i translated a lot of photocopier manuals in the past and i worked with technicians. so i should say that you missed some good stuff. those solenoid driven clutches control the shaft they are connected to. when you fire the solenoid, the free running gear engages. the point is, you don't have to put several motors and synchro them electronically. One big motor turns the entire gizmo. most modern laser scanner head (that six sided mirror thing) has a ceramic bearing which has a real tight tolerance. you can lift it and replace quite easily, however. fuser unit has a VERY powerful halogen bulb and ptc's and thermistors inside. toner dispensing unit has a very complex measurement algorithm which regulates the toner/developer (ferrite material) ratio electronically. one last word: maybe you noticed, you can not connect a wire to a wrong socket, they're all different in the entire machine. i especially noticed this with Japanese copiers.
Late to the party, but as an old copier tech, just a few notes. There is no 'secret harddrive' for capturing every copy the machines scan. If there was, it would fill up somewhere around the 1000th copy. There are digital copiers with integrated HDDs but you have to specifically tell the machines to archive the images There is a security feature on digital copier, that integrates machine identifying serial numbers into each image. The LED array you pulled off the Drum assembly frame is not for cleaning the drum, at least not really. The drum assembly has a cleaning blade to remove remaining toner from the drum prior to it rotating in front of the LED array, known as the Quenching array. The purpose of the LED is to neutralized the charge on the drum surface prior to it turning to the corona wire (which reapplys the charge). Basically the digital image is formed on the drum in the following sequence: 1. cleaning blade removes remaining toner 2. Quenching LED neutralize drum surface charge 3. Corona wires apply negative charge to the drum 4. The Rotating Mirror array throws the image on the drum, w/ light portions of the image imparting a negative charge to the drum 5. the drum rotates past a 'magnetic brush' which allows positively charged toner to come into proximity with the drum, with the positive toner coating the negatively charged portions of the drum. 6. drum rotates to fact paper, the paper is more positive than the drum, pulling the toner off the drum onto the paper 7. paper runs through fuser, and the toner is fused into the paper via heat and pressure 8 customer doesn't like the image (usually because they never clean the copier glass) and place a service call, where they spend most of the tech's time listening to them complain about the copier.
Clell Harmon Thanks for information! I have been trying to learn the parts and how they work. I deliver copiers and anytime we pick one up from a doctors office or government facility the hard drives have to wiped. I have been told that machines today can keep millions of past print jobs on the drives?
***** Like I said, there are digital copiers with integrated HDDs, but you have to tell the machines specifically to store a copy A quick check of the current corporate industry standards have the higher end units with three terabyte drives (some of the more absurd ones are actually installed with RAID arrays to ensure the images are safe) Millions of past copies? No. Not on any one machine 10s of thousands would be pushing it.
Clell Harmon I know from the security side that the buffers often keep the last x number of pages in network printers, I'm sure it's the same with digital copiers that work in a similar way. It eventually cycles over the buffers but some of them are rather large. So you may be able to get the last week's worth of data or so out depending on usage. But it's not infinite of course.
Ewan Marshall Not on a copier of this vintage. The image isn't really 'digitized' in any meaningful way. It's a straight through path from the optics to the organic drum, with only a minimal delay through the logic array. This model of copier does have memory, but only few pages worth (up to 20 if I recall correctly), and its plain old fashioned dynamic ram. Which means the ram reinitializes each time it's powered up... or the next duty cycle. Modern stuff, sure, you need to be careful. These >15 year old machines, not so much.
Yeah, I know, but you'll be surprised, that said, solid state buffers can be a problem to. And we have ways to maintain data through a power cycle of DRAM which takes hours for the data to naturally degrade fully and longer with tricks like the use of liquid nitrogen to cool it. Most computers do not actually wipe the memory on initialization just when they want to start using that page. Yes, it depends on the model as to how much of an issue it is. Finally, often a business the machine is never fully shut down so over the weekend a network attacker can often get to those buffers. Ideally one wants to be able to store the whole document in the buffer these days (scan once then correctly collate copies of multi-page documents, so those buffers have gotten bigger (to hundreds of pages these days) but even 20 pages can be a problem if that is medical records, bank records or financial statements.
I am an old TV/VCR repair tech., and today I have an interview for a job to repair copiers. Thanks for the review, you have prepared me for my interview.
Try to get a old Satellite to tear down that would be interesting. I repaired and programmed large business phone systems for 30 years, one day our copier screwed up in the office, we called a repair tech, We were really impressed on his knowledge of copiers, he had the thing torn all apart due to some cog out of alignment. But he got it repaired and it went on working for years after. Electronics repair is one thing having to align and adjust and troubleshoot just where the trouble is coming from is a whole different story. I believe my boss offered him a job before he left. Repair techs truly are talented people and are very hard to find, and must combine many, many skills. At our company new techs had to work with there trainer for 5 years before they were cut loose , some more some less. That laser scanner reminds me of the scanners where you check out in a store, almost the same design. Great hack material for sure. Interesting tear down, tho you did it many years ago, its timeless. Now go sell the scrape metal :)
As a copier tech of almost 20 years. you made me cringe. With every part I was yelling what it is. I hope this video opens some eyes as to what it takes to be a great copier tech. Customers always think copiers are simple. I love your videos, thank you.
When i was working as a photocopier technician I had to build atleast 10 machines from scraps during training, we had a shed we called the graveyard, filled with 100's of busted machines, managed to build all ten machines from the bottom up and have them calibrated to a T. great experience, never forget the pain and suffering it caused me though :'D in hindsight I wish I raided that shed for so many more parts haha
back when i worked in electronic scrap, i was the one who always got all these copy machines cause none other wanted to mess with them. we had to completely seperate all bits into various bins, alu, iron, plastics, wires and all that. i had fun ...
I'm a mechanical engineer and lead laser printer development for over 20 years. I began watching EEVBlog recently so allow me for such a super late comment. I enjoyed this video very much. You first thought clutch as motor but later you discovered what it is by yourself. And you did no know this is full digital copier at first but you found the right answer by yourself at the end. You really got great insight of engineering. Now, what I felt interesting was that you were very impressed seeing the main drive unit that comprises of one big DC motor and gears and clutches. Actually drive unit is not very difficult unit to design. Designing itself is rather straight forward and easy. While control panel with LCD and touch screen , that you were not interested in, rather impresses me, a mechanical engineer, more.
Thanks for the bit of Nostalgia. I used to work on this model just over 10 years ago :) The little motors are electro magnetic clutches.I'm happy to answer any questions (might be a bit rusty on specifics for this model)
Gears, motors, parts, plastic bits, boards. Man no one should pass the opportunity to tear one of these down. I've done quite a few, older ones. It's gritty but man the fun is worth it.
oh man, I wish I could dive through whatever dumpster you throw your teardown output into ;-) there's such a lot of cool stuff in that copier alone that I'd love to reuse for some of my projects..
I think we have improvements in CAD to thank for ever-more-complicated gadgets. Back in the day designers had to somehow force an extra dimension onto paper to make sure everything fit. Now that third dimension fits so neatly into the two of the computer screen, you can pretty much stick anything in there. And so now my radio makes coffee for no reason.
Unbelievable the amount of Engineering that went into creating that thing! Then think about sub-component contracting, manufacturing, Q/A, and field support!! Amazing they weren't $500K/ea back in the day. And at home I have a ink-jet printer that cost $29US and replacement cartridges (B/W and color) cost ~$60...cheaper to buy the printer than the ink cartridges. Yeah, its not a scanner/FAX/networked but it prints what I need. Great tear-down Dave!
Looks like your photocopier time machine got hit by a train! I had fun years ago scrapping a small desktop copier and got a ton of salvage parts out of it.
Now the real fun stuff is to try to put it back together :P The carry handles are standard equipment on all copiers. I worked in that biz 10 + years ago.
The flywheel is there to help stabilise the rotation of the drum and stop image abnormalities due to minute changes. Those smaller units in the paper feed section are drive clutches, quite common to have a single drive motor and clutches to engage drive to seperate sections. The HV unit can are quite high in voltage, our machines run in the order of 6000v for the transfer stages. Need to get you one of our retired colour machines with a transfer belt to tear down!
notice the shaft that you pulled the clutch off. The gear spins all the time driven by that first motor. The clutch alternately connects the gear to the shaft to spin the shaft at your discretion.
As someone who fixes this exact model of copier on a close to daily basis, this was fun to watch. Your pretty close for the most part about how everything works. Bravo.
I tore apart a Mita DC 4090 with the collator last year and it took me almost two weeks - All e-clips and screws - not a single hex bolt. Sold the plastic gears and Tsubaki timing/drive belts on eBay for almost $30. Got almost $20 for the scrap sheet steel minus the steel rods which I am saving. All the motors and clutches test good. There are some really good stepper motors in there!! Stocked up my electronics project parts. A lot of work but worth the effort. Excellent education project.
Interesting vjdeo! I have teardowned a photocopier once to steal some engines... I also was amazed how comlictated machine it is. Thanks to your video i can understand more how it works. And also i had bad time with the black toner :).
You should have a look inside of the Oce Jetstreams that I play with at work! A3 continuous feed in full colour duplex at 150 meters per minute! They cost several million each!
That was pretty amazing to see what's inside a copy machine. Growing up I often wondered how things work like for example a telephone. I got hired by AT&T and became a tech and so got to work inside Central offices where all those Switches are...I also installed stuff at customer locations and spent time outside in the field testing cable pairs.
I got around ten Nema 17 and one Nema 23 motors out of the Konica Minolta photocopier I ripped apart. Glad I did not tear down a Panasonic photocopier.
thank you Dave... It would be really nice if your can shed some light on how these electromechanical systems are actually designed and built... maybe a small DIY project from start to end..
I've worked on even older school Xerox 50xx and 53xx low volume copiers back in the 90's. Completely analog; all optics went straight to the photosensitive belt. All boards were through-hole boards, even the CPU board (Mains PWB). In the field we board level repair these things and send it to the factory. But even with those old 'analog' machines, it still gives me a great appreciation of engineering it requires to get these massive machines going. And that's the low volume stuff I worked on. The Xerox Docupress line was a behemoth machine filled with moving parts; never fails to give me a nerdy hard on. . . Next challenge for you. . .Reassemble it to it's original form lol. Great tear down vids. . .Keep em coming!
As a veteran it was a little painful to watch the tear down. Wonderfully complex mechanism with many useful part for inventing. I believe that was an organic drum. Selenium ,cadmium. are just too toxic for techs and the environment. Nice to reminisce, thanks for the trip down memory lane. .
Just a note about the clutches, they are spring wound clutches. Copier manufacturers have been using the since 1969 (I was working on these machines back then). There is a coil spring surrounding the shaft inside these things and the little metal plate floating on the end is pulled in toward the electromagnet to make it clutch. The plate is tied to the end of the coil spring and causes the spring to wrap tight on the shaft causing the gear and shaft to lock up. When the coil is de-energized the spring unwraps and the clutch freewheels. Some guys call these 'Chinese handcuff' clutchs for an obvious reason. Godfrey
Wrap-spring clutches go back many decades. Perhaps the Model 15 Teletype used them. The Friden Flexowriters definitely did. They often drove the load by one revolution and then disengaged. The ones I knew had springs wound with square or rectangular wire. They were lubricated, (but not likely with extreme-pressure oil!) When disengaged, the spring was held expanded to minimize wear. One end of the spring put some torque on the outer sleeve (spring inside), which was stalled by a pivoted pawl that was pulled out of engagement by an electromagnet. Power to the magnet released the sleeve, the spring contracted, wrapped, and gripped the continuously-rotating inner cylinder. Left by itself, the spring gripped the sleeve inside it. If the e. magnet stayed energized, the sleeve continued to rotate, and the spring didn't slip. If the magnet's power was cut off, its pawl-armature was ready to snag an outward projection on the sleeve. That made the spring expand, and the driven member stopped. However, inertia made the driven member overshoot slightly, and another pawl and "one-tooth ratchet" kept it from going backwards. That kept the spring expanded, minimizing wear. The driven shaft always stopped at exactly the same position. Incoming power rotated the cylinder inside the spring. Cylinder rotated on the output shaft, which extended the full length of the clutch. We called these single-revolution wrap spring clutches. They worked extremely well The Model 28 and later such Teletypes and the IBM Selectric typewriter used a different type of clutch, which had a few pawls inside a shallow cup with a cylindrical inside surface. Those clutches also had a pawl to "stall" the load and disengage the clutch. Cup drove the load. Releasing the first pawl used driving torque to engage another pawl, and as I recall, that second pawl made a third engage. The clutch simply did not slip! Stalling the first pawl made all three(?) disengage. HTH!
Incredible and advanced engineering. It just a dream to be able to design something like that, and its an awful lot of pains taking design work right down to the plastic moldered panel controls.
Those "flat motors" with the 2 blue wires aren't motors, they're electro-magnetic clutches. Machines like this typically have one big motor (the one on the PCB in this case) powering the drive train that does the paper handling, with clutches to enable the various stages in the sequence, eg; paper pickup from the current tray, etc. ETA: Heh. At 17 minutes, he's finally twigged that they're clutches. :)
Awesome vid! Thanks Dave! You should tear down some old multichannel reel-to-reel recorder with micro controller (some like a Studer A800 or A827) - I know it would be crime bit it'd be hella a tearing down!))
Tbh a drill with a bit for the screws really helps with the scrap time i got 1 recently and within a day i had it scrapped down to bare bits 3million screws 😂
The problem I'm having with such machines is that often there is literally no information to be found online about those, which accordingly often renders them useless (especially if you don't have the right testing equipment to get the specs). The mechanics however are spot on an you need no datasheet for looking at a set of cogs and how those rotate. :)
Those arms are to sidefeed the printer with an add on machine like a3 200g paper holder, or if you want to make a book you can add a staples machine where it folds the paper and staples then you have to use the sidefeeder or else the paper only sticks inside the machine 😉
In the past I've torn down dozens of scanners/copiers, and prised out those lenses you can see at around 40:30. They're super useful for inspecting PCBs, highly recommended!
I work on these damn things every day... It is fun watching someone else take one apart they are a hardware hackers dream! Dave- see if you can hack the lcd screen, been trying to do that for a while now.