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04-14-2021, 07:29 PM   #1
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K-70 underexposure...appears to be the stuck solenoid.

Greetings,
Suddenly my previously flawless K-70 is underexposing images in all modes. I used two different modern lenses, and it's not a lens problem.
Camera is 3 years old. Only 3,200 actuations.

Just checked the solenoid, using this helpful tutorial How to detect aperture-block failure/stuck solenoid on Pentax K-70 - PentaxForums.com
And it appears that it is indeed stuck. I only get correctly-exposed photos at f/16.
What should I do, in your opinions, get it fixed, or buy another Pentax body?


Last edited by DMITRY1; 04-14-2021 at 07:56 PM.
04-14-2021, 08:02 PM   #2
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If under warranty, get it fixed.

If not the repair is relatively simple and parts cost under $50. There is an excellent tutorial on this forum on how to do it.
Manual solenoid replacement Pentax K30 / Discharge flash-condenser / Solenoid choice - PentaxForums.com
04-14-2021, 08:03 PM   #3
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Got a soldering iron and some tiny screw drivers?
If it ever happens to me I'll repair it. Doesn't seem too bad. I already bought a white solenoid to have on hand.
Cost I think is $250ish to have professionally repaired I think.
04-14-2021, 08:06 PM   #4
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If not under warranty and you need the solenoid part, I will be listing some of the "white, made in Japan" solenoids here in the marketplace soon. Send me a PM if interested. I'm offering them at my cost - no profit for me. I should have a total of 6 available.

- Jon

---------- Post added 04-14-2021 at 08:10 PM ----------

Also, I think the prevailing theory is that cameras manufactured after 2015 didn't have the *really* bad solenoid, just a mediocre one. The problem is considered rare in K70s and thought only to impact the early ones - be sure to check the manufacturer date of your camera

EDIT: I have lined out a misleading phrase above that has caused unfortunate confusion and debate


Last edited by jon.partsch; 04-24-2021 at 05:05 PM.
04-15-2021, 01:33 AM - 1 Like   #5
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QuoteOriginally posted by DMITRY1 Quote
Greetings,
Suddenly my previously flawless K-70 is underexposing images in all modes. I used two different modern lenses, and it's not a lens problem.
Camera is 3 years old. Only 3,200 actuations.

Just checked the solenoid, using this helpful tutorial How to detect aperture-block failure/stuck solenoid on Pentax K-70 - PentaxForums.com
And it appears that it is indeed stuck. I only get correctly-exposed photos at f/16.
What should I do, in your opinions, get it fixed, or buy another Pentax body?
Another sample of low shuttercount!

Was your K-70 not used for a longer period?
Would be worthwhile to know!


If you didn't buy some special extended warranty, then of course after 3 years there is no more warranty.

A socalled professional fix is not safe in a long term, because it will be the same China-made solenoid, the Japan-DSLR-Solenoid is out of production since the K-x/K-r! Warranty for repair is max. 1 yr and cases when this went wrong do show up, particular as Precision Cameras occasionally messes up things and at times retreats to very strange behaviour:
Ricoh GR III scroll wheel problem (not regarding wobbly control dial) - PentaxForums.com

Repair it yourself, it is not very difficult!
If you really can't DIY and you won't find anybody who could do it for you,
then these days I'd even consider PC35lab:
They sand/file the plunger but it is only $100 plus shipping and they seem to give a long warranty, I even heard of unlimited warranty.

Read carefully this article:
Why you shouldn't file/sand the plunger of the green Chinasolenoid but replace it - PentaxForums.com
and then it is up to you to find the best solution.


The correct conducted repair is shown here*
Tutorial/Repair Pentax K-70 with aperture-problem: Exchange solenoid - PentaxForums.com
will not only guarantee that the solenoid won't be stuck ever again but your K-70.... a great Pentax... will perform better!
The Japan solenoid fires faster, with "finely tuned ears" you can even hear the difference when it actuates.

*@jatrax: Your link is for the K-30, not the K-70!

Last edited by photogem; 04-15-2021 at 01:39 AM.
04-15-2021, 03:34 AM   #6
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Big thanks to all that responded. I have some electronics soldering skills, but I don't know if I want to do the repair on my own. Luckily we have a well-known repair facility close to my home, Midstate Camera Repair. Has anyone dealt with them? Midstate Camera Repair - Film and Digital Pro Repairs - National, Rhode Island
I see that the Japanese solenoid is being offered for sale here - Pentax K-30 K-50 K-70 K-S1/S2 K-500 Genuine White Solenoid Part - Japan - | eBay
04-15-2021, 05:35 AM - 2 Likes   #7
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As someone suggested, I played with the DOF Preview function, which didn't do anything. I then set the Drive Mode to Continuous Shooting High, and shot a burst of several exposures, of which just the last one came out properly exposed, and the others were underexposed. I then shot another burst of a few exposures at f/1.7, and they all were exposed correctly. I don't know if I freed up the solenoid permanently, or this is a temporary fix, but I'm getting correctly-exposed frames now.
04-15-2021, 07:54 AM - 2 Likes   #8
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QuoteOriginally posted by DMITRY1 Quote
As someone suggested, I played with the DOF Preview function, which didn't do anything. I then set the Drive Mode to Continuous Shooting High, and shot a burst of several exposures, of which just the last one came out properly exposed, and the others were underexposed. I then shot another burst of a few exposures at f/1.7, and they all were exposed correctly. I don't know if I freed up the solenoid permanently, or this is a temporary fix, but I'm getting correctly-exposed frames now.
Just a note, the repair procedure is well documented by Photogem on the forums, I made a "pdf" file of it and posted on Mediafire if you would like to download it here is the link!

K70 Tutorial Repair

04-15-2021, 07:59 AM   #9
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Well, the bliss didn't last for long. I just took another f/1.7 exposure and it's back to darkness. The burst of shutter actuations 'wakes up" the solenoid, and then it goes back to sleep. The easy fix didn't come to be...

---------- Post added 04-15-21 at 08:00 AM ----------

QuoteOriginally posted by SharkyCA Quote
Just a note, the repair procedure is well documented by Photogem on the forums, I made a "pdf" file of it and posted on Mediafire if you would like to download it here is the link!

K70 Tutorial Repair
Thank you. Looks easy enough, but I'd rather a professional handles this.

Addendum: Called Midstate Camera , and they no longer service this model. Just my luck, the person who was repairing these cameras, retired 2 weeks ago...
04-15-2021, 08:14 AM   #10
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QuoteOriginally posted by DMITRY1 Quote
Well, the bliss didn't last for long. I just took another f/1.7 exposure and it's back to darkness. The burst of shutter actuations 'wakes up" the solenoid, and then it goes back to sleep. The easy fix didn't come to be...

Thank you. Looks easy enough, but I'd rather a professional handles this.

Addendum: Called Midstate Camera , and they no longer service this model. Just my luck, the person who was repairing these cameras, retired 2 weeks ago...
Another choice is to purchase an older fillm-era lens - typically an "FA" - that allows you to control aperture at the lens, and give up on having the body control it at all.
A third choice would be to use "KAF4" lenses; good for 55-300mm {the "PLM" version is "KAF4"}, but I don't know of any inexpensive shorter focal length lenses.
04-15-2021, 08:26 AM   #11
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QuoteOriginally posted by DMITRY1 Quote
Well, the bliss didn't last for long. I just took another f/1.7 exposure and it's back to darkness. The burst of shutter actuations 'wakes up" the solenoid, and then it goes back to sleep. The easy fix didn't come to be...

---------- Post added 04-15-21 at 08:00 AM ----------



Thank you. Looks easy enough, but I'd rather a professional handles this.

Addendum: Called Midstate Camera , and they no longer service this model. Just my luck, the person who was repairing these cameras, retired 2 weeks ago...
Next step:
Pentax Repair Facilities (Wordwide listing) - PentaxForums.com
04-15-2021, 08:32 AM   #12
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QuoteOriginally posted by DMITRY1 Quote
I see that the Japanese solenoid is being offered for sale here - Pentax K-30 K-50 K-70 K-S1/S2 K-500 Genuine White Solenoid Part - Japan - | eBay
I've read that Ebay seller has a good reputation, so don't be concerned about ordering. I will also have white Japan solenoids in the marketplace sometime in the next few days.

I'm going to see how hard these are to replace, if it's easy for me I may also offer replacement service for only the cost of shipping, but as I am not a business I cannot offer any kind of warranty on the service. I'm going to have a think on this regarding if I will open an offer to receive forum members cameras for repair.

- Jon
04-15-2021, 08:59 AM - 2 Likes   #13
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Ok, you've convinced me. I just ordered the Japan white solenoid, and will have a go at it.

Last edited by DMITRY1; 04-15-2021 at 09:07 AM.
04-15-2021, 09:07 AM   #14
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QuoteOriginally posted by DMITRY1 Quote
Ok, you've convinced me. I will be ordering the Japan white solenoid, and will have a go at it.
Good luck, and please report back on the results of your repair!
04-15-2021, 09:11 AM   #15
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QuoteOriginally posted by jon.partsch Quote
Also, I think the prevailing theory is that cameras manufactured after 2015 didn't have the *really* bad solenoid, just a mediocre one. The problem is considered rare in K70s and thought only to impact the early ones - be sure to check the manufacturer date of your camera
I didn't know this - thanks for the info - checked my K-70 and it was manufactured in 2020! Glad I didn't get old stock. But I guess 'mediocre' isn't very comforting. I do have extended warranty though as well
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