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10-09-2018, 01:42 PM   #76
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QuoteOriginally posted by photogem Quote
I have just ordered the "made in China" white solenoid (allthough I don't need it) and will take photos as soon as it has arrived.
So some of the "white" solenoids are made in China. Do you know whether they are also made of teflon, as the Japanese ones are?

10-09-2018, 05:55 PM   #77
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QuoteOriginally posted by reh321 Quote
So some of the "white" solenoids are made in China. Do you know whether they are also made of teflon, as the Japanese ones are?
And it is possible that green ones are made in Japan too. Yes, you can get PTFE in translucent green.
10-10-2018, 10:58 PM   #78
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QuoteOriginally posted by Not a Number Quote
And it is possible that green ones are made in Japan too. Yes, you can get PTFE in translucent green.
No, the green ones are all made in China.
10-19-2018, 07:10 PM   #79
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Member hnikesch has purchsed this complete aperture block recently from US-Camera. His has the green solenoid

10-19-2018, 08:57 PM   #80
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QuoteOriginally posted by photogem Quote
No, the green ones are all made in China.
And you know this how?

BTW: Taiwan is the Republic of China.
10-20-2018, 10:02 AM   #81
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QuoteOriginally posted by Not a Number Quote
And you know this how?

BTW: Taiwan is the Republic of China.
Because I know the original manufacturer from Japan, who moved manufacture of the solenoid outside Japan

to the People's Republic of China, i.e. in Jiansu.

They also have an office in Taiwan but manufacturing of our solenoid was in Jiansu.
01-13-2019, 02:17 AM - 1 Like   #82
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Impuls needed to actuate green and white solenoids

QuoteOriginally posted by LSAGuy Quote
I bought the complete replacement assembly with the white solenoid from USCamera for $35. Anyone replaced the whole assembly? Any suggestions would be greatly appreciated.

Rick

---------- Post added 10-02-18 at 07:26 AM ----------

I just compared the new assembly with the photograph of the solenoid on page one of this discussion. The difference in the new board (mfg date of 9/9/2017) is the neodymium magnet has been moved up so that there is a 1.5 mm (eye ball measurement ) gap between the magnet and the plastic coil bobbin. This seems to support the argument that the fix reduces the magnetic force drawing the plunger in.

Rick
Last week I received a Aperture controll block from USCamera which they call the Diaphragm Control Block . It was an expensive deal because of added VAT.


It has the China made green solenoid on it.

But it was a very useful buy because I could do some tests with it:

With the China green solenoid the release time of the horseshoe was 10 ms
Then I installed a white solenoid from a defunct Pentax K10D: Release time was 2 ms!


This explains what I always felt I heard as a difference and noticed also when I did a series of shots:


With the white Solenoid the K30 (and the others) shoot faster and more precise.

I have several times asked member LSAGuy to upload a photo or send me one of his block which he claimed had the white solenoid on it.
He never did, he wrote to me that he did not install the block into his body but purchased an used Pentax K20D instead.


I very much daubt that he got it with a white solenoid because several people I know of have meanwhile ordered the same unit:

All with the green solenoid!

Logic! Because the white solenoid is no longer manufactured since a long time!

I know that somebody was able to buy some white NOS (New Old Stock) solenoids in Tokyo Akihabara but I never found any direct link where one could get them directly from Japan

Last edited by photogem; 02-08-2019 at 03:23 AM.
02-08-2019, 03:23 AM   #83
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Addition Febr. 8th 2019:
Same test but with a stuck green solenoid:

it took about 110 ms to get the green solenoid to move.
Which is not the impuls the K30 gives, it would go damaged.

We continued over many times to "fire the solenoid" with those 110 ms and after a while it was able to actuate with the same 10ms as a green solenoid which was o.k. Yet: If one waited for roughly 15 minutes one had to start again with 110ms.

It seems to me that the plunger magnetizes quite quickly and then is saturated. Continuous firing seems to demagnetize the plunger a little bit. But even after many rapid fire actuations there remains some magnetism in the plunger due to the fact. My theoriy is that the opposite magnetic force induced in those two coils is not enough to demagnetice enough due to the fact, that the holding permanent magnetic force of the green solenoid is already higher than the holding force of the made in Japan white Solenoid!


This could explain why Pentax bodies not used for some time and even with low shuttercount do get affected much more than those in regular use and high shuttercount. Possibly more factors might well play a role as well.



We then installed a modified green solenoid into the circuit: it was modified via sanding the plunger.

It worked well enough, also the snap obvously sounded different. There was no difference to be noticed in how the mechanism linked with the plunger moved, we colour-coded the white wheel to see when the shutter would be wide open, closed and in between. All this worked alright.

The impuls to actuate it was about 6ms, so better than those 10ms of the green alright solenoid but still 3x worse than those 2ms of the white solenoid.
We sanded the plunger slightly more but noticed occasional faulty movements of the mechanism. With slight more sanding the force of the spring moving the plunger
downwards was too strong, the magnet could not hold it anymore. The solenoid was useless. I then installed it into the flash circuit of a K100D but no luck either.
The solenoid was finished now.

02-11-2019, 12:32 AM   #84
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One question

First thank you for your effort to try to understand this problem.

I have a question about this.

The measurements made on the solenoid would be the same with eneloop batteries?
02-11-2019, 03:24 AM   #85
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I can't tell, because I didn't try, no eneloops in my house anymore.


But as eneloops do have different characteristics I strongly guess measurements could vary!


Nevertheless, allthough some could run their Pentax longer using eneloops instead of the Li-Ion battery, later on many develop the same problem, just delayed.

I strongly believe that as soon as the problems starts, it is best to act then and not to wait, because further damage can occur.


Damage similar to applying the dreaded sanding method.


This affects the mechanism which is actuated by the solenoid itself:

This mechanism is then more difficult to move, it seems that the lever on which the plunger sits has more resistance to be moved, possibly due to misalignement of one of those wheels with sit on the backside of the complete block. Those wheels run in bearings themselves and get out of alignement due to the sloppy movement of the sanded plunger.
But this is (yet) theory.
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