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11-17-2018, 03:33 AM   #181
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QuoteOriginally posted by altopiet Quote
Yes, I had my K-30 fixed ("mirror box" replacement, which probably included the green part), under warranty. Just before I discovered they would fix it, I striped one of my old manual cameras, think it was an MX, and got the white part out, still have it locked up in a safe place, just in case I need it.
That was my first thought (keep the white one in a safe place), but then I imagined of a situation, that I might need to take some pictures and tha camera suddenly fails.. so this is why I still don't know what to do.

Anyway I think I'll go with the first option and see what will happen.
Thanx!

11-17-2018, 03:55 AM   #182
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QuoteOriginally posted by le0n Quote
That was my first thought (keep the white one in a safe place), but then I imagined of a situation, that I might need to take some pictures and tha camera suddenly fails.. so this is why I still don't know what to do.

Anyway I think I'll go with the first option and see what will happen.
Thanx!
Luckily it is not a problem of a "sudden" fail if I remember correctly, it usually starts with the first shot from cold start, then going fine, and getting worse over time, or did you experience it differently?

If so, it should give you time to fix, as you would, unlike the first time, immediately be able to identify the problem
11-18-2018, 03:34 AM - 1 Like   #183
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QuoteOriginally posted by altopiet Quote
Luckily it is not a problem of a "sudden" fail if I remember correctly, it usually starts with the first shot from cold start, then going fine, and getting worse over time, or did you experience it differently?

If so, it should give you time to fix, as you would, unlike the first time, immediately be able to identify the problem
with my first K30 I experienced it different:

The problem started all the sudden.

Then I had no idea yet about the solenoid nor (my luck!) that shooting in series would help for a while (but actually makes things worse, that's why I wrote "my luck")

Similar to a friends K30.

I would always recommend to go right away the perfect road, i.e. white solenoid.

I don't think the MX uses this solenoid!

Anyway, the solenoids I got from some MZ bodys had opposite polarisation, i.e. one would have to unsolder the lilac and pink wires from the circuitboard and exchange them with each other.

So safer to got for a broken early *ist or any broken later *ist, K100, K200, K10, K20, K2000 and Kx body (or buy it over ebay)

Also the voltage applied to the solenoids in the later DLSR bodies starting with the *ist is the same voltage.
The voltage used in earlier DLR bodies is lower. Those solenoids do work but I don't know if they will last as well as those from the DSLR bodies.

Last edited by photogem; 12-23-2018 at 07:07 AM.
11-18-2018, 11:01 AM - 1 Like   #184
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QuoteOriginally posted by altopiet Quote
Luckily it is not a problem of a "sudden" fail if I remember correctly, it usually starts with the first shot from cold start, then going fine, and getting worse over time, or did you experience it differently?

If so, it should give you time to fix, as you would, unlike the first time, immediately be able to identify the problem
My experience was the same as yours.

In May, the first shot of each day was dark, so I would take two shots to start the day, or I would exercise the aperture control mechanism first.
Over the next few months it took slowly reached the point of needing another few shots, until November, when I finally stopped trying to keep the mechanism going and switched to "Plan B" - my lenses with aperture rings.

11-20-2018, 06:28 AM   #185
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One thing that I've noticed about the green solenoid is that the coils and former do not appear to be parallel.

However, this may not be significant, as the force needed to pull the solenoid apart is over 600g.
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11-20-2018, 07:07 AM   #186
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QuoteOriginally posted by SteveDee Quote
One thing that I've noticed about the green solenoid is that the coils and former do not appear to be parallel.

However, this may not be significant, as the force needed to pull the solenoid apart is over 600g.
What is the difference between the breaking force, if any, between the two?

According to the Super Program service manual the armature should be repelled from the magnetic core when 3 VDC (pink +) is supplied to the electromagnet. Can you measure the if there is a difference in the force generated by the electromagnet?
11-20-2018, 07:56 AM   #187
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QuoteOriginally posted by Not a Number Quote
What is the difference between the breaking force, if any, between the two?...

Not exactly sure what you are asking, but I would estimate the difference between the white & green solendoids is approx 5%. However please read my notes as the test was very crude: Captain Bodgit: Fixing my Pentax K-30 exposure problem: #3 one problem leads to another!

I'm going to open the camera one more time to investigate the 'flapperty-flap' mirror problem, but If I can't fix that I'll gladly hang both solenoids on a variable d.c. supply and see what it takes to operate each of them.

---------- Post added 11-20-18 at 08:51 AM ----------

More...
I don't know about the white solenoid, but I can put 4.8V d.c. across the green one and it still does not release.

I'll definitely try the white one when I reopen the K-30.

Last edited by SteveDee; 11-20-2018 at 08:52 AM.
11-20-2018, 11:42 AM   #188
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QuoteOriginally posted by Not a Number Quote
What is the difference between the breaking force, if any, between the two?

According to the Super Program service manual the armature should be repelled from the magnetic core when 3 VDC (pink +) is supplied to the electromagnet. Can you measure the if there is a difference in the force generated by the electromagnet?
The important difference is in how they "age". Are you thinking breaking force would affect that somehow??

11-20-2018, 02:04 PM   #189
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QuoteOriginally posted by SteveDee Quote
Not exactly sure what you are asking, but I would estimate the difference between the white & green solendoids is approx 5%. However please read my notes as the test was very crude: Captain Bodgit: Fixing my Pentax K-30 exposure problem: #3 one problem leads to another!

I'm going to open the camera one more time to investigate the 'flapperty-flap' mirror problem, but If I can't fix that I'll gladly hang both solenoids on a variable d.c. supply and see what it takes to operate each of them.

---------- Post added 11-20-18 at 08:51 AM ----------

More...
I don't know about the white solenoid, but I can put 4.8V d.c. across the green one and it still does not release.

I'll definitely try the white one when I reopen the K-30.
Did you try changing polarity? The Super Program service manual says the wires are pink (+) and gray (-). The wires for the K-50 look like pink and lavender as far as I can make out from the photos and my monitor. The polarity might be different

It's also possible that the solenoids in DSLRs have a higher operating voltage. The Super Program runs on 3 VDC where as the DSLRs have what 5-7 volt batteries?

QuoteOriginally posted by reh321 Quote
The important difference is in how they "age". Are you thinking breaking force would affect that somehow??
It's been established (from "finely tuned fingers") that the green solenoid requires more force to pull out the armature. Such a precise instrument can't tell us how much of a difference though. And we have no way of knowing how much of a difference will cause failure. Also I don't think any one has compared a working green solenoid vs a working white one for breaking force.

What exactly is aging in the solenoid? Direct and prolonged contact with a permanent magnet does not magnetize metal. The metal has to move repeatedly through a magnetic field in one direction in order for the magnetic poles in the iron to line up. If you ever took a shop class how did they teach you to magnetize a nail or screwdriver? You stroke it across a permanent magnet repeatedly in one direction. I have a horse shoe magnet that is at least fifty years old with a field protector on it - an iron bar across both poles of the magnet. If I remove the bar it is not magnetized - iron filings will not stick to it. Any residual magnetism dispells rapid once it is removed from the field.

So what does that leave us? Oxidation on armature? The insulating varnish on the solenoid windings going bad? The plastic on the coils going bad? It has been claimed that the green solenoids use PET vs PTFE of the white solenoids. PET is very stable. It may not have the same wear resistance as PTFE but age not wear seems to be the problem. PTFE has the edge on PET for UV resistance but how much UV is there inside the camera body. They are about equal for ozone resistance.

Magnets get weaker with age, but it seems either the magnet on the green solenoids is stronger to begin with or the plastic warps or swells thus needing more force to move the armature. Which is perhaps why sanding/filing the armature sometimes restores function if only temporarily.

Again comparing a working green solenoid vs a failed one would be interesting (or not).

Last edited by Not a Number; 11-20-2018 at 02:12 PM.
11-21-2018, 03:06 PM   #190
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I carried out some further investigation on my K-30 today.

Long-story-short, I think any evaluation of solenoid break/release force using a d.c. supply is a waste of time, as that is not the way the solenoid is controlled in the camera. I cannot see a great difference between the green & white solenoids when testing using a d.c. supply, but there is a big difference when operating via a pulse.

As I have a white solenoid to use as a replacement for the apparently faulty green one, I'm going to move on and work on my flapping mirror problem, but my notes from today are here (Captain Bodgit: Fixing my Pentax K-30 exposure problem: #4 more details on solenoid ) for anyone interested.
11-21-2018, 04:12 PM   #191
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QuoteOriginally posted by Not a Number Quote
It's also possible that the solenoids in DSLRs have a higher operating voltage. The Super Program runs on 3 VDC where as the DSLRs have what 5-7 volt batteries?
The white solenoid was also used in the *istDS/DL's and K10/100/20/200D's and K2000/Kx.
All those apply a similar high voltage as does the K30/50/500D

This might be the reason why the solenoids of at least some of the old analog cameras have opposite polarisation (but work if polarisation is switched around).

QuoteOriginally posted by Not a Number Quote
It's been established (from "finely tuned fingers") that the green solenoid requires more force to pull out the armature. Such a precise instrument can't tell us how much of a difference though. And we have no way of knowing how much of a difference will cause failure. Also I don't think any one has compared a working green solenoid vs a working white one for breaking force.
.....

Again comparing a working green solenoid vs a failed one would be interesting (or not).

I have not only (first) established this difference in holding force but with help we measured the holding force

I have 3 working green solenoids here and one is new and directly from the manufacturer.
I have not measured them but they "feel" absolutly identical to the damaged solenoids.

The PET body of the green solenoid has more "play", the wires of the coils of the white solenoid are more perfect wired, a little bit more tension.
The copper of the Japan solenoid "might be cleaner" (less carbon), very often Chinese copper is pretty dirty because they often melt old cables to get cheap copper.
But this is only a guess.

The surface of the Japanese "plunger" (horse-shoe) is more smooth and does move with more ease in the PTFE body. PTFE is a far superior material than the cheaper PET. Of course UV is not the problem.

PTFE as used in the Japanese solenoid has been used as bearing material in high-end turntables such as the legendary Well Tempered Reference or the W.T. Signature turntables. A metall shaft just touches some tiny precise shaped PTFE pieces (teflon thrust bearing) and is even pressed against those (a clever patent invented by William Firebaugh, I got to know him personally when he visited a special show in Zuerich many many years ago and knew his then distributor very well) This concept was later copied by the famous Kuzma turntables. My own Well Tempered Reference turntable had at least 15.000 hours on it, its bearing was as new when I sold it. There was no wear on the teflon!


PET wears much more easely

There is a higher quality PET-P and an even more special PET reinforced with PTFE.

And yet, the best and most longlasting bearing material remains PTFE.
The German manufacturer Ensinger produces all four materials and claims their quality in this ladder from low to higher:
PET - PET-P - PET reinforced with PTFE - PTFE


But the bearing material is only one factor of many:

Friction versus bearing clearance are two more factors:

- the Japanese PTFE Solenoid has less clearance (due to being manufactured with less tolearance) AND less friction (due to smoother contact of PTFE AND smoother surface of the plunger)

- The plunger of the green China Solenoid can wobble and even jam (and it jammes easier if sanded due to more wobble)


All those factors together with the higher holding force of the green solenoid work together.


And for sure it is NOT magnetisation of the plunger: I have demagnetised the plunger of a stuck solenoid: Nothing changed, it remained stuck.
01-04-2019, 09:06 AM   #192
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Unfortunately my sporadically used K-50 (once every couple weeks/months) has started to show signs of the aperture solenoid not working. I'm looking to take care of this as soon as possible and plan on just straight replacing the solenoid for the better quality one. I have two questions, one general and one for a previous poster (or anyone that knows).

1. I've read through all the posts and I feel like there is conflicting information regarding this so I'm hoping to clear it up. Will the solenoid from a MZ50 work as a direct replacement for the K-50, or does the polarity have to be reversed?

2. In the post from SteveDee that has a picture of the two side by side, where did the white solenoid, with the "E" (I assume it means Ensinger?) come from? Was it taken from another camera or did you purchase it individually?


On ebay I can buy a refurbed solenoid for $45, or I can buy a MZ50 for $15-$30. I have no problem taking apart the MZ to harvest the solenoid, as I figure its good practice anyway. I'm just trying to determine the best place to source one for relatively cheap.
01-04-2019, 09:48 PM   #193
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QuoteOriginally posted by mattoak Quote
I've read through all the posts and I feel like there is conflicting information regarding this so I'm hoping to clear it up. Will the solenoid from a MZ50 work as a direct replacement for the K-50, or does the polarity have to be reversed?
If you apply 6V DC (2 x 3V batteries but not more than 7.2V) you can check the polarity.

Check it first on the green solenoid so you know which sides are plus and minus.

Make sure you apply the voltage only for a short time (an impulse).

I would spend then little bit more and buy the one from ebay, it is the save way to go.
01-05-2019, 09:21 AM   #194
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QuoteOriginally posted by photogem Quote
If you apply 6V DC (2 x 3V batteries but not more than 7.2V) you can check the polarity.

I would spend then little bit more and buy the one from ebay, it is the save way to go.
Thank you! I didn't know if these ones were reliable or not since they are not "brand new". I'll purchase one from ebay then and do the repair myself. Thanks
01-06-2019, 03:01 AM   #195
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the correct "white made in Japan" Solenoid for Pentax

Yesterday (Jan 5th 2019) I tested a Pentax MZ50 solenoid against the version of the K10D.

It's my sons birthday monday and I want to give him my K30. But since a few weeks the pop-up flash would not pop-up anymore. This never bothered me because I hardly ever use flash but for my son I wanted it right.


It was for the first time ever (for me) that a green solenoid failed in the pop-up flash.

I thought I try an MZ50 solenoid and bought a 2.nd had MZ50 very cheap. I unsoldered it and tested it:


It had obvious slightly less holding force than the white versions from the early Pentax DSLR bodies!

And again my sample had opposite polarity.

I installed this white MZ50 solenoid, polarity was zero problem because in the flash circuit the two wires can just be soldered the opposite way.
I was certain all would be alright, I had installed a white solenoid into the aperture mechanism few month ago.

But I had a new hitherto unknows problem:

The pop-up flash would suddenly not close anymore!
The power (holding force) of the solenoid was too weak! The pull on the horseshoe plunger was too strong and kept it in the open position.

Luckily I had a green solenoid from another K30 left over.

So I changed solenoids again, all was fine again.

This made me curious and I exchanged the early white solenoid (from an *istDL2) which I had installed before into this K30
against this white MZ50 solenoid (which included extra fuzzy work for changing polarity of the two wires!):

I had a new problem: Every 2nd or 3rd picture overexposed!

The reason was clearly obvious:
The horseshoe did not move back into its "Locked Position", similar as it did when used for the flash mechanism!

I then moved it manually with the tip of a screwdriver into the lock position, next photo was fine but then again it "stuck wide open".
If I chose the settings for proper speed for wide open, of course all was well.

Same problem using live-view.

I then took another "bad" green solenoid I had and I filed/sanded the anchor until I had similar holding force.
I built this one into the aperture circuit and voila: Same problem!!! This explained to me why so many filed or soldered green solenoids failed.

Changing the solenoids back against the one from the *ist DL2 and all was fine again.


So I recommend to get solenoids only from:

Pentax *ist D, *ist DS, *ist DL, *ist DL2, Samsung GX1/2, GX10/20

Pentax K10D, K20D, K100D, K110D, K200D, Km, Kx, Kr



I came across quite a few of those which had already the green solenoid in the flash circuit!

It seems to me that those green solenoids were only built into EU Pentax bodies because I have heard from several people
now that US, Canadien and Australien early Pentax DLSRs had 2 white solenoids!



I also heard that there is a difference in "Made in Japan" to "Made in Philippines" MZ bodies!?
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