[BJMCG]

Hi Guys,

I'm new to the forum, so apologies if I've posted this incorrectly.

My K-50 developed the aperture solenoid problem. I bought a cheap working K100D Super with the intention of using one of its Japanese solenoids to fix the K-50. However, when I opened the K-50 and looked at the solenoid, I noticed that there is a small magnet floating between the two arms of the solenoid...I flipped it, and flipped again, to see if there was a difference in how hard it held the armature in place...I found that flipping it from the original position resulted in a less powerful pull on the armature. My K-50 is now working. This might be just a temporary fix...I'll let you know how it goes. The K100D has proved to be such a cracking little camera and I'm glad I didn't have to scrap it, at least for now.

---

Last edited by BJMCG; 09-07-2022 at 11:56 AM.

[reh321]

Hi Guys,

I'm new to the forum, so apologies if I've posted this incorrectly.

My K-50 developed the aperture solenoid problem. I bought a cheap working K100D Super with the intention of using one of its Japanese solenoids to fix the K-50. However, when I opened the K-50 and looked at the solenoid, I noticed that there is a small magnet floating between the two arms of the solenoid...I flipped it, and flipped again, to see if the was a difference in how hard it held the armature in place...I found that flipping it from the original position resulted in a less powerful pull on the armature. My K-50 is now working. This might be just a temporary fix...I'll let you know how it goes. The K100D has proved to such a cracking little camera and I'm glad I didn't have to scrap it, at least for now.

@photogem can express an opinion that is better informed than mine is;
Personally I would continue to use the camera and see what develops.

BTW - I believe that the magnet is just a part of the solenoid.

[jumbleview]

Pentax K100D was the camera which moved me to the Pentax brand. It was 2008. I decided to try DSLR and came in to camera store. I looked for camera in $600 - $700 range. The only camera in that range which did not feel like plastic toy was K100D. I did not buy it yet but later through online search found that there is new Pentax 200d within the same price. That how I came to the Pentax.

[FozzFoster]

less powerful pull on the armature. My K-50 is now working.

keep us posted on how your images are turning out!

[BJMCG]

@photogem can express an opinion that is better informed than mine is;
Personally I would continue to use the camera and see what develops.

BTW - I believe that the magnet is just a part of the solenoid.

Yes, it is part of the solenoid but it's not physically attached. It's held in place purely by the magnetism. It's there to lightly lock the armature which is released when the solenoid receives voltage. I do wonder if the solenoid assembly is ok and it's the quality and/or the positioning of this magnet that is to blame. There is actually a significant amount of vertical play with the magnet...it's not necessarily in the same position on every camera. Whatever the reason for the aperture problem, it's just a pity that such a great camera should be let down by a 10 cent part.
I should just replace the solenoid, but it goes against the grain to scrap a perfectly good K100D.

[cowlitzJim]

Pentax K100D was the camera which moved me to the Pentax brand. It was 2008. I decided to try DSLR and came in to camera store. I looked for camera in $600 - $700 range. The only camera in that range which did not feel like plastic toy was K100D. I did not buy it yet but later through online search found that there is new Pentax 200d within the same price. That how I came to the Pentax.

I did the exact same thing. Sadly the hired help could not show me how to make my M40/2.8 work with the camera - so I spent a year and some amazing 2009 scenery on a "sony" A200 before rejoining the K-team.

But by then I'd traded the M40 for Alpha gear

[Joetitch]

Some donor cameras have two solenoids one operates the flash pop-up catch. There is a list somewhere. Then you only need to carry an external flash if required.

[swanlefitte]

The K100D has proved to such a cracking little camera and I'm glad I didn't have to scrap it, at least for now.

You can swap solenoids with the k100d flash and keep both. Let's hope your solution lasts awhile.

[photogem]

Hi Guys,

I'm new to the forum, so apologies if I've posted this incorrectly.

My K-50 developed the aperture solenoid problem. I bought a cheap working K100D Super with the intention of using one of its Japanese solenoids to fix the K-50. However, when I opened the K-50 and looked at the solenoid, I noticed that there is a small magnet floating between the two arms of the solenoid...I flipped it, and flipped again, to see if the was a difference in how hard it held the armature in place...I found that flipping it from the original position resulted in a less powerful pull on the armature. My K-50 is now working. This might be just a temporary fix...I'll let you know how it goes. The K100D has proved to such a cracking little camera and I'm glad I didn't have to scrap it, at least for now.

For sure it is only a temporary fix, if you would have unscrewed the the solenoid to take the plunger in and out you'd have the same effect:
The magnetism is gone for a while and thus the holding force is less for a short while.

It is sad because you already did 95% of all work, getting near the flash solenoid of your K100D is anyway pretty easy.

So swapping those two solenoids, the green one from your K30 into the flashcircuit of your K100D and vice versa was more or less right in front of you. So no scrapping of your K100D at all.


Disassembling cameras several times weakens the plastic-threads for fixing the screws! Particular that one deep in the battery compartment. You must then fix it with some extra glue or push something into the hole so this screw can get a grip again:
And you MUST do this, this screw is very important!
That is why the changed this with the K-S2 and K-70, there is no more screw there, the front and top grip in a different way into each other to hold tight.

[BJMCG]

For sure it is only a temporary fix, if you would have unscrewed the the solenoid to take the plunger in and out you'd have the same effect:
The magnetism is gone for a while and thus the holding force is less for a short while.

It is sad because you already did 95% of all work, getting near the flash solenoid of your K100D is anyway pretty easy.

So swapping those two solenoids, the green one from your K30 into the flashcircuit of your K100D and vice versa was more or less right in front of you. So no scrapping of your K100D at all.


Disassembling cameras several times weakens the plastic-threads for fixing the screws! Particular that one deep in the battery compartment. You must then fix it with some extra glue or push something into the hole so this screw can get a grip again:
And you MUST do this, this screw is very important!
That is why the changed this with the K-S2 and K-70, there is no more screw there, the front and top grip in a different way into each other to hold tight.

Yes, I should have replaced the solenoid, Trouble is, I have 2 K-50s and a K-30 and this is my first failure. This was a bit of a dry run, in anticipation of what is to come. I did remove the solenoid to have a closer look...with the magnet removed there was no discernible magnetism in the solenoid body or armature. I've looked at photos of the white and green solenoids and they both show a dark band towards the bottom of magnet, I saw no such marking on my K-50 magnet. How important is the polarity of the magnet when slotted into place?
Regarding the screws, you are right, anything more than finger tight will strip the plastic. It's a pet hate of mine when manufacturers cheap out and don't use machined screws and metal fixings.

[Not a Number]

Since the polarity on the power wires matters I would imagine it matters on the magnet as well.

[slartibartfast01]

For sure it is only a temporary fix, if you would have unscrewed the the solenoid to take the plunger in and out you'd have the same effect:
The magnetism is gone for a while and thus the holding force is less for a short while.

It is sad because you already did 95% of all work, getting near the flash solenoid of your K100D is anyway pretty easy.

So swapping those two solenoids, the green one from your K30 into the flashcircuit of your K100D and vice versa was more or less right in front of you. So no scrapping of your K100D at all.


Disassembling cameras several times weakens the plastic-threads for fixing the screws! Particular that one deep in the battery compartment. You must then fix it with some extra glue or push something into the hole so this screw can get a grip again:
And you MUST do this, this screw is very important!
That is why the changed this with the K-S2 and K-70, there is no more screw there, the front and top grip in a different way into each other to hold tight.

I have a feeling my long screw in the battery compartment is not as tight as it could be after only removing it once. If it was loose what problems would it cause?

[photogem]

I have a feeling my long screw in the battery compartment is not as tight as it could be after only removing it once. If it was loose what problems would it cause?

It tightens the top to the main chassis at an important region were the On/Off/Shutterrelease-Button sits.
Thus button has two parts:

The lower part which sits on the main chassis. Here quite similar from a K5:

The red arrow shows where this screw in the battery-box goes through to fix it to the upper part.

Upper part:


The mentioned screw "screwes" into this plastic rod behind the third red arrow (bottom).

You can see that this guarantees a good contact of both parts of that switch.
If the thread in the plastic in too lose, those fingers of the upper part of the switch which are elastic, i.e. have a "spring-like tension" cannot make good contact anymore.

[photogem]

How important is the polarity of the magnet when slotted into place?

As @Not a Number wrote, it has the same effect as the polarisation of the two coils.
This does NOT mean, that one can change polarisation by turning the magnet upside down for counteracting opposite polarisation of the coils!

Both polarisations have to be correct:

1. the orientation of the permanent magnet
2. the correct polarisation of the two coils