[slartibartfast01]

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There do seem to be a few out there that are no longer working, so at least you do not have to degrade a fully-working camera to achieve this repair!

I wouldn't be surprised if a fair number of the "no longer working" cameras have missing solenoids.

[martin42mm]

I wouldn't be surprised if a fair number of the "no longer working" cameras have missing solenoids.

Hence the need for reputable Pentax users to declare any changes to the solenoids of cameras if they subsequently sell them- and a firm grasp of the principle of 'caveat emptor' for those searching for solenoids from whatever source, donor camera or seller!

[photogem]

No need to grind:
From the school curriculum, I remember how they studied residual magnetisation, magnetic hysteresis in a physics lesson
hysteresis (greek ὑστέρησις - lagging, delay) which is a property of systems whose instantaneous response to the actions applied to them depends, among other things, on their current state, and the behavior of the system over a time interval is largely determined by its pre-history.

The ferro-alloy that is used in the Chinese solenoid has the property of accumulating a much higher remanence than the Japanese solenoid

Fully agreed, this is my observation as well and this is why often new or low shuttercount Pentax DSLR's developed that problem.
I came across ex-dem or ex-display bodies which developed that problem!

...therefore, you can simply demagnetize the piston

Many have tried this but because the plunger (which you name piston) stays 99,9% of its existance NEAR the magnet (and the rest of the magnetised body made out of the same alloy) it magnetises right away again.
If you take the plunger out, it loses its magnetism acutally very quickly.

But the problem comes very soon back. I only have heard of one confirmed case (and there some polishing was applied as well) where the problem came back.
I have observed/verified the return of the magnetism in many cases because I left test-cameras open to check behaviour in different situations.

.... but it is much better to replace the solenoid with a Japanese one and forget about this problem

That is the only real solution.

If a modification, then
a) like this which is the way one official Pentax repairshop (Kamerazeit Luebeck, Germany) does it, I think a clever solution
or
b)You drill a tiny hole into the plunger and fill it with epoxy

But I had a few of a) on my workbench which after about 1 year failed again.
b) I tried once, but also here the magnetism came back eventually.

[martin42mm]

Fully agreed, this is my observation as well and this is why often new or low shuttercount Pentax DSLR's developed that problem.
I came across ex-dem or ex-display bodies which developed that problem!


Many have tried this but because the plunger (which you name piston) stays 99,9% of its existance NEAR the magnet (and the rest of the magnetised body made out of the same alloy) it magnetises right away again.
If you take the plunger out, it loses its magnetism acutally very quickly.

But the problem comes very soon back. I only have heard of one confirmed case (and there some polishing was applied as well) where the problem came back.
I have observed/verified the return of the magnetism in many cases because I left test-cameras open to check behaviour in different situations.


That is the only real solution.

If a modification, then
a) like this which is the way one official Pentax repairshop (Kamerazeit Luebeck, Germany) does it, I think a clever solution
or
b)You drill a tiny hole into the plunger and fill it with epoxy

But I had a few of a) on my workbench which after about 1 year failed again.
b) I tried once, but also here the magnetism came back eventually.

It will be interesting when we have some data on the 'upgraded' Chinese solenoid that Pentax are reputed to be using in the current K-70s, and how they are faring where reliability is concerned..

[photogem]

It will be interesting when we have some data on the 'upgraded' Chinese solenoid that Pentax are reputed to be using in the current K-70s, and how they are faring where reliability is concerned..

If "data" means just statistics, those we have already:

The K-70 is now almost 6 years on the market, June 2016 it was introduded and it was a hit, many were sold.

So it was the first Pentax with solenoid that right from the beginning received the modified China-solenoid. That is more than enough time because we had good data with the K30 and K50 to compare. K50 manufactured for 2 1/2 years, K30 only 1 year!
Both, the K30 and K50 showed first signs of ABF after 1 year and a strong ongoing statistic by registered users of a German Pentaxforum showed:

- From 219 K30's 150 failures = 68,5%
- From 149 K50's 75 failures = 50,3% (not a single K50 manufactured post 12/2015!)

- From 53 K70's 7 failures = 13%
(all of those in the first year since introduction on the market, none after April 2017.... so no more failures since 4 years, a very strong figure!)

No survey for K-S1 and K-S2 but my personal experience is that the K-S1 has figures as high as the K50.
I repaired more K-S1's than K-50's!

K-S2 less, quite a few were still manufactured after 12/2015, I had only one of those for repair.

But ... actually this is a K-70 theme and in future belongs into the K-70 section.

[martin42mm]

If "data" means just statistics, those we have already:

The K-70 is now almost 6 years on the market, June 2016 it was introduded and it was a hit, many were sold.

So it was the first Pentax with solenoid that right from the beginning received the modified China-solenoid. That is more than enough time because we had good data with the K30 and K50 to compare. K50 manufactured for 2 1/2 years, K30 only 1 year!
Both, the K30 and K50 showed first signs of ABF after 1 year and a strong ongoing statistic by registered users of a German Pentaxforum showed:

- From 219 K30's 150 failures = 68,5%
- From 149 K50's 75 failures = 50,3% (not a single K50 manufactured post 12/2015!)

- From 53 K70's 7 failures = 13%
(all of those in the first year since introduction on the market, none after April 2017.... so no more failures since 4 years, a very strong figure!)

No survey for K-S1 and K-S2 but my personal experience is that the K-S1 has figures as high as the K50.
I repaired more K-S1's than K-50's!

K-S2 less, quite a few were still manufactured after 12/2015, I had only one of those for repair.

But ... actually this is a K-70 theme and in future belongs into the K-70 section.

Thanks, that's interesting and reassuring to know . All we need now is a reliable and reputable source of upgraded solenoids to avoid having the remove 'white ' ones from earlier still-working Pentax DSLRs, something that goes against the grain as a repairer. Ebay is littered with 'green' solenoids, but how do you sort the wheat from the chaff? Unless of course Pentax are releasing the 'upgraded' solenoids for general use.

[photogem]

Thanks, that's interesting and reassuring to know . All we need now is a reliable and reputable source of upgraded solenoids to avoid having the remove 'white ' ones from earlier still-working Pentax DSLRs, something that goes against the grain as a repairer. Ebay is littered with 'green' solenoids, but how do you sort the wheat from the chaff? Unless of course Pentax are releasing the 'upgraded' solenoids for general use.

On ebay.com there is only one "good" solenoid offered by that seller potmano.

ALL others are not Pentax solenoids but Lenovo DVD solenoids, too strong holding force, lacking the important upright pins for the wires.
Possible result:



And I do know how to solder!
I have done micro-soldering-work under the microscope.
Solderning a solenoid compared to that is like soldering a John Deere lawn-tractor-solenoid.

[martin42mm]

On ebay.com there is only one "good" solenoid offered by that seller potmano.

ALL others are not Pentax solenoids but Lenovo DVD solenoids, too strong holding force, lacking the important upright pins for the wires.
Possible result:



And I do know how to solder!
I have done micro-soldering-work under the microscope.
Solderning a solenoid compared to that is like soldering a John Deere lawn-tractor-solenoid.

Thanks for the info. I've checked out potamo's lists, and unfortunately the only ones I can find listed on ebay UK are their reconditioned 'white' solenoids. There is another UK-based seller who offers similar solenoids, and all the available 'green' ones listed are generic Chinese ones of unknown suitabilty-or should that be questionable suitability?
I'm going to contact Pentax's service centre in the UK and find out if they can supply directly the 'improved' solenoids. I'll post when I get a reply.

[photogem]

Thanks for the info. I've checked out potamo's lists.....

here it is:
Pentax K-30 K-50 K-70 K-S1/S2 K-500 Genuine White Solenoid Part - Japan - | eBay

[martin42mm]

here it is:
Pentax K-30 K-50 K-70 K-S1/S2 K-500 Genuine White Solenoid Part - Japan - | eBay

Yes, as I said I could only find their reconditioned ones pulled from earlier cameras just as I've done, but I would still like to source an upgraded 'current' solenoid to avoid the dismantling of fully-working Pentaxes other by myself, or by others..I've emailed one of Pentax's repair centres I've been in previous correspondance with to see if they can advise of a reputable source of the 'upgraded' solenoids currently used by Pentax, or if they are posssibly available direct from them. I will post the outcome in due course, but I know from past experience that for all sorts of spurious reasons camera manufacturers are increasingly loth to supply parts to anyone other than registered service centres. The days of being able to talk and deal directly with Pentax UK back in the screw-fit Spotmatic days have long gone, sadly!

[martin42mm]

Yes, as I said I could only find their reconditioned ones pulled from earlier cameras just as I've done, but I would still like to source an upgraded 'current' solenoid to avoid the dismantling of fully-working Pentaxes other by myself, or by others..I've emailed one of Pentax's repair centres I've been in previous correspondance with to see if they can advise of a reputable source of the 'upgraded' solenoids currently used by Pentax, or if they are posssibly available direct from them. I will post the outcome in due course, but I know from past experience that for all sorts of spurious reasons camera manufacturers are increasingly loth to supply parts to anyone other than registered service centres. The days of being able to talk and deal directly with Pentax UK back in the screw-fit Spotmatic days have long gone, sadly!

And an update.
I've been in touch with the Pentax-approved repairer in the UK, and they can supply solenoids for the K series cameras affected by the solenoid issue. Cost is a very reasonable £9 plus VAT including postage, so I've bought a couple to experiment with since my K-S1 that is becoming ever more reluctant to work properly unless 'exercised' at least a dozen times when first turning on. Since this is the solenoid supplied by Ricoh, even though it is a 'green insulation' solenoid, one would assume it is the 'upgraded' part they are using currently. I'll report back on how reliable it proves to be.

The repairers said they have had very few K-70s to repair compared with the other affected models, so it suggests that these are reliable in normal use. I also sought permission to pass on their details to other members of the forum, and they are quite happy for me to do so.

John Pye Technical
39-40 Marchington Industrial Estate
Stubby Lane
Uttoxeter
ST14 8LP
tel.01283384409
the Ricoh part number for the solenoid is 77650G119, and as I said cost is £9 plus VAT including postage in the UK.
Payment is required in advance, and you can pay by card over the 'phone, or using bank transfer , details :-
Name Natwest
Account John Pye & Sons Ltd - Office
Sort Code 60-80-09
Account No 61097535

If paying by bacs please use ref: JPT267.

[slartibartfast01]

And an update.
I've been in touch with the Pentax-approved repairer in the UK, and they can supply solenoids for the K series cameras affected by the solenoid issue. Cost is a very reasonable £9 plus VAT including postage, so I've bought a couple to experiment with since my K-S1 that is becoming ever more reluctant to work properly unless 'exercised' at least a dozen times when first turning on. Since this is the solenoid supplied by Ricoh, even though it is a 'green insulation' solenoid, one would assume it is the 'upgraded' part they are using currently. I'll report back on how reliable it proves to be.

The repairers said they have had very few K-70s to repair compared with the other affected models, so it suggests that these are reliable in normal use. I also sought permission to pass on their details to other members of the forum, and they are quite happy for me to do so.

John Pye Technical
39-40 Marchington Industrial Estate
Stubby Lane
Uttoxeter
ST14 8LP
tel.01283384409
the Ricoh part number for the solenoid is 77650G119, and as I said cost is £9 plus VAT including postage in the UK.
Payment is required in advance, and you can pay by card over the 'phone, or using bank transfer , details :-
Name Natwest
Account John Pye & Sons Ltd - Office
Sort Code 60-80-09
Account No 61097535

If paying by bacs please use ref: JPT267.

Interesting. Any idea how much they would charge to fit the solenoid?

[martin42mm]

Interesting. Any idea how much they would charge to fit the solenoid?

Last September when I enquired it was £94.50 plus VAT, so DIY makes a lot of sense.

[slartibartfast01]

Last September when I enquired it was £94.50 plus VAT, so DIY makes a lot of sense.

I accidentally left my K50 at a friend's house 200 miles away before Covid. I may get it back soon so it will be a good test of the theory that leaving the camera for long periods without using it increases the chances of failure. It's been 30 months so far. If I had known it would take this long I would have paid to have it posted back. I am not sure I trust the postal services with a rucksack full of gear though.

[martin42mm]

I accidentally left my K50 at a friend's house 200 miles away before Covid. I may get it back soon so it will be a good test of the theory that leaving the camera for long periods without using it increases the chances of failure. It's been 30 months so far. If I had known it would take this long I would have paid to have it posted back. I am not sure I trust the postal services with a rucksack full of gear though.

I shouldn't worry about postal services these days too much. I've posted hundreds of items all over the world over the past 20 years or so, as well as in the UK, and apart from two items going missing , one a LARGE box of camera repairs I was returning, and a couple of dented items, despite decent packaging, never had any real issues. Just make sure you have the right insurance cover. Even Hermes ( Evri) who used to allow camera gear, but included it in their 'permitted, but no compensation' category have changed their tune in receny years, as they had to do. If you buy or sell on ebay, provided you use Packlink, which connects to many couriers, you will get a payout from them, NOT the courier, so it makes sense to do it that way. They want your business, whereas some couriers used to enjoy an arm-wrestle even if they lost the package they had been contracted to deliver. Not any more in most cases. The only issue with sending items through the post is that what may be working when dispatched it no longer doing so on arrival, despite careful packing!