Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-22-2016, 12:45 PM   #196
Site Supporter
reh321's Avatar

Join Date: Nov 2014
Location: South Bend, IN, USA
Photos: Gallery | Albums
Posts: 2,724
QuoteOriginally posted by JoseFF Quote
Those of you who have had this kind of problems with your K30/50...please click on the link to answer the poll
https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/325832-poll-establis...re-issues.html
If I understand correctly, your survey was a followup to another survey
https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/325815-survey-shutte...r-failure.html
{please do answer these surveys if you do care about this matter - the results so far suggest that the problem is less serious than the stories would indicate}

07-23-2016, 08:43 AM   #197
Senior Member




Join Date: Feb 2016
Posts: 184
QuoteOriginally posted by reh321 Quote
If I understand correctly, your survey was a followup to another survey
https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/325815-survey-shutte...r-failure.html
{please do answer these surveys if you do care about this matter - the results so far suggest that the problem is less serious than the stories would indicate}
You could say so... but my poll is directed to find out if there is a relationship between the two issues. The result should let us know how many of the cameras that presented issue number 1 (Aperture failure) have also presented issue number 2.
My K-30 at the moment presents only number 1, so far nothing indicates symptoms of issue number 2. My fingers are crossed !!
07-25-2016, 10:30 AM - 2 Likes   #198
Loyal Site Supporter




Join Date: Apr 2008
Location: Upstate NY, USA
Posts: 246
QuoteOriginally posted by mt92 Quote
Does working on the magnetic latch as illustrated in the beginning of this thread do any good?
I have been looking at the aperture mechanism on a K-x (model I currently have with the covers off). It looks like the horseshoe solenoid referred to at the beginning of this thread is used to stop the aperture from closing down when the mirror motor is activated. I was experimenting using manual (M) mode and a long shutter time (in seconds).

If I set the aperture to the maximum value for the lens, the solenoid actuates immediately and the gear that drives the aperture lever does not turn when the mirror flips up. If I set a smaller aperture the solenoid activation looks to be delayed, and the gear turns part way to step the aperture down. Looking at the the photos of the aperture mechanism in the thread https://www.pentaxforums.com/forums/189-repairs-warranty-service/325334-k-30-...iy-repair.html it looks like the gear set include a rotation sensor (disc with holes in last photo) that could detect how far the aperture has opened. The lever may then be stopped at the required aperture by actuating the solenoid.

If the solenoid is sticking (or being held in place by magnetization of the core) it looks quite possible that the aperture would always close all the way down. Looking around the web, it appears the same basic design was also used back on the auto focus film cameras prior to the *ist D.
07-25-2016, 12:36 PM   #199
Site Supporter




Join Date: Mar 2014
Photos: Gallery
Posts: 723
QuoteOriginally posted by reduno Quote
I have been looking at the aperture mechanism on a K-x (model I currently have with the covers off). It looks like the horseshoe solenoid referred to at the beginning of this thread is used to stop the aperture from closing down when the mirror motor is activated. I was experimenting using manual (M) mode and a long shutter time (in seconds).

If I set the aperture to the maximum value for the lens, the solenoid actuates immediately and the gear that drives the aperture lever does not turn when the mirror flips up. If I set a smaller aperture the solenoid activation looks to be delayed, and the gear turns part way to step the aperture down. Looking at the the photos of the aperture mechanism in the thread https://www.pentaxforums.com/forums/189-repairs-warranty-service/325334-k-30-...iy-repair.html it looks like the gear set include a rotation sensor (disc with holes in last photo) that could detect how far the aperture has opened. The lever may then be stopped at the required aperture by actuating the solenoid.

If the solenoid is sticking (or being held in place by magnetization of the core) it looks quite possible that the aperture would always close all the way down. Looking around the web, it appears the same basic design was also used back on the auto focus film cameras prior to the *ist D.
Nice observation, point noted.

07-26-2016, 12:26 PM   #200
Senior Member




Join Date: Feb 2016
Posts: 184
QuoteOriginally posted by reduno Quote
I have been looking at the aperture mechanism on a K-x (model I currently have with the covers off). It looks like the horseshoe solenoid referred to at the beginning of this thread is used to stop the aperture from closing down when the mirror motor is activated. I was experimenting using manual (M) mode and a long shutter time (in seconds).

If I set the aperture to the maximum value for the lens, the solenoid actuates immediately and the gear that drives the aperture lever does not turn when the mirror flips up. If I set a smaller aperture the solenoid activation looks to be delayed, and the gear turns part way to step the aperture down. Looking at the the photos of the aperture mechanism in the thread https://www.pentaxforums.com/forums/189-repairs-warranty-service/325334-k-30-...iy-repair.html it looks like the gear set include a rotation sensor (disc with holes in last photo) that could detect how far the aperture has opened. The lever may then be stopped at the required aperture by actuating the solenoid.

If the solenoid is sticking (or being held in place by magnetization of the core) it looks quite possible that the aperture would always close all the way down. Looking around the web, it appears the same basic design was also used back on the auto focus film cameras prior to the *ist D.
That could let us jump to the conclusion that changing or repairing the solenoid will fix the problem...
09-07-2016, 01:49 PM   #201
New Member




Join Date: Oct 2012
Posts: 19
Using the Russian photos and instructions translated by Igor, I successfully disassembled my K-30, overhauled the armature, and reassembled the camera. My camera was starting to suffer from the dreaded aperture block problem after having been repaired for the same problem 2 years ago. Just keep in mind that that there are different lengths and types of screws when taking the covers off. Also, there's a chromed screw deep inside the battery compartment which holds down the top cover, and another screw under the bottom cover which holds down the front cover. I'll wait and see if this solved the problem, but in any case, the repair is simple enough that I'll go in and modify the armature again if necessary. Many thanks to all who contributed to the solution!
09-07-2016, 06:05 PM   #202
Site Supporter




Join Date: Mar 2014
Photos: Gallery
Posts: 723
QuoteOriginally posted by nihonsuki Quote
Using the Russian photos and instructions translated by Igor, I successfully disassembled my K-30, overhauled the armature, and reassembled the camera. My camera was starting to suffer from the dreaded aperture block problem after having been repaired for the same problem 2 years ago. Just keep in mind that that there are different lengths and types of screws when taking the covers off. Also, there's a chromed screw deep inside the battery compartment which holds down the top cover, and another screw under the bottom cover which holds down the front cover. I'll wait and see if this solved the problem, but in any case, the repair is simple enough that I'll go in and modify the armature again if necessary. Many thanks to all who contributed to the solution!
Keep us abreast of the situation , let us know if it indeed worked.
09-07-2016, 08:19 PM   #203
New Member




Join Date: Oct 2012
Posts: 19
QuoteOriginally posted by IgorZ Quote
I found the description of how this assembly works, the problem is how to translate it. The guy uses some physics jargon which I hardly understand in Russian

He says the following: "Описать действие узла я могу следующим образом:
В исходном состоянии рычаг управления диафрагмой притянут якорем в верхнем положении за счет поля постоянного магнита.
По приходу импульса на катушки эл.магнита создается магнитное поле, противодействующее полю постоянного магнита, вследствие чего
общая напряженность магнитного поля становится близкой к нулю.
Под действием пружины (рычаг управления диафрагмой подпружинен, и стремится вытащить якорь из каркаса катушек)
рычаг управления диафрагмой вместе с якорем уходит вниз и творит свое доброе дело. (не видно).
Начинают вращатся шестерни, которые после окончания импульса, через некоторое время возвращают рычаг с якорем в исходное состояние каким то толкателем.
Толкатель на шестерне проворачивается дальше и освобождает рычаг для следующего хода, шестерни останавливаются в исходном положении.
Рычаг с якорем удерживается магнитным полем постоянного магита и опять стремится выдернуть якорь и так по новой."

"I can describe the way this assembly works in the following manner. Initially, the arm that moves the aperture is held in the upper position by the electromagnetic field created by the magnet. Once the electric impulse reaches the coil, an electromagnetic field opposite to the current of the magnet is generated, the result of which is that the total electromagnetic field strength is close to zero. The arm that moves the aperture is spring loaded, which pulls it down to open the aperture. The cogs start spinning and when the electric impulse is gone, they return the arm that drives aperture into the initial position using a pin. The pin on the cog moves further and frees the arm that drives the aperture for the next actuation. The cogs return to the initial position and the arm that drives the aperture as well as the armature are held by the electromagnetic field generated by the magnet."

Sorry - haven't done physics in 20 years or so
What I don't understand is how this results in underexposed pictures. The aperture is normally fully open, spring loaded when the lens is twisted into the mount. Doesn't the solenoid allow the aperture to start closing? If the armature sticks, wouldn't this tend to keep the aperture open?

09-08-2016, 08:48 AM   #204
New Member




Join Date: Oct 2012
Posts: 19
QuoteOriginally posted by niceshot Quote
Keep us abreast of the situation , let us know if it indeed worked.
First shot of the day this morning was not underexposed! I have not seen any underexposed shots since I overhauled the solenoid yesterday. Looks like the problem has been fixed!
09-08-2016, 12:29 PM   #205
Site Supporter




Join Date: Mar 2014
Photos: Gallery
Posts: 723
QuoteOriginally posted by nihonsuki Quote
First shot of the day this morning was not underexposed! I have not seen any underexposed shots since I overhauled the solenoid yesterday. Looks like the problem has been fixed!
good deal
10-05-2016, 04:09 PM   #206
New Member




Join Date: Apr 2016
Posts: 21
QuoteOriginally posted by nihonsuki Quote
Using the Russian photos and instructions translated by Igor, I successfully disassembled my K-30, overhauled the armature, and reassembled the camera. My camera was starting to suffer from the dreaded aperture block problem after having been repaired for the same problem 2 years ago. Just keep in mind that that there are different lengths and types of screws when taking the covers off. Also, there's a chromed screw deep inside the battery compartment which holds down the top cover, and another screw under the bottom cover which holds down the front cover. I'll wait and see if this solved the problem, but in any case, the repair is simple enough that I'll go in and modify the armature again if necessary. Many thanks to all who contributed to the solution!
What exactly did you do to the armature to fix the problem?

Thanks
10-08-2016, 06:16 PM   #207
Site Supporter




Join Date: Apr 2016
Posts: 179
I tried to sort out my k-30 by grinding the two arms on the horseshoe piece down using sandpaper. A change of one millimetre made no difference. Sanding it down by around 1.5mm allowed the lens to work wide-open, but not stopped down. It's also caused a bigger issue. The mirror keeps flapping and so autofocus out of liveview doesn't work. The images also come out rather blurry.

The reason this change happened is because the arm is now too small to be attracted to the magnet which means the mirror and aperture control mechanism works without any 'control'. Not a good solution.

It looks as though there is an issue with the little lever that the armature controls. It seems like it isn't moving freely as it should. I'd like to maybe open it up but it would take way too long.

I also tried to take the arm out of my working k100d and it made no difference, even when I sanded that one down too. I replaced the shortened part back into the k100d and it still works perfectly, thank God!

I might try to glue the arm in place so that the mirror flap issue can stop. At least then I will be able to use manual aperture lenses.


I hope my input can help someone find a fix for their camera.

Last edited by HarisF1; 10-08-2016 at 06:25 PM.
10-13-2016, 12:59 PM - 1 Like   #208
New Member




Join Date: Oct 2016
Posts: 10
Hi,

DSLR and Flash tech is here. I work on all major DSLR systems.

When compared to others, Pentax is a very competent and high quality brand. They just suffered from bad management and supply chain issues since Hoya ownership. We will see how Ricoh would do.

Anyways...

I have been reading the posts and only a few have a clue on what the issue is.

First, the part called 'solenoid plunger' is defective. It is out of voltage specs, requiring more power (than normal plungers used in older models) to disengage and let the main metal aperture gear which runs inside an optocoupler to stop on time. When it does not release the horsehoe aperture gear has nothing to be stopped by and goes all the way down (i.e. F22)

If you sand or modify the plunger, it will very likely to stop disengaging since it is very delicate. The Russian method is wrong, DSLR are not make like Ladas.

The official solution is to replace the plunger with a good one from older models. It is a very hard to find part but you can use some donors.

On the other hand, K-1.K-3, K-5 and K-7 systems are entirely different. There is only one step motor to control the aperture and they are less likely to fail.

As far as I see, K-x (K-m), K-r and newer entry level models use solenoid controlled aperture block only and whenever there is a bad batch of solenoid plunger inside it will stop in the early life of the camera.

Good day to all!
10-13-2016, 02:09 PM   #209
Site Supporter
reh321's Avatar

Join Date: Nov 2014
Location: South Bend, IN, USA
Photos: Gallery | Albums
Posts: 2,724
QuoteOriginally posted by athlonus Quote
First, the part called 'solenoid plunger' is defective. It is out of voltage specs, requiring more power (than normal plungers used in older models) to disengage and let the main metal aperture gear which runs inside an optocoupler to stop on time. When it does not release the horsehoe aperture gear has nothing to be stopped by and goes all the way down (i.e. F22)
I wonder if this explains why using "AA" batteries seems to put off this problem - might they put out more "juice"??
10-13-2016, 10:42 PM - 1 Like   #210
New Member




Join Date: Oct 2016
Posts: 10
Normally it should not make any difference due to the voltage regulator IC, however the plunger is very sensitive to small voltage variations, I need to hook up my scope and read the values with different power cells.

Another fix would be increasing the tension on the counter spring of the arm attached to the plunger's horseshoe. I have not tried indeed.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
aperture, aperture block failue, block, block failue repair, camera, cameras, cost, details, failue repair solution, failure, forum, k-30, k-50, k-50 aperture block, mount, nikon, pentax k30, pentax k50, plate, post, repair, results, russian, translator, union, warranty
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wanted - Acquired: KatzEye Focus Screen for K-3 (K-3, K-5, K-5II, K-7, K-30, K-50, K-500), New or LN fwcetus Sold Items 15 05-07-2016 08:01 PM
Why A K-S1 Instead Of The K-50 / K-30? I'm A Pentaxian Pentax K-S1 & K-S2 71 12-24-2015 03:50 AM
Wanted - Acquired: Wanted K-30/K-50/K-500/K-r 12345 Sold Items 13 09-12-2015 09:51 AM
For Sale - Sold: Focusingscreens.com EE-S Screen for K-3, K-5, K-5II, K-7, K-30, K-50 & K-500 Aperturae Sold Items 6 10-06-2014 06:49 AM
For Sale - Sold: KatzEye Split-Prism Focusing Screen - for K-3, K-5, K-5II, K-7, K-30, K-50 & K-500 chickentender Sold Items 7 04-15-2014 08:35 PM



All times are GMT -7. The time now is 06:14 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top