Canon MP620 Service Manual And Parts List
I deal with these printers often enough that I've stopped treating the service manual like something sacred. It's a reference, not a bible. The Canon MP620 is a photo All-in-One from the mid-2000s, inkjet-based, and it has a few well-known failure modes that are straightforward to fix if you have the right documents open in front of you. The service manual for the MP620 is a printed circuit board (PCB) layout document, a parts breakdown with exploded views, and a troubleshooting flowchart. The parts list section alone is worth printing out because it maps every identifiable component to its Canon part number. Without those numbers you're guessing at online marketplaces, and that guesswork costs more in time than anything else. The manual lives on Canon's official support pages in most regions, though availability has degraded over the years. If the direct link is down, search for the service manual using the exact model code "MP620" alongside the word "service." You'll typically find PDF versions uploaded by third-party sites or shared on repair forums. The one on Canon's own site, when it works, is the cleanest version with proper diagrams.
Here is what the manual actually contains, and what matters most about it: The main PCB is numbered W142041000 or close to that depending on revision. The print head assembly is a separate part number, and replacing it without a clear procedure means you'll either strip a screw or crack the head carriage. The service manual spells out the exact screw sizes and the order to remove them. Follow that order. The encoder strip runs behind the print head carriage. It gets ink on it constantly, and when it does the printer starts mis-indexing pages. Cleaning it with distilled water and a lint-free cloth is standard practice, but the manual shows the removal procedure so you don't end up stretching the strip past its limit and ruining the calibration marks.
The waste ink pad counter is another thing the manual covers. The MP620 tracks absorbed ink through a software counter that triggers error codes when it hits a threshold. Replacing the physical pads doesn't reset the counter, and the manual tells you how to enter service mode to clear it. There are online tools that claim to do this, but they sometimes hard-reset the counter incorrectly and leave the printer in a weird state where it still reports a fault. The manual's method is slower but reliable.
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What the parts list is actually good for
The parts list section of the manual is not a casual shopping guide. It's organized by assembly, and each entry has a reference number that ties back to the exploded diagram. When you're hunting for a specific roller or gear, the part number from the manual is the only thing that matters. Generic descriptions like "feed roller" appear on too many aftermarket listings to be useful. The Canon part number removes that ambiguity. One thing most people miss: some parts in the MP620 are bundled as sub-assemblies. A platen might be listed under a larger assembly number even though you only need that one piece. The manual's diagrams show these relationships clearly, but they also sometimes list a higher-level part that includes components you don't need. Check the diagram before ordering, or you'll pay more and receive a lot of unused hardware. I once had a customer send me an MP620 with a paper feed error. The fault was a worn separator pad, a cheap part. I pulled the parts list from the manual, found the reference number, and ordered from a supplier who quoted it correctly. The customer received the wrong pad because the listing didn't specify the exact sub-assembly version. The manual would have shown me that there were two variants for different production runs. That kind of detail saves you a return shipping cost and three days of downtime.
Download and access notes
The manual is distributed as a PDF, usually around 15 to 20 megabytes depending on whether it includes the parts catalog or is split into separate files. Canon occasionally changes their file hosting, which means direct links rotate or go dead. If a link isn't working, try searching the Canon technical documents database rather than blindly clicking the first forum result, since those sometimes point to outdated revisions. The parts list portion can sometimes be accessed separately from the full service manual. Canon's portal separates them into different document categories in certain regions. If you only need part numbers for an inventory run, grabbing just the parts list cuts the download time and keeps the file size manageable.
Practical tips that aren't obvious
The MP620 uses a piezoelectric print head, which means the nozzles don't clog from sitting idle in the same way thermal inkjet heads do. However, the printhead is not user-serviceable in a meaningful way. If the manual shows a specific reflow or cleaning cycle that fails to restore nozzle patterns, replacing the head is the only real fix. Trying aggressive solvent soaks on these heads usually damages the delicate piezo elements and voids whatever warranty remains on a refurb unit. The carriage belt tension is set at the factory and the manual includes the correct deflection measurement. If you replace the belt and tension it yourself by feel, you will likely overtighten it. An overtightened belt causes premature bearing wear on the carriage shaft and introduces a grinding noise that gets worse over weeks. Use a light finger press to check deflection, and match the manual's specification rather than assuming tighter is better. Ink cartridge chips on this model are a common point of failure if you use refilled or third-party cartridges. The manual doesn't cover chip replacement directly, but it does identify the contact pin layout on the carriage PCB, which is helpful if you ever need to clean corroded contacts. Isopropyl alcohol and a cotton swab on the gold pins usually resolves a false empty-cartridge reading that persists even when the cartridge has ink.
Limitations of the service manual
The manual is thorough on mechanical disassembly and electrical schematics, but it's not great on firmware-level diagnostics. Error codes are listed with basic meanings, but the deeper diagnosis sometimes requires a service tool or the proprietary Canon diagnostic software that isn't publicly available. If you're dealing with a persistent communication error between the main PCB and the print head, the manual will tell you to check connectors and trace continuity, but it won't walk you through the firmware handshake sequence. In those cases, checking connector seating and measuring resistance across the relevant pins with a multimeter gets you most of the way there, but firmware corruption remains a possibility the manual can't fully address. Another gap: the parts list prices are outdated even at the time of printing, and current aftermarket pricing varies widely. The manual won't help you decide between an OEM part and a compatible one, and for this printer that's a relevant question since genuine Canon replacement parts have become harder to source at reasonable prices. A compatible waste ink pad kit might serve you just as well for a decade-old machine.
