[Stone G.]

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!

HI Mangusta,

Thanks for a very helpul and inspiring post! I would assume that your findings may also be of interest for those that encounter similar problems - though perhaps not so frequently - with other models using AA-cells.

Do you happen to have any photographs showing the posisition and the available space for a replacement capacitor?

[Mangusta]

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

[agnes]

Hello all,
I'm new here and I am not used to forums, I did not inroduce myelf as I am not sure to post correctly...
Mangusta, I was so happy to see your post! I did not use my My IST DL2 for some months and now it always shows the "battery empty" sign. Before that I used without problem CR-V3 lithium batteries or rechargeable ones during several years. And I tried pressing all possible buttons during switch on without success.
We (with my husband) are already starting to experiment with caps as you suggested... but a few photos would greatly help! How do you start stripping at the top when all screws are at the bottom?
I'll keep you posted if we manage to start it again!
Thanks for the helpful forum!

[Mangusta]

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.

Attached Images

 

[agnes]

Hello Mangusta,

Thanks for the photo. So far we had no success with the cap. But the only one we had at home (470 uF) is the size of my thumb, and we had to use big wires to connect it to the camera (with a paper scotched into the camera battery lid slit to make the camera beleive the lid is closed), so maybe it was too far from the camera to work correctly (impedance in the wires?) We had only cleps, not soldered wires. That was a saturday night work with what was at hand
Next step we'll try to start the camera with the DC input...

[gp1806]

Hello Mangusta,

Thanks for the photo. So far we had no success with the cap. But the only one we had at home (470 uF) is the size of my thumb, and we had to use big wires to connect it to the camera (with a paper scotched into the camera battery lid slit to make the camera beleive the lid is closed), so maybe it was too far from the camera to work correctly (impedance in the wires?) We had only cleps, not soldered wires. That was a saturday night work with what was at hand
Next step we'll try to start the camera with the DC input...

I have a DL that will not start with any batteries except Eneloops. Works fine on Eneloops, or Duracell rebranded Eneloops (same battery, different label). Have you tried Eneloops?

[UnknownVT]

I have a DL that will not start with any batteries except Eneloops. Works fine on Eneloops, or Duracell rebranded Eneloops (same battery, different label). Have you tried Eneloops?

I think this may not just be one thing.

Mangusta is right - there is a capacitor - that acts like a flywheel determining the battery's status/level -
without a functioning capacitor then the Pentax dSLR probably would not even turn on.

However it also comes down the batteries too.

I believe the Pentax dSLR initialization draws some current from the batteries and measures the voltage.

Even if the capacitor is fine - if the batteries do not manage to maintain their voltage under load for this initial test -
they will still fail to power the camera - or turn on with low battery.

So the solution is two fold - use either Lithium AAs (like the ones supplied with the camera in the USA) or use eneloops (or confirmed re-badges) properly fully charged - if those fail to turn on the camera - then perhaps the capacitor needs replacing.

[Stone G.]

I think this may not just be one thing.

Mangusta is right - there is a capacitor - that acts like a flywheel determining the battery's status/level -
-
-
-
So the solution is two fold - use either Lithium AAs (like the ones supplied with the camera in the USA) or use eneloops (or confirmed re-badges) properly fully charged - if those fail to turn on the camera - then perhaps the capacitor needs replacing.

Ah yes, this is certainly more than one thing: I have tried Energizer lithium AA's only once with succes on my *ist DL - after several futile attempts it finaly "accepted" these cells --- for once only. Next time an until now the camera would not accept them at all. Alkalines never worked either but CR-V3 litium batteries do work - and so do any of the rechargeable NiMH cells that I have tried, (i.e.: not only Eneloops).

So, I am a firm believer in Mangusta's capacitor solution and surely must try it out myself soon.

[GibbyTheMole]

I use the energizer rechargables with an *ist D, K100D, and a K-x, & they work very well. I get anywhere from 400-800 shots out of a charge, depending on screen use, flash, etc.

[Mangusta]

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.

[pixelsaurus]

I haven't had any problems yet with my *ist DS but you never know. I'm interested in knowing whether a tantalum cap could be used as a substitute for an electrolytic cap?

[gp1806]

I haven't had any problems yet with my *ist DS but you never know. I'm interested in knowing whether a tantalum cap could be used as a substitute for an electrolytic cap?

Yes, and Mylar too, as long as the specs for the cap are right. The really tough part looks to be getting inside the camera and installing it.
I never thought much about the DL only working with Eneloops. I wrote it off to Pentax 'battery issues' and moved on, it does still work, so I'm OK with it.

[gp1806]

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.

Could this have something to do with current? I've read that Eneloops have low internal resistance that allows more current to flow at start-up (inrush current). This increase (over other batteries) of available current at inrush would allow a higher voltage.

[agnes]

I managed to start the camera with a huge external capacitor and smaller wires. The trouble started again when I tried to use SMD ceramic caps instead: no way to make them work. These would have been small enough to fit inside the camera, but maybe the impedance was too high.
So finally I took yet another cap (from a broken modem - it is 680 uF but in my trials before I saw that around 350 uF is enough) and kept it outside of the camera, soldered to 2 wires themselves soldered to the battery terminals. When I hold the camera, the cap is above my right hand middle finger.
Now I can use my camera - thanks for the great idea!!!
(Hum, I just hope there are not too many others of these caps ready to break down inside the camera...)

[Mangusta]

Good news Agnes! A 470uF to 1000uF cap should do the job. Try and find a low voltage cap like 5 or 6.3V from a old pc motherboard. They are quite small. The higher you go in voltage rating, the bigger they get and does not offer any advantage in performance, because the camera works on 6V. I found this Tantalum cap on RS Components's website: Vishay | Passives | Capacitors | Tantalum Solid | SMT 85°C |595D108X96R3R2T
It is 6.3V and 1000uF and very small at 6 x 3.5 x 7.2mm. Or this Electrolytic one: RS | Passives | Capacitors | Aluminium | Radial 105°C It is also 6.3V and 1000uF and 8 x 11mm.