[sergiogonzalez]

Dear Community:
With the post #144 I have transmitted everything, absolutely everything I could investigate regarding the operation of the Chinese green solenoid.
The main conclusion is that with proper maintenance of the opening block, the ABF problem disappears and the camera returns to function as new.
The improvement explained in the post #144 experience it before the opening block intervention and I was able to determine that it actually works best.
I've even tried it after the intervention and it has a smoother and equally consistent operation which is why it can help someone
There's a character who challenges everything and this situation is unbearable.
It simply says it doesn't work and isn't even able to build a solenoid operating curve it owns.
I own only the original green solenoid of my camera and a modified Plunguer obtained from a solenoid from a CD floppy disk drive. That's all.
There are those who may doubt that my Ks2 does not work.
Attach one of the last photos taken during this month of May on our beautiful Mendocina mountain in autumn, in fully automatic mode that demonstrates the total and correct operation of the camera.
It has been a real pleasure to share everything and also to have received many recognitions from forum members which I sincerely appreciate.
This is my last post in this forum, as I consider the topic to be exhausted.

Best Regards!

---

Last edited by sergiogonzalez; 02-01-2022 at 01:32 PM.

[swanlefitte]

I switched my green for the white tonight. the static pull wasn't that different 164g for the white and 189g for the green.
That is all I have tested except that the aperture works now with the white. However the cable that operates aperture and back button focus came apart and I am having trouble getting it to stay connected. I am stuck on f8 and no af.

[swanlefitte]

I managed to get the cable back in place and restored control to my aperture and af. It took a bit of force to reseat the cable. Probably more force than to release both the white and green plungers at the same time. Now I just have about a million screws of differing sizes to put back in the correct holes. I will hold off on putting the k100d back and see if I can do some tests to the green solenoid. The white was needed.

[swanlefitte]

Static:
Ohmic coil resistance 29 ohm
Magnet locking effort: approx. 230/240 grams applying the load gradually and very slowly.
This value should not be less than 150 grams, because the magnet of solenoid, will not have enough power for mechanical rearmament by cam of the diaphragm control and may not be blocked

I used a multimeter to test ohms on my green solenoid. I was touching the 2 poles I unsoldered the wires from and I had a reading fluctuate mostly between 70-90 (spikes around 50 and 110) but no where near a single number.

[sergiogonzalez]

Usé un multímetro para probar ohmios en mi solenoide verde. Estaba tocando los 2 polos de los que desolde los cables y tuve una lectura que fluctuaba principalmente entre 70-90 (picos alrededor de 50 y 110) pero no cerca de un solo número.

Dear Swanlefitte:
I'm so glad your camera has worked with the white solenoid again.
Your data from the retention value for the white solenoid is great for me, as it confirms my observation that it needs less energy to unlock than green.
Also, the values you've measured are lower than the ones I got, but greater than 150 gr which is the logical limit.
The magnet that equips my green solenoid is more powerful (240 gr with original Plunguer and 230 gr with Plunguer modified according to post #144), than the one that equips your camera.
I believe these are the differences between the different sets of solenoids that are mounted on our Pentax.
As for the 29 ohm resistance, this is an important parameter, as it is determined by the diameter of the copper wire used to wind the reels and the number of turns that have been made. This determines the electromagnetic capacity of the solenoid in fact equal in the green and white solenoid, as has been shown in several forums.
Note that you have chosen the correct function in the multimeter normally identified with the Greek letter omega in its selector.
Keep me on top of your experience.
Best regards!

[sergiogonzalez]

More than 14000 shots with my K-s2, equipped with its original green solenoid!
More than 6000 failless ABF shots of the green solenoid after intervening and repairing the diaphragm control.
This camera had the first 7000 non-fault shots ABF.
1000 shots in the period of investigation and isolation of the fault.
6000 shots from the intervention of the ABF faultless opening aperture block control.
I am very happy with the consistent operation of my K-s2.
I attach one of the last photographs taken in the Sierras of Córdoba, Argentina.
Attentive greetings

[ChristianRock]

My K-S1 continues to work flawlessly with its replaced white solenoid. So if we are using anecdotal evidence, I don't think it can be denied that the white solenoid fixes the aperture issues.

My K-50 now has 41,995 actuations with the original green solenoid. So it's possible for the green solenoid to keep working well. I use mine frequently.

[sergiogonzalez]

Dear user community of Ks2.
Happy 2022 with a lot of health and many good photographs.
I want to tell you that my Ks 2 has already reached 15200 shots and I no longer experience the dreaded ABF.
I've been going over everything written in this thread, and the post that best describes the ABF problem is post #29. It accurately describes why the solenoid fails as a result of a poor electrical signal from the aperture control.
Doing the maintenance to this control is essential after about 4 years of use of the camera. This in turn allows us to maintain the design of our cameras.
The green solenoid has the electrical, mechanical and magnetic characteristics that the manufacturer has determined for the excellent and consistent operation of the aperture control.
Belittling the Chinese industry at this time I think is too much.
With this criterion we should think that every modern Pentax camera has lowered its quality by having most of its components of that origin.
It is irrefutable that the green solenoid works well in most cameras and also that it does well at least in its first 3 years of use.
This maintenance consists of renewing the lubricants and checking the state and quality of any electrical contact, static or dynamic of the system.
All the details are explained in some post of this thread.
A good guide to lubricants to use in cameras is in this same forum in the following thread uploaded in 2011 by Pacerr. He apart from suggesting lubricants gives applicative criteria in the different parts that can help those who venture to do the maintenance of their camera.
I hope it will be useful.

Lubricants - PentaxForums.com

Attentive greetings

[swanlefitte]

a result of a poor electrical signal from the aperture control.
Doing the maintenance to this control is essential after about 4 years of use of the camera.

I will not refute this. Your camera is evidence this is so. Yet if It has been shown I do not need that much electrical signal with a white solenoid, then why is this the preferred method? As white solenoids become rare this might be preferred.

Thank you for the update on your repair.

[Kai-Luke]

Having tested the modification of the U-shaped plungerer Sergio suggests it looks like this


But the very bad results are terrible.

I have taken some photos of a no dog poop sign to show it.
The K30 is still open because it got a white Japan solenoid afterwards.

F2,8 (Sigma F2,8-50mm AF-macro)


F11:


F18:


F25:


Afterwards when exchanged against the white Japan-Solenoid, all was fine.


To access the switch behind the diaphragm control unit you need to take the Pentax apart complety.
Having done so with a K100D just for fun, I never can recommend this on a K-30 or K-S2.

I also ask this question

Pentax K10D, K20D, Samsung GX10 and GX20 use the Japanese solenoid and are known to reach very high actuation numbers.
Why they never fail, nor K200D, K100D, ist and all other before K30 which use the solenoid?

It makes sense, it is logical.
Because the Japan solenoid works well.
Not necessary to take the Pentax apart.


Another question:
If I make this effort of complete disassembly of my Pentax I must take photos of each step.
Complicated soldering involved.

Many soldering points and wires which need to go back exactly to their place.


Everybody on modern days has a smartphone with a useful camera good enough to take such photos.
Why did you not take photos of each step?

[sergiogonzalez]

Having tested the modification of the U-shaped plungerer Sergio suggests it looks like this


But the very bad results are terrible.

I have taken some photos of a no dog poop sign to show it.
The K30 is still open because it got a white Japan solenoid afterwards.

F2,8 (Sigma F2,8-50mm AF-macro)


F11:


F18:


F25:


Afterwards when exchanged against the white Japan-Solenoid, all was fine.


To access the switch behind the diaphragm control unit you need to take the Pentax apart complety.
Having done so with a K100D just for fun, I never can recommend this on a K-30 or K-S2.

I also ask this question

Pentax K10D, K20D, Samsung GX10 and GX20 use the Japanese solenoid and are known to reach very high actuation numbers.
Why they never fail, nor K200D, K100D, ist and all other before K30 which use the solenoid?

It makes sense, it is logical.
Because the Japan solenoid works well.
Not necessary to take the Pentax apart.


Another question:
If I make this effort of complete disassembly of my Pentax I must take photos of each step.
Complicated soldering involved.

Many soldering points and wires which need to go back exactly to their place.


Everybody on modern days has a smartphone with a useful camera good enough to take such photos.

Dear Kai-Lucas: a pleasure to greet you.
From the photos you have uploaded it is clear that the solenoid you modified has lost the magnetic retention capacity, which has to be a minimum of 150 gr. according to what I explained in my post # 47.
If the solenoid does not lock, a fact that has to happen by a mechanical blow produced by the Aperture block when lowering the mirror when the photo is finished, it is because Plunguer's legs are very short, or there is some imperfection in the polishing of the surfaces that prevent the blockage.
I suggest a length of Plunguer's legs of 4 mm, but this length must be verified with a caliper, because the armor of the different sets of solenoids can be different dimensionally. You have to ensure that the legs reach the armor and a minimum light is produced between the heads of the coils and the Plunguer of at least 0.2 mm.
After you practiced the slots or reductions that I suggest in post #144, you must verify that the Plunguer is magnetically retained at least with more than 150 gr. You should study the graphics developed in post #91.
If the Plunguer does not lock, it will be permanently unlocked and loses the possibility of electromagnetic unlocking at the exact moment sent by the perforated crown of the Aperture block, which will select the diaphragm aperture determined by the processor. This is the reason of the overexposed photos you have taken. Directly the system stops working.
This modification of the solenoid, is designed to take advantage of a weakened signal of the Aperture block, and has the advantage of being able to be done without welding ability. Now if you have the white solenoid, use it and that's all, otherwise try to lower the consumption of green by following these tips.
My Ks2 camera, works with the original and reduced Plunguer without any problem. I have already sent many photos of it where it is shown to produce consistent exposures.
I hope this helps you.
Attentive greetings

---------- Post added 01-31-22 at 10:02 PM ----------

Dear user community of Ks2.
Happy 2022 with a lot of health and many good photographs.
I want to tell you that my Ks 2 has already reached 15200 shots and I no longer experience the dreaded ABF.
I've been going over everything written in this thread, and the post that best describes the ABF problem is post #29. It accurately describes why the solenoid fails as a result of a poor electrical signal from the aperture control.
Doing the maintenance to this control is essential after about 4 years of use of the camera. This in turn allows us to maintain the design of our cameras.
The green solenoid has the electrical, mechanical and magnetic characteristics that the manufacturer has determined for the excellent and consistent operation of the aperture control.
Belittling the Chinese industry at this time I think is too much.
With this criterion we should think that every modern Pentax camera has lowered its quality by having most of its components of that origin.
It is irrefutable that the green solenoid works well in most cameras and also that it does well at least in its first 3 years of use.
This maintenance consists of renewing the lubricants and checking the state and quality of any electrical contact, static or dynamic of the system.
All the details are explained in some post of this thread.
A good guide to lubricants to use in cameras is in this same forum in the following thread uploaded in 2011 by Pacerr. He apart from suggesting lubricants gives applicative criteria in the different parts that can help those who venture to do the maintenance of their camera.
I hope it will be useful.

Lubricants - PentaxForums.com

Attentive greetings

Dear Swanlefitte:
A pleasure to greet you in this 2022
Thank you for following this thread and your confidence in everything published.
I understand that intervening the Aperture block is a very complex operation and requires maximum qualification in welding and understanding the disassembly and assembly using equipment and measurement procedures that not everyone has or understands.
I have tried to explain as well and as clearly as possible all the procedures, but it is so complex that even having videos of the whole operation it would be very difficult to explain it.
Readers should also understand that my Ks2 is the only camera I have, and when intervening, use freehand graphics and reference photographs to then reconstruct the wiring.
Thank God, I did not have any accidents during the intervention, which allowed me to continue enjoying my Ks2.
Best Regards!

---------- Post added 01-31-22 at 10:05 PM ----------

I will not refute this. Your camera is evidence this is so. Yet if It has been shown I do not need that much electrical signal with a white solenoid, then why is this the preferred method? As white solenoids become rare this might be preferred.

Thank you for the update on your repair.

Dear Swanlefitte:
A pleasure to greet you in this 2022
Thank you for following this thread and your confidence in everything published.
I understand that intervening the Aperture block is a very complex operation and requires maximum qualification in welding and understanding the disassembly and assembly using equipment and measurement procedures that not everyone has or understands.
I have tried to explain as well and as clearly as possible all the procedures, but it is so complex that even having videos of the whole operation it would be very difficult to explain it.
Readers should also understand that my Ks2 is the only camera I have, and when intervening, use freehand graphics and reference photographs to then reconstruct the wiring.
Thank God, I did not have any accidents during the intervention, which allowed me to continue enjoying my Ks2.
Best Regards!

Read more at: Dark frames or dark expositure problems in KS2, K30, K50, etc. - Page 11 - PentaxForums.com

[Kai-Luke]

Dear Kai-Lucas: a pleasure to greet you.
From the photos you have uploaded it is clear that the solenoid you modified has lost the magnetic retention capacity, which has to be a minimum of 150 gr. according to what I explained in my post # 47.

This is not the case.
The magnet used in the solenoid is a rare earth magnet.
Rare earth magnets don't just lose their strength.
They need to be exposed to mechanical damage or strong heat.

Before the modification the plunger stuck too strong in the solenoid.
Because I have a few green solenoids from other Pentax cameras I did repair I was able to use a normal plunger as well.
Then the solenoid has its old strength back.
Which I expected.

If the solenoid does not lock, a fact that has to happen by a mechanical blow produced by the Aperture block when lowering the mirror when the photo is finished, it is because Plunguer's legs are very short.

The legs have not been shortened

Or there is some imperfection in the polishing of the surfaces that prevent the blockage.

The surface is neat and polished.

If the Plunguer does not lock, it will be permanently unlocked and loses the possibility of electromagnetic unlocking at the exact moment sent by the perforated crown of the Aperture block, which will select the diaphragm aperture determined by the processor. This is the reason of the overexposed photos you have taken. Directly the system stops working.

It stays permanently unlocked because there is too little material to be magnetized.

This modification of the solenoid, is designed to take advantage of a weakened signal of the Aperture block, and has the advantage of being able to be done without welding ability.

Welding?

Now if you have the white solenoid, use it and that's all, otherwise try to lower the consumption of green by following these tips.

My Ks2 camera, works with the original and reduced Plunguer without any problem. I have already sent many photos of it where it is shown to produce consistent exposures.

I thought your camera works because of the cleaning of contacts.
Why did you disassemble it again and modify the plunger as well?

[sergiogonzalez]

Dear Community
I consider that this issue is really resolved for me and it makes no sense to continue collaborating and receiving answers in which the experience that one has lived is underestimated.
It was a pleasure to share with some members of the forum, with others it has been unbearable.
Good luck.
Until never.

[MarkJerling]

Thanks OP.