[reh321]

Congratulations, this thread is now a sticky! I contacted adam last night. Now we don't have to worry about the thread disappearing in the page listings.

Great!

Now we don't have to hope that most of the aperture-control issues will be discussed here.

[Evie]

From my perspective, 18,220 is very good; most failures seem to occur from under-use {too much time off} rather than over-use.

As I see that some people counter shows 100K+ photos, I feel that I do not use the camera enough. I definitely don't use everyday, but more in waves - for example, yesterday I shot over 350 images (I have several a couple AF lenses with aperture ring, stuck with Sigma 70-300, because 50-500 is a bit too big to bring to event, when you are not press ). When I am traveling, I also take hundreds and thousands of shots. Astrophotography takes some shots as well (especially flats and darks), but sometimes camera is not touched for months.

[reh321]

As I see that some people counter shows 100K+ photos, I feel that I do not use the camera enough. I definitely don't use everyday, but more in waves - for example, yesterday I shot over 350 images (I have several a couple AF lenses with aperture ring, stuck with Sigma 70-300, because 50-500 is a bit too big to bring to event, when you are not press ). When I am traveling, I also take hundreds and thousands of shots. Astrophotography takes some shots as well (especially flats and darks), but sometimes camera is not touched for months.

My opinion is that some cameras have no issue, that only others would ever develop this problem. My opinion is that those vulnerable cameras eventually need to actually "exercise" the mechanism regularly, certainly weekly, perhaps more often than that {I've been either successfully taking a picture or pressing the 'optical preview' button at minimum every week; sometimes it fails the first try, but it works every time after that}.

[Evie]

My opinion is that some cameras have no issue, that only others would ever develop this problem. My opinion is that those vulnerable cameras eventually need to actually "exercise" the mechanism regularly, certainly weekly, perhaps more often than that {I've been either successfully taking a picture or pressing the 'optical preview' button at minimum every week; sometimes it fails the first try, but it works every time after that}.

I cannot guarantee that; mine started to show first one of few black frames a year ago. Sometimes there were first blacks, sometimes the images always were perfect. Before the final "blackout", I used the camera 6 days during May without any black-outs; last good use was May 25th, and June 5th came with fully black photos, all of them. Also, in May I once had overexposed first shot. So, it might be usage, or it might be not. But because before last usage on April 27th I did not use the camera since beginning of February, and there were no black images, I tend to think that this is not usage related...

[reh321]

I cannot guarantee that; mine started to show first one of few black frames a year ago. Sometimes there were first blacks, sometimes the images always were perfect. Before the final "blackout", I used the camera 6 days during May without any black-outs; last good use was May 25th, and June 5th came with fully black photos, all of them. Also, in May I once had overexposed first shot. So, it might be usage, or it might be not. But because before last usage on April 27th I did not use the camera since beginning of February, and there were no black images, I tend to think that this is not usage related...

How often did it fail in the middle of a session after having worked OK?

[billx2]

I first noticed my K30 started taking dark images last fall. Trying to take our annual family Halloween costume photo. It eventually started working after about 30 shots. Put it back in the case and had the same problem again around Christmas. (Not using it near as much these days). Took it out a week ago to get ready for my daughter's dance recital. Could not get it working. 50+ shots, a bunch of image previews. Finally read about the aperture solenoid problem. Took it apart and did some minor filing on the horseshoe, coated it in deoxit, it is working somewhat better, but I still get 5 or 10 dark images before it starts working.

So, I bid/won an auction for a $29 shipped *ist DS body today. Hopefully I get one that has two white solenoids.

My *ist DS came today and I quickly took out the flash solenoid (it was white) and put it in my ailing K30. The K30 seems to be working like new again! (before I took the green one out this AM, it took over 20 shots to start working.

I'm still trying to get the *ist DS to work again (flash not popping up)...If I don't, oh well. It was sold as a parts unit, but I found it to be working just fine today (before I took out the flash solenoid).

[Not a Number]

I'm still trying to get the *ist DS to work again (flash not popping up)...If I don't, oh well. It was sold as a parts unit, but I found it to be working just fine today (before I took out the flash solenoid).

Did you connect the solenoid up with the correct polarity?

[billx2]

Did you connect the solenoid up with the correct polarity?

I'm not sure. In my haste to fix the K30, I forgot to take a photo of the *ist DS wiring before de-soldering.
I think I hooked it up the same way, but it didn't work. So I swapped them around and it still didn't work.
I suspect I will need to do some additional filing on the horseshoe.

EDIT: Actually, I found a photo that verifies the wiring on the *ist DS...
here: http://fixpentax.blogspot.com/2010/11/fix-pentax-ist-camera-2-of-2.html

[Evie]

How often did it fail in the middle of a session after having worked OK?

Actually, I don't remember if it did stop working after turning the camera off or not. After the first failure I simply ignored it, ran a burst after each time I got black photos and hoped it will hold till Photokina. I DO know that the first time it did fail it was after taking shots all day (and couple previous days) perfectly, but I went outside to take astro shots, and first images were dark (so, max several hrs of not working, but hey, 2.5 months non-usage since February, and it did shoot perfectly on April, no first black image).

Oh well, my new KP just arrived (almost 3 hours ago), so I will mostly retire K-30.

[billx2]

I'm not sure. In my haste to fix the K30, I forgot to take a photo of the *ist DS wiring before de-soldering.
I think I hooked it up the same way, but it didn't work. So I swapped them around and it still didn't work.
I suspect I will need to do some additional filing on the horseshoe.

EDIT: Actually, I found a photo that verifies the wiring on the *ist DS...
here: How to fix Pentax ist* D DS DL Camera: Pentax ist* DS disassembling, part 2 of 2

Tried again, and no luck getting the green solenoid to work for the ist DS flash popup....Not sure if I borked the solenoid it somehow. For now, I'll just give it a rest and use the body sans flash. I checked and the ist DS only has a shutter count around 2200. I also checked the count on my K30, it is around 2500. Guess I haven't been using it near enough.

[Cee Cee]

I have now had my K-30 for 37 months, roughly 3100 on the shutter count. I took ten or so pictures last Saturday; today, after roughly five days rest I took a picture of our cat resting on the piano - first image was black, second {allegedly same settings} was OK. "Folklore" suggests that these cameras don't like time off. The five day rest mine had took one shot to recover from; the longer one yours had was more of an issue. I'll see whether mine needs less rest, or more "warmup"/"recovery" over time.

My theory , ...... normally (mostly) solenoids consist of a metal armature & a coil and return spring such that when the coil is energized it becomes an electromagnet and pulls the armature to the coil. When the coil is de-energized the spring returns it to it's resting position. ( there are other configurations but lets keep it simple). This is fairly straight forward and easy to understand. With the K30 solenoid in question it seems that the resting position of the armature is held in position by a permanent magnet and the energized coil repels the armature against the magnetic attraction of the permanent magnet (ie.opposite magnetic polarity), now if a piece of metal (Iron) is in contact with a permanent magnet some magnetism will be transferred to to the Iron. In this case the armature, this magnetism builds with time and will be of the same magnetic polarity (ie. same attraction). The act of energizing (operating) the coil to create a reverse magnetic field also demagnetizes the armature and maintains a balance. This is why.....

- its always the first frames that are dark - as the armature has been at rest and the magnetism has been building, then you fire off some shots and the demagnetizing effect on the coil operation comes into play and the solenoid starts working again - until the camera is at rest for some time and the magnetism builds up in the armature again.

- this may also explain why some people report differing results with batteries of different strengths - due to stronger energizing / demagnetizing pulse.

- the fixing procedure of filing the ends of the armature or using a spacer is all to do with reducing the transfer of magnetism from the permanent magnet to the armature.


Demagnetizing the assembly using an external demagnetizing wand was something I was beginning to look into ( if only I could have found my old CRT TV screen degausser ) when I remembered I had taken out an extended 5 year warranty and was able to get my K30 fixed under warranty (replacement solenoid).


So I would suggest the original solenoids had a magnet that was a little to strong or the spacing of the armature in the resting position a little off, or the energizing pulse a little week, or maybe even the composition of the armature material allowing it to absorb more magnetism, or perhaps a combination of factors. Certainly a difficult failure mode to predict !

[Not a Number]

- its always the first frames that are dark - as the armature has been at rest and the magnetism has been building, then you fire off some shots and the demagnetizing effect on the coil operation comes into play and the solenoid starts working again - until the camera is at rest for some time and the magnetism builds up in the armature again.

- this may also explain why some people report differing results with batteries of different strengths - due to stronger energizing / demagnetizing pulse.

- the fixing procedure of filing the ends of the armature or using a spacer is all to do with reducing the transfer of magnetism from the permanent magnet to the armature.


Demagnetizing the assembly using an external demagnetizing wand was something I was beginning to look into ( if only I could have found my old CRT TV screen degausser ) when I remembered I had taken out an extended 5 year warranty and was able to get my K30 fixed under warranty (replacement solenoid).

A reasonable hypothesis however people who have done the filing/sanding fix have reported no evidence that the core has been magnetized. The core//horseshoe metal piece/plunger never comes in direct contact with the permanent magnet which is surround by a metal frame.

[Cee Cee]

A reasonable hypothesis however people who have done the filing/sanding fix have reported no evidence that the core has been magnetized. The core//horseshoe metal piece/plunger never comes in direct contact with the permanent magnet which is surround by a metal frame.

yes, still just a theory, I may have made assumptions which are not correct (again). I would have known more by now but as my camera was fixed under warranty I didn't have to dive into it. This was based on my knowledge of electronics and the photos and anecdotal evidence provided here. I didn't review everything before posting this so maybe I'll take another look.

That's the way I always work, just chuck a theory or idea out there and let it be proved or disproved . the majority of the time it pans out. Well I'm still in business after all these years, electronic repairs are always time sensitive, after all the client is paying by the hour, there's not a lot of time for theories.
BTW it may not need to be in direct contact just within the magnetic field, .... perhaps. . I'll get back to you.

[photogem]

My theory , ...... normally (mostly) solenoids consist of a metal armature & a coil and return spring such that when the coil is energized it becomes an electromagnet and pulls the armature to the coil. When the coil is de-energized the spring returns it to it's resting position. ( there are other configurations but lets keep it simple). This is fairly straight forward and easy to understand. With the K30 solenoid in question it seems that the resting position of the armature is held in position by a permanent magnet and the energized coil repels the armature against the magnetic attraction of the permanent magnet (ie.opposite magnetic polarity), now if a piece of metal (Iron) is in contact with a permanent magnet some magnetism will be transferred to to the Iron. In this case the armature, this magnetism builds with time and will be of the same magnetic polarity (ie. same attraction). The act of energizing (operating) the coil to create a reverse magnetic field also demagnetizes the armature and maintains a balance. This is why.....

- its always the first frames that are dark - as the armature has been at rest and the magnetism has been building, then you fire off some shots and the demagnetizing effect on the coil operation comes into play and the solenoid starts working again - until the camera is at rest for some time and the magnetism builds up in the armature again.

- this may also explain why some people report differing results with batteries of different strengths - due to stronger energizing / demagnetizing pulse.

- the fixing procedure of filing the ends of the armature or using a spacer is all to do with reducing the transfer of magnetism from the permanent magnet to the armature.


Demagnetizing the assembly using an external demagnetizing wand was something I was beginning to look into ( if only I could have found my old CRT TV screen degausser ) when I remembered I had taken out an extended 5 year warranty and was able to get my K30 fixed under warranty (replacement solenoid).


So I would suggest the original solenoids had a magnet that was a little to strong or the spacing of the armature in the resting position a little off, or the energizing pulse a little week, or maybe even the composition of the armature material allowing it to absorb more magnetism, or perhaps a combination of factors. Certainly a difficult failure mode to predict !

Read
my post # 653

it is not that easy and many people have done sufficient research.

The sanding method can lead to much worse results, the SANDING METHOD is for sure NOT THE CORRECT SOLUTION.

It is always recommended first to do a prober research (for example here on the forum) to see what was already done before investing a tons of thoughts into something that already has been studied and researched.


Imo all those "new theories" can mislead "newcomers" to this shutter-problem because they then think those last postings are the actual state of affairs when they aren't at all.

[MarkJerling]

Maybe we need a "theory" thread and a "fact" thread. Someone care to start those - and we can close this one?