Restoration of a Xerox 4000 copier

I have been looking for a Xerox 4000 copier for a long time, which I could play with. In February 2019, I was contacted by Xerox Venray in the Netherlands, and they had two Xerox 4000 copiers. They asked if I was interested in the machines, and of course I was.

On Monday March 18 2019, I received the two Xerox 4000 copiers. Since I had no other suitable place, they were put in my garage. It was winter outside and cold in the garage, so I thought I would wait until it was spring and better temperature outside before trying to start the machines. On Saturday, March 30, I could not wait any longer and started up one of the two Xerox 4000 copiers. After the machine had warmed up, I tried to make a copy, but as expected, no copy came out of the machine. There was obviously something wrong.

After a while I found out what the problem was - the machine could not feed paper from the main paper tray. I added paper in the aux tray and tried to make a copy, but the same thing happened there too… the feed rollers could not feed the paper further into the machine.

I thought maybe it had something to do with the electronics in the machine. Since I had a spare machine, I switched one circuit board at a time from the spare machine to the problem machine. After I had replaced all circuit boards, the problem was still the same and I gave up trying to get the machine repaired.

A retired Xerox technician contacted me

In early January 2020, I got in touch with a technician in the United States who had been a product specialist on Xerox 4000, and I told him that I had a "paper feed issue" with one machine. He had a buddy that he had worked with in Xerox before, and I posted some videos of the paper feeding issue. They saw that the feed clutch was activated at the wrong time. From the videos it looked like the feed clutch was being energized at the wrong time they said. I was told that a common problem was a black cam on the cycle control would crack and slip on the horizontal shaft causing it to be out of time. For the aux tray the feed clutch is energized when the cycle control switch S2 is actuated. For the main tray, the feed clutch is energized when S7 is actuated. They told me the cycle control assembly must be timed to the drives.

I am not a Xerox technician, but I have some technical and mechanical understanding. Now the job began to try to solve this "paper feeding issue".

I checked the S2 and S7 on the cam, but they were not loose in any way. Both technicians had seen more of the video, and they believed that there was a "timing issue" with the machine that led to the paper not being fed into the machine.

Here is a picture of the back of the machine and the Xerox technicians had explained several of the parts.

Here is a list of steps I needed to do:

1. Hand crank the main drive motor clockwise until the pin can be inserted into the scan cam
2. In the front of the machine place the pin through the frame and into the disk of the A transport (this may require loosening and repositioning the drive chain in the back of the machine for the rough setting and reposition the hub to obtain perfect alignment)
3. With the scan cam pinned, align the cycle control using a smaller pin from the right end (you may need to remove the drive belt to get the pin to slide into the hole of the cams)
4. Reinstall the cycle control drive belt (you may need to loosen the two small screw on the hub of the pulley to get the correct alignment)
5. Remove all the pins and power the machine up and see if it feeds paper (the copy will be mostly black but we can deal with that later)

Part of the problem was to find out where the different parts indicated in the picture were, and then it was also to understand the technical language that was in English. My native language is Norwegian, but I have had English at school. Yet with so many technical words in English, it got a little confusing at times.

I managed to hand crank the machine, so that I could insert the stick into the scan cam as described in step 1.

According to step 2, I should insert a pin into the disk of the A transport. See the picture below.

In step 3 I should “align the cycle control using a smaller pin from the right end (you may need to remove the drive belt to get the pin to slide into the hole of the cams)” When working on this step, I had problems to understand exactly what to do.

May 24th 2020 - breakthrough

Because of the Corona pandemic and some email issues, I have not had contact with the Xerox technicians for a while. It was now May and I started the work again to get the machine fixed. I was still stuck in step 3 and there were several emails back and forth, between me and the Xerox technicians because I needed more detailed explanations.
After a lot more detailed instructions, I managed to complete step 3, and performed step 4 and 5.

It was Sunday 24th May 2020, and I powered up the Xerox 4000 and was ready to make a copy and see if the paper went through the machine. When pushing the start print button, the machine cycled as normal when started copying after power up. I remembered that I sat on my knees and looked into the machine while it was running, and then it suddenly stopped. I thought there was the feeding issue again, but that’s not the problem… when I got up, I saw a copy in the output tray. Finally, a copy was successfully made!!!!

There was only a blank paper on the platen, but the copy that came out had a lot of streaks on it. There was obviously more that needed to be done. Below is a image of the first copy.

The next step was to clean the mirrors inside the machine. I had to remove the cover on the left side of the machine, but I could not do that since it was next to a refrigerator. I had to get a jack trolley to move the machine so that I could clean the mirrors. After a couple of weeks, I got hold of a jack trolley, and moved the machine so that I could clean the mirrors.

Adjusting copy quality

The doctor blade in the machine also had to be replaced, and I ordered it from Partsdrop.com. They did not have the correct blade, but they found one that fit anyway even though it was intended for another Xerox model. It took a little over a month before I received the doctor blade. When I received the blade it was installed. Now everything was in place… mirrors were made clean, and the machine had a new doctor blade. I was very eager to print a copy now.

Below you can see how the copy looked. There were areas where the text was washed out, and there were also some black dots there.

After sending over a picture of the copy to the Xerox technicians in the US, they thought that the areas that were washed out were caused by "developer chute blockage". A dirty or failed corotron wire could cause the black dots, or pepper tracks as they called it.

To fix the "developer chute blockage" problem, I was recommended to slip a plastic strips partway into the slot about ¾ of the way up the smooth curved face of the developer housing and slide it back and forth a few times.

I cleaned all the corotrons and hoped that the pepper tracks were gone. After this was done, I ran new copies that got much better.

Below is an image of copies produced by the Xerox 4000 copier after the adjustments.

I was very satisfied with the quality of the copies, and the mission was complete!

With a great deal of help by the two Xerox technicians, I finally had a Xerox copier that worked. I am forever grateful for all the help I got from the two technicians, and that they had patience with me when I had problems understanding the different instructions, they sent me.