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Forum: Pentax K-30 & K-50 04-26-2019, 08:43 PM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
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.
Forum: Pentax K-30 & K-50 04-18-2019, 02:20 PM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
Please show me your data on the 99%(you) and the !%(me). I have heard that 99% of all statistics are made up on the spot. This is an American saying by a noted author, Mark Twain I believe but I could be wrong. We also have a saying in automotive that the problem was the nut behind the wheel. Of course this is not insulting in any way either. I admitted that I was wrong about how this particular solenoid works and I admit that I could be wrong that the solenoid is the only problem but as yet no one has proven it to me. You have never admitted being wrong at any time on this thread and always reply with a condescending remark when questioned and yet, you cannot tell me anything about the voltage that runs the solenoid or at least have not yet. Could it be you are wrong? You should just accept the possibility too. There is nothing wrong with that.
reh321, I did not see the solenoid move at all. I looked through the lens and saw a small spot of light and figured that was the aperture. When I look through my K200 and K7, I also saw that the small spot was the same no matter the aperture so the spot was no indication of how wide the aperture so looking back, I cannot say for sure that the aperture never moved. I shined a flashlight down through the lens and absolutely cannot see the aperture. The only way I can see it on my lenses (sigma 18-200, tamron 15-50) is to remove them from the camera and move the aperture lever. So are you saying the solenoid is supposed to move the aperture lever to the correct opening? I thought photogem would answer that but he never did. Another thing, when I turn on the K7 camera it makes a short kind of swish sound. When I turn on the K50 problem child, I get three or four distinct, rapid knocks. At first I thought it was the mirror but after investigation it is not.
Forum: Pentax K-30 & K-50 04-16-2019, 07:58 AM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
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".
Forum: Pentax K-30 & K-50 04-15-2019, 05:48 AM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
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?
Forum: Pentax K-30 & K-50 04-14-2019, 09:40 AM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
So, no other advise, just "too bad, then something possibly went wrong"? What went wrong was that my K50 started taking black pictures.
Forum: Pentax K-30 & K-50 04-12-2019, 11:30 AM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
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.
Forum: Pentax K-30 & K-50 04-11-2019, 02:28 PM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
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.
Forum: Pentax K-30 & K-50 04-11-2019, 10:24 AM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
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?
Forum: Pentax K-30 & K-50 04-10-2019, 05:11 PM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
I did the reset. I had already updated to the latest firmware. There is no short as indicated by the approximately 32 Ohm reading on the multimeter. As for testing for polarity, polarity is used on power supplies to determine positive and negative. There is no power on a solenoid by itself. The only way to make a solenoid work one way and not the other is for it to have a diode in line with it. There is no diode in either of my solenoids as indicated by having the same reading no matter which post had positive or negative leads on it. I have worked in automotive electrical systems and computers and have repaired circuit boards, etc for over 30 years. The process of replacing the solenoid went smoothly, nothing fell into the camera and everything that worked when I took it apart worked when I put it back together. I have opened up the camera twice more to make sure nothing had gone bad.
Forum: Pentax K-30 & K-50 04-10-2019, 01:06 PM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
I forgot to say that I updated the firmware and tried what a user on another forum did that did not involve disassembly. It was to define the raw/fx button to optical preview, then in manual or av mode push the button 10 to 20 times. He said he did this and pictures usually were good but sometimes not so he repeated the process and after the third time, his pictures were all good. I did this and could hear something inside slamming back and forth with each push. However it did nothing to improve my pictures no matter how many times I pushed the button.

---------- Post added 04-10-19 at 02:18 PM ----------

I do not know how to post pictures but I set the camera on ISO 400. The Av picture of our flower garden in the sunlight was black, the picture in live view was slightly overexposed.
Forum: Pentax K-30 & K-50 04-10-2019, 12:33 PM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
I soldered the wires to the solenoid exactly as they came off the old solenoid. Because they are clamped together near the solenoid, one would have been too long and the other too short to solder the wrong way. After having read results of "black pictures on K50" on Google for hours, I was reluctant to try to use burst because of what the guy who offers to fix them warned not to do this. I put a manual lens on and enabled the shutter and changed the green button to Tav and the camera took nice pictures. Reading this thread I became convinced that the problem could only be the solenoid and I ordered the white one and installed it. The problem was not rectified in auto, scene, P, TV or AV. As it has always worked in auto ISO, that is where I left it. I don't think I have used live view 5 times in the years I have owned the camera until I saw here that it might help trouble shoot my problem. After the white solenoid did not fix the problem, I tried burst mode which did nothing except give me a bunch of black pictures. I tried all the different auto focus modes. I am curious as to why "hopefully not auto" ISO? I went to the Ricoh/Pentax website and was directed to Precision for repair. The sight said they could give an estimate on repairs, just tell the product and model. The estimate was $175 and I didn't even say what was wrong with it. I called and asked if there was a recall because others had the same problem. They said not recall, the solenoid wasn't the only thing that could cause black pictures and if I wanted it fixed send it in and then they would figure it out. I figured out that buying a used F7 and a 2.8 zoom lens for $200 was a much better deal but I would still love to have the K50 working right instead of a manual lens only camera. Thank you people for trying to help me out.
Forum: Welcomes and Introductions 04-09-2019, 01:51 PM  
new dummy
Posted By Ron O
Replies: 5
Views: 358
I just joined today although I have lurked here off and on for years. I started photography with an ME Super, took bunches of pictures but when kids started to appear, I couldn't afford film and developing like I could before. Digital cameras appeared and made a PZ Pentax quite affordable other than film and developing costs. Then I moved to digital with a K1000D and wow, taking pictures was affordable. Since then I gave the K1000D to my sister and bought a K200 which is still my backup. I purchased a K50 and was blazing along the Pentax trail when suddenly, pictures turned black or nearly so. I tried the "white aperture solenoid" fix but it didn't work so I purchased a used K5 and am very happy with it so far. I am from the state of colorful Colorado in the southeast corner where it is not so colorful but what can you do? I want to thank everyone who contributed to the dark picture threads for their knowledge and ideas.
Forum: Pentax K-30 & K-50 04-09-2019, 01:27 PM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
If I go to plus 5, I can get a picture that is only moderately underexposed.
Forum: Pentax K-30 & K-50 04-09-2019, 12:44 PM  
K-50 / K-500 Aperture Solenoid fix (DIY with pics)
Posted By Ron O
Replies: 327
Views: 49,440
I replaced my solenoid with the white version on eBay for $45 but the pictures were still very dark to black. I unsoldered one wire and checked continuity with my fluke multimeter and it was the correct approximately 30 ohms. I resoldered the wire back again thinking it might have been a cold solder joint but it still does not work. Any ideas? It does take brighter pictures in live view but they are not correctly exposed. I have multiple Pentax cameras and like them very much and would love to have my K50 work again. Thanks for your time.
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