Has your repaired Aperture Control Block stayed fixed?

nihonsuki · 09-07-2016, 09:21 AM

I had mine replaced a couple years ago and it's starting to fail again, about 20K exposures later.

**niceshot** · 09-07-2016, 06:07 PM

Originally posted by nihonsuki

I had mine replaced a couple years ago and it's starting to fail again, about 20K exposures later.

I hope for your sake it is not the shutter block

nihonsuki · 09-07-2016, 07:04 PM

The symptoms are exactly the same: one or two initial underexposed pictures after the camera has not been used for a few hours, gradually getting worse (happening more often and more underexposed shots). Today I followed the repair procedure for the solenoid armature and I'll see if that fixes it.

**patrick9** · 11-20-2016, 03:15 PM

Originally posted by nihonsuki

Today I followed the repair procedure for the solenoid armature and I'll see if that fixes it.

What repair procedure? Mine failed a few weeks ago. I just had it repaired( Not part replaced). It is working fine, But not sure how they fixed it other that some things I have read towards a repair of the solenoid. All I know is the fellow that repaired it said it was a fairly easy repair.

nihonsuki · 11-20-2016, 03:50 PM

https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/321871-k-30-k-50-ape...available.html

So far the repair is holding up.

nihonsuki · 11-22-2016, 12:29 PM

Originally posted by filmamigo

I am facing a repair of the Diaphragm Control Block on my K-S2, same as many K-30 and K-50 owners....

If you had your camera repaired, did it stay repaired? Or did they install the same flawed design of ACB and it will eventually fail/has failed again?

First repair lasted a couple years, ~20,000 exposures. Did the second repair myself (using instructions found on the Forum) and after a few months it's still holding up.

**patrick9** · 11-23-2016, 04:27 AM

Originally posted by nihonsuki

https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/321871-k-30-k-50-ape...available.html

So far the repair is holding up.

This is the repair I assume that Mark did on my K30. I was unwilling to try it myself because I was uncertain of the rough translation.
It is good to know it worked for you.

**niceshot** · 12-25-2016, 07:45 PM

Originally posted by patrick9

This is the repair I assume that Mark did on my K30. I was unwilling to try it myself because I was uncertain of the rough translation.
It is good to know it worked for you.

I think you just need to demagnetize the solenoid horse shoe , no big deal but you need a horse shoe magnet . Then you run this solenoid magnet over the big magnet and rotate in many different directions to achieve demagnetization . then reassemble it

**patrick9** · 12-26-2016, 05:05 AM

Originally posted by niceshot

I think you just need to demagnetize the solenoid horse shoe , no big deal but you need a horse shoe magnet . Then you run this solenoid magnet over the big magnet and rotate in many different directions to achieve demagnetization . then reassemble it

My understanding ( from what I have read) is that you also need to enlarge the air gap a hair after demagnetizing it. Otherwise the issue will return.

**niceshot** · 12-27-2016, 02:28 PM

Originally posted by patrick9

My understanding ( from what I have read) is that you also need to enlarge the air gap a hair after demagnetizing it. Otherwise the issue will return.

No it is the magnetization of the armature that causes the sticktion .

**patrick9** · 12-27-2016, 06:51 PM

Originally posted by niceshot

No it is the magnetization of the armature that causes the sticktion .

Understand that. By opening the gap my understanding is that the magnet is weaker or moved enough to keep the solenoid from becoming magnetized

rom01 · 09-10-2017, 04:24 AM

May or may not help anyone - just an update, after they replaced the guts of my camera the last time i posted because of the problem the OP had - a year later it stuffed up again and the mirror kept staying up and I had to remove the battery to get it to switch off/on, after looking into it, I think it has a "malfunctioning aperture mechanism". I took it apart following a youtube vid, filed and sanded something that looks like a horseshoe (someone posted about that above) and it seems to have temporarily fixed it, not sure if I opened the gap up enough as the patrick9 mentioned. Probably won't last long, hope it does. Might need a new camera if it doesn't...

nihonsuki · 10-03-2017, 03:56 PM

The repair I made to the solenoid armature about a year ago started to give out a couple months ago (first shot of the day underexposed), and recently this started happening more than once a day so I took the camera apart again and ground a little more off of the armature. It's been about 12,000 shutter actuations since the last repair. By the way, here's an annotated guide to the screws on the bottom cover and battery compartment. "f" means fine thread, for metal holes.

**kernos** · 10-14-2017, 07:05 PM

My K50 went back to failure after repair but it was fixed by shooting a long burst. So far so good.

**patrick9** · 10-15-2017, 07:15 PM

I may just take mine apart for the experience. It die a horrible death a few months after the repair. fell about 4or 5 feet off my tripod. cracked the housing messed the meter up. I tried to use it in M mode that worked for a few days then it decided to over expose one shot then under expose then correct the over the correct then under etc. no idea what exposure you would actually get till checking the shot. Even back to back shots with the same settings, the exposure would be different. In other words It is none working period.

11-20-2016, 03:50 PM	#20
nihonsuki New Member Join Date: Oct 2012 Posts: 21	https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/321871-k-30-k-50-ape...available.html So far the repair is holding up. Last edited by nihonsuki; 11-20-2016 at 03:52 PM. Reason: Added information.

10-03-2017, 03:56 PM	#28
nihonsuki New Member Join Date: Oct 2012 Posts: 21	The repair I made to the solenoid armature about a year ago started to give out a couple months ago (first shot of the day underexposed), and recently this started happening more than once a day so I took the camera apart again and ground a little more off of the armature. It's been about 12,000 shutter actuations since the last repair. By the way, here's an annotated guide to the screws on the bottom cover and battery compartment. "f" means fine thread, for metal holes. Attached Images

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09-07-2016, 09:21 AM	#16
nihonsuki New Member Join Date: Oct 2012 Posts: 21	I had mine replaced a couple years ago and it's starting to fail again, about 20K exposures later.

09-07-2016, 06:07 PM	#17
niceshot Site Supporter Join Date: Mar 2014 Location: NY Photos: Gallery Posts: 1,565	Originally posted by nihonsuki I had mine replaced a couple years ago and it's starting to fail again, about 20K exposures later. I hope for your sake it is not the shutter block

09-07-2016, 07:04 PM	#18
nihonsuki New Member Join Date: Oct 2012 Posts: 21	The symptoms are exactly the same: one or two initial underexposed pictures after the camera has not been used for a few hours, gradually getting worse (happening more often and more underexposed shots). Today I followed the repair procedure for the solenoid armature and I'll see if that fixes it.

11-20-2016, 03:15 PM	#19
patrick9 Site Supporter Join Date: Feb 2011 Location: Murfreesboro Tennessee Photos: Gallery \| Albums Posts: 3,458	Originally posted by nihonsuki Today I followed the repair procedure for the solenoid armature and I'll see if that fixes it. What repair procedure? Mine failed a few weeks ago. I just had it repaired( Not part replaced). It is working fine, But not sure how they fixed it other that some things I have read towards a repair of the solenoid. All I know is the fellow that repaired it said it was a fairly easy repair.

11-22-2016, 12:29 PM	#21
nihonsuki New Member Join Date: Oct 2012 Posts: 21	Originally posted by filmamigo I am facing a repair of the Diaphragm Control Block on my K-S2, same as many K-30 and K-50 owners.... If you had your camera repaired, did it stay repaired? Or did they install the same flawed design of ACB and it will eventually fail/has failed again? First repair lasted a couple years, ~20,000 exposures. Did the second repair myself (using instructions found on the Forum) and after a few months it's still holding up.

11-23-2016, 04:27 AM	#22
patrick9 Site Supporter Join Date: Feb 2011 Location: Murfreesboro Tennessee Photos: Gallery \| Albums Posts: 3,458	Originally posted by nihonsuki https://www.pentaxforums.com/forums/151-pentax-k-30-k-50/321871-k-30-k-50-ape...available.html So far the repair is holding up. This is the repair I assume that Mark did on my K30. I was unwilling to try it myself because I was uncertain of the rough translation. It is good to know it worked for you.

12-25-2016, 07:45 PM	#23
niceshot Site Supporter Join Date: Mar 2014 Location: NY Photos: Gallery Posts: 1,565	Originally posted by patrick9 This is the repair I assume that Mark did on my K30. I was unwilling to try it myself because I was uncertain of the rough translation. It is good to know it worked for you. I think you just need to demagnetize the solenoid horse shoe , no big deal but you need a horse shoe magnet . Then you run this solenoid magnet over the big magnet and rotate in many different directions to achieve demagnetization . then reassemble it

12-26-2016, 05:05 AM	#24
patrick9 Site Supporter Join Date: Feb 2011 Location: Murfreesboro Tennessee Photos: Gallery \| Albums Posts: 3,458	Originally posted by niceshot I think you just need to demagnetize the solenoid horse shoe , no big deal but you need a horse shoe magnet . Then you run this solenoid magnet over the big magnet and rotate in many different directions to achieve demagnetization . then reassemble it My understanding ( from what I have read) is that you also need to enlarge the air gap a hair after demagnetizing it. Otherwise the issue will return.

12-27-2016, 02:28 PM	#25
niceshot Site Supporter Join Date: Mar 2014 Location: NY Photos: Gallery Posts: 1,565	Originally posted by patrick9 My understanding ( from what I have read) is that you also need to enlarge the air gap a hair after demagnetizing it. Otherwise the issue will return. No it is the magnetization of the armature that causes the sticktion .

12-27-2016, 06:51 PM	#26
patrick9 Site Supporter Join Date: Feb 2011 Location: Murfreesboro Tennessee Photos: Gallery \| Albums Posts: 3,458	Originally posted by niceshot No it is the magnetization of the armature that causes the sticktion . Understand that. By opening the gap my understanding is that the magnet is weaker or moved enough to keep the solenoid from becoming magnetized

10-14-2017, 07:05 PM	#29
kernos Site Supporter Join Date: Feb 2013 Posts: 456	My K50 went back to failure after repair but it was fixed by shooting a long burst. So far so good.

10-15-2017, 07:15 PM	#30
patrick9 Site Supporter Join Date: Feb 2011 Location: Murfreesboro Tennessee Photos: Gallery \| Albums Posts: 3,458	I may just take mine apart for the experience. It die a horrible death a few months after the repair. fell about 4or 5 feet off my tripod. cracked the housing messed the meter up. I tried to use it in M mode that worked for a few days then it decided to over expose one shot then under expose then correct the over the correct then under etc. no idea what exposure you would actually get till checking the shot. Even back to back shots with the same settings, the exposure would be different. In other words It is none working period.