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Treve Kneebone
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 18, 2004 - 09:45 am: | 
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Hi there!
I've just picked up this camera from E-Bay that used to use the PX625 mercury battery.
I've read about the many options that are open to me (Wein, 675 zinc air with o-ring, CRIS adapter, etc.)
I'd like to go down the SR44 silver-oxide button cell route and recalibrate the meter in my QL17 GIII to cope with the higher voltage.
Can anyone advise me how to go about doing this, or point me to an article where this might be explained?
Is there are variable resistor under the bottom plate somewhere? Or would I need to solder in a diode next to the battery compartment?
Thanks for your help.
Treve |
miles
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 18, 2004 - 12:17 pm: |
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Treve,
I found that the two simplest options are:
1) 675 Zinc-air cell with a spacer, e.g. o-ring.
2) Solder a diode on to battery wire. (On some cameras this is not so simple.)
A good manual for option 2) is Frans de Gruijter's at
http://www.rolleiclub.nl/batterijadapterUS.php
Rick Oleson has great information on his website.
http://www.rolleiclub.nl/batterijadapterUS.php |
miles
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 18, 2004 - 12:19 pm: |
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Sorry:
http://rick_oleson.tripod.com/index-27.html |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 18, 2004 - 01:27 pm: |
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I don't know whether the adjustment range of the QL17 meter is wide enough but it IS possible to adjust it.
First, set the variable resistor behind the galvanometer such that you get a linear reading over the full speed setting range. I.e., with constant lighting (and the camera pointing to an evenly lighted object, such as a non-structured wall) the aperture reading should change exactly 1 f-stop as you change the speed setting.
This done, you have to loosen a small set screw on the galvanometer mount. It is located towards the shutter release button and can be accessed with a tiny (and long) screwdriver peeping through the gap between the frame counter and the galvanometer mount. After loosening this screw, turn the galvanometer body such that you get an accurate reading at a given speed setting. You should check this with an accurate handheld meter, or, according to notes you left on the original meter readings with a 1.35 cell.
The battery indicator is NOT adjustable, so you will get wrong reading on the QL17 non-GIII (which shows battery power inside the viewfinder), or the indicator lamp on the GIII will be reliable no more. The latter will also be the case if you use the MR9 battery adaptor or the trick with a Schottky diode. |
Charles Fallis
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 20, 2004 - 03:34 pm: |
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Last time I was in Ritz, which was about a month ago, they had Wein #625 zinc/air cells in stock. I bought a couple of them to test a pair of Yashica Lynx 5000s and they worked fine in one (the other turned out to have a thoroughly dead light meter). |
Frank Scheitrowsky
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 26, 2004 - 02:19 pm: |
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Is it possible to solder a Schottky diode in the power lead from the battery? |
Jon Goodman
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 26, 2004 - 02:56 pm: |
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Yes, definitely you can do this...use a BAT 83 Schottky or NTE585, if that is handier to find. I think you'll find the BAT 83/NTE585 will work fine for meters with a max current draw of around 600 to 700 uA. For a camera with a larger draw (up to about 2 ma), you might try using a BAT 43 or equivalent.
Jon |
miles
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 26, 2004 - 08:37 pm: |
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I found another good article on how to solder a diode inline with a wire from the battery. It discusses the error inherent in any recalibration.
See,
http://olympus.dementia.org/Hardware/
Look near bottom for article on OM1 by Tim Hughes. |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 27, 2004 - 03:53 am: |
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On the Canonet QL17-GIII (with battery indicator light) the battery check will not work correctly with a Schottky diode since the bulb draws several mA and thus causes larger voltage drop. |
Stuart Willis
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 30, 2004 - 07:24 am: |
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You don't need to go a complicated recalibration route. Provided you have a physical-fit Silver Oxide cell - all you need to do is drop its voltage to that of the Mercury cell.
Silver Oxide cell yields 1.5v.
Mercury cell yields 1.35v.
The easy fix is to series solder a germanium diode into the battery hot wire lead. The voltage drop across the germanium will ensure that the camera sees the voltage it expects.
Tip. My experience is that germaniums from Tandy/Radio Shack - have voltage drops all over the place. Goto a specialist electronics components supplier and pay 2 cents more.
It is conceivable that the copper cores of the battery leads may be black wire corroded and thus unsolderable. This is typical of Mercury cell powered cameras. In such case you will have to replace the entire length of wire.
Also - the battery compartment terminals on most Mercury cell powered cameras are of stainless steel rather than the usual tinned copper alloy.
You will need to use common plumber's solder and flux in order to tin the contacts. It cannot be done with electrical resin-core solder and an instrument iron. The trick is not to remove the existing tinning from the contact.
Hope this helps
Stuart Willis
[email protected] |
