u/DenKHK

Hi all, I would like to ask if anyone has a favourite effective way of removing melted rubber residues from nickel plated surfaces. So far I see this most on OM-1 and -2 top covers, courtesy of the accessory shoes.

I've tried many times using, on each attempt, IPA, dishwashing liquid, acetone, naptha (lighter fluid), micro-abrasive cream cleanser (equivalent to Soft Scrub/Scrub Daddy)... all to no avail. I might have also tried vinegar, but I can't be sure about that. Either way, residue is still there.

Thank you in advance!

Dear all, this is the same lens from my previous post here.

I would like to seek guidance on what could have gone wrong with the focusing key.

1. One of the few things that worked fine on this lens when I got it was the focusing mechanism. Dry, but functioned without problem otherwise.
2. I had since taken the lens entirely apart and restored/cleaned up what I can. For the helicoids, I separated them (having marked point of separation), cleaned them, and applied tiny amount of fresh grease.
3. I recoupled the helicoids along the marks I made, and they rotate fine individually. I then aligned the helicoids according to the number of turns each took to separate, which I had previously noted, and installed the focusing key. The screwholes for the key on rear ring and the and the trench in the inner helicoid for the key to slide in aligned OK, so I screwed it down.
4. The whole mechanism would then be jammed solid (or move with the utmost difficulty) until I removed the focusing key. What could I have done wrong?

Caveat: I did align the helicoids along the marks I made when recoupling them. However, as a novice I may have been overcautious and made too many marks (broadly, at infinity zoom, MFD, and point of separation respectively) so I might have used the wrong reference marks so please do not discount this possibility.

Dear all, I have been trying to find information on this particular Mitsubishi IC for a long time without success. This PCB dates from around 1982-ish. It handles exposure measurement for a camera by taking inputs from an LDR (measuring incoming light) and several potentiometers (representing camera shutter and film settings), then outputs to 3 LEDs to indicate over-exposure, ideal, and under-exposure. So it seems to be a comparator of some sort, or basic microcontroller.

I have also attached the schematic of the circuit it comes from to help give an idea as to what it does and help confirm identity via the pinouts.

This IC does not appear in the 1984 and 1989 Mitsubishi databooks that I managed to find. Google was unfortunately absolutely no help. The closest I got are the:-

1. M51978P, which is also a linear circuit and also has the circuit function ID (78), but is a switching regulator controller; and

2. M51848P, which has the same linear circuit range ID (18) but different circuit function ID, and is a single timer.

I have given up searching online and thought to ask real human experts in this field for help. Thank you in advance!

Dear all, this is a repost because for some reason the photos did not appear on the original one. I've also taken out a question that was solved despite that (thank you u/DesignerAd9). As a backup I've uploaded the photos separately at https://imgur.com/a/mOVdK99

I picked up a beat-up Olympus F.Zuiko 50mm f/1.8 lens to practice CLA and restoration on. It's an older silver-nose model (Pic 1).

I have 2 questions I would like to seek your help on, from easiest to most difficult.

1. The lens had quite some fungus both on the glass and even on the body interior. The rear optical unit had some on its body as well (Pic 2).

I managed to clean most of it off with hydrogen peroxide-ammonia mix, but there's still some white stuff left (Pic 3).

I have not been able to clean it completely even with cotton buds and fine paintbrushes, and because it's a sealed unit, I am reluctant to just soak it in the peroxide mix. What other ways can I try to get rid of it, or is it just dead fungus and ok to leave it there?

*****

2. On all the parts diagrams and videos I have seen on disassembling this lens model, after removing the name ing and the filter ring the front element can be removed as a single unit by unscrewing it out with a lens wrench. However, my unit is different - there are no notches or holes for a lens wrench on the front element. Instead, a front ring unscrews off, followed by 2 layers of bare optical lens (with a retaining ring on the inner one). What I am left with is what might be analogous to the body of a front element in the lens barrel (Pic 4).

Problem: I can't get that element body out. Again, no holes or slots/notches for a wrench, and wouldn't unscrew out even with rubber lens tools.

After some searching I found a parts diagram for this lens, which appears to be a Type 1 version of this model, and I've added an excerpt of the parts diagram with the stuck unit marked with an arrow (Pic 5).

I have tried dripping at different times IPA, acetone and WD 40 along the edge of the unit, but the unit it still completely stuck. I would really appreciate any help or advise on what else I can try, especially if you have encountered such strongly-glued lens before!

Thank you all in advance and apologies for the long post!