Getting aperture control block on my K-S2 :(

**photogem** · 01-23-2020, 05:30 AM

Originally posted by krgroothuis

I hope the ones that are fixed by repairshops get the white solenoid type used in the older camera's . K-x and before.
Normally Pentax official repair partners usually get only a new green one (made in China).

The repairshops never use the white one because they can't get it new.
The green one possibly costs "them" 1-2 dollars so why should they:
- invest about 30 min. time to disassemble an old *ist/K100D/Kx etc including testing the solenoid?
- spend the money for an old DSLR body?
when they can have it the cheap way?

Some even modify the green solenoid!

Originally posted by robtcorl

I do see an ad for fixing the 30, 50, et al for $100, guess I'll have to do that if/when it gets worse.

This is photolab35 in California. He does the grinding/filing job and what comes out you can see here:
Solenoid problem return plus sound - Page 2 - PentaxForums.com

But it can happen worse, I have seen this to happen:

The white wheel got blocked because the filed/sanded plunger in this green China solenoid jammed and thus the spring "jumped out".

This then means a lot of work because one needs to exchange the complete diaphragm block:
Pentax 77860-G0100 Diaphragm Control Block | K-S2 | K-30 | K-50 | PartsUSCamera

Then a good solution is to swap the green China-solenoid on this block against the white Japan version
because often the green bugger sticks again.

Last edited by photogem; 01-26-2020 at 05:30 AM.

k22 · 04-10-2020, 08:08 PM

Just did the repair on my K-S2. Noticed the plunger was a bit gummy, as if lubricant had dried. Cleaned with alcohol and lightly sanded the tips. Not difficult to do. We'll see how long it lasts. So glad to have the camera working. Missed it.

**photogem** · 04-10-2020, 09:55 PM

There is no lubricant on the solenoid. Maybe somebody else lubed it before you bought it thinking lubing might help which is thinking in error.
But sanding the tips of the plunger is an error as well. I have explained this in detail.
The biggest problem can be misalignment of the complex mechanism which simultaniously controls mirror up and diaphragm control.
This photo shows a corroded plunger, it's surface has been sanded:

And this photo shows exodus after misalignment when one of the toothed wheels got blocked:

If the gearmechanism is misaligned one has to change the complete diaphragm-control-block and then align, it takes hour, did it once, never again:
https://www.pentaxforums.com/forums/members/85274-photogem/albums/13069-gear...ture125488.jpg

k22 · 04-11-2020, 04:58 AM

bought it new. it felt very lightly gummy. doubt the lightest sanding with fine paper will change alignment. plunger already has small amount of play. btw, read somewhere that the cause could be magnetization of plunger. checked with magnetometer and there was none - fwiw...

**photogem** · 04-11-2020, 01:50 PM

The magnetisation is lost pretty soon.

The solenoid acts as a push-pull device:
- The plunger pulls out and away from the permanent magnet when the two coils produce an opposite magnetic field (field-coil) and it acts to drive the diaphragm/aperture

- The plunger pushes back in and.... remains in this position near the permanent magnet!... when not used. So one could say that 99% of its live it is magnetised.
But the magnetism isn't a problem at all, the main factors/problems have been explained in detail.

**skolkmeier** · 05-07-2020, 08:46 AM

I have the problem on my ks-2. It is seldom used, so I'm not surprised. I did the optical preview several times, with the red warning on the bottom of the screen. But after about 6 or 7 tries, the warning turned green, indicating that the apperture had set correctly. That cleared the problem for now.

**photogem** · 05-08-2020, 12:34 AM

For now yes, but it won't last!
Don't wait too long but start to search for a Japanese solenoid and then DIY.

elpavorealduos · 05-08-2020, 01:56 AM

Originally posted by photogem

For now yes, but it won't last!
Don't wait too long but start to search for a Japanese solenoid and then DIY.

Or just take out the existing one and give it a bit of sandpaper polish. I did it maybe a year ago and i haven't had any problems since. Just be careful with AF switch, it is easy to leave it manual position when reasambling.

**photogem** · 05-08-2020, 07:30 AM

Originally posted by elpavorealduos

Or just take out the existing one and give it a bit of sandpaper polish. I did it maybe a year ago and i haven't had any problems since. Just be careful with AF switch, it is easy to leave it manual position when reasambling.

Better first to study:
Why you shouldn't file/sand the plunger of the green Chinasolenoid but replace it - PentaxForums.com
and maybe this thread:
Solenoid problem return plus sound - PentaxForums.com

It is a very bad idea and has led in many cases to serious damage!
Not always, but if one understands the difference between the Japanese and the Chinese solenoid then it is clear!

**skolkmeier** · 05-23-2020, 10:43 AM

Originally posted by photogem

Better first to study:
Why you shouldn't file/sand the plunger of the green Chinasolenoid but replace it - PentaxForums.com
and maybe this thread:
Solenoid problem return plus sound - PentaxForums.com

It is a very bad idea and has led in many cases to serious damage!
Not always, but if one understands the difference between the Japanese and the Chinese solenoid then it is clear!

My ks2 was manufactured 5-2017. Works fine with any of the zoom lenses I have, but gets a dark frame with the primes (35 2.4, 50 1.8)

**photogem** · 05-23-2020, 02:19 PM

Check as described here with the primes:
How to detect aperture block failure on Pentax K-S1 (and K-S2) - PentaxForums.com
Which zooms are those?
The DA55-300PLM would still work fine because it doesn't need the solenoid.

**skolkmeier** · 05-23-2020, 05:04 PM

Originally posted by photogem

Check as described here with the primes:
How to detect aperture block failure on Pentax K-S1 (and K-S2) - PentaxForums.com
Which zooms are those?
The DA55-300PLM would still work fine because it doesn't need the solenoid.

Really, the plm doesn't use the solenoid? I didn't know that. How does that work?

BTW, the plm is the zoom that always works. I found that one of my other zooms failed once or twice today (55-300 wr , not plm)

thanks

---------- Post added 05-23-20 at 05:08 PM ----------

Originally posted by skolkmeier

Really, the plm doesn't use the solenoid? I didn't know that. How does that work?

BTW, the plm is the zoom that always works. I found that one of my other zooms failed once or twice today (55-300 wr , not plm)

thanks

found the answer here:
Unlike earlier Pentax lenses, the aperture stop-down lever in the camera is not used to control the diaphragm of this lens. A DSLR launched in 2013 or later is needed to operate this new system (the K-500 is not compatible).

thanks

Desperado · 05-25-2020, 12:26 AM

Hi friends,is there any specific reason why some of those selenoids die early?Frequency of use,humidity,dust?

**photogem** · 05-25-2020, 02:15 AM

Read HERE

Not a Number · 08-30-2020, 12:54 PM

Originally posted by Angryman51

Any ideas what may be causing it?

Maybe the polarity on the connections are reversed? It happens sometimes, though I don't know what the symptoms are. I believe the youtube video on repairing a K-50 shows the solenoid in action after being replaced. Perhaps you can compare it to your camera?

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01-23-2020, 05:30 AM	#151
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Originally posted by krgroothuis I hope the ones that are fixed by repairshops get the white solenoid type used in the older camera's . K-x and before. Normally Pentax official repair partners usually get only a new green one (made in China). The repairshops never use the white one because they can't get it new. The green one possibly costs "them" 1-2 dollars so why should they: - invest about 30 min. time to disassemble an old ist/K100D/Kx etc including testing the solenoid? - spend the money for an old DSLR body? when they can have it the cheap way? Some even modify the green solenoid! Originally posted by robtcorl I do see an ad for fixing the 30, 50, et al for $100, guess I'll have to do that if/when it gets worse. This is photolab35 in California. He does the grinding/filing job and what comes out you can see here: Solenoid problem return plus sound - Page 2 - PentaxForums.com But it can happen worse, I have seen this to happen: The white wheel got blocked because the filed/sanded plunger in this green China solenoid jammed and thus the spring "jumped out". This then means a lot of work because one needs to exchange the complete diaphragm block: Pentax 77860-G0100 Diaphragm Control Block \| K-S2 \| K-30 \| K-50 \| PartsUSCamera Then a good solution is to swap the green China-solenoid on this block against the white Japan version because often the green* bugger sticks again. Last edited by photogem; 01-26-2020 at 05:30 AM.

04-10-2020, 08:08 PM	#152
k22 Site Supporter Join Date: Dec 2015 Posts: 153	Just did the repair on my K-S2. Noticed the plunger was a bit gummy, as if lubricant had dried. Cleaned with alcohol and lightly sanded the tips. Not difficult to do. We'll see how long it lasts. So glad to have the camera working. Missed it.

04-10-2020, 09:55 PM	#153
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	There is no lubricant on the solenoid. Maybe somebody else lubed it before you bought it thinking lubing might help which is thinking in error. But sanding the tips of the plunger is an error as well. I have explained this in detail. The biggest problem can be misalignment of the complex mechanism which simultaniously controls mirror up and diaphragm control. This photo shows a corroded plunger, it's surface has been sanded: And this photo shows exodus after misalignment when one of the toothed wheels got blocked: If the gearmechanism is misaligned one has to change the complete diaphragm-control-block and then align, it takes hour, did it once, never again: https://www.pentaxforums.com/forums/members/85274-photogem/albums/13069-gear...ture125488.jpg

04-11-2020, 04:58 AM	#154
k22 Site Supporter Join Date: Dec 2015 Posts: 153	bought it new. it felt very lightly gummy. doubt the lightest sanding with fine paper will change alignment. plunger already has small amount of play. btw, read somewhere that the cause could be magnetization of plunger. checked with magnetometer and there was none - fwiw...

04-11-2020, 01:50 PM	#155
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	The magnetisation is lost pretty soon. The solenoid acts as a push-pull device: - The plunger pulls out and away from the permanent magnet when the two coils produce an opposite magnetic field (field-coil) and it acts to drive the diaphragm/aperture - The plunger pushes back in and.... remains in this position near the permanent magnet!... when not used. So one could say that 99% of its live it is magnetised. But the magnetism isn't a problem at all, the main factors/problems have been explained in detail.

05-07-2020, 08:46 AM	#156
skolkmeier Loyal Site Supporter Join Date: Mar 2018 Location: Granbury, TX Photos: Gallery Posts: 941	I have the problem on my ks-2. It is seldom used, so I'm not surprised. I did the optical preview several times, with the red warning on the bottom of the screen. But after about 6 or 7 tries, the warning turned green, indicating that the apperture had set correctly. That cleared the problem for now.

05-08-2020, 12:34 AM	#157
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	For now yes, but it won't last! Don't wait too long but start to search for a Japanese solenoid and then DIY.

05-08-2020, 01:56 AM	#158
elpavorealduos New Member Join Date: Jul 2019 Posts: 5	Originally posted by photogem For now yes, but it won't last! Don't wait too long but start to search for a Japanese solenoid and then DIY. Or just take out the existing one and give it a bit of sandpaper polish. I did it maybe a year ago and i haven't had any problems since. Just be careful with AF switch, it is easy to leave it manual position when reasambling.

05-08-2020, 07:30 AM	#159
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Originally posted by elpavorealduos Or just take out the existing one and give it a bit of sandpaper polish. I did it maybe a year ago and i haven't had any problems since. Just be careful with AF switch, it is easy to leave it manual position when reasambling. Better first to study: Why you shouldn't file/sand the plunger of the green Chinasolenoid but replace it - PentaxForums.com and maybe this thread: Solenoid problem return plus sound - PentaxForums.com It is a very bad idea and has led in many cases to serious damage! Not always, but if one understands the difference between the Japanese and the Chinese solenoid then it is clear!

05-23-2020, 10:43 AM	#160
skolkmeier Loyal Site Supporter Join Date: Mar 2018 Location: Granbury, TX Photos: Gallery Posts: 941	Originally posted by photogem Better first to study: Why you shouldn't file/sand the plunger of the green Chinasolenoid but replace it - PentaxForums.com and maybe this thread: Solenoid problem return plus sound - PentaxForums.com It is a very bad idea and has led in many cases to serious damage! Not always, but if one understands the difference between the Japanese and the Chinese solenoid then it is clear! My ks2 was manufactured 5-2017. Works fine with any of the zoom lenses I have, but gets a dark frame with the primes (35 2.4, 50 1.8)

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05-23-2020, 02:19 PM	#161
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Check as described here with the primes: How to detect aperture block failure on Pentax K-S1 (and K-S2) - PentaxForums.com Which zooms are those? The DA55-300PLM would still work fine because it doesn't need the solenoid.

05-23-2020, 05:04 PM	#162
skolkmeier Loyal Site Supporter Join Date: Mar 2018 Location: Granbury, TX Photos: Gallery Posts: 941	Originally posted by photogem Check as described here with the primes: How to detect aperture block failure on Pentax K-S1 (and K-S2) - PentaxForums.com Which zooms are those? The DA55-300PLM would still work fine because it doesn't need the solenoid. Really, the plm doesn't use the solenoid? I didn't know that. How does that work? BTW, the plm is the zoom that always works. I found that one of my other zooms failed once or twice today (55-300 wr , not plm) thanks ---------- Post added 05-23-20 at 05:08 PM ---------- Originally posted by skolkmeier Really, the plm doesn't use the solenoid? I didn't know that. How does that work? BTW, the plm is the zoom that always works. I found that one of my other zooms failed once or twice today (55-300 wr , not plm) thanks found the answer here: Unlike earlier Pentax lenses, the aperture stop-down lever in the camera is not used to control the diaphragm of this lens. A DSLR launched in 2013 or later is needed to operate this new system (the K-500 is not compatible). thanks

05-25-2020, 12:26 AM	#163
Desperado Forum Member Join Date: Jul 2016 Posts: 51	Hi friends,is there any specific reason why some of those selenoids die early?Frequency of use,humidity,dust?

05-25-2020, 02:15 AM	#164
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Read HERE

08-30-2020, 12:54 PM	#165
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Originally posted by Angryman51 Any ideas what may be causing it? Maybe the polarity on the connections are reversed? It happens sometimes, though I don't know what the symptoms are. I believe the youtube video on repairing a K-50 shows the solenoid in action after being replaced. Perhaps you can compare it to your camera?