Jamming at the horizontal transport unit exit

I am running up a new Bizhub C754e today with a FS-534 finisher and I am reminded of some problems with paper jams that I have had with this combination.
The first time we had trouble was with a customer who was an hour and a half drive away and was reporting "Jamming everywhere in the copier". Jamming everywhere usually means a jam in the finisher or towards the end of the paper path. Larger printers have multiple sheets of paper running through them at once to keep the time between prints as short as possible. A jam like this means that there is paper all through the machine when the jam occures and they all need to be removed before the machine will work again. This is described by normal people as jamming everywhere. In fact it is only jamming in the finisher.

I wasn't the first tech to have a look at the problem but the guy who was did a lot of testing but couldn't get it to jam. A couple of days later another call came in for the same problem so I went to have a look. All photocopiers keep a log of the latest jams including a code that describes where the jam occurred, the time, date and what paper was being used. When I looked at the log all I could see were document feeder jams. So I cleaned the ADF and replaced the feed rollers and then gave the machine a good test.

Since it was a decent drive to the office where the machine was located I really wanted to make sure that the problem was fixed but I had doubts. I was worried that we are missing something with jams not being logged so I turned on the option for the machine to display jam codes. Normally when there is a jam the machine will display a picture showing where paper needs to be removed from the machine but no information about what caused the jam. Now when there is a jam a code will be displayed on the screen. I asked the girl at reception if she could keep a manual log of any codes if the machine jams so we could have a better chance of fixing it.

Sure enough a couple of days later we got a call that the jamming had not stopped. I was surprised when I arrived that the receptionist had not only taken note of the lack of jam codes displayed but had used her phone to take pictures of the paper jammed in the machine before it was cleared. I was interested to see that not only wasn't the machine logging jam codes but won't display them either. The pictures though showed clearly that the front corner of the paper was catching at the finisher entrance. 

It didn't take too long after looking at the pictures that there was a groove cut into the plastic lower guide at the exit of the horizontal transport unit. 

The lower guide is removable (3 screws) and has a series of ridges that look like they are there to reduce the friction of the paper sliding over the plastic. However with the C754/FS-534 combo the edge of an A4 sheet lines up perfectly with the inside edge of the front most ridge. After a 200000 pages or so have gone through the paper actually cuts the plastic an causes a groove on the inside of this ridge. This causes the jamming.

To fix the problem we replaced this guide with a new one but that only fixed the problem for another 200000 pages and the jamming started again. So a final fix was to use a sharp knife to remove the bridge and then polish the plastic to smooth it out completely.

So the lesson here is to not always believe the logs.

Customers annoyed that I am fixing their copier?

I just had a job to do a periodic black drum replacement on a Bizhub C552. This was an automated call so the customer did not call us but should have known we were coming because there was a message on the copiers screen. Replacing the drum hardware only takes less than 5 minutes and then I would need another 5 minutes to perform gradations and stabilisation adjustments. 

Before I could finish replacing the drum I had a guy looking over my shoulder to see where his printing was. Since I don't turn the machine off while doing this procedure the print job was in the queue so I quickly shut the machine to allow his print job to complete while replacing the filters in the back of the machine.

Since there are no more jobs in the queue I switched to service mode to do the calibrations. The gradation adjustments involve printing a pattern of gradation bars and placing the print on the scanner to allow the mc to analyse them. The first page worked fine but the second failed. I started the sequence again but while printing a girl came over and grabbed the gradation sheet from the output tray thinking it was her print job. She took one look at the coloured bars on the page, gave an annoyed grunt and then asked if the printer was working. 

She had to walk around me, a stranger to this office, step over my open tool bag but only thought to ask if the machine was working after she had grabbed my printing? Clearly not the brightest and unfortunately not the only unobservant person in this office. During the following problems I stopped what I was doing several times to allow printing but was constantly getting questions about when the machine can be used by annoyed looking staff. My reply was, as always, to smile and say that they can print but may need to wait a minute to collect their jobs. The responses were universally grunts or moans.

The problem I had was that I was printing the gradation patterns on A4 paper and the copier was not accepting the first pattern but gave no explanation. The pattern looked ok to me so I first cleaned the scanner optics (pausing for print jobs) and tried again but failed. So I next cleaned the IDC sensors, performed initialisation and stabilisation and tried again but still failed. So while pausing again for any print jobs I had a look at the gradation prints and noticed that the patterns were evenly centred on the pages. Normally they are closer to the bottom of the page. Hmmmm.

The machine normally takes its paper from trays 1 and 2 for gradation prints so I pulled them out as well as tray 3 which had pre-printed letterhead loaded in it and tried again. I wanted one of the lower trays as they are large capacity trays that are only for A4 and therefore have their guides fixed to the machine and so there will be less centring issues. Sure enough the gradations worked.

So the problem was with either tray 1 or tray 2 not being centred. These trays can hold several sizes of paper by having their guides opened or narrowed to suit. The guides can also be moved forward and back in the machine to adjust the centring of the paper by loosening two screws and then adjusting them. A notch on the metal base plate lines up with a scale on the plastic tray to give an indication of where the centring currently is. On this machine both trays were currently pushed all the way to the rear off the scale. Gouge marks in the plastic around the fastening screws showed that the guides had been forced to the back without loosening the screws so my guess is that someone had tried to open the guides without releasing them first and this caused the centring to change.

Easily fixed.

While not being able to complete the gradations or the centring problem with trays 1 and 2 were not critical problems and probably not noticeable to most of the people on this office it would have been nice to fix them without all the negative comments and noises. I am just trying to help.

IH power supply failure

I was having lunch at the office when a call came in for a Bizhub 552 that had stopped working and was displaying an error code. The customer was good enough to read us the code which was C-3B07. I knew from memory that codes starting with 3B are problems with the inductive heating system in the fuser. These codes have stuck in my memory as I have had a couple of difficult jobs that started with these codes.

We had a look at the service manual and confirmed that C-3B07 is the IH power supply reading a low input voltage. While the service manual tells us to check the supply voltage, fuser and heating coils first we know from experience to skip all these and go straight for the IH power supply board itself. 

Do we have the part? A look in the parts manual for the part number and then a check of the inventory shows us that we don't. What we do have is a couple of C552 colour copiers that I can pull parts off. While the 552 is the same as a C552 except for the lack of colour imaging units I wanted to check that the power supply was the same but my boss said not to worry about it. "Of course it will be the same". So I grabbed the board and headed out.

First I reset the error and then restarted the machine and as soon as it tried to print the error came up again. That's good because I hate intermittent faults.

It only took me 15 minutes to change the power supply and start the machine up again but then another error comes up! C-3B02 this time. A look in the manual says that this error occurs if an incorrect IH power supply board has been installed in the machine or by a general CPU error.

The first thing that comes to mind is that I have the wrong board. I am thinking that no, a C552 IH power supply does not fit a 552. I am about to call my boss and let him know that he has stuffed up but decide to compare the part manuals for the two machines first. Interestingly my boss was right and the board is the same  for both machines.

 So why the error? I know the IH power supply worked in the C552 at the office so why won't it work now? It is the right part for this machine so the first part of the error description in the service manual is wrong. That leaves the general IH power supply CPU error. The printer control board in the back of the machine cannot talk to the control chip on the IH power supply board. 

Since I know the board worked before I touched it then my next thought is that I caused this fault. How? The obvious answer is that I forgot to plug a connector in.

I pull the covers off and have a look. The connector for the wiring that runs from the printer control board to the IH power supply looks good as do the coil terminals. But the input power connector? I forgot that completely. My only excuse is that it is at the bottom of the board while all the others are close to the top. However the connector I missed is three times the size of the others and has some heavy gauge wire so it is normally hard to miss. 

Once that is fixed I check the other connectors again, put the covers on and power up the machine. It works great.

Careful with mylars

Here is a very common cause of jams in Automatic Document Feeders (ADF). All ADFs that I have seen from all manufactures have sheets of plastic called mylar stuck in the paper path to help guide paper over various rollers. These mylar sheets may be completely stuck down but mostly are glued down at the front edge and the trailing edge flaps loosely usually ending at the leading edge of a roller. The engineers who designed the copiers add these to to prevent the leading edge of the paper from running into the side of the roller and buckling against the roller instead of smoothly running over top of the roller.

However, sometimes the ADF jams and the user tries to remove the paper by grabing the trailing edge of the paper and pulling it back out of the ADF the way it went in. If there is any creases or holes in the paper the paper may catch on a mylar and then drag the trailing edge of the mylar back up the paper path. This is called a flipped mylar.

Now when paper is fed through the ADF the paper will hit the flipped mylar and jam. If your lucky the paper may force the mylar back to where it should be but often a technician will be called to fix the mylar.

I can just use a spring hook or tweezers to gently pull the mylar back into place but care needs to be taken not to do any more damage. Folds and creases can be flattened out but tears and holes will lead to the mylar needing to be replaced.

So if your ADF jams then you should first try to pull the paper out of the ADF in the direction that the paper would normally be fed. If paper needs to be pulled back through the paper path then please keep the mylars in mind and be careful.

Why I started this blog

The obvious reason for why I would start a blog like this is so I can winge and complain about my employer and/or customers. This is only partly true.
There are a lot times when I would like to explain what I have done and why while fixing a photocopier to a customer but they either don't seem to care or are not technically minded enough to understand. This leaves me feeling frustrated that I can't boast about finding a tricky fault or rant about how the engineers who designed these machines should be thrown out a window.
I can't talk to my co-workers about these things that interest me during a common day as they have their own problems and couldn't care less about my insignificant muttering. This is fair really since I don't want to hear about all their jobs either.
And like all married men my wife doesn't really care about what I do all day but just wants me to listen to her tell me about the trouble the kids caused or the latest rummors about the neighbors when I get home.
So I am turning to the internet to vent my thoughts. Maybe someone will read this one day or maybe it will sit on a server somewhere collecting dust. Doesn't matter really.