[photogem]

Solenoid-Replacement Pentax K-70
(Pentax K-S2 is almost identical exept screw of solenoid situated on left instead of left side!)

Tools required:
- Soldering iron with pencil-tip: Ersa Multi-Pro 20W or soldering needle/USB soldering iron. Butan-gas s.iron = No-Go! Too hot, it will do damage!
- Solder: Good quality thin resin flux solder (I use thin leaded solder, for such a small work it is not really dangerous due to its lead-content)

- Screwdrivers JIS 000 or PH000 + PH00 (JIS size works for all screws, if you use PH, then you need the PH000 for the solenoid screw. JIS is preferable!)

- Tweezers or precision pliers
- Headlamp is very useful, makes things easier
- photos of K-70 with location of screws


Preparation:
- Print out all those photos, glue them on some cardboard, drill 2mm holes were the screws are located so you can later on stick all those screws into those holes. Makes it easier and safe due to different length of the screws.
- Make sure you took the battery out 24 hours prior undertaking the repair. This is for discharging the flash-condenser, which is well protected within the K-70, nevertheless you don't want to risk getting a nasty shock! This condenser charges as soon as you open the pop-up-flash with battery inside the switched-on camera! So don't open the flash prior removal of the battery! You need to open it for access of 3 screws!
- For another option how to discharge the flash-condenser read HERE


Sequence of opening the body (Body-cap is mounted on the K-mount for protection of sensor etc.)

1. Remove all screws from the bottom part:
- 11 x screws direct access (green arrows)
- 3 x behind the battery-door (red arrows)

- Like with other Pentax DSLR, there is one screw deep within battery-case left side: DON'T take this one out!


2. Remove all 3 x screws from the left side (2 of them hidden behind the rubber grip):






3. Remove all 3 x screws from the right side (all 3 hidden behind the rubber grip):






4. Open the flash (battery is out!):
Remove the 2 x screws there underneath the pop-up-flash and the 2 x screws where next to where you fix the strap/belt:





5. Remove the 2 x screws behind the rubber-eye-cup:





6. Now you lift the TOP-PART (with the open flash) about 1 cm. This is very important because otherwise the front-part is more difficult to remove!


7. Set the AF-MF switch on MF (see photo #2 but there it is on AF)! Check position again when you assemble it back!
Make sure you understand its position: When on MF, the screwdrive is in/retreated, when on AF, it comes out of this small hole of the stainless-steel bayonet!
Take the FRONT-PART OFF: It is a bit tight, you might have to lever a bit to release it but don't worry, this is normal!


8. Now you have access to the green solenoid:



9. Unsolder both leads and unscrew the screw on the LEFT SIDE (K-S2 has it on the right side, otherwise everything is the same). Take the solenoid out.


10. Install the white-Japan-made Solenoid (the only correct solution, avoid filing/grinding/sanding):





11. Make sure you tighten the screw, you might want to fix it with threat-locking-laquer or nail-varnish, but I never needed to do it!


12.Solder the two wires back to the pins (left=pink//right=lilac). Crucial to do a good job, hold the wires with tweezers and pull to make sure they really are well soldered!

14. Now bring the top-part (with flash) back into position for being able to test the solenoid.
You might want to fix it with 2 screws (right to the viewfinder and the on the right strapholder, so the buttons have a good contact!
CLOSE THE POP-UP-FLASH!
Insert the battery and plug on a lens.
Switch the camera ON, in Av-Mode wide open take a photo.
You can see if the solenoid actuates and the photo should be alright.
If all is alright, take the lens, battery and the 2 screws off again.

15. Lift the Top part again slightly

16. AF-MF-Switch alignement: The is crucial now:
- Outer part of AF-MF-switch on the front-housing on MF:




- The internal part (black plastic, white arrow left) has to be upwards...

.... so the screwdrive mechanism "retreats" into this tiny hole (white arrow right). The rod of the AF-MF switch connects with the internal part!
(you have checked this before and understood the principle well, remember!)


17. Assemble the front part back and then the top-part (with flash).


18. Test AF-MF-Switch again! If it doesn't work correctly, take the front-part off again and realign!


19. There is this small plastic ring on the microphone-socket, don't lose it!

When you come to the bottom-plate, make sure you haven't missed this small part, which sometimes comes off:


It slides just on and off easely and is there to protect the cables from the display:


On its place it looks like this:


and with the bottomplate back on place it looks like this:



20. The rest is clear now, all screws in the same order as you got them out.


21. Test the K-70 and all should be fine

I have not written here about the differences of the solenoids, you can find that all HERE
Good luck!

If you are interested in this very interesting history of the development of the solenoid in Pentax SLR and DSLR bodies, then read this post:
A little history about the development of solenoids in Pentax cameras

---

Last edited by MarkJerling; 05-12-2021 at 01:43 AM. Reason: Photogem added information.

[automorphism]

So the K70 has this problem, too? Regardless, looks like a great guide. Thanks for posting.

[Mwellman]

The AF switch info I needed for my K50! Thanks

[FozzFoster]

awesome tutorial! thank you for your contributions!

[jatrax]

In the first image you say "- 3 x behind the battery-door (blue arrows)" But I think the arrows are actually red if I am reading it correctly.


Thank you so much for this contribution and your other work on this issue. I am sure many people have benefited.

[The Squirrel Mafia]

Sucks that even some K-70 bodies will be affected by this problem, but thanks for your hard work!

[photogem]

So the K70 has this problem, too? Regardless, looks like a great guide. Thanks for posting.

Some! From December 2015 Ricoh has done something, because late-production K50's, K-S1's and KS2's already had a strong decline in developing this aperture-problem (all those post 12/2015 manufacture).

The AF switch info I needed for my K50! Thanks

I actually wrote a tutorial for the K30/50 where I had explained this the first time, you find it HERE

In the first image you say "- 3 x behind the battery-door (blue arrows)" But I think the arrows are actually red if I am reading it correctly.
Thank you so much for this contribution and your other work on this issue. I am sure many people have benefited.

Thanks in both cases: I took over the text from the K-S2 tutorial and forgot to change this due to color matching body-color! I corrected the arrow-colour!

[yucatanPentax]

Very nice step-by-step and photos of the process. Thanks for posting this!

[SharkyCA]

Solenoid-Replacement Pentax K-70
(Pentax K-S2 is almost identical exept screw of solenoid situated on left instead of left side!)

Tools required:
- Soldering iron with precision soldering-tip (such as Ersa Multi-Pro 20W)
- Screwdrivers JIS 000 or PH000 + PH00 (JIS size works for all screws, PH000 for solenoid screw. JIS is preferable!)
- Tweezers or precision pliers
- Headlamp is very useful, makes things easier
- photos of K-70 with location of screws


Preparation:
- Print out all those photos, glue them on some cardboard, drill 2mm holes were the screws are located so you can later on stick all those screws into those holes. Makes it easier and safe due to different length of the screws.
- Make sure you took the battery out 24 hours prior undertaking the repair. This is for discharging the flash-condenser, which is well protected within the K-70, nevertheless you don't want to risk getting a nasty shock! This condenser charges as soon as you open the pop-up-flash with battery inside the switched-on camera! So don't open the flash prior removal of the battery! You need to open it for access of 3 screws!
- For another option how to discharge the flash-condenser read HERE


Sequence of opening the body (Body-cap is mounted on the K-mount for protection of sensor etc.)

1. Remove all screws from the bottom part:
- 11 x screws direct access (green arrows)
- 3 x behind the battery-door (red arrows)

- Like with other Pentax DSLR, there is one screw deep within battery-case left side: DON'T take this one out!


2. Remove all 3 x screws from the left side (2 of them hidden behind the rubber grip):






3. Remove all 3 x screws from the right side (all 3 hidden behind the rubber grip):






4. Open the flash (battery is out!):
Remove the 2 x screws there underneath the pop-up-flash and the 2 x screws where next to where you fix the strap/belt:





5. Remove the 2 x screws behind the rubber-eye-cup:





6. Now you lift the TOP-PART (with the open flash) about 1 cm. This is very important because otherwise the front-part is more difficult to remove!


7. Set the AF-M switch on AF (see photo #2)! Check position again when you assemble it back!
Make sure you understand its position: When on AF, the screwdrive is out, when on M, it is retreated inside this small hole of the stainless-steel bayonet!
Take the FRONT-PART OFF: It is a bit tight, you might have to lever a bit to release it but don't worry, this is normal!


8. Now you have access to the green solenoid:



9. Unsolder both leads and unscrew the screw on the right side (K-S2 on right side, only difference). Take the solenoid out.


10. Install the white-Japan-made Solenoid (the only correct solution, avoid filing/grinding/sanding):





11. Make sure you tighten the screw, you might want to fix it with threat-locking-laquer or nail-varnish, but I never needed to do it!



12.Solder the two wires back to the pins (left=pink//right=lilac). Crucial to do a good job, hold the wires with tweezers and pull to make sure they really are well soldered!



13. AF-M-Switch alignement: The is crucial now:
- Outer part of AF-M-switch on the front-housing on AF:

- The inner part (black plastic) has to be downwards.....

.... so the screwdrive mechanism "pokes out" of this tiny hole
(you have checked this before and understood the principle well, remember!):




14. Assemble the front part back and then the top-part (with flash).


15. Test AF-S-Switch! If it doesn't work correctly, take the front-part off again and realign!


16. There is this small plastic ring on the microphone-socket, don't lose it!


17. The rest is clear now, all screws in the same order as you got them out.


18. Test the K-70 and all should be fine

I have not written here about the differences of the solenoids, you can find that all HERE
Good luck!

If you are interested in this very interesting history of the development of the solenoid in Pentax SLR and DSLR bodies, then read this post:
A little history about the development of solenoids in Pentax cameras

Well done Photogem! I think I will print it out for future reference, thanks for your hard work!

[tvdtvdtvd]

Nicely done, thanks for sharing.

[jeallen01]

Nicely done, thanks for sharing.

@photogem
Brilliant! - very many thanks indeed (and I have a white solenoid "in the cupboard" should "that failure" unfortunately ever happen)

[rwhynacht]

Thanks for your hard work on this. Good note re the autofocus switch. Precision repaired my K-70 recently and I had to return it to have that issue corrected.

[photogem]

Thanks for your hard work on this. Good note re the autofocus switch. Precision repaired my K-70 recently and I had to return it to have that issue corrected.

Well, sometimes they even make errors with imaginary resistors . It can happen but shouldn't happen.
I had recently a K30 for repair which received the diaphragm-control-block by an official repair place. It failed after 15 months again.
When I opened the camera I noticed that one screw (inside) was missing.

Now this K30 works well again, better than ever before.

[Mwellman]

Some! From December 2015 Ricoh has done something, because late-production K50's, K-S1's and KS2's already had a strong decline in developing this aperture-problem (all those post 12/2015 manufacture).

I actually wrote a tutorial for the K30/50 where I had explained this the first time, you find it HERE

Thanks in both cases: I took over the text from the K-S2 tutorial and forgot to change this due to color matching body-color! I corrected the arrow-colour!

Thanks even better. My Xmas holiday project.

[Mcgutierre]

Thank you very much! I could fix my k70 using a white solenoid, It would have been very difficult without your marvelous explanation. Using this tips it's an easy process except for one step: soldering those tiny cables.