Nikon F-301: Shutter replacement

I won't be able to do anything more for this Nikon F-301, but a look inside will be interesting.

Coming soon here

Be careful with the bottom of the battery case - it looks filthy and spoiled...

Once you have access to the shutter you may be able to cock it and re-align those blades. May not be a terminal case.

forest bagger said:

Be careful with the bottom of the battery case - it looks filthy and spoiled...

Click to expand...

I don't know what was done to it, battery acid leaked out inside and the metal on the outside is damaged.

ic-racer said:

Once you have access to the shutter you may be able to cock it and re-align those blades. May not be a terminal case.

Click to expand...

I don't know, the slats seem to be bent.

In any case, it's exciting!

That's the famous self-diagnosing shutter! When it does that it's kaput!

mshchem said:

That's the famous self-diagnosing shutter! When it does that it's kaput!

Click to expand...

Good luck getting the top cover off. They have made this task next to impossible without breaking the sliding lever, and the film rewind C-clamp is also quite an obstacle!

Andreas Thaler said:

I don't know what was done to it, battery acid leaked out inside and the metal on the outside is damaged.

Click to expand...

That should be fine, I have cleaned a couple of those battery compartments and they are hard to repaint but keep ticking for years

Andreas Thaler said:

I don't know, the slats seem to be bent.

In any case, it's exciting!

Click to expand...

mshchem said:

That's the famous self-diagnosing shutter! When it does that it's kaput!

Click to expand...

George Mann said:

Good luck getting the top cover off. They have made this task next to impossible without breaking the sliding lever, and the film rewind C-clamp is also quite an obstacle!

Click to expand...

All nothing a big hammer can't deal with !

George Mann said:

Good luck getting the top cover off. They have made this task next to impossible without breaking the sliding lever, and the film rewind C-clamp is also quite an obstacle!

Click to expand...

Thank you, I'm really looking forward to it.

If necessary, I have no qualms about using the Dremel

neilt3 said:

All nothing a big hammer can't deal with !

Click to expand...

Cameras can withstand a surprising amount of stress thanks to the usual die-cast chassis.

This means that flattening them completely with a hammer is difficult

titrisol said:

That should be fine, I have cleaned a couple of those battery compartments and they are hard to repaint but keep ticking for years

Click to expand...

When the battery acid gets behind the contacts, things get exciting.

Andreas Thaler said:

When the battery acid gets behind the contacts, things get exciting.

Click to expand...

I bought my F301 in the early 90s, and it is a great camera. I've bought a few in thriftstores for next to nothing and the batterys are almost always there and need to be cleaned. What you mention makes things more exciting, but still realitvely easy to clean/repair.
Once you need to open the top is a bear and I don't go there

Andreas Thaler said:

Cameras can withstand a surprising amount of stress thanks to the usual die-cast chassis.

This means that flattening them completely with a hammer is difficult

Click to expand...

Yes , but it can be extremely satisfying !

And no , it didn't get it working , but by that point I didn't care !

neilt3 said:

Yes , but it can be extremely satisfying !

And no , it didn't get it working , but by that point I didn't care !

Click to expand...

It is true, I know the desire to get the hammer when a repair does not work

Andreas Thaler said:

View attachment 368698

View attachment 368697

I won't be able to do anything more for this Nikon F-301, but a look inside will be interesting.

Coming soon here

Click to expand...

We start soon

There will be a lot of work to do before I reach the damaged shutter.

Removing the top cover with mountings, the base plate, the front panel, and desoldering some cables.

Here from the repair manual:




The shutter seems to be quite simply assembled, but there is a some electronics connected to it.

Part 1/2 of my report in German is available on Netzwerk Fotografie (NF). I will post the English translation here tomorrow, Sunday.

It was exciting again

First check








The external condition is acceptable.

Are there obvious signs of chemical treatment on the metal base plate?




Remains of leaked battery acid in the battery compartment.

The contacts of the battery holder (not shown in the picture) are also affected.




I don't know what happened here.




The contact spring has fallen out of its retaining tabs. This can be fixed.

Corrosion caused by battery acid can also be seen here.




The tripod connection is also corroded.


Check the power supply (4 x AAA batteries = 6 volts)




I don't measure any voltage on the two pairs of batteries, each connected in series.

I clean the contacts with the fiber glass pen.

The multimeter now shows 3.1 volts in each case.

This means that the contacts are now conducting.

A measurement across the battery holder from minus to plus shows no voltage.

But the camera needs a 6 volt supply voltage?




I measure the batteries directly in series: 6.2 volts.

That's how it should be.

Also in the battery holder.

But how is it wired?




The battery compartment provides the answer:

A contact bridge is installed here so that all four AAA batteries in series add up to 6 volts.

That's why I couldn't measure the total voltage in the battery holder. The two pairs of batteries were not electrically connected to each other.




The battery holder is inserted into the battery compartment.

I don't measure any voltage on the two contact springs, so I still have to clean the contacts in between with the fiber glass pen.




Now I'm measuring 6.2 volts on the two contacts that connect the circuit to the battery voltage.

So my cleaning of the battery compartment and the battery holder was successful.

But no LEDs light up in the viewfinder when I press the shutter button.

So there are either further problems with the power supply inside the camera or a problem in the circuit.

Hopefully I'll figure it out.


Dismantling the top cover

Since I want to get to the shutter, I first have to remove the top cover. Then I move on to the bottom plate and front panel.






Removing the plastic cover on the handle.


Jimmy from iFixit is perfect for removing glued leatherettes. Today it is being premiered.

It separates without cutting and pries. The flexible blade adjusts itself.

This makes it quicker and safer than before with needle, probe or tweezers.





Rewind crank and ASA wheel are off.

The top cover is fixed with seven screws.

Six of them are visible from the outside, I found the seventh after looking in the repair manual. It is hidden under the adhesive residue on the handle.


On the upper flexible circuit board of the F-301




A look under the hood.




The top cover is connected to the housing via nine cables.

These two are desoldered from the cover ...




… and the remaining from the circuit board.




Completed




The rotary switch at the bottom right turns the signal tone on and off.






On the underside of the top cover you can see its coupled switch with wipers.

• First position: switch off, no contact
• Second position: switch on, contact

This is the shutter release contact.

To the right above are contact tracks and wipers on a rotating disc that is coupled to the shutter speed button on the top cover.




An IC from Mitsubishi with a designation whose data sheet I hope to find on the web.




The rotatable ASA/exposure correction unit.

Settings are transferred to contact tracks via sliders.




Rear view




The parts removed so far.


Removing the battery compartment




The battery compartment is removed after loosening five screws.

View of part of the motor gearbox.




The battery compartment is connected to the housing via two contacts.

Corrosion caused by battery acid can also be seen here.

As is often the case, it is not enough to just clean the battery compartment. The battery acid also creeps into the area behind it and destroys contacts.


Problem with the power supply found




And now it becomes clear why the camera's circuit cannot receive operating voltage:

The left contact spring on the battery compartment is missing. So there is no connection to the contact in the camera housing.

An attempt has obviously already been made to repair it using glue.

I'll deal with that later.


Improvised external power supply

To determine whether the circuit works, I build an improvised external power supply from the battery holder.

It would have been easier to use my laboratory power supply, which outputs the desired voltage at the push of a button.

But I also wanted to use it to test the battery holder, which will then be reinstalled.




I connect the two pairs of batteries with a cable with crocodile clips (on the left in the picture). This replaces the contact bridge in the battery compartment. All batteries are now connected in series.

On the right you can see the crocodile clip of the negative connection of my multimeter, which I will then use to measure the open circuit voltage on the battery holder.




Since the contact springs for the pressure are missing, I insert the halves of a toothpick as wedges. Now the two contacts are connected to the batteries.




It works, 6.21 volts are now present at the battery holder.


Mounting the shutter blades






I can put the shutter blades back into their guide.

But they remain deformed.

There is nothing that can be corrected here.

I think the blades are made of aluminum. They are flexible and can be bent, but they retain their shape. Once they are compressed or bent, it's over.


Connecting the camera to the external power supply




I connect the battery holder to the two contacts in the camera housing using two crocodile clip cables.

The black cable (negative connection of the power supply) is connected to the contact in the camera housing. At the same time, the crocodile clip also contacts the metal chassis. Since all those involved are at the same potential, the camera ground, that's fine.

The red cable is the positive connection. The crocodile clip may only be connected to the contact in the camera housing and must be electrically separated from the camera ground, otherwise the batteries will short-circuit. The plastic handle of a cleaning swab helps as insulation.




The external power supply is connected.


Test exposure metering system, automatic film feed and shutter release




An exciting moment:

I activate the light meter by closing the first of two switches on top of each other, which is equivalent to tapping the shutter button.




Wonderful, the LEDs in the viewfinder are lit!

The circuit is intact so far.

And not only that.

When the second switch is activated, the motor is running and the automatic film feed with three forward switches starts.

The shutter blades remain closed.

It took me a while to figure out how to release the shutter even when the backdoor is open.

The small switch in the camera body, which is pressed when the back is closed, must be held during the automatic film feed.

Then the shutter can be operated.

And it works.

The blades do not jump out of their guide in the film window.


Excursus release contact

Sequence of the shutter release with two switches on top of each other:



Release contact in standby (= shutter button not pressed)




Exposure metering system activated: First switch closed (= shutter button half pressed)




Shutter released: Second switch closed (= shutter button fully pressed)

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Conclusion 1/2

• This is a positive interim result for today.
• The shutter is working again.
• The problem with the power supply has been found.
• The front panel does not have to be removed to get to the shutter, because
• unfortunately the shutter blades cannot be corrected even when removed. The bend remains and thus the shutter, consisting of two shutter curtains, is no longer light-tight. If it only affected the rear shutter curtain, this would probably not be a problem. But the front curtain, which shields the film from the light coming through the lens, is also damaged.

But that is not tragic, since this F-301 no longer needs to work, but was actually intended for a section as a presumed total loss.




Soon we will continue with the repair of the battery holder, cleaning and assembly

---

The repair manual for the Nikon F-501 comprises 295 pages and guides you very well through the disassembly process:






It is also interesting to read because it contains detailed descriptions of functions and circuits, which became less frequent in later models and were then almost completely omitted. Presumably because the steadily increasing range of functions and circuits of the cameras would have exceeded the format.

It also shows that Nikon was proud of its first SLR with a built-in motor drive, which came onto the market in 1985.

And rightly so



The F-301 is computer controlled

Data sheet for the IC - the chip family should be correct, but this is probably a different version:




(p. 242 PDF; 51,7 MB)

I now have two options for how to proceed with the F-301:

1. After repairing the battery compartment and cleaning it, I put it back together. It then works, but cannot be used for taking photos because the shutter is damaged.
2. I take the front panel off and see if I can remove the shutter. And look for a replacement.

I'm at 1, because I can still do 2, I already know part of the way.

And disassembling the camera now but only getting a replacement at some point means that I keep the parts and only put everything back together later. But then I have to get back to work and have already forgotten part of the process.

But the goal is not necessarily to get the F-301 back to work, but to get to know it, practice on it and make partial repairs in order to find procedures and ideas.




Next Monday we continue


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George Mann said:

Good luck getting the top cover off. They have made this task next to impossible without breaking the sliding lever, and the film rewind C-clamp is also quite an obstacle!

Click to expand...

The top cover could be easily removed after loosening seven screws?