Canon EF 500mm 1:4 L IS USM disassembly stripdown

Hello, I am tearing down my 500mm prime lens to clean and regrease all the parts as well as cleaning the glass/lenses. So far, so good. However I am unable to figure out how to detach part C21-8471 so that I can clean the lenses YN2-1216 and YN2-1215.

Btw, here is some more images of the process. I even managed to strip down the USM motor to the bone (including bearings) and put it all back together.

awesome work!
can you check that part number though? my parts list shows C21-8471 is the parts catalog itself...

Did you remove the 3 XA9-1052 ?

Hi, thank you.
In lack of a better name for this section of parts I used the page reference to name it. Page 5, right side. I am trying to disconnect this section from the left section on the same page. This is where I am stuck.

Hello,
I did remove them, but nothing started moving after that. I tried to apply some force in all directions, as well as applying both lube and then alcohol into the module that seems to connect the two sections of the lens. However nothing moved and everything is really stuck so I'm not sure if this is the way to disconnect the parts of each other or not.. Perhaps they can't be disconnected.. May be some glue somewhere that assures that it won't..

As seen in the attached pictures it looks like someone has been here before because there is some "marks" and stuff. Perhaps someone glued it really hard or bent it somehow.

In this photo, can you indicate where you are trying to separate it? The diagram makes it seem that the shiny black ring is YA2-3737 and it is held to the YA2-3736 section by the six roller pins XA1-1200-259 which seem to still be installed. But it's very likely that I don't understand where you are in the disassembly.

tedlin01 wrote in post #19387509

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forum: Canon Lenses

Did you happen to remove the three XA1-1200-609 screws? Those look to release YA2-3737.

As you said, the shiny black ring is YA2-3737 but YA2-3736 is already detached. See this image:

Sure did and it loosens YA2-3737 but it's still stuck between the parts above/below as they seem to be connected without the help of YA-3737.

After thinking on this, I believe the set screws are the giveaway. I have them on my old Canon FD 800mm 5.6 lens and where they are used is where the parts unscrew. I found the parts catalog pdf and on page 5 it seems to show threads on the part in question.

WOW....excellent work.

Question: Do you guys think Canon will have parts for these lenses in the future? If they stop making the EF's will you still be able to DIY repair?

I missed a chance at a used 300mm 2.8 last year and kick myself for not doing it. But was worried about ending up with a $6000 block of nothing if it failed.

Mike

Aronis wrote in post #19390125
WOW....excellent work.

Question: Do you guys think Canon will have parts for these lenses in the future? If they stop making the EF's will you still be able to DIY repair?

I missed a chance at a used 300mm 2.8 last year and kick myself for not doing it. But was worried about ending up with a $6000 block of nothing if it failed.

Mike

I think the main factor in future repair: Common parts that fail. These parts will be used up and will also be the most likely to cause you to need repairs.
This issue can also make the less common part failures easier, as longs as the 'junked' lenses due to unavailability of common fail parts are kept.

You won't end up with a block of nothing, rather a cool doorstop.

So a little update.. I never manages to dettach the front part of the lens from the middle part but I did manage to clean the middle lenses by patiently cleaning them with sensor swabs through the small holes used by the focusing system to move one of the lenses inside the barrel. That problem is fixes now.

I've swapped one of those before between a 70-200 f4 usm unit and a 85 1.8 if I recall correctly. The USM assembly was the same size. The 500mm USM motor in your photos looks different than those found in the smaller lenses. Looks like it has two armatures for adjusting focus than the usual one. Best advice I can give is join this facebook group called 'Learn Camera Repair'. A lot of very knowledgeable and experienced individuals there and while they mostly work on pre-digital, when they do encounter a digital problem they certainly know their stuff. Maybe someone would know how many different sizes there are, kind of like a compatibility list.

https://www.facebook.c​om/groups/360490091319​202/

Ebay and aliexpress.com seem to be calling them USM sensor strips or bars, a search for 'Canon Sensor strip' yields some results like this one for a 70-200 2.8 which should be a larger sensor than other lenses. But it is a gamble if it the same size as those used in super telephoto USM.

https://www.aliexpress​.com …211200001613639​9411%21sea

https://www.ebay.com …trip&LH_PrefLoc​=2&_sop=16

Lastly, don't forget the Canon parts phone number, they do sell parts to the public.

Best of luck.