. There is a feature on most copiers called blank page removal. While most users have never heard of it it is pretty obvious. When copying or scanning if the machine detects that a page has nothing on it (a blank page) then the machine has the option to remove that page to save paper or scanned file size.

Why would you copy a blank page? Double sided scanning mostely. If you scan two sheets that contain three pages so the last side is blank then you don't want a PDF file with a fourth blank image. Selecting blank page removal solves this. 

However we have a had a couple of machines with DF-701 dual scan document feeders that won't do this blank page removal. The DF-701 has a Contact Image Scanner built in so it can scan the back side of the page at the same time that the front side is scanned and thus doubling scanning speeds. However some of these CIS units don't calibrate correctly and pick up a shadow on all pages and reports that the page is not blank. The shadow does not show on any scans or copies but prevents the bank page removal from working.

I am sure a firmware update will come along to fix this but until then I was given a work around. If you go into the service mode and turn off CIS calibration under system 2 then the blank page removal will work fine. Just remember to turn the copier off and on after changing the setting.

Original left on glass part 2

Not long after my last post about dirt on the scanner glass causing the copier to constantly detect A3 size paper on the glass I got a call about a machine constantly detecting A4 on the glass. The machine is a Bizhub C364e that I had recently replaced a board in and the problem had occurred repeatedly since that repair. 

Since the last thing to happen to the copier was the board replacement I first had another look at that board to see if a connector was loose. I pulled the copier out away from the wall and took the rear covers off to have a look but found nothing wrong. I tested the copier before putting it back together and could no longer get it to detect A4 when there wasn't one on the glass. Yay, fixed. I put the covers back on and pushed it back into place and tested it again and the problem was back. Hmmmm.

As in my previous post the copier looks for an original on the glass when the ADF is lowered. With the last problem it was the original length sensor that was detecting something that wasn't there. This machine was using the scanner CCD to detect something that isn't there. Testing different combinations of A4, A4R and A3  showed me that the problem was towards the front of the scanner because it couldn't tell the difference between A4 and A4R. The copier was seeing something at the front of the glass that it was interpreting as an A4 length piece of paper.

The problem only occurs when the machine is against the wall so I pulled it out away from the wall and tried again. No problem. I have an idea. I look at the carpet for divots left by the copiers castors and found none. This is really nice carpet and the machine has not left a mark on it since it was installed. This also means that I don't know where the machine was exactly positioned when installed. Aha!

When I had the original problem I moved the machine back against the wall and a little to the right away from a shredder that was there. I thought it was a little close and there was space for it to be moved so I did. When I pushed the copier back 10cm to the left closer to the shredder the original detection problem went away. So the position of the copier was causing the problem. Why?

With the copier 10cm to the right the scanner mirrors are directly underneath a set of ceiling lights and when the ADF is lowered the scanner "sees" the light and is interpreting it as light reflected off a piece of paper. A few cm in any direction puts the mirrors out from under the light and the scanner cannot see it.

So remember: Position, Position, Position! If the scanner is detecting something that isn't there try moving the copier a little.

Original left on glass

Today I went to a call for a Bizhub C754e that was constantly complaining that an original had been left on the glass and was not allowing users to copy or scan until it had been removed. However nothing was on the glass to be removed. This is not the first time I had seen this.
Switching the machine off and on again would allow users to use the copy and scan options if the document feeder was used until the document feeder (ADF) was lifted and an original placed on the glass. The problem can be replicated by simply lifting the ADF and closing it without putting an original on the glass. The detected original on the glass was always A3. The fault: dirty or streaky glass.
When the ADF is lowered it activates a switch at the back which triggers the scanners original detection. You can see this as the scanner lamp coming on when the ADF is still raised about 20 degrees. The reason the lamp comes on is because the machine is using the scanner to look for the width of an original. It is done before closing to get the contrast of the paper against the open platen cover. But this isn't the problem area.
At the other end of the scanner bed is one or more sensors that are used to detect the originals length. This is what detects the difference between A4 and A3. It consists of an infrared LED and a detector. Infrared light is shone up at the original and if an original is present will be reflected back at the detector. This can be tested in Sensor Check under State Confirmation in Service Mode.
But if there is no original what is the sensor detecting?
The first time I saw this was in an office where the copier was located near a kitchen. It seems that someone in the office took it on themselves to clean the scanner glass and used the conveniently located dishwashing soap to do it. The soap left a film on the glass that looked clean but was refelecting the infrared light back to the sensor. I gave the glass a good polish with a dry cloth and the problem went away.
However today's machine is not located near a kitchen nor had anyone owned up to cleaning it recently. But after giving it a good clean and polish the machine started working again.
Another thing to keep in mind is that we have had problems with a copier that would have this problem only late in the day. About 4pm this problem would happen but the next morning it would be fine. After arranging to have a tech arrive after 4pm it quickly became clear that the machine was near a window and the afternoon sun would shine through into the scanner. It was the sun light messing with the original length sensor and of course the next morning the sun would be shining from a different direction. That was easily fixed by closing the curtain.

Bizhub C35 miss feeding

Once again I got a call to fix a jammed Bizhub C35 that the customer could not find the jam. The simple answer to this is that the machine has not jammed. If the user had actually read the screen they would see that the message on the screen says that there has been a miss feed in the tray and can the user check the paper in the tray then open and close the right hand side door. It does not say the word "Jam" anywhere.
The problem occurs when the machine tries to feed the paper during printing but is unable to pick up the sheet from the tray and hence a miss feed. Since no paper actually moved from the tray there is no jam but the error message on the screen looks similar to that of a jam with the message to open and close the right hand side door. The reason to open and close the door is that this is the way that the machines controller clears the error message from memory. However, since it looks like a jam screen most users expect to find a sheet of paper inside the right hand side door and believe that the machine is broken because there is none.
So for these cases I explain that if there is a miss feed displayed on the screen then they need to check the paper loaded in the tray and this is most likely what they will find:

The most common cause is that a sheet of paper is sticking out to the right from somewhere in the middle of the stack of paper. The part that sticks out folds up along the inside of the tray. As the top sheets are fed into the machine the stack decreases until the sticking out sheet gets between the top sheet and the feed roller. I don't know how this happens but it has happened many, many times.

Since the feed roller is mounted to the paper tray it is easy to test the feed by turning the roller by hand. If the paper doesn't feed check that the top sheet is touching the roller. If it is check for the sticking out sheet in the middle of the stack.

P.S. I just had this same problem on an Okifax F-305 so it is not just the Konica machines that do this. The Oki also made a loud shuddering noise as the feed roller skipped across the top of the paper.

Tray 3 horizontal transport jams

I have a Bizhub C654e with jamming in the tray 3 horizontal transport unit (J-1730). 

The C654e and C754e or their black and white counterparts have large capacity trays for the bottom two trays. Tray 3 can hold 1500 sheets of 80gsm and tray 4 1000. The trays are position side by side with tray 3 on the left so to get paper from tray 3 to the vertical feed path on the right of the machine a hozontal transport unit is fitted above tray 4. This is why tray 4 is smaller.

J-1730 jams in this horizontal transport unit are just the same as jams at the vertical feed and mean that while paper pick-up was good there was a problem with the paper feed or separation rollers. So first thing is to change the worn looking feed and separation rollers. Easy.

Still jamming.

When removing the jammed paper I can see that the paper has not yet entered the horizontal transport unit so the problem must be in the feed station. There are a set of horizontal feed rollers in the feed station itself so I pull the cover off to have a look but didn't find anything suspicious. While the cover was off I removed the feed sensor actuator to have a look to see if the sensor was dusty. This is what I found:

If you look at the face of the actuator you can see a groove cut into it at about the same height that the paper would hit it. 

I had a look at the paper that had jammed and could see marks on the edge at the position of the sensor. Next I manually feed paper into the sensor to see if it would catch on the groove. Yes it does.

It seems that paper hitting the actuator at the exact same spot 200 thousand odd times had worn a groove that was causing the jams. Strange that I had not seen this before. But I had never looked for this before either. I will now.

I sanded and polished the face of the actuator and ran some paper through the machine from tray 3 and could no longer get it to jam so I will definitely need to remember this.