Question about AF USM unit sizes

Before I started asking, perhaps you guys would like to have a quick read on this thread to understand my situation first.

Basically, I have a broken Canon 100mm USM Macro Lens that I bought last December. It has no-responsive auto-focus. I brought it to the local repair center in Perth, Western Australia on beginning of January and up until now (6 freaking weeks) the lens hasn't been repaired because of 'waiting for replacement parts' from Canon. Same lame excuse everytime I check the repair status.

So I said to them to cancel the repair and I'll take the lens back the tomorrow.

I know that the problem with my lens, the Auto-focus unit (the USM ring) is somehow doesn't work. Perhaps the PCB got busted or the USM ring itself that busted, I'm not sure. But the thing is, the auto-focus won't work and I believe the only way to repair it is to replace the USM unit itself.

As I don't trust my local repair shop & the Canon service center anymore (their service sucks :mad, I'm thinking to repair the lens myself. Hence, I need more info about the USM unit.

1. Has anyone ever tried to replace the lens part before? Was it complicated? Do I have to solder any parts on the PCB to the USM unit?

2. We all know that Canon 100mm USM has the 'ring-type' unit. Are there any other lens that have the same diameter size as the 100mm Macro USM?

3. Are the USM unit itself supossed to look 'dry'? Does the USM unit actually needs to be lubricated in order to work? I looked up on my lens' USM unit, and the rings are dead-dry. They're not rusting but it's certainly dry, no grease whatsoever.

So if anyone has any experience with this kind of situation, any help would be very much appreciated. Thanks in andvance.

It's most probably specific to the lens itself. Otherwise, wouldn't the repair centre have simply taken one ouf of the parts bin or another duff lens to fix yours?

Any other opinions?

Well..

Can you live without AF? For Macro work MF is still largely used for its accuracy and the VERY thin depth of field involved...

Well, I do feel ripped off paying AU$550 for such an expensive lens without AF. On top of that, I also spent $99 for so-claimed-'repair' that turns out to be nothing.

Sure I do most of my macro shots in MF, but I use this lens not just for macro work. So I think AF is crucial for me.

Move along, referring to this thread, I found that he had the same problem with the USM unit. After couple of periods sitting on the shelf, the AF starts to busting up. Similar case with my 100mm Macro USM.

I have followed his tutorial fixing the USM unit, but doesn't seem to work on mine.

So the problem on my faulty AF lens could be on either:
1. the USM unit itself
2. the PCB, solid one or those flexible cables I don't know.

Just FYI, on the solid PCB on my 100mm Macro USM have a number 193 written down with marker. I wonder if other ring-USM lens like EF 10-22mm etc, have the same number on it?

Is there anyway for me to order the specific lens part directly from Canon USA or Australia or wherever?

What, no one interested?

tried contacting canon for parts #s?

The reason you paid $99 for 'nothing' is because you didn't wait it out. Now I'm not saying that 6 weeks is reasonable (it's not, and you have every right to be frustrated), but you seriously think they would not have repaired it? At the very least, you could have them give it back to you and let you know when the part comes in so you can bring it in for the repair.

Not that that will do you any good.

Yep, as someone who used to do electrical repairs; sometimes as a shop waiting for parts, you just get screwed by your distribution channel. What you should have done was politely b*tched and got some portion or all of the $99 waived since it took so long.

The reason there are authorized repair centers is because you are talking about fairly delicate repairs. Not having worked on lenses I'm not saying you couldn't do it on your own, but having worked on various electronics over the years I can say its likely to be substantially more complex than you might think without forehand knowledge in terms of acquiring parts and information.

OK I think I finally found the problem with my lens.

The reason why my AF doesn't work is caused by the flexible cable that connects the main PCB to the USM stator.

Anyone know where can I order this cable online?

Call these guys:

http://shop.thefotogee​ks.com …ry=25&PageActio​n=VIEWCATS

If they don't have it they may well know where you can get it.

Call Canon Parts Australia. Don't know their number, but I know, at least in the US, the Canon Parts department is very helpful, and ships VERY quickly.

To return to an earlier question about the dry parts. As I understand it, there are no "moving" parts in the USM, instead it vibrates (at ultrasonic frequency, so no surprises there), and has no need of lubrication. In fact going anywhere near it with any oil or grease is sure to ruin it.

A very clever bit of design. By a college student who approached Canon with the idea.

I can definetely confirm now that it IS the flexible PCB that caused the AF not working.
When I opened the lens, I found 4 thin flexible PCBs:
- 1 connects to the AF/MF switch. This one works fine, the lens recognize the signal when I switch to MF or AF.
- 1 connects to the electromagnetic diaphragm. This one works fine as well, as I can still change the aperture from the camera.
- 1 connects to the inner side of the focusing ring. This one I believe transmit the focus signal, which I think still works fine as well. Because my lens on MF still can transmit the focusing signal to the camera.

- Lastly, the problem, 1 that connects to the USM ring stator. This one should transmit the signal to stator which then powers the rotor to move the focusing glass. For some reason, the rotor in my 100mm macro doesn't move at all.
According to my discussion with kimmik from the email, he mentioned that to determine if the USM is still repairable or not is to listen when in AF mode, is there any faint noise that indicates if the rotor is actually moving or not. In my case, I didn't hear any noise from the rotor.
So I can conclude that it's the stator that cause all of this broken AF problem & needs to be replaced, to be precise, the flexible pcb on the stator.

And thanks for those replacement parts store info guys. Unfortunately the fotogeeks doesn't sell the specific parts I wanted. Even when I called Canon Aussie just now, Canon said that don't sell individual PCB parts. They only sell the whole USM focusing unit 'for just' freaking $230 now. So I said, meh for that.

I just found out from the Canon Lens work III book, there are only 2 sizes of USM ring unit. There's MI type, the most common one with diameter 62mm. And the other one the larger LI, with diameter 72mm mostly used on those white lenses.

Now I know that the 100mm Macro uses MI type, so I figure out it might be better to find other cheap ring type USM lenses & then I'll just canibalize the USM unit to the other.

And just on my luck here, I found the old EF 28-80mm f/3.5-5.6 USM mark I on eBay for just mere AU$70 + $13 shipping.

So what I'll do is I'll be waiting for the lens to arrive, then starts replace the stator unit on my 100mm Macro with the new one from 28-80mm.