[reh321]

Okay, I can see I was wrong about how this solenoid works. I hooked it up a 6V battery and one way was stronger and the other way was weaker, so I deduce that the solenoid is working correctly. What now? And why does the lens aperture work in live view?

There are several reports here of cases where LV and viewfinder exposure differ, such as
K30 Liveview Vs Viewfinder Differences - PentaxForums.com

Member @RedSky sent his in for repair - they did the standard repair for aperture control issue ..... and it still didn't work right
TWO K-50s giving me the same error !!! Pentax is no help. HELP!! - PentaxForums.com

I believe that some of these cameras have a different issue .... one involving metering {light is measured differently when you take an LV photo as compared to when you take a photo using the viewfinder}. @RedSky got the usual 'help' here - everyone thinks of aperture control first, second, and third, but not all exposure issues are due to that problem - and eventually left in frustration. That is why I suggest that people use a very constrained approach - fixed ISO with Av mode - and record the shutter speed requested in LV and in viewfinder mode. If the shutter speed requested is significantly different, then it is actually a metering problem.

[photogem]

Best way is to go step by step:

1. sand/grind the green solenoid, built it in and test.
if the same results... too bad.. then something possibly went wrong

2. if all the sudden it works, something wrong with the white solenoid

make sure polarity is really right!

[Ron O]

photogenic, in your post to me at first you just said check polarity which the only way I knew was to make sure the wires were soldered on the correct post and they were, beings they were the power wires and you cannot get them wrong on my k50 unless you remove a clamp that holds the two wires together. They were also identical to the pictures posted by you. I did not know that the solenoid works like it does. In a later post you told another member that you told me how to check it which had to be by testing it with a battery because that was the only other instruction other than to grind the green solenoid.

---------- Post added 04-11-19 at 03:56 PM ----------

reh321, the same scene taken with live view was 1/50 at 2.8, 1/2500 at 2.8in av, both at ISO 400.

---------- Post added 04-11-19 at 04:16 PM ----------

I took a picture of the same scene with the same lens at 2.8 and ISO 400 on my K200 and shutter speed was 1/3000.

[reh321]

reh321, the same scene taken with live view was 1/50 at 2.8, 1/2500 at 2.8in av, both at ISO 400.

I took a picture of the same scene with the same lens at 2.8 and ISO 400 on my K200 and shutter speed was 1/3000.

So you took three photos of the same scene using the same lens?
(1) K-50 LV: ISO=400 aperture f/2.8, shutter 1/50
(2) K-50 viewfinder: ISO=400 aperture f/2.8, shutter 1/2500
(3) K200 viewfinder: ISO=400 aperture f/2.8 shutter 1/3000

What did the three photos look like?

[Ron O]

This is according to data from the pictures themselves, the LV picture at 1/50 at 2.8 and Iso 400 was good; the picture in AV mode at 1/2500 was completely black and the picture from the K200 with all the same settings with a shutter speed of 1/3000 was very nice. When I went to manual mode with the K50 and used a shutter speed of 1/50 the picture was acceptable but in bright sunlight, 1/50 sec. at 2.8 aperture and ISO 400 seems completely wrong.

[EricTielen]

I did the repair myself today… everything went very well. I had bought the spare solenoid via a german ebay seller. Its the white quality and no grinding needed at all. My camera is functioning like a new one. I am very pleased. Thanks for all the feedback here together with the manual this german guy send me in pdf (english) the job was not really hard. Good tip print out the pictures of screwholes and attach the screws on the paper with doublesided carpet tape. If anyone wants the link to the ebay seller let me know. The price i payed was about 50 or 60 euro.

[photogem]

Well done Eric!


How I do it: l glue the photos onto 3mm hardboard (high-density-fiberboard) and then to drill 2mm holes for just sticking the screws in there.

But if one has to do it once, of course doublesided carpet tape is pretty straight forward.

[MarkJerling]

I did the repair myself today… everything went very well. I had bought the spare solenoid via a german ebay seller. Its the white quality and no grinding needed at all. My camera is functioning like a new one. I am very pleased. Thanks for all the feedback here together with the manual this german guy send me in pdf (english) the job was not really hard. Good tip print out the pictures of screwholes and attach the screws on the paper with doublesided carpet tape. If anyone wants the link to the ebay seller let me know. The price i payed was about 50 or 60 euro.

Feel free to post the link here.

[Ron O]

So, no other advise, just "too bad, then something possibly went wrong"? What went wrong was that my K50 started taking black pictures.

[reh321]

So, no other advise, just "too bad, then something possibly went wrong"? What went wrong was that my K50 started taking black pictures.

Your experience doesn't make any sense to me

This is according to data from the pictures themselves, the LV picture at 1/50 at 2.8 and Iso 400 was good; the picture in AV mode at 1/2500 was completely black and the picture from the K200 with all the same settings with a shutter speed of 1/3000 was very nice. When I went to manual mode with the K50 and used a shutter speed of 1/50 the picture was acceptable but in bright sunlight, 1/50 sec. at 2.8 aperture and ISO 400 seems completely wrong.

Since the LV at 1/50 gives a good photo, but using viewfinder at 1/2500 gives dark results, I would say that the meter in the prism housing is faulty. Having K200 {1/3000} and K-50 {1/2500} viewfinder settings be very close - but results be completely different - makes no sense at all.

[photogem]

So, no other advise, just "too bad, then something possibly went wrong"?

Who wrote that? I missed that.

What went wrong was that my K50 started taking black pictures.

That I do remember, also that you actually got advice.

Did you grind the plunger of the green solenoid and built it in?
Did you watch the solenoid of your K50 in action (i.e. open)?

those where some hints I gave you to try out, but no response yet (at least in that direction).

I mean you where able to take the white solenoid out and test it for polarity.

To follow my advice up then and to reinstall the green one would have been 5 minutes more work???

[EricTielen]

Solenoid f Blendensteuerung Pentax K30, K50, K500, K-S2, S1, K70 in Saarbrücken - Saarbrücken-Mitte | Digitalkamera & Zubehör gebraucht kaufen | eBay Kleinanzeigen


Here is link to good solenoid, I hope.
Ordered it, replaced the Green, and my camera functions well.

Gr eric

[Ron O]

photogem, see post 287 for quote. My green solenoid is much tighter than the heavily used ones in photos on this thread. When tested for polarity, it releases and gets harder to release depending which way the battery is hooked up, just like the white one. Under high magnification, the inside of the coil, the green plastic shows no sign of wear and the wear pattern on the holes in the solenoid shows no evidence of tipping. Why do you suggest putting the green solenoid, which you say is the only cause of the problem, back into the camera, when you said the only real answer is the white solenoid? You, yourself have warned against grinding saying it might cause terminal problems. I am also hesitant to keep bending the wires to the solenoid to solder them as small wires tend to break after being bent a few times. I followed the instructions in this thread to replace the solenoid very carefully, had no problem soldering the wires back, tested both solenoids under the same condition and all I have is $45 less in my pocket and a camera that still takes black pictures. Does the solenoid use different voltages for different apertures or does the solenoid just release and allow the the aperture to move? What should the voltage be?

[photogem]

First open the camera and check if the solenoid works!

If it doesn't work: Then you have the option for a short try to check with a sanded green solenoid.
Just to see what happens, using it a short time will not do any damage.

If then the K30 works, something is wrong with the white solenoid. What, no idea.
Impedance alone is not all that counts.

And yet, even if one thinks one did follow all instructions well, it is as with taking good photos:
The problem usually sits behind the camera.

[Ron O]

The solenoid has never moved, the aperture has never moved. It seems stuck shut.. Live view has to expose at 1/50 instead of 1/2500 to get an acceptable picture. The green solenoid sanded did not change anything and your insulting is not appreciated. The representative at Precision, the authorized Pentax repair told me that the aperture is not the only thing that causes dark pictures but you insist your knowledge goes beyond theirs. I have no doubt that the white solenoid is an improvement over the green and that people have fixed a problem with dark pictures by changing solenoids. I also know that diagnostic trouble codes in vehicles identify parts that are not working according to specifications but that replacing the part is sometimes not the problem, it is the wiring, back feed from other sources, etc. You have the attitude that you know everything about the problem and if your solution does not fix the situation, it is someone else fault. When I ask what kind of power goes to the solenoid and whether it just unlocks like the flash solenoid or holds different positions, all I get is the same drivel. Does anyone know? Does it use a duty cycle to hold position? variable voltage? Or does the solenoid just lock it in place. If it moves the aperture, does anyone have specifications like f8 at 4.1 volts or f8 at 30% duty cycle? I have followed all photogem's suggestions and what I have gotten so far is -$45 and "The problem usually sits behind the camera".