I fixed my Minolta 7000 (aperture magnet problem)

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Thomas Steffen

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Apr 2, 2000, 4:00:00 AM4/2/00
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Hi!

The most common problem of the Minolta 7000 is the failure of the
aperture magnet. The aperture will close down to minimum whatever
value has been set. This posting tells you how to repair the problem.
If you are reasonable comfortable with small parts and soldering, you
have a fair chance of fixing this problem without breaking anything
else. Since the aperture mechanism is at the very hard of the camera,
this posting also tells you how to nearly completely unassemble the
Minolta 7000.

* The problem

Set the camera to manual mode, and select a big aperture (low aperture
value) and a time of about 1 second. Open the back, fire the camera
and lock through it. You should see the lense, and the aperture is
either wide open (ok), or a very small hole (you have the problem).
With some lenses, you can also see the aperture from the front.

* You need

a Minolta 7000 (obviously) with the mentioned problem, 5000 way work.
a soldering iron with a fine tip (SMD soldering).
a good size 1 philips screw driver and a pair of pliers.
a good memory (or take pictures and notes while unassembling).
several hours of time and concentration.
good luck.

* Step 1: Easy steps

Place the camera flat in front of you, viewfinder at the top, the
bajonett pointing upwards towards you. All directions are given for
this view.

Remove the batteries and the two plastic "shields" on the front cover,
they are hold by sticky tape.

* Step 2: Remove the case

Remove the plastic case: top part (6 screws), bottom part (7 screws),
batteries case/grip (2 screws), front part (2 screws). AF has to be
switched on to remove the front part. Take care with the wires to
flash mount on the top part, they could break. Remember where they
lead, just in case.

* Step 3: Disconnect the electronics (for step 4)

There are two mechanical connections, one is under the external LCD
display, the other on the right side near the lock of the camera back.
Unscrew them both.

The other connections have to be unsoldered:
Left of the bajonett, the red and white wire, and the 3-pin foil
connection.
Left bottom of the camera: all 6 pin connections to the pcb, as well
as the 4 wires to the batteries and the 5 wires to the shutter and the
2 wires going around the left front of the camera (black and purple).
Left front of the camear: the leftmost pair of red/black wires has to
be unsoldered.
Top of the camera (to the left of the pentaprism): the orange yellow
pair of wires.
Right of the bajonett: one ground connection (soldered).

(I hope this list is complete, but I might have missed 1 or 2 wires.)

* Step 4: Two halves

It is time to seperate the metal frame with the bajonett and the
plastic case of the camera.

First, unscrew the internal display (in front of the pentaprism) and
the light metering cell (above the viewfinder, back of the camera).

Unscrew the metal base and 3/8" mount (5 screws) and the plate of
metal to the left of it (3 screws). Unscrew the 2 screws left near the
viewfinder (silver ones). Unscrew the last 4 black screws that connect
the metal frame with the plastic case (one in every corner) from the
front.

Now you should be able to seperate the two parts. 2 gray wires (TTL)
are still between them, there is imho no need to unsolder them.

* Step 5: The aperture mechanism

is behind the left part of the metal frame. The magnet is at the very
top (red and white wire), and it can be removed after unscrewing 2
screws and another 2.

It is a permanent magnet, that is temporarily compensator by an
electro magnet. Once it loses its grip, the lever goes into a cog
wheel and stops the aperture from closing any further. If the thing
gets out of ballance (i thing the permanent magnet gets actually to
weak ?), it stops working, and the lever just sticks to the magnet.

I made the two contact surfaces of the magnet rough (with a file), so
that it doesn't stick as strong to the lever. This seems to work, but
maybe you have a better idea. You should also check whether the
electro magnet still works.

(If my theory is correct, and the electromagnet is actually too
*strong*, it should be possible to fix the problem without
unassembling the whole camera, by just inserting a resistor into the
circuit. This could be done after Step 2! Please tell me if you have
tried this.)

That's it.

* Step 6: Reassemble the camera

Just go through everything in reverse order. Be carefull when
inserting the metal plate with the one cog wheel and a lever left of
the 3/8" mount. The cog wheel and the aperture mechanism have to be at
its stopper (the lever being closest to the centre of the cog wheel).
Otherwise, the camere will jam instead of winding. Luckily, this seems
to be the only pitfall.

* Step 7: Does it work?

Good luck. If you did everything correctly, the camera should work
again. If not, try again or use it as spare parts. But don't blame me,
I told you that you need some luck. Sorry.

If you have any questions, don't hesitate to contact me. My account
ths (at) who dot net should work for years to come. Maybe this
instruction will make it onto my web page (ths.home.pages.de).

Thomas Steffen

ed romney

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Apr 2, 2000, 4:00:00 AM4/2/00
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That's a good post.

anon

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Apr 2, 2000, 4:00:00 AM4/2/00
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I repaired tons of 5000 and 7000 Maxxums with this problem at Minolta,
you don't even have to file the surfaces. In fact the official repair
at Minolta iwas just to clean the surfaces or replace the aperture
control magnet assy. When we would clean them we just used solvent, at
that time we used Freon TA

On 02 Apr 2000 16:08:16 +0200, Thomas Steffen
<for_repl...@iname.com> wrotf:

Thomas Steffen

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Apr 3, 2000, 3:00:00 AM4/3/00
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an...@anon.com (anon) writes:

> I repaired tons of 5000 and 7000 Maxxums with this problem at Minolta,
> you don't even have to file the surfaces. In fact the official repair
> at Minolta iwas just to clean the surfaces or replace the aperture
> control magnet assy. When we would clean them we just used solvent, at
> that time we used Freon TA

:-)

So the problem is indeed some stick stuff (oil) between the magnet and
the lever, and not a deterioration of the permanent magnet or similar.
What a shame, no shortcut to the procedure then.

I still think that filing should prevent the problem from reappearing.
The magnetic force is still more than enough to hold the level, and
the sticking should be prevented even if oil/dust/whatever comes back.

Thanks for the comment.

Thomas

ed romney

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Apr 3, 2000, 3:00:00 AM4/3/00
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Overlubrication of cameras is very common in CLA (cleaning lubrication and
adjustment services offered by camera stores) It insures that the camera
comes back pretty soon for more work.. Ed Romney

Thomas Steffen wrote:

> an...@anon.com (anon) writes:
>
> > I repaired tons of 5000 and 7000 Maxxums with this problem at Minolta,
> > you don't even have to file the surfaces. In fact the official repair
> > at Minolta iwas just to clean the surfaces or replace the aperture
> > control magnet assy. When we would clean them we just used solvent, at
> > that time we used Freon TA
>

ed romney

unread,
Apr 3, 2000, 3:00:00 AM4/3/00
to
Overlubrication of cameras is very common in CLA (cleaning lubrication and
adjustment services offered by camera stores) It insures that the camera
comes back pretty soon for more work.. Ed Romney

Thomas Steffen wrote:

> an...@anon.com (anon) writes:
>
> > I repaired tons of 5000 and 7000 Maxxums with this problem at Minolta,
> > you don't even have to file the surfaces. In fact the official repair
> > at Minolta iwas just to clean the surfaces or replace the aperture
> > control magnet assy. When we would clean them we just used solvent, at
> > that time we used Freon TA
>

anon

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Apr 4, 2000, 3:00:00 AM4/4/00
to

There is some real thin grease applied at the factory in the aperture
control mechanism. After a while some of the oil separates out and
migrates to the magnet surfaces. Worsened by keeping the camera in hot
areas.

On 03 Apr 2000 10:53:51 +0200, Thomas Steffen
<for_repl...@iname.com> wrotf:

>an...@anon.com (anon) writes:
>
>> I repaired tons of 5000 and 7000 Maxxums with this problem at Minolta,
>> you don't even have to file the surfaces. In fact the official repair
>> at Minolta iwas just to clean the surfaces or replace the aperture
>> control magnet assy. When we would clean them we just used solvent, at
>> that time we used Freon TA
>

praetori...@gmail.com

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Dec 14, 2016, 2:50:28 PM12/14/16
to
Just wanted to say thanks for the guide and the detailed info. Having the same issues with 5000, but considering I bought it for 3 pounds I think I cannot complain.

I first thought that the lens was defective (it had drop damage on it), so I jammed it to be always open. Got a new one hours ago and same problem - so thank you. I'll see to fix it in the next few days by cleaning.

mz...@outlook.com

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Dec 17, 2016, 3:02:05 PM12/17/16
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Different account, same person as the one from a few days ago.

Magnet wasn't the issue, the gears on the ring that spins have been worn out. Three of them actually, right at the end, which in turn blocks the ring from spinning fully.

Looks like off to spare parts for this Minolta 5000
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