Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-07-2019, 09:03 AM   #811
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Posts: 308
The dreaded sanding and filing method for the pentax solenoid

Just found by sheer accident:

Pentax Camera Repair in California does indeed use the dreaded filing / sanding method.

There is a negative 1* customer review on the Amazon website for the K50 A person named RAB comments and recommends Pentax Camera Repair by PC35 Photolab:

He mentions that they use the sanding/filing method.


Explains why cameras had to be sent back to them within the warranty time.

Anyway, with warranty it is not so bad, must that we know that this method can lead to further damage.

02-11-2019, 03:28 AM   #812
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Posts: 308
QuoteOriginally posted by albertoM Quote
See this page... Figure specifications of the solenoid..... 6 v.....
link removed
4 AA - 6v.
lithium battery 7 v.....
coincidence?? That's why it works better with AA?? it is a question....
This is NOT the solenoid used by Pentax! They have it made for them by the same manufacturer in China!
But this one is 200 ohms!


The Pentax solenoid has 30 ohms!


The original made in Japan solenoid works perfect with the Li-Ion battery, as it already proved for long time used in the K10D and K20D!

---------- Post added 02-11-19 at 03:36 AM ----------

QuoteOriginally posted by RayeR Quote
Oh, it's bad but still not a 100% proof that it was caused by sanding and didn't fail for other reason/wear out. Probably it depens on a camera load if someone would use it only as a backup body it may be OK as there are people using their sanded cams for an year or more...
It is no proof, you are quite right. But statistics have some value.

I just wrote about what I found out after I had a K30 which failed after having been modified by using the dreaded sanding method.

What do you think? Which colour does it have? Is it green or white?
And ... sold from China!

This is not what you want.
02-15-2019, 03:18 AM   #813
New Member




Join Date: Mar 2009
Posts: 13
Hi folks.

So for a bit of repair fun I picked up a cheap eBay K50 with the failed aperture solenoid. It was not working on arrival but would come good after firing a lot of shots in continuous mode. I read through this and took note of the warnings about sanding the actuator, but thought I would give it a try temporarily until I found a decent replacement part.

I watched one video and was intrigued by how little they took off the actuator compared to some that I have seen. I confirmed that the fault was there just before disassembly. Looking at my actuator I couldn't see any obvious burrs or deformation. So as an experiment I took off just the tiniest amount from the top end and corners - not really changing the shape at all. If anything it removed the tiniest ridge from the top edges but it wasn't much if any at all. I cleaned it with isopropyl alcohol then reinstalled it. So far it seems fine over a few hours and on off cycles - I will be interested to see how long it lasts.

What I am wondering is whether this is not a purely mechanical binding problem but rather one of the ends of the actuator becoming electrically higher resistance than required by the design. I am thinking that maybe the sanding/alcohol restores its low resistance and this restoration of the "shorting" of the magnetic field in the actuator is why it starts working again. When I removed the part it really felt stuck quite powerfully to the magnetised end, but when it went back in after cleaning it was much freer.

This is all speculation of course, but I took so little material off I am skeptical that it was a binding issue. Happy to hear why my idea might be way off the mark!
02-16-2019, 12:49 AM   #814
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Posts: 308
Read through the threads and study them well. Then you get the right answers.

All was said hitherto already many many times.

02-16-2019, 01:19 AM   #815
New Member




Join Date: Mar 2009
Posts: 13
QuoteOriginally posted by photogem Quote
Read through the threads and study them well. Then you get the right answers.All was said hitherto already many many times.
I have had a good read through the various threads and the ideas don't fit well with what I saw with mine. I took so little off the end of my actuator that if anything it made the top surface flatter - there was no significant reduction of surface area that would result in a reduced contact area and resulting reduction in holding force. What I took off would have had no effect on the actuator's contact with the internal plastic guide of the solenoid.
02-16-2019, 07:43 AM   #816
retired sw engineer
Loyal Site Supporter
reh321's Avatar

Join Date: Nov 2014
Location: South Bend, IN, USA
Photos: Gallery | Albums
Posts: 11,994
QuoteOriginally posted by K50lives Quote
I have had a good read through the various threads and the ideas don't fit well with what I saw with mine. I took so little off the end of my actuator that if anything it made the top surface flatter - there was no significant reduction of surface area that would result in a reduced contact area and resulting reduction in holding force. What I took off would have had no effect on the actuator's contact with the internal plastic guide of the solenoid.
Then use the camera for awhile, and report back to us - I don't remember an attempt similar to yours.
02-16-2019, 02:19 PM   #817
New Member




Join Date: Mar 2009
Posts: 13
QuoteOriginally posted by reh321 Quote
Then use the camera for awhile, and report back to us - I don't remember an attempt similar to yours.
Will do! Working great so far.
02-17-2019, 12:52 AM   #818
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Posts: 308
grinding and sanding

QuoteOriginally posted by K50lives Quote
I have had a good read through the various threads and the ideas don't fit well with what I saw with mine. I took so little off the end of my actuator that if anything it made the top surface flatter - there was no significant reduction of surface area that would result in a reduced contact area and resulting reduction in holding force. What I took off would have had no effect on the actuator's contact with the internal plastic guide of the solenoid.
It seems to me that you missed a few important points in those various threads.

Taking the plunger out already demagnetises it a bit

The solenoid even works again for a while if one just lifts the tiny permanent magnet out of its position.

And of course will filing even tiniest edges off the plunger as you described it affect both:


- Magnetism (i.e. through the filing/sanding) it demagnetises even more


and


- it will evidently have that tiny bit less contact.



But after all the question remains why searching and investing into the wrong direction (in the dark!)?

If I make the effort to open a K50 or K30 and taking the solenoid off (not to mention you stripping off few DVD drives to get solenoids but noticing that they were the wrong ones) then I would go the whole hog and do it properly, i.e. install the real made in Japan solenoid.

Until you had a made in Japan white solenoid in your hands and you could compare it with the faulty green one:

What use are your findings for?

Even if it would be to compare the holding forces of the two which is pretty easy and straight forward to do if you have enough sensivitity in your fingers.
Some don't, that's fine, they then have to do measurements (as we did as well)


Having worked with a little modification of a green solenoid is basically close to zero experience.

We did measurements on holding force etc. on the different solenoids.

Again: Just to take the magnet or the plunger off actives the green solenoid again. As does installing a green one. They just jam after a while again.
And have done in some cases further harm, i.e. left the K30/50 unrepairable.


Last edited by photogem; 02-17-2019 at 01:01 AM.
02-17-2019, 02:08 PM   #819
New Member




Join Date: Mar 2009
Posts: 13
QuoteOriginally posted by photogem Quote
It seems to me that you missed a few important points in those various threads.
That's possible - there's a lot to read there. The impression I got though was that a single reason for the failure hadn't been nailed down. Is it wear/binding or excess magnetic holding? This is why I decided to do my own experiment - I hope given your own leanings toward a scientific method you can respect that decision ;-)


I don't fear that removing the plunger once will cause a problematic change in residual magnetism that is designed into the system. In my mind that possibility doesn't fit with a stable component design. There appeared to be no noticeable residual magnetism in my plunger. I don't expect the minimal amount of sanding/filing I did would cause any problems either in this regard.


I will keep an eye out for a donor MZ camera in case it is needed.
02-18-2019, 01:12 AM   #820
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Posts: 308
QuoteOriginally posted by K50lives Quote
That's possible - there's a lot to read there. The impression I got though was that a single reason for the failure hadn't been nailed down.
No, we never spoke of a single reason but of many, as it was stated also many times.


QuoteOriginally posted by K50lives Quote
Is it wear/binding or excess magnetic holding?

- too strong magnetic force
- cheap PET material for the body, which wears
- possibly different material for the plunger

QuoteOriginally posted by K50lives Quote
This is why I decided to do my own experiment - I hope given your own leanings toward a scientific method you can respect that decision ;-)
well, that is never the question, of course anybody is free to do his or her own experiment.

"When you know what you're doing, you can do what you want."

But of course to know one has to experiment.

There is nothing wrong with this as long as one doesn't harm others! That is the crucial point always.

And that is what I am after:
One should only give advice if it is founded on true experience and not if on guesswork.



QuoteOriginally posted by K50lives Quote
I don't fear that removing the plunger once will cause a problematic change in residual magnetism that is designed into the system.
Who said it will?



QuoteOriginally posted by K50lives Quote
In my mind that possibility doesn't fit with a stable component design. There appeared to be no noticeable residual magnetism in my plunger. I don't expect the minimal amount of sanding/filing I did would cause any problems either in this regard
You see, here we go where it can be misleading.


ANY solenoid plunger will have a noticeable residual magnetism.

It is just that you cannot notice it. That is a major difference!

The minimal sanding will change the way the plunger moves in the PET body.

It has that minimal less guidance.
And... it has led in the past to further damage.

You see, it is not a question of "what you expect or don't expect" but a question what people who have done research have found out.

Expectation does only help if one has done a certain amount of reasearch but not if one has worked a very first time with a solenoid.


QuoteOriginally posted by K50lives Quote
I will keep an eye out for a donor MZ camera in case it is needed.
Then make sure it is polarised the right way, most solenoids of MZ cameras have had opposite polarisation.
Also I have made some measurements with those: They differ slighty from the solenoids in the *ist, K100D etc.
Better to get one of those as a donor.
02-18-2019, 02:11 AM   #821
New Member




Join Date: Mar 2009
Posts: 13
QuoteOriginally posted by photogem Quote
Originally posted by K50lives QuoteI don't fear that removing the plunger once will cause a problematic change in residual magnetism that is designed into the system.Who said it will?

QuoteOriginally posted by photogem Quote
Taking the plunger out already demagnetises it a bit
Maybe I misunderstood this?


QuoteOriginally posted by photogem Quote
The minimal sanding will change the way the plunger moves in the PET body.
The sanding I did was so minimal that there would be no change in the way the plunger moves in the body.


QuoteOriginally posted by photogem Quote
One should only give advice if it is founded on true experience and not if on guesswork.
QuoteOriginally posted by photogem Quote
Expectation does only help if one has done a certain amount of reasearch but not if one has worked a very first time with a solenoid.
Sure, but also we shouldn't always make assumptions regarding a person's experience with a solenoid ;-)


QuoteOriginally posted by photogem Quote
Then make sure it is polarised the right way, most solenoids of MZ cameras have had opposite polarisation.Also I have made some measurements with those: They differ slighty from the solenoids in the *ist, K100D etc.Better to get one of those as a donor.
Thanks, this is useful information.
02-28-2019, 12:14 PM - 1 Like   #822
Site Supporter
Site Supporter
Navmaxlp's Avatar

Join Date: Nov 2010
Location: Pennsylvania
Posts: 154
Just a follow up here. Got the solenoid, broke it down and got it installed. This definitely tested my skill as a tech. I think I mentioned it's been about a decade since I've had to do any soldering and I was nervous. My eyesight isn't nearly as good as it once was and the soldering on this was quite a bit more precise than I've ever had to do (I never got to 2M Micro Mini). I had a coworker hold the wire on the terminal as I soldered the connection. I was a bit lucky in that enough of the original solder came off on the wire to get it soldered back onto the new posts. I did have to add a little to the pink lead. I may not have done things according to the best procedure however. I did mount the new solenoid to the camera body prior to soldering. I just couldn't have gotten it done otherwise. Since I had a brand new solenoid, I left the connections in the bottom of the camera and soldered at the solenoid.

Long story short, I got it in and everything seems to be working properly. I'll need to test things a little more to be 100% positive but, it appears to be working perfectly at this point. My only problem is, one of the screws will not go back in. It's the screw inside the battery compartment right up at the front portion under the battery lid. I can provide a picture later. I can get the screw in there but it never grabs anything. I got the other 4 million screws back in though so, I'm just going to leave it. I'm pretty sure I got the right screw. When I took them out, I printed out pictures of the camera and punched the screws into the picture where the screw goes. Two screws had fallen out of the paper but neither of them would fit. They were both the same screw. Again, I'm not worried about it but, anyone attempting this fix should make certain to keep track of which screws go where. They are not all the same width or height. There are several types and not all fit in each hole.

Thanks to everyone here for the hard work they've done for this. I now have a nearly brand new camera for the $45 price of a solenoid. It was not as easy as I thought it would be prior to opening the camera up but, I was able to get it done. Not sure everyone can do this but, if you have some skill and some patience, it should be doable.
03-01-2019, 01:20 AM   #823
Site Supporter
Site Supporter




Join Date: Apr 2015
Location: Winterthur
Posts: 308
I think one crucial point is the tip of the soldering iron. I have several soldering irons, but on all I can change the tip.
A pencil tip is obligatory.

Also I recommend very thin leaded solder! It flows better and holds better and needs lower temperatures than unleaded solder.
Do not use silver-solder! Needs much higher temperatures.

I know, leaded solder is only allowed on certain applications, but here one solders once, the danger is near to zero, have a window open

and all is fine.


It is always a good idea to first solder the two rods on the solenoid itself, particular it is is new as you say (are you certain?).
I always solder the bare ends of the wires AND the pins/rods of the solenoid.


About the longer screw in the batterie compartment: I encountered this problem several times, this is possibly due to the fact that when the camera was factory assembled, the person applied that bit too much force onto this screw. I have enough screws so I can choose another one which fits.

In your case I would add a tiny bit of epoxy just at the threads of the screw ... and really just a touch.... and then screw it in but not too tight.

Otherwise, well done!

Last edited by photogem; 03-01-2019 at 01:29 AM.
03-01-2019, 05:42 AM   #824
Site Supporter
Site Supporter
Navmaxlp's Avatar

Join Date: Nov 2010
Location: Pennsylvania
Posts: 154
QuoteOriginally posted by photogem Quote
I think one crucial point is the tip of the soldering iron. I have several soldering irons, but on all I can change the tip.
A pencil tip is obligatory.

Also I recommend very thin leaded solder! It flows better and holds better and needs lower temperatures than unleaded solder.
Do not use silver-solder! Needs much higher temperatures.

I know, leaded solder is only allowed on certain applications, but here one solders once, the danger is near to zero, have a window open

and all is fine.


It is always a good idea to first solder the two rods on the solenoid itself, particular it is is new as you say (are you certain?).
I always solder the bare ends of the wires AND the pins/rods of the solenoid.


About the longer screw in the batterie compartment: I encountered this problem several times, this is possibly due to the fact that when the camera was factory assembled, the person applied that bit too much force onto this screw. I have enough screws so I can choose another one which fits.

In your case I would add a tiny bit of epoxy just at the threads of the screw ... and really just a touch.... and then screw it in but not too tight.

Otherwise, well done!
Thanks.

Yes I had a pencil tip on the soldering iron. Glad we splurged on the good irons now. I didn't have the lead solder. Had to make due with what we have on hand but it ended up working fine. It's such a thin wire (I'm used to much larger gauge wire) that I tinned the wire by just adding a bit to the tip of the iron then placed the wire on the post and quickly hit it from the bottom to get the solder to make the connection. I was a bit worried that having the solenoid already attached to the camera would be a problem. Was worried for two reasons. One was that I would drip solder down into the camera and the other was the camera would act as a heat sink and cause me to have to use more heat. I was nervous the extra heat would damage the solenoid or other parts. In the end though, it was necessary. I don't have the skill or extra tools available to hold such small parts and allow for the precise soldering. I just made sure to be extra careful. If I felt like I was getting into trouble, I would have stopped and tried it another way.

I'm not too worried about the screw. There's another screw right next to it in the battery compartment less than a quarter inch away. The only thing I feel like it changes is the weather sealing of the camera. I've got my K-3 if I need to use it in that environment. The K-30 will be used by my wife mostly. She's not as likely to go out and take pictures in inclement weather. I'll also keep an eye on it and warn her not to get it wet. If I can get to it, I'll do the epoxy thing. I just worry about getting it back out again if I need to take it apart for any reason.

Thanks again for everyone's efforts with this. I gave the camera a good workout last night using in in green mode, aperture priority mode, shutter priority mode and manual. Everything seemed to be working perfectly. I'm glad I waited to try my hand at this and swapped the green solenoid out for the white one. I fell like I can relax about it and not worry about having to address the problem again.
03-03-2019, 02:22 AM   #825
New Member




Join Date: Jul 2018
Posts: 17
Hi,

I have been reading these threds with interest, I know that the white solenoids are seen as the best way to repair this issue, but is it likely that the solenoids that you can buy from Ricoh/Pentax and presumably used by their authorised repairers are still likely to be the same bad batch/poor quality ones that caused the problem in the first place. I know that Ricoh have tried to ignore the issue, but would they be stupid enough to repair using bad solenoids even after all this time?

Andy
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
aperture, aperture block failue, block, block failue repair, camera, cameras, cost, details, failue repair solution, failure, forum, k-30, k-50, k-50 aperture block, mount, nikon, pentax k30, pentax k50, plate, post, repair, results, russian, translator, union, warranty
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wanted - Acquired: KatzEye Focus Screen for K-3 (K-3, K-5, K-5II, K-7, K-30, K-50, K-500), New or LN fwcetus Sold Items 15 05-07-2016 08:01 PM
Why A K-S1 Instead Of The K-50 / K-30? I'm A Pentaxian Pentax K-S1 & K-S2 71 12-24-2015 03:50 AM
Wanted - Acquired: Wanted K-30/K-50/K-500/K-r 12345 Sold Items 13 09-12-2015 09:51 AM
For Sale - Sold: Focusingscreens.com EE-S Screen for K-3, K-5, K-5II, K-7, K-30, K-50 & K-500 Aperturae Sold Items 6 10-06-2014 06:49 AM
For Sale - Sold: KatzEye Split-Prism Focusing Screen - for K-3, K-5, K-5II, K-7, K-30, K-50 & K-500 chickentender Sold Items 7 04-15-2014 08:35 PM



All times are GMT -7. The time now is 10:00 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top