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Forum: Pentax DSLR Discussion
07-03-2011, 12:19 PM
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Forum: Pentax DSLR Discussion
06-29-2011, 02:26 PM
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I have found the following: If you take the very same 4 AA batteries that the ist says are empty, and you connect them in series and connect to the 6V dc input at the side of the camera, the camera starts up every time and does not complain. I am therefore sure that the internal circuit where the battery and DC input connects, differs. I am not sure what type of capacitor the circuit uses, but it is a fact that Electrolytic capacitors degrade with age. They have thin oil inside which can dry out. This happens many times in swithcmode power supplies in TV's and VCR's. The reason some batteries perform better at switch-on, is that they just have that marginal less voltage dip at the moment of switch-on. :cool:
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Forum: Pentax DSLR Discussion
06-26-2011, 03:00 PM
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Hi Agnes
I must warn that it is very difficult to strip and assemble the camera without breaking something else. Another option is to not open the camera and solder 2 thin wires to the battery terminals and connect them to a capacitor or two and insert these in between the small space between the batteries. The space is much smaller than available inside. The 4 batteries are all in series, so that is 6 Volts. Look at the foto I added. The 6V negative terminal is the one top right, and the positive terminal bottom right. Find capacitors which voltage rating is not higher than 5 or 6V, because the lower the rating, the smaller they are. But their Microfarad rating (capacity) should be as high as possible. Surface mounted type capacitors are also smaller. One can put capacitors in parallel to double their microfarad rating. I did this experiment and it worked for sure. Any good electronic technician will agree that adding a capacitor will enhance any battery's momentarily performance at the switching on of the camera, as a capacitor works much the same as a flywheel. If you cannot get the camera to work and cannot add the capacitors, you can use a small 6V battery pack and connect it with a lenght of wire to the camera's 6,5V DC input, and put the battery pack in your pocket or attach it to your belt. This method should also help your camera's internal circuitry to recover again after it hasn't been used for some time, and you might find that normal battery performance will return. :cool:
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Forum: Pentax DSLR Discussion
05-24-2011, 07:42 AM
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A few photos is a good idea. Only problem is, my camera cannot photograph itself! But I will use another camera and post the photos.
Mangusta:)
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Forum: Pentax DSLR Discussion
04-07-2011, 09:49 AM
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I agree that batt contacts can become dirty and should be cleaned, but with the ist DL, if you remove and install the same batteries 10 times in a row, you will get about 5 different readouts from die batt indicator. The camera's batt contacts are goldplated, and should not need cleaning, but if need be, be very carefull. Moisten an earbud with small amount of contact cleaner and gently rub contacts.
The ist DL also has a power jack input on it's side. You can use the same batteries which gives the low batt message, connect them in series and connect to the jack, and it will give a consistant batt full message.
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Forum: Pentax DSLR Discussion
04-06-2011, 10:20 AM
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Hi Widleaf
Sorry for the delay, I was away for a while. To answer your questions:
1) Some batteries has a better "flywheel effect" than others. As I have explained, the microprosessor only takes samples of the batt voltage now and then. It is more concerned about the sudden drop in batt voltage when it is switched on than in a steady state lower voltage, which it should not be. By pressing another button when switching on, it seems that this sudden drop is cushened out a bit.
2) This is the same issue.
3) Capacitors is widely found in many electronic devices, equipment and electronic shops.
A cap will give that flywheel effect to filter out that sudden voltage drop. It should have it inbuild, and I am sure it has. I have add a small 470uF 6.3V Electrolytic cap to my ist DL by soldering it to the battery contacts inside the camera. The space is limited. The cap's fisical size is determined by it's uF value and its voltage rating. One should not go lower than 6V which is the battery voltage. One can go higher than 470uF if it will fit, or connect 2 of them in parallel. Polarity is important. A Ceramic type cap has the least leaking current, but the highest uF value it comes in is about 100uF, but one can connect as many as you like in parallel. Look for GRM series. I am not sure what the lowest uF value is which will cure the problem, but I would suspect a 100 to 220uF.
Bigest problem though are to open and close the Pentax without breaking or losing something. Some tips: The cap or caps must be added at the top of the camera where the batt contacts are, so start stripping at the top. And mark or document every screw's position. There is some unused space in the camera between the batteries. One can use 2 thin insulated wires from the battery terminals to mount the cap remotely and glue them to the plastic. Hope this helps!
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Forum: Pentax DSLR Discussion
01-08-2011, 07:28 AM
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I am an electronics engineer. I will gladly share my knowledge for free.
I have just bought a 2nd hand ist DL and have also experienced the battery "empty" problem. I have plugged a 6V, 4.5Ah sealed lead acid battery into the DC input terminal, and the camera worked fine. I then connected the same battery to the contacts where the AA batteries are inserted. It gave the same "empty" display. I then connected a 2200uF capacitor over the battery terminals, and it displayed battery full and the camera worked. It also works with AA batteries with the cap.
What happens here is that the camera draws a lot of current for a split second when it is switched on. It causes the battery voltage to dip for that split second to just under the low battery threshold, which is measured by it's micro processor. It decides that the battery is too weak to switch the camera on.
The capacitor works like a flywheel in which energy are stored. It can supply enough current for that split second so that the voltage does not dip too low.
I suspect that the internal capacitor is not doing it's job anymore. If it is a electrolytic cap, they tend to dry out if it is of poor quality.
The solution is to open the camera and find the cap and replace it, or to leave the original cap where it is and find a small space to just solder in a new cap in parallel with the + and - battery terminals. I have not determined yet what minimum capacitance is needed to solve the problem. It's voltage need not be higher than 6V. The size of a capacitor is determined by it's voltage and Farad value.
It will be difficult for non electronic or practical people to do this mod. I will be able to do it for a fee, but lives in South Africa, and I do not know what shipping will cost. I will be on holiday this coming week, so it will not help to write to me.
Shalom
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Forum: Pentax DSLR Discussion
01-07-2011, 04:07 PM
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:cool:Hi guys
This is my first writing to this forum. I was searching Google to find out if other people also experience this problem. I am an electronics technician, and have found out what exactly causes this problem. So, if there still people out there struggling, let me know and I will help.
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