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Andreas Berg
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 12, 2004 - 07:02 am: | 
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I just bought an exposure meter from Gossen called Polysix. I think i dates from the late sixties. The measuring angle can be adjusted between 10 and 30 degrees (nice!), and it has a small viewfinder. It obviously needs adjustment (indicates about 2-3 stops less expousure than other meters). Does anyone know how to do this? On the underside, there are two sealed screws - perhaps for adjustment of the high and low sensitivity ranges?
I also opened it and took a quick look inside. I found four or five potentiometers, all unmarked. I could, of course, take the road of trial an error, but if anyone knows how to make the adjustments, I would be most thankful. |
Christian
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 07:06 am: |
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Mine behaves alike. If you, or someone else has found out by now how to adjust the beast, please contact me.
Regarding the potentiometers I thing there are 2 which are candidates for adjustment. The other 3 near the transistor seem to belong to the comparator not to the bridge, so keep away from them.
I think that the 2 ranges (red and green) must be adjusted separately. With my meter under certain light conditions I can't bring both bulbs to light ( the green is over and the red range is under). |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 10, 2005 - 10:33 am: |
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The Gossen -----six series usually have five potentiometers associated with calibration/indication. There is a pair for the high range, a pair for the low range and one for the battery test indicator.
for an indication of what is involved, go to the Camera Article section and scroll down to the bottom. There you will find a link to a French site that has details of a Lunasix calibration.
Meter dates from 1968 and appeared in mark 1 and 11 models. I do not know what the differences are between the original and updated models.
I have no knowledge of the circuit of this meter, but have found that a bit of gentle tweaking of the pots of the -----six series soon identifies which is which. You need to do this with the meter pointing at a light source relevant to the range in question.
On a general note; Gossen hold spares only for the Black Body Lunasix. They do not service or repair the grey type. I do not know what the situation is for the less popular types of analogue meter they produced. |
Christian
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 11, 2005 - 07:23 am: |
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Hi Glenn
Thank you for the very useful information about Lunasix.
Anyway Polysix has a different system. It has a build in gray ramp transparent which controls the restistence of the cds below which is in turn compared with a fix resistor value (actually a small potentiometer). The comparator is transistorized with own pots. So there have to be just 2 resitors, one for each range.
The comparator design makes the whole thing voltage independant, so there is no problem with wrong or weak batteries.
This is quite different from Lunasix where us have an analog meter. Polysix is (rather) digital, it tells you the right value on the dial when both lamps light. So the gradient of the curve makes no sense to adjust, except for smoothness of transition of the 2 lights.
When I find make some experiments soon and when I find out more I will post it here |
glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 11, 2005 - 11:02 am: |
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Christian,
Thanks for that info,it has let me identify some repair notes I obtained a while ago.The pages came out of a loose leaf note book and did not identify the meter.I now have the notes nearly complete - it looks as if there should be a page of circuit notes and adjustment procedures! I will have a good look through the boxes this weekend and let you know. The notes originally belonged to a late friend who had a camera repair business.He was very meticulous in his note keeping and if he had repaired a Polysix I will have a diagram - somewhere!
Glenn |
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