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photogem | |
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09-20-2020, 10:19 AM - 2 Likes | #31 |
Your history of the selenoids used in Pentax bodies is a real gem, photogem. Using low-quality selenoids in a succession of entry-to-midrange bodies, even after they must have understood the issues, remains one of the biggest Pentax fails. In my book, it is right up there with the notorious first-generation SDM failures. The latter has ultimately kept me from investing in a single early-SDM lens, and the former makes me dread the day when I may have to explain to my wife why the K-70 I so warmly recommended to her has taken to produce black images. (Knock on wood, so far it has been working great.) Now, humans are bound to make mistakes, and I understand the need to find cost-effective solutions when you have to run a successful business. But, to my mind, one of the key takeaways from the selenoid story is how hard it can be to rectify going cheap once you've gone down into that rabbit hole, even when it starts to dawn on you that you've made a serious mistake. Even when Ricoh understood what was going on, it seems they concluded they would just use a somewhat better, yet still possibly-inferior selenoid (compared to the no-longer-available Japan model) for the K-70. However, consumer trust is also a kind of capital, one that is hard to restore and one that shouldn't be squandered for perceived short-term benefits. Having the first Pentax DSLR body they ever tried fail on them just after the warranty period had ended may have driven many a beginner away from the brand before they became more deeply invested in the system, which would be a shame. (End of rant. You guys know how much I love Pentax digital for all the things it has done right.) Last edited by Madaboutpix; 09-20-2020 at 11:29 AM. Reason: More nuance. | |
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09-20-2020, 11:28 AM - 2 Likes | #32 |
Ah... but you see, they didn't know really. They knew the solenoid was different, possibly they knew it was now made in China. But they tested the solenoid in the more simple circuit of the K100D, K200D, K110D, K-m, K-x and K-r. So quite a few years without any failure. When the first failures appeared with the K30, nobody knew then. It was the Russians finding out first applying the soldering method and it was shedding light into what had to come. The dreaded sanding method appeared but soon proved to be wrong. I have the latest K70 solenoid right here on my workbench and it is even better then the one from my first K70. I purchased this late K70 because it was repaired and failed again. So just today I had the chance to search for this mysterious resistor-chip, well, I could not find any! But I managed to resist chips, but some need to be more careful During the next week I will meet the son of the most experienced electrical engineer I ever met in my life, he himself is now a master of electronics as well, his dad sadly left this planet few years ago. With him I will study the circuit any further just to make sure I didn't miss anything but I think I didn't. Last edited by photogem; 09-20-2020 at 11:03 PM. | |
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09-20-2020, 11:50 AM - 1 Like | #33 |
Ah... but you see, they didn't know really. They knew the solenoid was different, possibly they knew it was now made in China.But they tested the solenoid in the more simple circuit of the K100D, K200D, K110D, K-m, K-x and K-r. So quite a few years without any failure. When the first failures appeared with the K30, nobody new then. It was the Russians finding out first applying the soldering method and it was shedding light into what had to come. The dreaded sanding method appeared but soon proved to be wrong. I have the latest K70 solenoid right here on my workbench and it is even better then the one from my first K70.I purchased this late K70 because it was repaired and failed again. So just today I had the chance to search for this mysterious resistor-chip, well, I could not find any! But I managed to resist chips,but some need to be more careful. During the next week I will meet the son of the most experienced electrical engineer I ever met in my life, he himself is now a master of electronics as well, his dad sadly left this planet few years ago. With him I will study the circuit any further just to make sure I didn't miss anything which I daubt. Well, I would be willing to give them the benefit of the doubt then. But still, given that they made the K-70 so nice in so many other respects, I wish they had just let the tried-and-tested stepper motor trickle down to it too. Would it really have made the K-70 so much more expensive than the competition? I know I'm probably suggesting this in hindsight. And they do deserve some credit for trying to source even better selenoids for later K-70s. I just hope the right people at Ricoh will read all the commendable research you have accumulated. You're a real asset for the brand, photogem. | |
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09-20-2020, 11:01 PM - 3 Likes | #34 |
The K-S1 was a unique design because of not giving up the K-design. Other companies changed their mount: Vintage lenses could not be used anymore. Not so with Pentax! But the K-S1 was not that well received aside of Japan. In Japan they were rightly very proud of it. But this is also linked to the fact, that many Japanese have smaller hands and fingers! For those the K-S1 was a revelation. Impossible to achieve with a stepper-motor. What happens if you you a stepper-motor and yet want to keep it small could be seen with the K-01. It was similar in size as the K-S1 but kind of castrated. So the K-S2 and then the K-70 (99,5% identical body) were an attempt to keep it small as possible plus WR + flip-screen Plus amazing other extras such as pixel-shift. Impossible to achieve for that price and size with a stepper-motor! I do think that from that moment on when they 'got it' that it was just and only the solenoid, everything was done to solve it. It took time though. And some still insist that it must be more than the solenoid (Ant & Bee and the 'make-believe-rainbow') and try to fabricate something that never existed. There is all evidence that is needed: The made in Japan solenoid never failed, i.e. is the evidence per se. Of course no forensic evidence, this ain't no crime! Nothing more is needed. Nothing else failed ever than the made in China solenoid. Different interests, different view-points, different education etc. Ah.... I almost forgot: Stubbornness and ignorance! Don't know which was there first, kind of 'hen or egg'. But there might be another problem: I call it the co-existence of the designer and the engineer. A good designer is the person who can see into the future, has the idea, is the entrepreneur. He might even have quite some technical knowledge but he is not the person who can make it alive (the end-product). That is the work of the engineer. In older days the engineer was as much respected, not so much these days anymore. But they need to work well together, not so easy anymore when business-economists have the saying. That's the modern problem: Business-economists are often very inexperienced about real live, juggle with figures and thus often have a very onesided/tilted view of reality. | |
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09-21-2020, 05:44 AM | #35 |
I believe the solenoid was a “tried-and-tested design which had trickled down to it”; photogem’s history shows why the designers would think that way - all it needed was a simple tweak. Now they have shown that the “tweak” does not work reliably, so now it is time to give up on it.
Last edited by reh321; 09-21-2020 at 06:17 AM. | |
09-21-2020, 06:38 AM | #36 |
There is no need to give up on the principal of the solenoid. All.... really all that needs to be done is to get a Japan-Solenoid, send it in to the manufacturer with a sledge-hammer and ask the manufacturer to find a magnet which holds the plunger with exactly the same holding force as does the Japan solenoid. That would solve it. Just this weekend I opened a K-70 of very recent manufacture.... It still had warranty and was repaired on warranty but failed again. So a good chance to fish for chips (it was quite a resisting chip, seems to be a stealth chip Anyway, the solenoid was even better than the previous one. Almost correct holding force. So if you quote my words and particular and in this thread, do it correct please and don't misalign what I said! Last edited by photogem; 09-22-2020 at 11:39 PM. | |
11-04-2020, 09:12 PM - 1 Like | #37 |
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12-26-2020, 10:31 AM - 1 Like | #38 |
Thanks for everyone who posted here. I was having the same aperture issue with my K-X and decided to take a leap of faith and crack open the camera. I had ordered the "white solenoid" from Japan in the hope of finding the green one when I open the body. To my surprise, the K-X I have already had the white one. And since there was no picture out there that clearly shows where exactly it sits, I took that picture below. You can now clearly see it as soon as the plastic body is removed. Tip: note down where screws go as there are about 5 different sizes. Since the wires and solder dots are microscopic I did not yet want to replace the solenoid with another white one. What I ended up doing instead is remove the tape holding the wires, unscrew the solenoid in place and leave it wired. Once the solenoid is lose, you can pull it apart in two pieces, where the "bottom part with no screw" (left side of it, looking at the picture) can be removed and tapped on a table to remove some remnants of magnetic field. Then put everything back together. Just doing this did the trick for me. I still have the spare white solenoid in case this small operation was not enough and I have to put the new one in place. | |
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12-26-2020, 10:49 AM | #39 |
Fascinating.
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12-26-2020, 03:29 PM | #40 |
Thanks for everyone who posted here. I was having the same aperture issue with my K-X and decided to take a leap of faith and crack open the camera. I had ordered the "white solenoid" from Japan in the hope of finding the green one when I open the body. To my surprise, the K-X I have already had the white one. Nevertheless, it would have been the first time ever that a white Japan-Solenoid failed and if it would be wrong (which I daubt) it should go wrong again very soon. Tapping the solenoid parts on the table to remove remnants of the magnetic-field was never a solution for the green China-Solenoid ever! It cannot work because when the Pentax is NOT IN USE the plunger is ALWAYS NEAR THE PERMANENT MAGNET and gets magnetized. Thats the problem and the too strong holding force. So if your solenoid or better if you K-x will continue to work then it was not the solenoid, that I know for sure. | |
12-27-2020, 08:17 AM - 1 Like | #41 |
The K-X, so as mine, has a history of having battery issues. Normal batteries last few shots, while high voltage Eneloops or Lithium batteries last longer. So maybe my solenoid issue is in fact due to not enough voltage to move the solenoid off the magnet itself...
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12-27-2020, 03:42 PM | #42 |
Battery type AA/NiMH/Eneloop in K-x, K-r, K30 K50, K500 as well as *ist/K100/200/2000 - PentaxForums.com But it is not the voltage which is important, it is milli-amperes! The surge-power. But the holding-force of the Japan-Solenoid is very exact and never needed any manipulation. the PTFE makes the plunger move much more easely, both those facts together with the alloy make all the difference. I have seen white solenoids from Pentax DSLR bodies with very high shuttercount: Never any failure! | |
12-27-2020, 08:46 PM - 1 Like | #43 |
There is no need to give up on the principal of the solenoid. All.... really all that needs to be done is to get a Japan-Solenoid, send it in to the manufacturer with a sledge-hammer and ask the manufacturer to find a magnet which holds the plunger with exactly the same holding force as does the Japan solenoid. That would solve it. ................................ So if you quote my words and particular and in this thread, do it correct please and don't misalign what I said! | |
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12-27-2020, 09:58 PM - 1 Like | #44 |
If I understand what photogem is saying correctly (and what you are saying), then when the company transferred production from Japan to China, it also abandoned the "Japan solenoid" Teflon design in favour of the presumably cheaper alternative, PET. If the Teflon variant is out of production, I wonder if Ricoh would be willing to purchase a sufficient volume to make it worth setting up the needed assembly line at the new plant. Alternatively, wouldn't a better plan from Ricoh's perspective be to transfer all body tiers to the stepping motor? | |
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12-28-2020, 08:59 AM | #45 |
Larger bodies, more weight and more expensive. Read here what I wrote about this issue: Buying a new camera body - Page 4 - PentaxForums.com | |
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aperture, approach, battery, bodies, camera, cameras, clicks, date, evidence, force, gn, k-30, k-50, k-70, kp, magnet, motor, pentax, pentax k30, pentax k50, production, resin, result, samsung, self, solenoid, teflon, unit, vibrations, vs |
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