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Help on a *IST DS - It sets continuously aperture

DIY
Posted 04/03/2012 - 21:00 Link
Hello, my *IST DS, as soon as I turn it on, starts to set the aperture continuously at a rate of about 1 setting for second, and does not stop until the camera is on, all control buttons seems to have no effect, so I cannot use menus, or review images shooted, however the camera shoots correctly if I press the shutter release button.
Images are well shooted but I cannot see them as normally by pushing the review button, it is possible only inserting the SD card in the PC.
I tried to change lens with several others, to turn on camera without lens, to change batteries (well charged), to update the firmware (now 2.02), to well clean lens and camera contacts but the camera continues to set noisy the aperture, as long as it is on.
I tried to turn camera on keeping shutter release button pressed (it is a reset mode?) but no results.
Some ideas about?
Greetings

Giovanni
Edited by DIY: 04/03/2012 - 21:11
Adqam
Posted 06/03/2012 - 13:44 Link
Giovanni, it's not exactly clear what you mean by "set the aperture continuously". You mention that it's noisy, which sounds like you mean that the aperture ring is actually being stepped down constantly? When looking through the viewfinder, do you see the image getting darker when it happens?

If so, it sounds like you may have a problem with a stuck button or microswitch. In particular, the on/off lever has a third position, marked with an aperture symbol, that does step down the aperture - I wonder if the switch that this triggers has been stuck down, meaning that all the while your camera is on it is doing this?

One answer might be to try and un-stick the switch, if this really is the problem. I have heard that people have solved similar problems with the control dial by using isopropyl alcohol or the like to clean the contacts - however, please be very careful with this as it would be quite easy to damage the camera! I don't know if it might be possible to take the camera apart and mechanically clean the troublesome component?
DIY
Posted 06/03/2012 - 15:26 Link
Hello Ad, in effects the lens used has no aperture ring, however I noticed in the last days that, inside the lens mounting hole, the small aperture control lever moves from one stop side to the other side quickly and repeatedly, until the camera is turned on.
I think to exclude a defect on-off-aperture control lever, because when I put it in the "aperture control" position, the problem stopped but it restarted when I have released that lever.
Today I turned on the camera and **"miracle"** the camera not started as usual to have that problem, I have used the menus in order to reset the function to factory settings, but I think that the problem is still there, because I noticed that the display lights up sometimes without any apparent cause.
It seems to me that there will be some defective contact in the camera's supply circuits, is like the power supply is removed and reconnected quickly many times.
Mannesty
Posted 06/03/2012 - 17:34 Link
I would try using only one battery in the body, then the other, to see if you have a faulty battery problem.
Peter E Smith - flickr Photostream
DIY
Posted 06/03/2012 - 18:46 Link
Hello Peter, the camera uses four AA type batteries or 2 CR-V3, as I use to do. The batteries seems not to be wired in parallel, because the camera does not turn on with only one battery in the body, in one slot or other. Also, considering that each CR-V3 battery has a nominal voltage of about 3,7V, and that the external DC power supply is 6,5V, I think that they are wired in series, to supply the required voltage.
Edited by DIY: 06/03/2012 - 18:46
Mannesty
Posted 06/03/2012 - 23:22 Link
My apologies, I totally forgot that the DS uses AA cells, and you are correct, they are wired in series to provide a nominal 6V (4 x 1.5V) with Alkaline cells.

Have you tried a fresh set of batteries? It's probably worth buying a set of 4 Duracell Ultra's or similar just to eliminate battery issues.
Peter E Smith - flickr Photostream
Adqam
Posted 07/03/2012 - 18:18 Link
Suggest lithiums as best batteries to use when trying to eliminate such issues - they are the recommended disposable for Pentax cameras, and are much more stable.

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