[photogem]

Mine seemed to fail after I had let it sit for quite a while with the battery in and no use. Either way fingers crossed that it holds for now as I don't have the $ for something newer right now.

It will hold because you used the white Japan solenoid. Now it doesn't matter anymore if it "sits around" for a long time.

[pdl1945]

Hello everyone,

Occasionally people create new threads about their K-30 or K-50 taking dark exposures. In the interest of reducing the amount of new threads regarding the matter, I have decided to create a step-by step tutorial on the matter, albeit without any images so hope people are good with written instruction. There does tend to be an issue with some (not all) K-30 and K-50 cameras, where they take dark frames, and will require professional service either by warranty or out of warranty paid repair. This issue is known as aperture block failure. While the issue does seem to be more of a WHEN rather than an IF situation, not all dark exposure problems are caused by this issue, so no need to get prematurely paranoid about it. The goal of this tutorial is not to unnecessarily upset anyone, or discourage purchases of K-30/K-50 units (my aperture block failed in my K-50, and while I find it sad I do still use the K-50 in a limited capacity and definitely love the camera), the purpose of this tutorial is to help you diagnose possible aperture block failure in your camera, without the need to create a new thread about it.

What you will need:

1.) Possibly defective K-30/K-50 unit.
2.) A lens that has an aperture ring with an "A" setting. Or kit lens and some other manual lens with aperture ring.
3.) A few moments of your time.

As you can see, there isn't a lot required for this test, and it only takes a few minutes to perform. For the test, you will want to be in an area with adequate lighting, after all... what's the point of doing this test if you're in a dark room?
We'll do 3 different routes, one for people with lenses that have focus rings with an "A" setting, one for those without who have to use 2 separate lenses, and finally one for people who do not have any lenses with aperture rings. Please bear in mind that some instances of aperture failure can be intermittent. Intermittent failure can be caused by the motor working at some times and not working others, but it WILL eventually degrade to a constant failure state over time.

For those with lenses that have the "A" setting on an aperture ring-

Step 1:

a.) Mount the lens on the camera.
b.) Set aperture ring to "A" setting.
c.) Take a picture.
d.) Set aperture ring to an aperture value that should take a properly exposed image.
e.) Take a 2nd picture.
f.) Examine both exposures.

If the image you took when the aperture ring was set to "A" is severely underexposed (dark exposure), and the image you took with the aperture ring set to a specific value is NOT underexposed, you more than likely have aperture block failure in your unit. If BOTH exposures are dark, this could indicate a more severe problem with the unit, or there may be an issue with the lens. To rule out lens issues, try again with a different lens. Should the second lens replicate both images with dark exposures, then it might be an issue with the light meter sensor, or the image sensor.

For those who do not have a lens with "A" setting on an aperture ring (such as the kit lens)-

Step 1:

a.) Mount first lens (without aperture ring) to the camera.
b.) Set camera settings to what will supposedly create a proper exposure.
c.) Take a picture.
d.) Turn off unit and swap to manual lens.
e.) Set aperture on lens with aperture ring to an appropriate aperture value.
f.) Take another picture.
g.) Examine both exposures.

As with the previous route for those with the "A" setting, we need to examine the exposures that you took with each lens. If the exposure taken with the lens that did not have an aperture ring is dark, and the exposure taken with the lens with the aperture ring is normal, you may have aperture block failure.

For those who do not have a lens with an aperture ring-

Step 1:

a.) Mount lens to camera.
b.) Set aperture setting in camera to a value where the lens iris will be fairly open upon shutter release.
c.) Look down into lens while under decent lighting, and press shutter button.
d.) Note whether iris opens up or stays narrow.

If during your testing, the aperture iris did not widen, then you more than likely have aperture block failure. You are free to try this with multiple lenses to rule out lens issues.

Step 2: (this step is for everyone from any of the above step paths)

Upon determining that aperture block failure is the most likely cause of your problem, determine whether or not it is feasible to be repaired, or if replacing the unit will be the more cost effective option. Those who are still covered under warranty should most definitely send the unit in for repair. Those out of warranty have a difficult choice ahead of them. In my case, my k-50 aperture block failed outside of warranty. To have it repaired would have cost almost as much as a brand new in box body. I eventually relegated the k-50 to alternate/crippled usage, and purchased a K-3II as my new primary body. Not all people decide to opt for the solution I ultimately took. Several do spend the money to have the unit repaired. The choice is completely up to you.


This concludes my very brief tutorial on testing for aperture block failure in the K-30/K-50. I hope you checked here first before starting a new thread on the subject, and that you found the information here useful. If enough people consider the tutorial to be helpful, please suggest that this become a sticky topic, so that it doesn't become lost in the ever-revolving shuffle of forum topics.

Hello, I recently encountered this "dark exposure problem" w/my K-50. I've tested the camera & put my lenses on my older K-10D (they work good with the K-10D body). You mentioned you bought the K-3II, so I'll have to do some research on which body works for me. I'm glad I found your post on this, thank you, Paul

[photogem]

Hello, I recently encountered this "dark exposure problem" w/my K-50. I've tested the camera & put my lenses on my older K-10D (they work good with the K-10D body). You mentioned you bought the K-3II, so I'll have to do some research on which body works for me. I'm glad I found your post on this, thank you, Paul

Aside of buying another body, you can repair your K-50:
Manual solenoid replacement Pentax K30 / Discharge flash-condenser / Solenoid choice - PentaxForums.com

[Emi77]

Aside of buying another body, you can repair your K-50:
Manual solenoid replacement Pentax K30 / Discharge flash-condenser / Solenoid choice - PentaxForums.com

Hi photgem
You have a private message.

---------- Post added 03-27-20 at 01:40 PM ----------

Hi to everyone
I am new to this forum. I am a longtime Pentaxian, my first Pentax were a MX and a MESuper. I have two K50s which show the apperture/solenoid problem. I am looking for someone in the Zurich/Switzerland area who can help me to fix it the cameras, because I am not very experienced in repairing electronic devices. Any advice will be highly appreciated.

[Frenchkiddo]

Hello everyone,

Occasionally people create new threads about their K-30 or K-50 taking dark exposures. In the interest of reducing the amount of new threads regarding the matter, I have decided to create a step-by step tutorial on the matter, albeit without any images so hope people are good with written instruction. There does tend to be an issue with some (not all) K-30 and K-50 cameras, where they take dark frames, and will require professional service either by warranty or out of warranty paid repair. This issue is known as aperture block failure. While the issue does seem to be more of a WHEN rather than an IF situation, not all dark exposure problems are caused by this issue, so no need to get prematurely paranoid about it. The goal of this tutorial is not to unnecessarily upset anyone, or discourage purchases of K-30/K-50 units (my aperture block failed in my K-50, and while I find it sad I do still use the K-50 in a limited capacity and definitely love the camera), the purpose of this tutorial is to help you diagnose possible aperture block failure in your camera, without the need to create a new thread about it.

What you will need:

1.) Possibly defective K-30/K-50 unit.
2.) A lens that has an aperture ring with an "A" setting. Or kit lens and some other manual lens with aperture ring.
3.) A few moments of your time.

As you can see, there isn't a lot required for this test, and it only takes a few minutes to perform. For the test, you will want to be in an area with adequate lighting, after all... what's the point of doing this test if you're in a dark room?
We'll do 3 different routes, one for people with lenses that have focus rings with an "A" setting, one for those without who have to use 2 separate lenses, and finally one for people who do not have any lenses with aperture rings. Please bear in mind that some instances of aperture failure can be intermittent. Intermittent failure can be caused by the motor working at some times and not working others, but it WILL eventually degrade to a constant failure state over time.

For those with lenses that have the "A" setting on an aperture ring-

Step 1:

a.) Mount the lens on the camera.
b.) Set aperture ring to "A" setting.
c.) Take a picture.
d.) Set aperture ring to an aperture value that should take a properly exposed image.
e.) Take a 2nd picture.
f.) Examine both exposures.

If the image you took when the aperture ring was set to "A" is severely underexposed (dark exposure), and the image you took with the aperture ring set to a specific value is NOT underexposed, you more than likely have aperture block failure in your unit. If BOTH exposures are dark, this could indicate a more severe problem with the unit, or there may be an issue with the lens. To rule out lens issues, try again with a different lens. Should the second lens replicate both images with dark exposures, then it might be an issue with the light meter sensor, or the image sensor.

For those who do not have a lens with "A" setting on an aperture ring (such as the kit lens)-

Step 1:

a.) Mount first lens (without aperture ring) to the camera.
b.) Set camera settings to what will supposedly create a proper exposure.
c.) Take a picture.
d.) Turn off unit and swap to manual lens.
e.) Set aperture on lens with aperture ring to an appropriate aperture value.
f.) Take another picture.
g.) Examine both exposures.

As with the previous route for those with the "A" setting, we need to examine the exposures that you took with each lens. If the exposure taken with the lens that did not have an aperture ring is dark, and the exposure taken with the lens with the aperture ring is normal, you may have aperture block failure.

For those who do not have a lens with an aperture ring-

Step 1:

a.) Mount lens to camera.
b.) Set aperture setting in camera to a value where the lens iris will be fairly open upon shutter release.
c.) Look down into lens while under decent lighting, and press shutter button.
d.) Note whether iris opens up or stays narrow.

If during your testing, the aperture iris did not widen, then you more than likely have aperture block failure. You are free to try this with multiple lenses to rule out lens issues.

Step 2: (this step is for everyone from any of the above step paths)

Upon determining that aperture block failure is the most likely cause of your problem, determine whether or not it is feasible to be repaired, or if replacing the unit will be the more cost effective option. Those who are still covered under warranty should most definitely send the unit in for repair. Those out of warranty have a difficult choice ahead of them. In my case, my k-50 aperture block failed outside of warranty. To have it repaired would have cost almost as much as a brand new in box body. I eventually relegated the k-50 to alternate/crippled usage, and purchased a K-3II as my new primary body. Not all people decide to opt for the solution I ultimately took. Several do spend the money to have the unit repaired. The choice is completely up to you.


This concludes my very brief tutorial on testing for aperture block failure in the K-30/K-50. I hope you checked here first before starting a new thread on the subject, and that you found the information here useful. If enough people consider the tutorial to be helpful, please suggest that this become a sticky topic, so that it doesn't become lost in the ever-revolving shuffle of forum topics.

My K-01 has a similar issue. Regardless whether the aperture is on A or not, it will take the shot properly exposed but then the screen goes black with f.stop and ISO flashing in red. It won't allow me to take another shot until I restart the camera. While the screen is flashing, I'm still able to review my the shot and use the menu. If I use a manual vintage lens such as my Rikenon 50mm f2.0 L lens, the camera works as it should with no issues. Has anyone encountered similar issues with their K-01?

[photogem]

My K-01 has a similar issue. Regardless whether the aperture is on A or not, it will take the shot properly exposed but then the screen goes black with f.stop and ISO flashing in red. It won't allow me to take another shot until I restart the camera. While the screen is flashing, I'm still able to review my the shot and use the menu. If I use a manual vintage lens such as my Rikenon 50mm f2.0 L lens, the camera works as it should with no issues. Has anyone encountered similar issues with their K-01?

This is something completly different:

This thread is about "underexposed photos" AS A RESULT OF A SMALL PART CALLED SOLENOID which jams!
So nothing in common with the screen (LCD) going black after you took one photo.

The K-01 doesn't use a solenoid but a stepper motor such as the K7/5/3/KP etc.


Of course such a motor can also go wrong but I daubt this would affect the function of the screen / LCD.
No idea what this could be.

[Frenchkiddo]

Thank you for the prompt reply. At least, I've eliminated one suspect thanks to your feedback. I will carry on my investigation

[a200user]

...
The comparison with German car-manufacturers is not up to it:

Those car manufacturers knew that they were cheating, Ricoh didn't cheat, it was their supplier who changed it without letting Ricoh know that they
now manufacture this item in China with cheaper material and different magnetic holding force.

...

This is my first comment here regarding the aperture block failure. My K30 failed after 5,300 actuations only about 18 months after purchasing it new. The failure was well known at the time, albeit no definitive cause. I was really disappointed in the response I got from Pentax, basically telling me 'that's too bad, contact someone for a repair quote, but we're not covering it".

I really appreciate photogem's research into the issue. But I have a problem with "Ricoh didn't cheat, it was their supplier who changed it without letting Ricoh know that they
now manufacture this item in China with cheaper material and different magnetic holding force."

Yes I believe that Ricoh/Pentax did not intentionally cheat. But I bought my K30 from an authorized Ricoh/Pentax retailer. I didn't buy any component from a Chinese parts supplier.
Anything Ricoh bought to put in their product becomes Ricoh's responsibility. I worked in manufacturing for 40 years. There is an obligation to ensure that outsourced parts are within specifications. You just don't take the supplier's word for it. Either Ricoh didn't do their due diligence on incoming parts or the Ricoh specification tolerance for magnetic holding force on this part was too broad. Either way it's Ricoh's failure.

I saw a survey as to owners of the affected models. A failure rate of approximately 1 in 3 seems to be the case for the K30. Maybe the sample size isn't large enough to convince Ricoh, but it was in the range of 300 samples as I recall. That is nowhere close to being acceptable for a device that is supposed to have a shutter life of 100k. Where I worked, unacceptable failure rates were measured in ppm (parts per million).

---------- Post added 04-24-2020 at 03:34 PM ----------

Being shut in due to the Coronavirus and having nothing better to do, I decided to dismantle my failed K30. It has sat unused for several years since it failed (ABF).

Thanks again to phtogem for the 'manual' that guided me through the dismantle. I heeded the caution not to sand the horseshoe plunger.
I have a K100d, but after getting into the K30 the very small size of the component and limitations of my 70 year old eyes scared me off of de-soldering and re-soldering.
So all I did was pull the plunger out and inspect the two ends making sure there was no debris or corrosion. Then I put it back together, and it has been working good as new for 3 days now.

I think I messed up the location of the 'AF-S, C, M' lever when putting the front back on as I get continuous shutter releases in both AF-S and C positions. 'M' (manual focus) works as it should.
I expect to get a relapse of the ABF, so will address that issue then.

I'm just curious as to why the aperture worked for a year and half, then failed, now works again by just reinserting the plunger.
So is it a combination of 3 issues?
1. Magnetic holding force,
2. the gap that the plunger travels through is also too sloppy in terms of fit and parallelism,
3. difference in material; PET vs PTFE (green vs white).

Referring to my last post, Ricoh isn't clean on this. The newer part has a higher magnetic holding force which should be measurable, the photos showing the gap and parallelism between the original part and the new is obviously different, and just the change in color (white to green) should have been enough to warrant a sourcing investigation. To me it's unconscionable that Ricoh would be repairing customer's K30/K50's with the same 'bad' part.

[Cee Cee]

I'm just curious as to why the aperture worked for a year and half, then failed, now works again by just reinserting the plunger.So is it a combination of 3 issues?

let me ask, is it possible you reversed the magnetic polarity the plunger ( flipped it 180` ) when you reinserted it, this would counteract any residual magnetism in the plunger, if indeed the issue is caused by a build up of residual magnetism in the the horse shoe plunger.

I wonder if someone else with a non working camera could try this, just mark to top surface of the plunger with a marker pen, remove the plunger and refit it with the marked side down, this will reverse the magnetic poles and should counteract any residual magnetism in the plunger.

[a200user]

Cee Cee,

It's possible but I didn't keep track. I really didn't expect it to be successful and thought, oh crap, I should have kept track of the orientation.
But not due to polarity, just how it fits. I'm not convinced that everything is symmetric, seems like sloppy tolerances. Still begs the question, why did it work for 5,300 actuations, then failed, and now works?

And sorry, but I'm not taking it apart to flip it. I'm leaving well enough alone for now. Today I happened to dig out my K100d that's been stored away for years. It works fine.
But, if the K30 fails again I will cannibalise the 'white' solenoid from the pop-up flash of my K100d for the K30. I might put the 'green' solenoid from the K30 in the K100d too, but scanning through this thread I think I saw that someone tried that and it didn't work in the K100d?

This is my line up:
Left to right, K100d, K20, K30, K5 ii s

[Cee Cee]

It's possible but I didn't keep track. I really didn't expect it to be successful and thought, oh crap, I should have kept track of the orientation.But not due to polarity, just how it fits. I'm not convinced that everything is symmetric, seems like sloppy tolerances. Still begs the question, why did it work for 5,300 actuations, then failed, and now works?

I gather from reading these threads that some solenoids have other quality issues as you say. But I asked similar questions when mine failed, I had just on 5 years and well over 10K activations when it failed. Luckily I had taken a 5 year extended warranty when I purchased, and had it replaced under that warranty. They returned the faulty solenoid to me and I've got to say it looked pristine, and well made, no quality control issues or poor fitting that I could see. And testing it it seemed to work fine with no binding, sloppiness or other issues. Using a spring tension gauge and pulsing the coil with a suitable current to release the plunger I've been able to see a clear difference in the release force required to remove the plunger depending on the magnetic polarity (or the orientation) of the plunger.

[photogem]

let me ask, is it possible you reversed the magnetic polarity the plunger ( flipped it 180` ) when you reinserted it, this would counteract any residual magnetism in the plunger, if indeed the issue is caused by a build up of residual magnetism in the the horse shoe plunger.

This is not at all the case: Polarity does built up for a short moment but is not reversed by reversing the plunger!
Even ... if it would (which isn't the case: It then would built up again.


The holding force by itself is too strong even with a new China-Solenoid.
I have 3 original never used solenoids here, so it is verified.

Using a spring tension gauge and pulsing the coil with a suitable current to release the plunger I've been able to see a clear difference in the release force required to remove the plunger depending on the magnetic polarity (or the orientation) of the plunger.

With about 15 China-Solenoid available, all having a too strong holding force and with previous tests done,
I never ever found any change in the holding force.

[Cee Cee]

The biggest nonsense I ever read concering the "dark-exposure-problems". Polarity does built up for a short moment but it isn't reversed by reversing the plunger.But even if it would, it would built up again.The holding force by itself is too strong even with a new China-Solenoid.I have 3 original never used solenoids here, so it is verified.

so which part of what I said is nonsense,

I won't insult you by giving a lesson in magnetic theory 101. But with the plunger in it's original orientation any residual magnetism can only add to the attraction and reversing poles can only reduce the attraction, you must know that to be true.

The only holding force that's relevant here is the holding force when the shutter is activated and there should be zero holding force as the electromagnetic field generated by current through the coil should perfectly cancel the fixed magnetic field of the solenoid, under these conditions I'm saying that I can detect a clear difference in the required extraction force depending on the orientation of the plunger.

[photogem]

I won't insult you by giving a lesson in magnetic theory 101.

Fine:
It's called remanence, i.e. residual magnetism = magnetism which stays in a "zero field", i.e. away from the magnetic field.

Now: This statement of yours:

The only holding force that's relevant here is the holding force when the shutter is activated ....

is just wrong!

The holding force comes from the permanent magnet and is relevant because when the SHUTTER IS NOT ACTIVATED!
We have one in two moments when the solenoid is in action and the plunger is moving for a fraction of a second away from the magnet:
- shutteractivation
- live-view (shutter open as well, so activated for a longer time).
Those are the only two moments when the holding force is not relevant for a moment, or better: When the holding force is not present!


One can measure the time it is away: If you do very long exposures and have your camera open you can actually see it, i.e. 1 sec. etc.
The exposure time but when this gets faster, you cannot measure it anymore, the mechanism doesn't allow the solenoid to act with lets say 1/1000 sec.

So it is the very opposite as you explain it.

But with the plunger in it's original orientation any residual magnetism can only add to the attraction and reversing poles can only reduce the attraction, you must know that to be true.

No, I "must know nothing" if you say so! Knowledge anyway is not enough, one must experience, verify.
As soon as the plunger is away from the permanent magnet it loses magnetism/rememance! Very quickly. And thus any possible polarity.

But lets say there would remain polarity: It would go the same direction/field-lines as the permanent magnet is oriented.
But you can't stick the plunger with its wide side into the body of the solenoid.

and there should be zero holding force as the electromagnetic field generated by current through the coil ...

Not one coil but two coils! Yes, they counteract the holding force , ... we know that since a long time, nothing new.
At this moment when those 2 coils induce the electro-magnetic field, the magnetism is gone.
Not enough to counteract:
- residual magnetism built up in the plunger because the moment is too short
- friction of the PET housing (material, problems of sloppy built quality, use)

All this we know since a long time

But to study it in detail, you have to inspect the action of a solenoid with the complete diaphragm-control-block outside of the camera so you can see what happens to the plunger of a new (Chinese) solenoid and a used (Chinese) solenoid.
And then compare it to the white solenoid.

Now... if it would be remanence causing the problem, it would affect the white Japan solenoid as well?!
But it doesn't!

...should perfectly cancel the fixed magnetic field of the solenoid, under these conditions. I'm saying that I can detect a clear difference in the required extraction force depending on the orientation of the plunger.

Please don't invent things, not a good idea! Difficult to get out!

I have more than those pictured green solenoids and I have tested ALL those pictured including a few white ones:



ZERO DIFFERENCE IN REQUIRED EXTRACTION FORCE

....when mine failed, I had just on 5 years and well over 10K activations when it failed. Luckily I had taken a 5 year extended warranty when I purchased, and had it replaced under that warranty. They returned the faulty solenoid to me and I've got to say it looked pristine, and well made, no quality control issues or poor fitting that I could see. And testing it it seemed to work fine with no binding, sloppiness or other issues.

I recall that you then mentioned theories about what could be wrong and you also recommended degaussing which you later said was a joke. You never ever mentioned this thing about polarity of the plunger. Maybe this was a joke was well and I misunderstood.


Anyway, this was quite a long time ago and having just one single solenoid without any others and particular without any white Japanese solenoids to compare:


What do you take for comparison/what is your reference?


I once thought that there would be more residual magnetism in the plunger but I was wrong.


Today I just took a very fine file and filed some "magnetic iron dust" away from a nail.


I took the plunger out, held it with my pliers directly onto the magnet and then into this iron-dust to inspect it then with a strong magnifying glass: Some of those tiny iron particles did stick on the plunger.
But as soon as I held the plunger with my fingers they fell of.

I then magnetised the plunger with a very powerful magnet of an Altec Lansing 15" woofer.
Less magnetism! This tiny rare-earth magnet inside the solenoid is strong enough.
I then tried it with a more powerfull rare-earth magnet: Nothing changed.


The residual-magnetism goes down to such an extend, that it cannot play a role.
And thus, even if there would be polarity it would be gone before you swapped the plunger into any other direction.


The difficulty for me is that somebody has a theory and makes this into facts (in your case polarity of the plunger)
and you write about it as if it were facts, people believe it.

One has to be responsible.

People will apply such a method and then at least be disappointed.

And I say it again:

To disassemble a K30 is already some work.

To disassemble the solenoid with wires connected is prone to more damage than to unsolder the 2 wires with a fine soldering iron.

But then to swap the direction of the plunger in hope it might work again:


To me a total waste of time.

If you do it, do it once and do it right.
(But first you have to actually do it)

[BigMackCam]

@photogem - Heinrich, please remain courteous and not confrontational. I know your intentions are absolutely noble, and you have an awful lot of experience in this particular matter, but please pay careful attention to the manner of your posting as we've discussed previously.

Thanks