K-S2 Aperture block failure repaired

[PIngp0NGMW]

Hello everyone, a few months ago I reported that I was experiencing the black images problem on my K-S2. I came to realize that this was the dreaded aperture block failure problem. My camera was out of warranty (just about 2 years old now) and any third-party solution looked to be about $250 USD or so - quite steep.

I decided to take the plunge and fix it myself. I figured that if it worked that was awesome and if it didn't, well, the camera was out of warranty and a sunk cost.

I used this youtube video;

as a guide, even though it was for a K-50. The instructions were largely similar.



I am VERY pleased to report that the repair was a success! My K-S2 is working back as usual with normal, proper exposure pictures from the get go. I am so happy my K-S2 is back to life. I was not relishing dropping hundreds of dollars on a new camera after this one was still so young. I am looking to many years of continued use of my little Stormtrooper.




So many screws!






With the skin peeled off...






The notorious aperture block.






The source of all my problems. Thankfully, fixed!

 

[TomWret]

PIngp0NGMW, congratulation you really do have a "BIG PAIR"

Job well done, Tom W(ret)

 

[brett nz]

Well done!

I am hoping to buy one of these for my daughter who starts photography at school next year

Regards,

Brett

 

[ozdean]

So is the problem the block is too long or it gets dirty or just a bit rough at the ends?

 

[PIngp0NGMW]

Thanks TomW! I just figured that if I did kill the camera, well, it was basically unusable anyway. But so many people reported with success that the fix worked that I decided I just had to try for myself. Luckily it did work which I am quite pleased about. That new KP will just have to wait, haha.

 

[PIngp0NGMW]

So is the problem the block is too long or it gets dirty or just a bit rough at the ends?

 

[LightBug]

Congrats on a successful repair, it's great news for those afflicted by this issue.

Thanks for sharing the link, I've learned a few things about camera repair

Joey

 

[flektogon]

Sorry, but as an engineer I do not get it. What was then wrong with the core? If it got stuck inside the relay, definitely filing of the core edges can't help. Maybe making the core narrower could help. While no one can explain what exactly is the cause of the problem, the whole business of filing the core is a kind of charlatanism. The source of the problems could be easily just a bad contact to the relay coil, which you accidentally "fixed" when you moved that damn relay. Sorry...

--
Regards,
Peter

 

[KPM2]

Hello Pingp0NGMW and flektogon

Sorry, but as an engineer I do not get it. What was then wrong with the core? If it got stuck inside the relay, definitely filing of the core edges can't help. Maybe making the core narrower could help. While no one can explain what exactly is the cause of the problem, the whole business of filing the core is a kind of charlatanism. The source of the problems could be easily just a bad contact to the relay coil, which you accidentally "fixed" when you moved that damn relay. Sorry...

--
Regards,
Peter

Pingp0NGMW congratulation !

To flektogon: I read about it that the anchor can tilted, and don't move because this. You solve the problem like Pingp0NGMW did.

Now maybe a little Teflon-spray helps also for to keep it in work ?

best regards KPM2

 

[Zshuterbug]

Reading the Pentax Forums site in detail, it appears that the analysis eventually leads to a buildup of residual magnetism causing additional friction in the armature. Opening up additional gaps on either the ends or the sides of the armature breaks up the loop and restores proper operation.This may be supported by the reports that AA fresh batteries with possibly more available power can temporarily restore operation (until the magnetism builds up even more).

Heck, from watching the video, maybe even using the metal file across the ends demagnetizes the coil partially. Now if anyone documents before and after the magnetic field of the armature we may have a data driven answer.

 

[flektogon]

Reading the Pentax Forums site in detail, it appears that the analysis eventually leads to a buildup of residual magnetism causing additional friction in the armature. Opening up additional gaps on either the ends or the sides of the armature breaks up the loop and restores proper operation.This may be supported by the reports that AA fresh batteries with possibly more available power can temporarily restore operation (until the magnetism builds up even more).

Heck, from watching the video, maybe even using the metal file across the ends demagnetizes the coil partially. Now if anyone documents before and after the magnetic field of the armature we may have a data driven answer.

Tha't exactly my thought. Yes, the lousy material can be the culprit. By then I would rather replace the entire relay for a more reliable one, as it is now currently discussed in another thread.

 

[PIngp0NGMW]

Sorry, but as an engineer I do not get it. What was then wrong with the core? If it got stuck inside the relay, definitely filing of the core edges can't help. Maybe making the core narrower could help. While no one can explain what exactly is the cause of the problem, the whole business of filing the core is a kind of charlatanism. The source of the problems could be easily just a bad contact to the relay coil, which you accidentally "fixed" when you moved that damn relay. Sorry...

 

[GPGeneralPhoto]

I think that you did a great job. Not many people on this forum would even attempt this repair. It's good to see a fellow tinkerer win the camera repair game.

 

[ozdean]

Because not all K30/50 suffer this problem could it be that some of the core castings have ragged ends that are binding?

If this were true however you would think it would happen at the start and not through mid life?

Thinking further the blackouts are caused by the core fully retracting and closing down the aperture so maybe it is a build up of magnetism?

When my friends started doing it the camera would come good after the the first 4 shots or so until turned off which suggests the opposite?

All very curious?

--
Regards Dean - Capturing Creation
N.B. All my Images are Protected by Copyright

 

[DAVID MANZE]

Firstly, well done!

Going back to my sound recording days, a build up of residual magnetisation was a common problem on audio tape recording heads, it caused a background grumble and other. It was routine to demagnetize the heads with an iron cored copper wound coil with an AC current which would "shake" the molecules around until their pole orientation was neutral.

From what I read here maybe the problem could also be cured by demagnetizing the offending core piece, it's a shame that many bodies find their way to the dumpster because of it!

 

[flektogon]

Firstly, well done!

Going back to my sound recording days, a build up of residual magnetisation was a common problem on audio tape recording heads, it caused a background grumble and other. It was routine to demagnetize the heads with an iron cored copper wound coil with an AC current which would "shake" the molecules around until their pole orientation was neutral.

From what I read here maybe the problem could also be cured by demagnetizing the offending core piece, it's a shame that many bodies find their way to the dumpster because of it!

 

[flektogon]

Firstly, well done!

Going back to my sound recording days, a build up of residual magnetisation was a common problem on audio tape recording heads, it caused a background grumble and other. It was routine to demagnetize the heads with an iron cored copper wound coil with an AC current which would "shake" the molecules around until their pole orientation was neutral.

From what I read here maybe the problem could also be cured by demagnetizing the offending core piece, it's a shame that many bodies find their way to the dumpster because of it!

--
Dave's clichés

Dave,

Actually that's an excellent idea, which could be even implemented by an addition to the camera F/W. Just like dust removal, or other "maintenance" setting, there could be the "demagnetization" setting, where this solenoid would be driven by an AC current with a slowly decaying amplitude. Well, the lens probably would need to be removed during such procedure, but within a second or two the core would be completely free of any residual magnetism.

--
Regards,
Peter

I've got another idea. Because those failing cameras have plastic bodies, it might be possible to demagnetize this solenoid core from outside, just circling a suitable demagnetization tool as close as possible above this solenoid. Once I made such a tool for exactly what you mentioned, for the tape recording heads. It was a simple coil for 120V, but I drove it from the 220V AC power outlet (just for a short time) and as the core I used, well now I do not remember what kind of iron/steel rode it was, but some ferromagnetic material with the minimal residual magnetism. The rod protruded from the coils around 10cm. I have successfully demagnetized the audio tape recorder heads in all households along the entire street where we used to live .

So, do we have a skilled electro-technician around here, who have access to suitable material and could build such a tool? Well, it should be verified that it works, and if yes, such a tool can be "circled" around all unfortunate Pentax owners.

--
Regards,
Peter

 

[flektogon]

Firstly, well done!

Going back to my sound recording days, a build up of residual magnetisation was a common problem on audio tape recording heads, it caused a background grumble and other. It was routine to demagnetize the heads with an iron cored copper wound coil with an AC current which would "shake" the molecules around until their pole orientation was neutral.

From what I read here maybe the problem could also be cured by demagnetizing the offending core piece, it's a shame that many bodies find their way to the dumpster because of it!

 

[DAVID MANZE]

Firstly, well done!

Going back to my sound recording days, a build up of residual magnetisation was a common problem on audio tape recording heads, it caused a background grumble and other. It was routine to demagnetize the heads with an iron cored copper wound coil with an AC current which would "shake" the molecules around until their pole orientation was neutral.

From what I read here maybe the problem could also be cured by demagnetizing the offending core piece, it's a shame that many bodies find their way to the dumpster because of it!

--
Dave's clichés

Dave,

Actually that's an excellent idea, which could be even implemented by an addition to the camera F/W. Just like dust removal, or other "maintenance" setting, there could be the "demagnetization" setting, where this solenoid would be driven by an AC current with a slowly decaying amplitude. Well, the lens probably would need to be removed during such procedure, but within a second or two the core would be completely free of any residual magnetism.

--
Regards,
Peter

I've got another idea. Because those failing cameras have plastic bodies, it might be possible to demagnetize this solenoid core from outside, just circling a suitable demagnetization tool as close as possible above this solenoid. Once I made such a tool for exactly what you mentioned, for the tape recording heads. It was a simple coil for 120V, but I drove it from the 220V AC power outlet (just for a short time) and as the core I used, well now I do not remember what kind of iron/steel rode it was, but some ferromagnetic material with the minimal residual magnetism. The rod protruded from the coils around 10cm. I have successfully demagnetized the audio tape recorder heads in all households along the entire street where we used to live .

So, do we have a skilled electro-technician around here, who have access to suitable material and could build such a tool? Well, it should be verified that it works, and if yes, such a tool can be "circled" around all unfortunate Pentax owners.

--
Regards,
Peter

And my third (last ?) contribution to this problem: If this solenoid core/plunger can't be demagnetized from outside (circling with the demagnetization tool around the plastic body), it might be demagnetized through the aperture control lever, which is accessible when you remove lens, as this lever directly moves the aperture lever on the lens. This (body, not lens) lever is visible as a shaft inserted to the hole of the plunger, as OP shows in his pictures. Hopefully this lever is made from ferromagnetic material as well. Certainly there are ways how to beat even the least caring manufacturer.

--
Regards,
Peter

One of the problems will be that, the two coils look to be wound with very fine wire with many hundreds of turns, any varying magnetic field will of course induce a voltage across the coil, possibly many hundreds of volts, very likely enough to destroy surrounding components.

It's also very likely in this situation to have a diode across the coils, eliminating the back EMF reverse voltage spike as the magnetic field collapses, this could cause havoc with an AC changing magnetic field. So there would have to be some way to isolate the coils, already things are getting complicated.

I can't see a way in which avoiding disassembly would be possible here, it's best to demagnetize and clean the iron "H" piece independently. It doesn't look the most impossible of jobs and someone brave enough to make a utube video showing the procedure could go a long way to help.

Dave's clichés

 

[flektogon]

Yes, I am aware of such danger. So, then the only way to fix this problem without disassembling camera is to shoot in the burst mode, but in such burst mode, in which the aperture movement is fully engaged. As someone already tried it, it is in the LV mode. This "fixing" is a kind of demagnetization using a low frequency (5-6 Hz) AC current.

--
Regards,
Peter