Another K-50 Aperture Block Failure

**West Penn** · 10-22-2019, 11:55 AM

Our second K-50 (my wife's red K-50 with 1,366 actuations) failed last week from aperture block failure. It joins my K-50 that failed some time back. On the bright side, I purchased an AS-IS *ist DS from KEH last month and, after opening it up, I found two of the white solenoids inside. One that controls the aperture and the other that controls the flash release mechanism. Also got a matte focusing screen.

Had no real problems opening up the *ist DS. I simply removed all the screws I could find. There were two screws in the battery compartment, one of which took a while to find. I pried the pop-up flash compartment open using a pocket knife. I shorted out the capacitor using a screwdriver across the two terminals.

Don't know when I'll get around to operating on the two K-50s. I've got a K-3II and I've mounted an "A" lens on the red one.

reh321 · 10-22-2019, 12:21 PM

Originally posted by West Penn

Our second K-50 (my wife's red K-50 with 1,366 actuations) failed last week from aperture block failure. It joins my K-50 that failed some time back. On the bright side, I purchased an AS-IS *ist DS from KEH last month and, after opening it up, I found two of the white solenoids inside. One that controls the aperture and the other that controls the flash release mechanism. Also got a matte focusing screen.

Had no real problems opening up the *ist DS. I simply removed all the screws I could find. There were two screws in the battery compartment, one of which took a while to find. I pried the pop-up flash compartment open using a pocket knife. I shorted out the capacitor using a screwdriver across the two terminals.

Don't know when I'll get around to operating on the two K-50s. I've got a K-3II and I've mounted an "A" lens on the red one.

Have you actually used the red one with the A-lens since the body’s aperture-control failed? I found using them that way to be so convenient I never bothered to operate on my K-30, but I wish you good luck on your ‘surgery’ if you do decide to ‘fix’ the cameras.

stevebrot · 10-22-2019, 12:23 PM

Originally posted by West Penn

I found two of the white solenoids inside. One that controls the aperture and the other that controls the flash release mechanism. Also got a matte focusing screen.

Good luck on doing the repair. I hope the replacement solenoids do the trick. As for the focusing screen...it is not compatible.

Steve

**jatrax** · 10-22-2019, 12:27 PM - **1 Like**

Good luck on the repair. I did a K-50 a few months ago and though it was a scary process all went quite smoothly following the available instructions.

Not a Number · 10-22-2019, 12:35 PM

I think you should measure the ohms of the solenoids. I seem to recall the one from the flash don't work, having 15 ohms versus 30 ohms on the diaphragm control block. But I could be mistaken.

**West Penn** · 10-22-2019, 12:44 PM

Originally posted by reh321

Have you actually used the red one with the A-lens since the body’s aperture-control failed? I found using them that way to be so convenient I never bothered to operate on my K-30, but I wish you good luck on your ‘surgery’ if you do decide to ‘fix’ the cameras.

Yes, I made sure it was working with the green button and also using AV mode with exposure compensation. But, if my wife has trouble using it that way, I'll operate on both starting with mine and learning on that one because I've still got the K-3II if something happens.

**kiwi_jono** · 10-22-2019, 12:46 PM - **1 Like**

Wow thats a pretty low number of actuations. Sorry to hear.
Good luck with the repair(s) - from what I have heard once repaired it should last a long time..

**West Penn** · 10-22-2019, 12:49 PM

Originally posted by stevebrot

Good luck on doing the repair. I hope the replacement solenoids do the trick. As for the focusing screen...it is not compatible.

Steve

Thanks, Steve. Even though the *ist DS was an as-is item, it actually worked but ate up batteries rapidly, so I expect both solenoids were in good working order. Was surprised how small those things are. As for the focusing screen, I believe it fits the K-20 or K-10 so I don't know what I'll do with it along with all the other parts from *ist DS. Just keeping all the "junk" in a plastic storage back.

**AggieDad** · 10-22-2019, 01:01 PM

A HINT. Pay careful attention to the screw lengths and which ones came from where.

This advice comes from experience opening up a K-5iis. If my memory serves me, there are 21 screws on the K-5iis of 4 different lengths. The lengths only vary by a millimeter or two. I would (wish I did) take photos as you remove them & keep the different lengths separate.

You can probably see the majority of the screws, but there most likely will be some that are hidden. On the K-5 there are two screws up at the flash that you see only after you pop the flash up, two under the battery door and one at the bottom of the battery compartment. And there was one under the rubber grip below the K-5iis logo. The K-50 may have its own hiding places.

Good luck!

stevebrot · 10-22-2019, 01:03 PM

Originally posted by West Penn

As for the focusing screen, I believe it fits the K-20 or K-10

This archived page from the Katzeye Optical Web site might be helpful.

Wayback Machine | Katzeye Optical (FEB 6, 2015)

Steve

reh321 · 10-22-2019, 01:04 PM

Originally posted by kiwi_jono

Wow thats a pretty low number of actuations. Sorry to hear.
Good luck with the repair(s) - from what I have heard once repaired it should last a long time..

My understanding is that calendar time has much more effect than anything else does. A K-30 or K-50 is ‘living on borrowed time’ once it has reached its second or third birthday, regardless of high/low its shutter count is.

**West Penn** · 10-22-2019, 01:05 PM - **1 Like**

Originally posted by Not a Number

I think you should measure the ohms of the solenoids. I seem to recall the one from the flash don't work, having 15 ohms versus 30 ohms on the diaphragm control block. But I could be mistaken.

Thanks, not a number, I checked the two solenoids and got 36 ohms on both, so I expect they will both work. Although I must admit, it's a bit difficult to keep the meter's probes on those solenoid contacts in order to get a reading as those solenoids are quite tiny. I was quite surprised at how small those things really are, never having opened up a digital camera before. I plan to use the one from the flash circuit in my K-50, in case there is some sort of issue. If all goes well, I'll move on to the red one.

**Sir Nameless** · 10-22-2019, 01:07 PM

Sorry to hear, good luck with the repair! (Says the fellow K50 owner.)

---------- Post added 10-22-19 at 01:08 PM ----------

Originally posted by reh321

A K-30 or K-50 is ‘living on borrowed time’ once it has reached its second or third birthday, regardless of high/low its shutter count is.

You did not make my day. Mine's about 4 years old now. No problems yet, but not looking forward to the big day.

**West Penn** · 10-22-2019, 01:29 PM

Originally posted by AggieDad

A HINT. Pay careful attention to the screw lengths and which ones came from where.

This advice comes from experience opening up a K-5iis. If my memory serves me, there are 21 screws on the K-5iis of 4 different lengths. The lengths only vary by a millimeter or two. I would (wish I did) take photos as you remove them & keep the different lengths separate.

You can probably see the majority of the screws, but there most likely will be some that are hidden. On the K-5 there are two screws up at the flash that you see only after you pop the flash up, two under the battery door and one at the bottom of the battery compartment. And there was one under the rubber grip below the K-5iis logo. The K-50 may have its own hiding places.

Good luck!

Thanks for the hint, AggieDad. I saw where others had made drawings or made photo copies of the various areas of the camera and then put each screw in the proper place on the paper copy. Seems like the best way to keep track of everything.

In disassembling the *ist DS, I used a micro screwdriver set that I got at Harbor Freight for about $10. It has over 20 tips -- torx, philips, flat, hex -- and is of decent quality. I used the phillips 000 tip to disassemble the camera.

The Squirrel Mafia · 10-22-2019, 01:46 PM

What a drag. The same thing happened to me. The black K-50 started failing in August of 2017. I had to fix it quickly 'cause I was about to go on a trip to Japan, so I ordered a "white" solenoid & did the fix on my own. It took me about +-3 hours to do. In June of 2018, the red one stated failing. I did the same thing. They've both been trouble free since, even the black one with the ultra shoddy soldering. Haha!

I did a much better job on the red one.

But yeah. It's annoying that I had to fix them on my own. Mind you that both of these had about +-25,000 actuations or so before failing so it wasn't due of the lack of use.

10-22-2019, 11:55 AM	#1
West Penn Site Supporter Join Date: Apr 2012 Posts: 250	Another K-50 Aperture Block Failure Our second K-50 (my wife's red K-50 with 1,366 actuations) failed last week from aperture block failure. It joins my K-50 that failed some time back. On the bright side, I purchased an AS-IS ist DS from KEH last month and, after opening it up, I found two of the white solenoids inside. One that controls the aperture and the other that controls the flash release mechanism. Also got a matte focusing screen. Had no real problems opening up the ist DS. I simply removed all the screws I could find. There were two screws in the battery compartment, one of which took a while to find. I pried the pop-up flash compartment open using a pocket knife. I shorted out the capacitor using a screwdriver across the two terminals. Don't know when I'll get around to operating on the two K-50s. I've got a K-3II and I've mounted an "A" lens on the red one.

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10-22-2019, 12:21 PM	#2
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,177	Originally posted by West Penn Our second K-50 (my wife's red K-50 with 1,366 actuations) failed last week from aperture block failure. It joins my K-50 that failed some time back. On the bright side, I purchased an AS-IS ist DS from KEH last month and, after opening it up, I found two of the white solenoids inside. One that controls the aperture and the other that controls the flash release mechanism. Also got a matte focusing screen. Had no real problems opening up the ist DS. I simply removed all the screws I could find. There were two screws in the battery compartment, one of which took a while to find. I pried the pop-up flash compartment open using a pocket knife. I shorted out the capacitor using a screwdriver across the two terminals. Don't know when I'll get around to operating on the two K-50s. I've got a K-3II and I've mounted an "A" lens on the red one. Have you actually used the red one with the A-lens since the body’s aperture-control failed? I found using them that way to be so convenient I never bothered to operate on my K-30, but I wish you good luck on your ‘surgery’ if you do decide to ‘fix’ the cameras.

10-22-2019, 12:23 PM	#3
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by West Penn I found two of the white solenoids inside. One that controls the aperture and the other that controls the flash release mechanism. Also got a matte focusing screen. Good luck on doing the repair. I hope the replacement solenoids do the trick. As for the focusing screen...it is not compatible. Steve

10-22-2019, 12:27 PM - 1 Like	#4
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Good luck on the repair. I did a K-50 a few months ago and though it was a scary process all went quite smoothly following the available instructions.

10-22-2019, 12:35 PM	#5
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	I think you should measure the ohms of the solenoids. I seem to recall the one from the flash don't work, having 15 ohms versus 30 ohms on the diaphragm control block. But I could be mistaken.

10-22-2019, 12:44 PM	#6
West Penn Site Supporter Join Date: Apr 2012 Posts: 250 Original Poster	Originally posted by reh321 Have you actually used the red one with the A-lens since the body’s aperture-control failed? I found using them that way to be so convenient I never bothered to operate on my K-30, but I wish you good luck on your ‘surgery’ if you do decide to ‘fix’ the cameras. Yes, I made sure it was working with the green button and also using AV mode with exposure compensation. But, if my wife has trouble using it that way, I'll operate on both starting with mine and learning on that one because I've still got the K-3II if something happens.

10-22-2019, 12:46 PM - 1 Like	#7
kiwi_jono Loyal Site Supporter Join Date: Dec 2009 Location: Christchurch, New Zealand Photos: Gallery \| Albums Posts: 2,437	Wow thats a pretty low number of actuations. Sorry to hear. Good luck with the repair(s) - from what I have heard once repaired it should last a long time..

10-22-2019, 12:49 PM	#8
West Penn Site Supporter Join Date: Apr 2012 Posts: 250 Original Poster	Originally posted by stevebrot Good luck on doing the repair. I hope the replacement solenoids do the trick. As for the focusing screen...it is not compatible. Steve Thanks, Steve. Even though the ist DS was an as-is item, it actually worked but ate up batteries rapidly, so I expect both solenoids were in good working order. Was surprised how small those things are. As for the focusing screen, I believe it fits the K-20 or K-10 so I don't know what I'll do with it along with all the other parts from ist DS. Just keeping all the "junk" in a plastic storage back.

10-22-2019, 01:01 PM	#9
AggieDad Site Supporter Join Date: Jan 2015 Location: Houston, TX Photos: Gallery \| Albums Posts: 1,452	A HINT. Pay careful attention to the screw lengths and which ones came from where. This advice comes from experience opening up a K-5iis. If my memory serves me, there are 21 screws on the K-5iis of 4 different lengths. The lengths only vary by a millimeter or two. I would (wish I did) take photos as you remove them & keep the different lengths separate. You can probably see the majority of the screws, but there most likely will be some that are hidden. On the K-5 there are two screws up at the flash that you see only after you pop the flash up, two under the battery door and one at the bottom of the battery compartment. And there was one under the rubber grip below the K-5iis logo. The K-50 may have its own hiding places. Good luck!

10-22-2019, 01:03 PM	#10
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by West Penn As for the focusing screen, I believe it fits the K-20 or K-10 This archived page from the Katzeye Optical Web site might be helpful. Wayback Machine \| Katzeye Optical (FEB 6, 2015) Steve

10-22-2019, 01:04 PM	#11
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,177	Originally posted by kiwi_jono Wow thats a pretty low number of actuations. Sorry to hear. Good luck with the repair(s) - from what I have heard once repaired it should last a long time.. My understanding is that calendar time has much more effect than anything else does. A K-30 or K-50 is ‘living on borrowed time’ once it has reached its second or third birthday, regardless of high/low its shutter count is.

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10-22-2019, 01:05 PM - 1 Like	#12
West Penn Site Supporter Join Date: Apr 2012 Posts: 250 Original Poster	Originally posted by Not a Number I think you should measure the ohms of the solenoids. I seem to recall the one from the flash don't work, having 15 ohms versus 30 ohms on the diaphragm control block. But I could be mistaken. Thanks, not a number, I checked the two solenoids and got 36 ohms on both, so I expect they will both work. Although I must admit, it's a bit difficult to keep the meter's probes on those solenoid contacts in order to get a reading as those solenoids are quite tiny. I was quite surprised at how small those things really are, never having opened up a digital camera before. I plan to use the one from the flash circuit in my K-50, in case there is some sort of issue. If all goes well, I'll move on to the red one.

10-22-2019, 01:07 PM	#13
Sir Nameless Site Supporter Join Date: Jul 2015 Location: Mass a chew sits Photos: Gallery Posts: 574	Sorry to hear, good luck with the repair! (Says the fellow K50 owner.) ---------- Post added 10-22-19 at 01:08 PM ---------- Originally posted by reh321 A K-30 or K-50 is ‘living on borrowed time’ once it has reached its second or third birthday, regardless of high/low its shutter count is. You did not make my day. Mine's about 4 years old now. No problems yet, but not looking forward to the big day.

10-22-2019, 01:29 PM	#14
West Penn Site Supporter Join Date: Apr 2012 Posts: 250 Original Poster	Originally posted by AggieDad A HINT. Pay careful attention to the screw lengths and which ones came from where. This advice comes from experience opening up a K-5iis. If my memory serves me, there are 21 screws on the K-5iis of 4 different lengths. The lengths only vary by a millimeter or two. I would (wish I did) take photos as you remove them & keep the different lengths separate. You can probably see the majority of the screws, but there most likely will be some that are hidden. On the K-5 there are two screws up at the flash that you see only after you pop the flash up, two under the battery door and one at the bottom of the battery compartment. And there was one under the rubber grip below the K-5iis logo. The K-50 may have its own hiding places. Good luck! Thanks for the hint, AggieDad. I saw where others had made drawings or made photo copies of the various areas of the camera and then put each screw in the proper place on the paper copy. Seems like the best way to keep track of everything. In disassembling the *ist DS, I used a micro screwdriver set that I got at Harbor Freight for about $10. It has over 20 tips -- torx, philips, flat, hex -- and is of decent quality. I used the phillips 000 tip to disassemble the camera.

10-22-2019, 01:46 PM	#15
The Squirrel Mafia Pentaxian Join Date: Jan 2015 Posts: 3,053	What a drag. The same thing happened to me. The black K-50 started failing in August of 2017. I had to fix it quickly 'cause I was about to go on a trip to Japan, so I ordered a "white" solenoid & did the fix on my own. It took me about +-3 hours to do. In June of 2018, the red one stated failing. I did the same thing. They've both been trouble free since, even the black one with the ultra shoddy soldering. Haha! I did a much better job on the red one. But yeah. It's annoying that I had to fix them on my own. Mind you that both of these had about +-25,000 actuations or so before failing so it wasn't due of the lack of use.