Minolta SR-T 303 / SR-T 101 mirror stuck

This is very much a beginner's thread as I decided I wanted to dedicate some time to attempt simple repairs and restorations, and in general to understand how cameras work.
I have some tools apt for the task, but some serious lack of knowledge.
Anyway, I have been picking a few cameras to fiddle with.

The minolta is in good conditions, but the mirror is now getting stuck every shot. It has likely been kept lift up in the "locked" position for a long while.
Reading around I read that a common problem is linked to a gear in the bottom of the camera. here:


Upon shutter release, the gear is meant to hit with the "A" knob on the "B" lever, that triggers the mirror release.
I did lubricate the gear lightly (some spills have since been drained) with moebius oil. It moves and it hits the lever, but apparently with not enough strength to push the lever.
if I force the lever a bit with a toothpick, it just releases the mirror correctly. It does not require a great amount of force.

So it seems that the gear is not generating enough force to hit and make the lever release - or that there is excessive friction preventing the lever movement - but I don't see dirt or major impediments.

I though of the very inelegant solution of finding something to make knob "A" bigger so it pushes further, but I am not sure what to use, and it does not seem a clean solution.
Any suggestions?

Actually I got the service manual and will attempt to fully dismantle and clean it as a project

That kind of non-release can be binding from dirt and such. It can also be from limited range, maybe out of adjustment. Any chance that the the screw holding lever B, the pivot point I expect, is eccentric and that rotating it one way or another will make the lever move tip A more or less distance?

Most likely the solution lies at the other end of lever B, which appears to be along the top edge of your photo. Weak spring? Whatever pushed B needs to be adjusted for more travel of B to release what A pushes against?

Thanks Dan - I'll check shortly as all these bits are readily accessible.
Also it makes sense I think if the camera was stored for a long while with some parts in tension (the spring), maybe such parts lost a bit of "springiness" - excuse the term...

Many times 35mm SLRs are designed so the second curtain will trigger the mirror to come down. If the second curtain is sluggish, the second curtain brake will stop it before triggering the mirror release and the mirror will stay up. Cleaning all the moving parts of the second curtain mechanism should fix it, though the spring of the second curtain may need additional tension, or the brake is too strong.

The second curtain should take about 14 milliseconds to travel the distance of the film gate.

negativefunk said:

Any suggestions?

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IMO, Minolta SRT is not one of the easiest 35 mm SLRs to service, in part because the inclusion of TTL metering with mechanical viewfinder readouts added a fair amount of complexity, which you will need to deal with! But while they may seem needlessly frustrating, there is logic to the system of strings and pulleys, and they are designed so that they can be disassembled. and provided that you take the time to route the strings properly, they should not fray or break.

If it helps, remember that once upon a time, experienced assemblers were probably stringing these things by the dozens without breaking into a sweat! Your challenge is that you will be learning the various little tips and tricks from scratch, because YT videos and service literature can only convey so much, versus having a senior technician looking over your shoulder. Should you encounter an "impossible" reassembly situation, take a break (sometimes mine last for days) and you may realize that you've been going about things the wrong way. The correct way typically does not require superhuman dexterity or a 3rd hand.

I did not need to fully disassemble the camera, but I did separate mirror box from main body casting, along with a module containing much of the film transport mechanism. This gave me decent access to pretty much everything.

The CLA'd camera went from getting stuck midway though it's mirror cycle to being buttery-smooth with no hiccups whatsoever, without my increasing spring tensions.

Your reward for learning to fix these cameras is access to really cheap yet quality SRT cameras that others can't have.

Thanks all
Seems that this one won't be needing a full CLA, at least not yet. I also seem to have solved a problem by creating another, but the new one seems less of a worry.

I cleansed all the bottom-accessible parts of the mirror mechanism. The screw did not seem to play a role in the range of the A-knob, but still was not enough - although B was more sensitive.

I took off the spring on the top right - it was leaning on a material much like the light seals, that went bad and was preventing the spring to be... springy, again. I soaked it in acetone and cleansed the camera (probably the foam was there for a reason, like reducing friction, so I maybe should put some new one back). Now it works wonders. Happy it was this easy

The drawback: i had to remove the metal latch held by the two black screws to access the spring proper. This plays some role in the film back locking mechanism so now it does not lock :/. But I will figure it out!

On another note...
What is a range of SLR easy to work on as a start?
I got a couple of "as is" spotmatics I got for a pittance on their way as I like spotmatics and I thought they could be learning grounds

That's how it goes- the ankle bone is connected to the wrist bone, but there was no way to see this until one part was out

A very helpful tool, if you haven't been doing this already, is a digital camera. Take photos all the time. For a variety of angles. You may have no idea what you need to see when you are removing parts. Sometimes the answer to a spring or latch is in the corner of a shot of something completely different.

A general principle to pay attention to is that parts are meant to be in particular places. There will be notches for springs to sit in, shoulders on screws, all sorts of little things. Most parts can 'tell' you where they belong if you look carefully.

As 4season said in a different way, humans put these together. Humans can take them apart and put them back together again. As you work on different cameras, you'll start seeing the same problems again and again, and often the same solutions.

negativefunk said:

What is a range of SLR easy to work on as a start?
I got a couple of "as is" spotmatics I got for a pittance on their way as I like spotmatics and I thought they could be learning grounds

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Zenit-E, 12SD, 15M, 212, 412 et al
Nikkormat FTn
Nikon F (but I don't know about the Photomic finder)
Olympus OM-1

I have serviced Pentax cameras, but not Spotmatic. I expect that the earlier models with stopped-down metering would be pretty simple (by the standards of camera repair).

The usual factory camera repair manuals assume you are already a trained camera technician.

On the "Learn Camera Repair" site there are more resources that hold your hand through the entire disassembly and re-assembly of a camera.

Two I recall of hand are the K1000 and the Nikon F (see screen shots of the contents). . Either one of those would be a good starter camera to tear apart. Realize that camera repair is like learning a musical instrument. If you got a guitar today, how many years or months before you can play well?

Hi, yes I am familiar with the site - I started with the "lessons" some time ago but even at 1$\each they add up, so I now take only what I need.
I took the CLA walkthrough for the minolta and a similar one for the ME super (I have two and would like to restore one more in the future) and they look thorough, so I will take advantage of those.

As per camera repair in general, it's an hobby and I don't have any kind of urgency. I would like to restore objects that I like, and the financial commitment is low.

As per the Minolta, I am trying to look for an alternative for the spring in the door latch which is what I seem to have lost while unfastening the bottom. Maybe a ballpen spring will fit with some doing

negativefunk said:

As per the Minolta, I am trying to look for an alternative for the spring in the door latch which is what I seem to have lost while unfastening the bottom. Maybe a ballpen spring will fit with some doing

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This is where gathering up dead cameras can be helpful. Most likely the door latch is a mechanism used on a variety of Minolta cameras, for example. I've found that for some reason the Pentax K1000 is full of useful springs and gears and screws for other cameras. Search through Ebay every now and then for things like 'parts Minolta.'

And then for fun, springs! - the shipping will kill you on a single item-