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04-25-2019, 10:47 AM   #316
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QuoteOriginally posted by photogem Quote
Next time I have a K30 or similar open, I shall check this. I only checked in M-Mode and my guess is that whenever an A-lens is not in A-position, the solenoid is not engaged at all.
It isn't engaged in M-Mode for sure, this I have verified.
With modern lenses (no aperture ring), I can confirm (K-S2) that the green solenoid causes problems in M mode just like in Av mode. I didn't observe its state/operation directly though, just noted that replacement with white solenoid fixed the issue reproduced in M.

04-26-2019, 12:38 AM   #317
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This is different.


You need manual lenses which allow you to set the value of aperture on the lens!
04-26-2019, 08:43 PM   #318
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RayeR, it looks to me like this is not a PWM solenoid because the line is flat; is that correct? What is the voltage on the flat yellow line and what is it on the push line? What does it drop to at the release point? I found on TLX Technologies website some solenoid theory articles. It said polarity is important on latch solenoids as a permanent magnet holds the armature and reversing the polarity either strengthens or weakens the magnet. From the graph it seems that this solenoid just latches and unlatches and is not proportional. Is this correct? Or does the push line vary according to aperture opening? This is most helpful.
04-30-2019, 05:11 AM   #319
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QuoteOriginally posted by slartibartfast01 Quote
Thanks I always wondered about that. Does the same apply to Optical Preview ?
I didn't see this question of yours:

I have to check next time one of those cameras with a jammed solenoid is on my worktable.
Never checked this before.

05-29-2019, 06:25 AM   #320
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Optical Preview K30 no function w. damaged solenoid and slower when filed/sanded!

QuoteOriginally posted by slartibartfast01 Quote
QuoteOriginally posted by photogem Quote
QuoteOriginally posted by slartibartfast01 Quote
Does stop down metering with the green button use the solenoid?
No it doesn't! That's the whole point.

But those toothed wheels which a linked with the solenoid are in action and must be in action:

If you look into the lens and you chose (in M-Mode) any aperture-value, you can see that when you press the green button (or AE-L on those without the green button)
the aperture closes to the chose value (except wide open of course). And a 2.nd time taking the photo.

And with each push on the green button you can hear a sound. This is the sound of those wheels and the lever for the aperture. The sound comes from the springs which bring this lever and the wheels back into position. And the 2.nd time as well (inluding the sound of the shutter).
Thanks I always wondered about that. Does the same apply to Optical Preview ?
I have had the chance now to check about Optical Preview:

When the RAW Button is set to Optical-Preview in the Menu, it works perfectly with my own repaired K30 having the white "made in Japan" Solenoid within.

Very fast Optical Preview!


Now I had a K50 here with a bad green "made in China" Solenoid here.

The optical preview does NOT WORK!

With the F50/1,7 I have of course perfect optical preview at f1,7 because nothing needs to happen, it is wide open! But from f.2,8 it closes full down to f22! Same with the DA50/1,8. Not so with the DA55-300PLM but this as to be expected! The mechanism is not in use at all but is electronic.


So I made an experiment:

Prior unsoldering the green solenoid to swap it with the original "made in Japan" white solenoid I was too curious to find something out you indirectly led me to:

I precision filed/sanded the plunger of the green solenoid until it worked "to my satisfaction" (not that I could really be satisfied with a working filed green solenoid, you can't really be if you see (and hear) it in action compared to the white one...)

I checked again, the K50 worked quite alright but not as fast and not with this precise sound/snap which only the white Japan solenoid is able to give:
Optical Preview worked as well but it was slower than on my K30 (with the K50 1.10 firmware of course).

After this experiment I unsoldered the green gremlin and installed the "made in Japan" solenoid to check again:
Everything was now as with my K30: Fast snappy sound when the solenoid releases, fast snappy Optical Preview.
05-29-2019, 12:05 PM   #321
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The reason I asked about "Optical Preview" initially is that I believe it uses the exact same machinery to accomplish the exact same 'stop down' task that is usually the first step of taking a photo
1a. stop down lens
1b. move mirror out of the way
2. trip shutter & record image
3a. open up lens again
3b. return mirror

{the a. and b. steps may happen simultaneously; I listed them separately because they are done by different mechanisms, and listing them this way makes it easier to talk about them}

When I was using my K-30 regularly, I often would use Optical Preview to exercise the mechanism, to free it up without putting stress on the shutter.
06-13-2019, 06:39 PM   #322
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Just checking in to say that the $45 eBay (used, white) solenoid fixed my K-50.
I should have made better drawings of the screw locations, as I had 2 leftover screws from the operation!
I haven't been following this thread very deeply lately, has anyone posted drawings (i.e. pdf's) of the screw locations?
It is nice to have a potato again!
B^)
06-13-2019, 09:29 PM   #323
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You find the photos right there at the 1.st post of this thread:
K-50 / K-500 Aperture Solenoid fix (DIY with pics) - PentaxForums.com

06-14-2019, 08:12 PM - 1 Like   #324
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I just completed my repair on a K-30. I had a DL with a broken sensor at roughly the same sensor count, so the white solenoid should be barely used. Since my white solenoid had wires, I chose to remove the top plate and solder to the board like the OP. The K-30 makes it harder to access the screw holding the solenoid, but fortunately it wasn't in that tight. I discharged the flash like this: yesterday I took a flash shot with a manual lens, which fires at full power. Then I immediately shut off the camera. Today the flash capacitor had no measurable voltage. I took another risk and used the hacked firmware to make it act like a K-50. Changed some settings to be like my other cameras and it's all good.
06-15-2019, 05:01 AM   #325
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QuoteOriginally posted by TheZuke Quote
Just checking in to say that the $45 eBay (used, white) solenoid fixed my K-50.
I should have made better drawings of the screw locations, as I had 2 leftover screws from the operation!
I haven't been following this thread very deeply lately, has anyone posted drawings (i.e. pdf's) of the screw locations?
It is nice to have a potato again!
B^)
I'd hardly describe a K50 as a potatoe. 😤
06-15-2019, 07:15 AM   #326
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QuoteOriginally posted by Just1MoreDave Quote
I just completed my repair on a K-30. I had a DL with a broken sensor at roughly the same sensor count, so the white solenoid should be barely used. Since my white solenoid had wires, I chose to remove the top plate and solder to the board like the OP.
I don't recommend this for 2 reasons:
1. The flat ribboncable there is very easely hurt/bent. I know of at least 3 cases where this happened. It means exodus!
2. To unsolder the wires from the board is much more difficult because it is actually not a board but like a very thick ribbon cable (I don't know the English name for those) One has no access to the other side and applies quite a lot of heat. Unsoldering the cables from the solenoid is much easier and more elegant, not danger
"burning" the board or whatever this is!


QuoteOriginally posted by Just1MoreDave Quote
The K-30 makes it harder to access the screw holding the solenoid, but fortunately it wasn't in that tight.
The problem is that most use PH screwdrivers. A long JIS does the job with ease and there is less of an angle!


QuoteOriginally posted by Just1MoreDave Quote
I discharged the flash like this: yesterday I took a flash shot with a manual lens, which fires at full power. Then I immediately shut off the camera. Today the flash capacitor had no measurable voltage.
The electrolytic capacitor charges right away within a split of a second. Much faster than you can turn your K30 off. I have tried it and measure, there was always enough voltage left over to give you a nice shock. The discharge goes quick enough.


QuoteOriginally posted by Just1MoreDave Quote
I took another risk and used the hacked firmware to make it act like a K-50. Changed some settings to be like my other cameras and it's all good.
Actually zero risk! Ricoh uses it!
06-15-2019, 09:25 AM   #327
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QuoteOriginally posted by photogem Quote
The electrolytic capacitor charges right away within a split of a second. Much faster than you can turn your K30 off. I have tried it and measure, there was always enough voltage left over to give you a nice shock. The discharge goes quick enough.
Probably too much of this thread is wasted in arguments, so I will just say this. Pick up the closest DSLR and install an M42 or M type lens. Set the camera to M mode, 1/180, manual focus. That should allow you to take several shots in quick succession. Set the camera to allow you to shoot while the flash is charging. Pop up the flash. Take several quick shots.

The first shot, the flash fires at 100%. The next shot, I say it doesn't. Which I conclude means the capacitor takes time to charge. That might be why Pentax includes a Custom setting in all my cameras to allow shooting while the flash is charging.

Anyone can try this on their own and decide if I am right.
06-16-2019, 01:24 AM   #328
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How to discharge the photoflash-capacitor on a Pentax K-30/K-50/K-500 the right way

Look, it is not really about arguing and who is wrong or right. Because then it would be a personal thing, which I am not interested in nor the user who hopes for help.

Many times I have written about how to discharge the photoflash capacitor .

I have worked for decades with high-voltage audio-and recordingstudio equipment (i.e. tube/valve equipment) and I know about the characteristics of electrolytic (and other) capacitors.
We have particularely used photoflash-capacitors in regions where this very fast charging was important. If a capacitor discharges very fast and powerful (which is the aim of a photoflash capacitor!) it also will charge very fast, that is its nature/design!

So when I give this kind of advice it is for the safety of the user and... in this case for the safety of the camera!
Because some have damaged their K-30/K-50's when they neglected this condensor!

The way you do it there is the (verified!) risk that there is resitual voltage. Particular on the K-30/K-50/K-500 you can touch a part on the board which where you don't expect high voltage, but it is right there (marked red):


So it is not about:

*WHO* is right or wrong ..... but it is about

*WHAT* is right and wrong!

This makes a huge difference. I don't measure anymore the voltage of the flash-condensor because I don't need to. I built myself a little help-device with a 60W light-bulb:

This I also use for discharging electrolytic capacitors used on tube-amplifiers or studio-equipment with tubes. Because the 240V/60W lightbulb is sensitive, I wrapped some material around it to protect it, doesn't look very elegant but it works well.

When you replace the solenoid you anyway have the body open! So it is easy and straight forward to discharge the capacitor:


When the condensor is fully charged it illuminates, a very powerful light!


But sometimes I believe "ah... now the condensor should be discharged" I still do this little extra step and discharge it with this device and in many cases I was wrong,
there was some residual-voltage and the bulb illuminated but shorter!


The voltage is still strong enough to give you a shock, particular when you believe there is no voltage anymore!


If you then due to this sudden shock drop the camera or ... more likely:

... if while unscrewing of soldering the solenoid receive this shock and slip of the screw or worse, the pins and touch other parts of the camera with the hot tip of your soldering-iron: You might do some very stupid damage to your camera!


You want to avoid this and for that reason you don't apply half-hearted methods!


If you don't want to discharge the photoflash capacitor with a lightbulb, a resistor or a voltmeter (the latter takes much to long time and most don't have old-style analog voltmeters anymore, only those would work!)


... then do it the passive but correct way and just take the battery out, wait 24 hours or a bit longer and then the capacitor is discharged.
06-18-2019, 07:23 PM   #329
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QuoteOriginally posted by photogem Quote
You find the photos right there at the 1.st post of this thread:
K-50 / K-500 Aperture Solenoid fix (DIY with pics) - PentaxForums.com
Doh!
06-19-2019, 11:40 AM   #330
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Replacement used solenoid ??

Hi madphys;
Is there a list of what Pentax's can be robbed for "White Solenoid(s) ?? Does anybody know if the "X" series of bodies has them ?? I believe somebody stated that one of the old film bodies had the same looking (different color) item but it didn't work. How about the higher end film bodies like the Super Program, or any of the point and shoots,, etc. I guess if anybody has a bunch of part lists they could search by part number and see what comes up..

My take on the "Green" part,, first history tells the story look up "Pentax Aperture Lock" see what comes up Google tells all.. There apparently has been no failures in the istD thru the K200. There seems to be some question of if the K-x or K-r have the "Green" or the "White" ,, it's presently unclear , in searching I did see that some K-x models appear to have the issue, yet it appears if true it's very small numbers. When one compares the two , well one sees that there is no comparison the white parts are manufactured completely differently the white part had time put into it the machining , well there is machining, the magnet is different and located in a different location. The coils of the white (seen 5) one are strait , the green (I've only seen 2) , the green used one the coils are closure at one end , a new part they appear to be straight, so my guess would be that after time the green one distorts {Has anybody replaced a green that the coils were strait ?}. Small note on the white ones there coils are not as nicely wound (could indicate that the green part was wound to look pretty and not wound to spec.).

Lastly has anybody put a non-modded green part back into a D20 or istD ??? Did it work better ?? I ask because I'm going to pullthe IR filter, and I don't want to waste a good "White" part. Instead of modding the green part by sanding or soldering with like some foam in the bottom of the u on the plunger or maybe build up some NU metal in the same location ?



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