[photogem]

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So those are more than useless.
Why invest into the wrong direction when a 1001 times it was already posted where you actually can find the "good solenoid"?
I have done some measurements with three white solenoid of some MZ series bodies from an MZ50 and an MZ7 all made in the Philippines
and can tell know the difference to those in the *ist DS; DL; DL2; K100D, K110D, K200D, K2000 (K-m); K-x
and I will post that later on when I have done further research.
What I can say is that there is a tiny difference in size which makes the plunger sit that tiny bit (0.8mm) more in the front of the mechanism it moves!

This is due to a difference in body size: 0,4mm for the solenoids in the MZ Series and 0,32mm for those from the mentioned digital bodies.
Also the magnetic force is different.
I came to do this reasearch after I read a post in a German forum where somebody tried to use solenoids from an MZ after the filing method went wrong.
He had to reverse polarity first and then got the opposite effect, i.e. the plunger did stay open too often, overexposed photos. As I had similar experiences with MZ bodies I purchased an MZ7 (cheap, as it had a usable lens on it) and a MZ50.


The white solenoid from the MZ bodies fires too quickly.

So again:
Get an *ist or any other DLSR which are cheap to find and don't search in the wrong direction.

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Last edited by photogem; 02-18-2019 at 01:27 AM.

[K50lives]

So those are more than useless.Why invest into the wrong direction when a 1001 times it was already posted where you actually can find the "good solenoid"?

Because it was easy and took no time at all and I was interested. I didn't make any recommendations on whether or not they were useful, it was just a casual observation, so I don't see the harm in it.


I'm going to keep to myself now I think - my postings seem to antagonize you for some reason and I don't really want to keep that going. I do appreciate your efforts in this problem though.

[reh321]

I'm going to keep to myself now I think - my postings seem to antagonize you for some reason

Anyone who disagrees with his research seems to antagonizes him - don't take it personally.

[sys3175]

Anyone who disagrees with his research seems to antagonizes him - don't take it personally.

Finally, someone who sees it the same way. I think he or she's usurping the threads with posts which are based on conjecture.

No source for the statement where the solenoids are made; stating the material is Teflon or PET, no proof; stating that the plunger gets magnetized (it doesn't); stating that the friction in the coil causes the problem (highly doubtful, in my experience the bearing isn't tight enough); putting out unproven FUD against some methods to mitigate the problem; I could go on and on.

That there's a connection to the power supply circuit, as can be easily deduced from the fact that the problem changes when using 1.5/1.2V batteries instead of the LiIon is something he or she prefers to play down OTOH.

I think that the ultimate cause for the problem is still unknown to everyone posting here. I've seen cameras with a white solenoid go bad again after a year, so go figure...

I'd rather have people keeping an open mind than someone hijacking every thread about the problem and reiterating after every new post the things he or she has already said before, that's so tiresome.
Just my 2 cents.

[Not a Number]

Why not share links to this aforementioned German forum? It's not like there are no other German speaking PF members or on-line translations. People had no problem sharing links to the Russian forums and blogs which started all this solenoid squabbling in the first place.

[Ajax156]

Anyone who disagrees with his research seems to antagonizes him - don't take it personally.

Agreed entirely!

I would add that I have now fixed two cameras with the green solenoid from DVD drives (30ohm variety). They are cheap and easy to find and IF it breaks again I'm really not too fussed.

Hakuna Matata

[MarkJerling]

Because it was easy and took no time at all and I was interested. I didn't make any recommendations on whether or not they were useful, it was just a casual observation, so I don't see the harm in it.


I'm going to keep to myself now I think - my postings seem to antagonize you for some reason and I don't really want to keep that going. I do appreciate your efforts in this problem though.

You are welcome here.

[K50lives]

Anyone who disagrees with his research seems to antagonizes him - don't take it personally.

You are welcome here.

Thanks everyone :-) I'll report any further interesting findings in the hope that some members find them useful.

[Ajax156]

Thanks everyone :-) I'll report any further interesting findings in the hope that some members find them useful.

One thing I noticed is that the solenoid in the k-50 can move around in the slot made for it. I wondered if this could be the reason for the act of taking many shots in quick succession seems to fix it in some cases. Perhaps the magnet moves to a position where the solenoid doesn't work properly to a slightly different position which then allows it to work?

This may have already been covered elsewhere but just wanted to share my observations.

Cheers

[Navmaxlp]

I just want to make sure I get everything here. I have a K-30 with the aperture issue. I have ordered a white solenoid from ebay which should arrive in a week or so. I am an electronics tech by trade but, having been in management for some time, my skills at soldering may be slightly rusty. It's ok, I can practice them a bit and I'll be ok. I've got a K-3 now anyway so getting this one running again will just be for a backup.

Here's what I want to verify:

I got this part;

https://www.ebay.com/itm/Pentax-K-30-K-50-K-S1-S2-K-500-Genuine-Aperture-Sol...53.m2749.l2649

That should be correct yes?

Also, when installing it, since this one does not have the wires, I'll need to get through the protection covering the solder joints. I may just trim the existing wire. Is there enough length there to trim or would I need to use new wire? Do I need to add some protection back or can I just make a good solder joint and leave it be?

I read something about reversing polarity. Can someone explain or is this is something I need to worry about?

I guess my biggest concern is doing other damage to the camera during the process. Anything I should look out for?

I have to admit to being a little nervous about this. I'd hate to ruin the little functionality I have with the K-30 but I also don't want to have to buy a whole new set of lenses just for that camera. None of the lenses I own have an aperture ring except an A 50/2.0.

Thanks for all the work that has gone into this so far. Simply amazing!

[The Squirrel Mafia]

^ Same one I got almost 2 years ago. Still works good. There's enough wire to trim. Keep in mind that its all very tiny. You'll see when you open the camera. Lots of patience is required, but it's really not that hard.

[sys3175]

Also, when installing it, since this one does not have the wires, I'll need to get through the protection covering the solder joints. I may just trim the existing wire. Is there enough length there to trim or would I need to use new wire? Do I need to add some protection back or can I just make a good solder joint and leave it be?

I read something about reversing polarity. Can someone explain or is this is something I need to worry about?

I guess my biggest concern is doing other damage to the camera during the process. Anything I should look out for?

The protection on the solder is really just a dot of felt marker paint, maybe to signal that the joint has been checked, you can just unsolder it. Then, unscrew the old part, put in the new one and solder the wires in the same way that they were attached to the old one. It's not difficult provided your solder iron has a tip that's reasonably fine. Just make it hot and solder quickly that the plastic coil carrier doesn't get deformed.

The polarity is only a problem with parts ripped from other devices, it seems there are solenoids where the coil is wrapped the other way rotation-wise, it shouldn't be a problem with your part.

Damage to the camera: it seems that most collateral damage occurs under the top plate of the camera where there are some sensitive ribbon connectors that are easy to screw up; I would recommend not removing the top, just loosening the screws a bit so that the other panels can be wiggled out.

Another common problem is that the AF switch gets misaligned during reassembly, check that it works in both directions before you put the screws back in.
And be careful not to touch the contacts of the flash condensor (battery-like object on the side where there's no grip), it may be charged with high voltage.

Don't be timid, it's less difficult than it seems.

[SteveDee]

Navmaxlp, I'd suggest you use an anti-static wrist band and clip the lead to the metalwork as soon as you have removed the bottom cover. Unfortunately my K30 developed the 'random flapping mirror' problem at some stage while operating the camera with the covers off, after replacing the solenoid. I don't know the reason why, but I guess I could have zapped it.

Polarity-wise; just physically compare the old solenoid with the new one and wire the same way. The way this system works is that the bar magnet normally holds the horseshoe in place. When you take a shot, a short pulse is applied across the solenoid creating an electromagnetic force which is opposite to the force from the bar magnet. This is not strong enough to 'eject' the horseshoe, but an additional downward pull is applied by the system mechanism, and the horseshoe is released.

So you can see that the polarity is important, because if connected the wrong way around, the magnetic force created by the pulse on the solenoid coil will just add to the bar magnet force, rather than opposing it.

You can also see from this that there are a few other variables which may result in the same apparent problem including; wear on the solenoid slot and mating pin (this may reduce pre-load, reduce downward force movement range when mechanism operates, and explain why filing the horseshoe sometimes works). The electronics that produces the pulse could be faulty; e.g. pulse width too narrow and/or timing marginal (this may explain why different battery voltages may appear to influence performance, but not offer a real solution.

But you can safely rule out ideas that the horseshoe has become 'partly magnetised' or that any differences in plastic former material are causing the problem.

[Not a Number]

This is not strong enough to 'eject' the horseshoe, but an additional downward pull is applied by the system mechanism, and the horseshoe is released.

The service manual for the Super Program reads: "The armature must be repelled from the magnet core when supplying voltage to the electromagnet."

[photogem]

I got this part; Pentax K-30 K-50 K-S1/S2 K-500 Genuine Aperture Solenoid Plunger Part - Japan - | eBay That should be correct yes?

Indeed, this is the right one!


As this is a used one from a K-x or similar, you most likely find a tiny amount of solder on the two pins facing you.
Don't touch the 2 pins that go sidewards because here the tiny wires have of the two coils are attached/soldered!

Also, when installing it, since this one does not have the wires, I'll need to get through the protection covering the solder joints.

There is no added protection covering soldering joints. Solder protects itself via its own flux! Sometimes you find dirt due to bad soldering for example if the tip of the soldering iron touched the insulation of the wires and it melts or in this case of the tip of the soldering iron was too large and touched the green PET which melts much quicker then the PTFE of the Japan white solenoid.

First you unsolder the two wires. Then you unscrew this tiny screw of the solenoid, best by taking a JIS +0 or +00 screwdriver because all screws in Pentax cameras are JIS and not Philips.


Then:

I may just trim the existing wire. Is there enough length there to trim or would I need to use new wire? Do I need to add some protection back or can I just make a good solder joint and leave it be?

You won't need to trim the wires. This part which was soldered on the solenoid with solder on its bare-wire-end will be long enough.
But you can carefully add some extra solder on it.


Then you first install the replacement solenoid into the camera and screw this tiny screw tight back on. You might fix the screw and the other hole of the solenoid
carefully with a tiny amount of nail polish or threadlock-paint.

But make sure none of this laquer or paint does drop down!

I read something about reversing polarity. Can someone explain or is this is something I need to worry about?

No worry for this solenoid.
Some people including me myself have found solenoids in pre-DSLR bodys which had reverse polarity, but NEVER any solenoid from the digital bodies.

I guess my biggest concern is doing other damage to the camera during the process. Anything I should look out for?

Yes, several important points:

- Open the flash for access of the 3 screws but without battery in the battery-compartment!

- read
Here about how to discharge the flash-capacitor

As soon as you open the flash AND switch the camera ON, it charges! Then BY NO MEANS work on it before you haven't discharged it.

- Only lift the top part to make sure you have better access to the solenoid itself and for removing the frontpart.
Do not completly lift it up because then you could do damage to the flat laser-ribbon-cable. You don't want to bend this one!


- always clean your soldering-iron tip prior soldering. Use a wet sponge for this. You don't want to bring dirt into the soldering joint.


- When the solenoid is built in, you can make a few test shoots (but don't open the flash with the battery in to avoid charging)


- If all photos prove you did it right and you see the plunger moving, take the lens off, battery out (!!!) and open the flash again, lift the top part again
and make sure the AF Switch on the front part is on AF (green) and the inner part which is moved by the external part is facing DOWNWARDS!
When the front part is on place right away check that the AF switch moves the extension of the screwdrive motor in and out of this tine hole!
If it doesn't, take the front part off again and really get those two parts of the AF switch into the correct alignment. It sounds much more complicated here
than it really is but we had several cases here where people forgot this and then the AF switch either was stuck on M or on AF. You want to avoid this.

- Don't forget this tiny screw which fixes the front part on the bottom side sitting next to the battery lever!

It all sounds here more complicated than it is. Don't hesitate but do it.