[slartibartfast01]

K x, K m, K100D, K200D I found had again just one usefull (for aperture mechanism), the solenoid used for the popup flash was the same green version as used in the K30 etc.!

The fact that these cameras used different solenoids for the two functions speaks volumes. Pentax must have been aware of a difference between them at that time.

[photogem]

The fact that these cameras used different solenoids for the two functions speaks volumes. Pentax must have been aware of a difference between them at that time.

Yes, this might well be so!

Kind of obvious actually. I was really surprised to find the green solenoids there. And those bodys where in use within family, so no chance that anybody would have tampered with them, i.e. exchanged solenoids!

[suraswami]

So the quality of the new green solenoid not the same as before, hmm hopefully the replacement that Ricoh does is of better quality and lasts longer.

[photogem]

So the quality of the new green solenoid not the same as before, hmm hopefully the replacement that Ricoh does is of better quality and lasts longer.

There is no "new green solenoid"!

There is just "a green solenoid" which does not make problems in a surrounding where it is not stressed, i.e. for pop-up flash
and makes problems when it is stressed (aperture mechanism)

Some replacement green solenoids which were built in into some Pentax K50's by Ricoh on warranty already went bad again.

[Corsair3811]

If this would be the case, i.e. a mechanical problem... something wears out, why then are often bodies affected with low shutter-count?



I think this is a possibility:

The horseshoe of each "white solenoid" which I inspected prior building could be released more evenly or smoother with less (subjective) force when I gently and evenly pulled on it.

And it is this smoother release of the horseshow which one can find using the "russian" method.

The use of AA-batteries (Eneloops) as you do it seems also "to do something" which helps that the solenoid can release the horseshoe enough
so all seems to work fine. So Eneloops seem to give enough power (either in mA or in even or high enough voltage?) that this works.

In my case I know that all K30/50's I had repaired with the white solenoid work well, so it seems very cleary this solenoid which was used in
older bodys and there never failed (exception the K r which when used with the Li-Ion battery developed mirror-flop, but not if used with Eneloops only .... as far as I have heard).

I filed one horseshoe of a green solenoid just to see how it releases and of course it releases more even.

So your guess that something gets sticky or stiff and then the horseshoe of the green solenoid sticks itself seems to be a possibility
but I feel it is the horseshoe itself which gets sticky or stiff within the housing of the solenoid, which has those coils to produce the magnetic
field to counteract the magnic force of this tiny permanent magnet to hold the horseshoe in place.

My guess is still same as I wrote earlier on in this thread (post # 26) that it is the material of

- the horseshoe (plunger) itself, i.e. its surface is slightly more uneven and in one case developed some kind of corrosion
- the housing which seems to be more precice made in case of the white solenoid

So we are back to square one

K50 black frames
Set of 4 eneloops has about 5.2 Volts new, Lion battery has 8.4 Volts with no load. I checked the voltage on OEM battery with 2 Amps load - it is still at 7.2 V, that is enough for powering the solenoid actuator. According my measurements, same solenoid from CD ROM needs about 320 mA to release at approx. 4 Volts. My K50 has black frames with OEM battery, but with eneloops only first frame is underexposed, after 28 months and 2400 clicks only.

[suraswami]

K50 black frames
Set of 4 eneloops has about 5.2 Volts new, Lion battery has 8.4 Volts with no load. I checked the voltage on OEM battery with 2 Amps load - it is still at 7.2 V, that is enough for powering the solenoid actuator. According my measurements, same solenoid from CD ROM needs about 320 mA to release at approx. 4 Volts. My K50 has black frames with OEM battery, but with eneloops only first frame is underexposed, after 28 months and 2400 clicks only.

It will eventually fail, mine worked for few months and unless I do Hi FPS shooting for 10+ frames even with Eneloops it's all black frames. I can get away with Live view first shot and then all good. I changed the solenoid and all good for a month now with about 250 clicks since changing and using OEM battery.

[Corsair3811]

There are some strange points. Why the black frame problem is worse with higher voltage even when the OEM battery can deliver enough current ? - If the battery is overloaded, the result is complete shutdown of the camera.
Mechanical wear with 2k clicks ? Probably not.
It looks like a problem in the electronics. The camera internal electronics is powered with stabilized voltage from some switching stabilizer. In standby mode energy consumption is low, just for powering electronics parts. But when you press the release button, a lot of mechanical equipment is involved - mirror, aperture block and so on. This consumes a lot of power. The stabilizer has to deliver a lot of energy in couple of msecs. And this is the point - the reaction time of the stabilizer circuit, when powered from higher voltage is longer than with low voltage from eneloops. This corresponds with your experience with LiveView - mirror is already down, electronics is in full operation and stabiliser is settled under load. It has probably something to do with capacitors loosing their capacity especially when not used for longer period. With changed solenoid {white with smaller magnet} or with filed anchor the magnetic force is lower and camera needs less current to release it.
- Everything i wrote above are just speculations -

[reh321]

There are some strange points. Why the black frame problem is worse with higher voltage even when the OEM battery can deliver enough current ? - If the battery is overloaded, the result is complete shutdown of the camera.
Mechanical wear with 2k clicks ? Probably not.
It looks like a problem in the electronics. The camera internal electronics is powered with stabilized voltage from some switching stabilizer. In standby mode energy consumption is low, just for powering electronics parts. But when you press the release button, a lot of mechanical equipment is involved - mirror, aperture block and so on. This consumes a lot of power. The stabilizer has to deliver a lot of energy in couple of msecs. And this is the point - the reaction time of the stabilizer circuit, when powered from higher voltage is longer than with low voltage from eneloops. This corresponds with your experience with LiveView - mirror is already down, electronics is in full operation and stabiliser is settled under load. It has probably something to do with capacitors loosing their capacity especially when not used for longer period. With changed solenoid {white with smaller magnet} or with filed anchor the magnetic force is lower and camera needs less current to release it.
- Everything i wrote above are just speculations -

The problem is, if you went through this thread, and others on the same general subject, you'd find all kinds of factors blamed for this issue.

For example

If this would be the case, i.e. a mechanical problem... something wears out, why then are often bodies affected with low shutter-count?

I think this is a possibility:

The horseshoe of each "white solenoid" which I inspected prior building could be released more evenly or smoother with less (subjective) force when I gently and evenly pulled on it.

And it is this smoother release of the horseshow which one can find using the "russian" method.

The use of AA-batteries (Eneloops) as you do it seems also "to do something" which helps that the solenoid can release the horseshoe enough
so all seems to work fine. So Eneloops seem to give enough power (either in mA or in even or high enough voltage?) that this works.

In my case I know that all K30/50's I had repaired with the white solenoid work well, so it seems very cleary this solenoid which was used in
older bodys and there never failed (exception the K r which when used with the Li-Ion battery developed mirror-flop, but not if used with Eneloops only .... as far as I have heard).

I filed one horseshoe of a green solenoid just to see how it releases and of course it releases more even.

So your guess that something gets sticky or stiff and then the horseshoe of the green solenoid sticks itself seems to be a possibility
but I feel it is the horseshoe itself which gets sticky or stiff within the housing of the solenoid, which has those coils to produce the magnetic
field to counteract the magnic force of this tiny permanent magnet to hold the horseshoe in place.

My guess is still same as I wrote earlier on in this thread (post # 26) that it is the material of

- the horseshoe (plunger) itself, i.e. its surface is slightly more uneven and in one case developed some kind of corrosion
- the housing which seems to be more precice made in case of the white solenoid

So we are back to square one

[mikeirl]

I have a K 50 which won't work with the rechargeable battery any more, but currently works fine with AA batteries. I guess I'm looking at this repair somewhere down the line... But, my camera has another fault, where sometimes everything freezes after switching on the camera. None of the buttons respond, and the screen remains illuminated. Removing the battery is the only way to switch off the camera. Is this a symptom of the faulty solenoid, or do I have another unrelated problem with my camera?

[reh321]

I have a K 50 which won't work with the rechargeable battery any more, but currently works fine with AA batteries. I guess I'm looking at this repair somewhere down the line... But, my camera has another fault, where sometimes everything freezes after switching on the camera. None of the buttons respond, and the screen remains illuminated. Removing the battery is the only way to switch off the camera. Is this a symptom of the faulty solenoid, or do I have another unrelated problem with my camera?

Sounds more like a power or processor issue to me - but maybe someone else has experienced these symptoms

[suraswami]

I have a K 50 which won't work with the rechargeable battery any more, but currently works fine with AA batteries. I guess I'm looking at this repair somewhere down the line... But, my camera has another fault, where sometimes everything freezes after switching on the camera. None of the buttons respond, and the screen remains illuminated. Removing the battery is the only way to switch off the camera. Is this a symptom of the faulty solenoid, or do I have another unrelated problem with my camera?

Did you update the firmware on your camera?

[mikeirl]

Did you update the firmware on your camera?

Yes, the camera is currently running Ver: 1.10

[sawitar]

My K-50 suddenly started suffering from dark frames few weeks ago.

I gathered couple old laptop CD/DVD drives in hope I will be able to devour solenoid from one of these.

I have removed bottom and front cover from my camera and located faulty solenoid (as per instruction from first page. No need to remove top cover). Now having clear view on failed part I opened first DVD-ROM drive disc tray, and behold, solenoid used in tray opening mechanism was almost identical to the one in camera. One difference I have notices is that magnet used in DVD drive solenoid is slightly (1mm) higher than the one in the camera but all external/important dimensions were the same.
Using small scissors I cut ribbon cable solenoid in DVD drive was soldered to and gently removed it from enclosure, making sure I do not break tiny wires. Now using precise soldering iron and ‘third hand’ I desoldered what was left of ribbon cable.
Now back to camera. Desoldered two wires going to solenoid, unscrew it and removed from camera. Put new solenoid in its place and solder the wires to it. I have put both covers temporarily back on and tested camera. It was not working any better. After some deliberation I flipped little magnet in solenoid upside down. And camera spring back to life. I have make about hundred test photos since. All well exposed.

HINT ON SOLDERING: Before soldering make sure wires are wetted with solder and put some soldering flux on both soldered parts
HINT TO HINT: if you do not have soldering flux at hand you can use some clear alcohol (Polish vodka is the best and has so many more uses :-) )

Internal resistance (measured using cheap Chinese multi-meter) of both parts :
- Original green Pentax solenoid: 14 ohm
- DVD ripped solenoid: 26 ohm

Btw. I do not recommend soldering wires midway as this is actually more difficult to do and involves way more solder and heat.

Tools I have used:
- precise screwdrivers set (B&Q 6GBP) with proper size handles
Do not use those small all metal chinese made 'precise' screwdrivers.
Those have small handles and are usually made with some soft steel.
- precise soldering iron set (includes some solder with flux, precise pliers) (Amazon 17GBP)
Either but proper soldering iron or do not buy it at all.
Soldering station available from German shop starting with 'L' won't do as it doesn't have right tip.
Soldering irons available in diy shop do not allow for temperature control and don't have right tip.
- soldering flux (Amazon ~2GBP)
- small scissors (wife)
- third hand (Amazon)

Good luck.

[suraswami]

My K-50 suddenly started suffering from dark frames few weeks ago.

I gathered couple old laptop CD/DVD drives in hope I will be able to devour solenoid from one of these.

I have removed bottom and front cover from my camera and located faulty solenoid (as per instruction from first page. No need to remove top cover). Now having clear view on failed part I opened first DVD-ROM drive disc tray, and behold, solenoid used in tray opening mechanism was almost identical to the one in camera. One difference I have notices is that magnet used in DVD drive solenoid is slightly (1mm) higher than the one in the camera but all external/important dimensions were the same.
Using small scissors I cut ribbon cable solenoid in DVD drive was soldered to and gently removed it from enclosure, making sure I do not break tiny wires. Now using precise soldering iron and ‘third hand’ I desoldered what was left of ribbon cable.
Now back to camera. Desoldered two wires going to solenoid, unscrew it and removed from camera. Put new solenoid in its place and solder the wires to it. I have put both covers temporarily back on and tested camera. It was not working any better. After some deliberation I flipped little magnet in solenoid upside down. And camera spring back to life. I have make about hundred test photos since. All well exposed.

HINT ON SOLDERING: Before soldering make sure wires are wetted with solder and put some soldering flux on both soldered parts
HINT TO HINT: if you do not have soldering flux at hand you can use some clear alcohol (Polish vodka is the best and has so many more uses :-) )

Internal resistance (measured using cheap Chinese multi-meter) of both parts :
- Original green Pentax solenoid: 14 ohm
- DVD ripped solenoid: 26 ohm

Btw. I do not recommend soldering wires midway as this is actually more difficult to do and involves way more solder and heat.

Tools I have used:
- precise screwdrivers set (B&Q 6GBP) with proper size handles
Do not use those small all metal chinese made 'precise' screwdrivers.
Those have small handles and are usually made with some soft steel.
- precise soldering iron set (includes some solder with flux, precise pliers) (Amazon 17GBP)
Either but proper soldering iron or do not buy it at all.
Soldering station available from German shop starting with 'L' won't do as it doesn't have right tip.
Soldering irons available in diy shop do not allow for temperature control and don't have right tip.
- soldering flux (Amazon ~2GBP)
- small scissors (wife)
- third hand (Amazon)

Good luck.

YAY!! good job. We have more doctors graduating from PF University qualifying to perform life saving surgery on K50 .

Hope Ricoh use better parts in newer models

[Corsair3811]

My K-50 suddenly started suffering from dark frames few weeks ago.

I gathered couple old laptop CD/DVD drives in hope I will be able to devour solenoid from one of these.

I have removed bottom and front cover from my camera and located faulty solenoid (as per instruction from first page. No need to remove top cover). Now having clear view on failed part I opened first DVD-ROM drive disc tray, and behold, solenoid used in tray opening mechanism was almost identical to the one in camera. One difference I have notices is that magnet used in DVD drive solenoid is slightly (1mm) higher than the one in the camera but all external/important dimensions were the same.
Using small scissors I cut ribbon cable solenoid in DVD drive was soldered to and gently removed it from enclosure, making sure I do not break tiny wires. Now using precise soldering iron and ‘third hand’ I desoldered what was left of ribbon cable.
Now back to camera. Desoldered two wires going to solenoid, unscrew it and removed from camera. Put new solenoid in its place and solder the wires to it. I have put both covers temporarily back on and tested camera. It was not working any better. After some deliberation I flipped little magnet in solenoid upside down. And camera spring back to life. I have make about hundred test photos since. All well exposed.

HINT ON SOLDERING: Before soldering make sure wires are wetted with solder and put some soldering flux on both soldered parts
HINT TO HINT: if you do not have soldering flux at hand you can use some clear alcohol (Polish vodka is the best and has so many more uses :-) )

Internal resistance (measured using cheap Chinese multi-meter) of both parts :
- Original green Pentax solenoid: 14 ohm
- DVD ripped solenoid: 26 ohm

Btw. I do not recommend soldering wires midway as this is actually more difficult to do and involves way more solder and heat.

Tools I have used:
- precise screwdrivers set (B&Q 6GBP) with proper size handles
Do not use those small all metal chinese made 'precise' screwdrivers.
Those have small handles and are usually made with some soft steel.
- precise soldering iron set (includes some solder with flux, precise pliers) (Amazon 17GBP)
Either but proper soldering iron or do not buy it at all.
Soldering station available from German shop starting with 'L' won't do as it doesn't have right tip.
Soldering irons available in diy shop do not allow for temperature control and don't have right tip.
- soldering flux (Amazon ~2GBP)
- small scissors (wife)
- third hand (Amazon)

Good luck.

Good job, very interesting post.

Internal resistance (measured using cheap Chinese multi-meter) of both parts :
- Original green Pentax solenoid: 14 ohm
- DVD ripped solenoid: 26 ohm

Somebody here in forum measured the internal resistance of the original 'green' solenoid and it has been about 31 ohms. I have also measured the resistance at solenoid from an old HP DVD drive and it was 14 ohms. This is vice versa to yours measurement. The DVD solenoid is with 'white' plastic body. Does that mean PENTAX used solenoids with different specs ? Can the solenoid with lower resistance damage the output transistor with higher current flowing trough ?

Now back to camera. Desoldered two wires going to solenoid, unscrew it and removed from camera. Put new solenoid in its place and solder the wires to it. I have put both covers temporarily back on and tested camera. It was not working any better. After some deliberation I flipped little magnet in solenoid upside down. And camera spring back to life. I have make about hundred test photos since. All well exposed

Maybe it would be enough to change the wires on the solenoid to change the direction of magnetic field.

I hope that when my K50 dies { I have sometimes first frame black} I can use a DVD solenoid for repair too.

Thanks