photo4ls
Well-known
Just got the Canonet 28, put in a new 625
battery and it seems everything works ok
except the meter:bang:. Is there a quick fix for this
or should I send it out for repair ?
Nelson
battery and it seems everything works ok
except the meter:bang:. Is there a quick fix for this
or should I send it out for repair ?
Nelson
Murray Kelly
Well-known
I have a working Canonet-28 but no mercury cell (1.35V). With a silver cell (1.55V) the camera will obviously underexpose. I am going thru recallibrating it.
Now, on auto, the meter deflects and as you press the button a clamp grabs the needle and sets the shutter speed/stop combo. The camera will default to 1/30th off auto or with no needle deflection, for whatever reason - no battery or no light. If the meter is burned out then it must be replaced. There's a few wires between the battery holder and the meter (including a switch when you go to auto) so the problem could be some poor joint betwixt the battery/meter. Top and bottom off. Look for dirt or corrosion.
It's easy to reverse any other battery - I've done it - but all that happens is the needle won't move. No harm done. Since I don't have the mercury cell I can only imagine you can't do that by the construction of the holder.
I couldn't find a lot on the 28 as the QL-17 is most popular but there is a circuit diagram which is way more complicated than the plain 28 which looks to me as if it is a microammeter in series with a CdS cell and a small (1.5K) trimmer up top, behind the meter itself. Will take a lot of Googling but it's out there.
Cheers
Murray
Now, on auto, the meter deflects and as you press the button a clamp grabs the needle and sets the shutter speed/stop combo. The camera will default to 1/30th off auto or with no needle deflection, for whatever reason - no battery or no light. If the meter is burned out then it must be replaced. There's a few wires between the battery holder and the meter (including a switch when you go to auto) so the problem could be some poor joint betwixt the battery/meter. Top and bottom off. Look for dirt or corrosion.
It's easy to reverse any other battery - I've done it - but all that happens is the needle won't move. No harm done. Since I don't have the mercury cell I can only imagine you can't do that by the construction of the holder.
I couldn't find a lot on the 28 as the QL-17 is most popular but there is a circuit diagram which is way more complicated than the plain 28 which looks to me as if it is a microammeter in series with a CdS cell and a small (1.5K) trimmer up top, behind the meter itself. Will take a lot of Googling but it's out there.
Cheers
Murray
photo4ls
Well-known
Thanks Murray,
I think maybe I will try to find the Mercury cell
to fix my problem since I am using the silver cell.
The needle will move down when I press the shutter,
therefore it appears the meter may have some
life left in it. Will let you know how the mercury cell
works once I get hold of one.
Nelson
I think maybe I will try to find the Mercury cell
to fix my problem since I am using the silver cell.
The needle will move down when I press the shutter,
therefore it appears the meter may have some
life left in it. Will let you know how the mercury cell
works once I get hold of one.
Nelson
Murray Kelly
Well-known
Don't go crazy on a mercury cell until you're sure the meter mechanism is OK. I have seen some outrageous prices for Hg cells.
If the meter moves down a bit it's either the battery is in backwards (unlikely but possible) or what you are seeing is the needle being grabbed by the clamp just before exposure. I'ts a mechanical thing, and I noticed it on mine but thought it was unique - perhaps not?
Get readings with the silver cell before you jump. The cell can be 2-3x the price you paid for the camera!
Murray
If the meter moves down a bit it's either the battery is in backwards (unlikely but possible) or what you are seeing is the needle being grabbed by the clamp just before exposure. I'ts a mechanical thing, and I noticed it on mine but thought it was unique - perhaps not?
Get readings with the silver cell before you jump. The cell can be 2-3x the price you paid for the camera!
Murray
FallisPhoto
Veteran
Well, I'm not sure whether you mean that the meter doesn't work at all or that it is giving you incorrect readings. In the event that you mean the readings are off:
Are you using a Wein cell or are you using a 625 silver or alkaline battery? If you are using the alkaline battery or the silver cell, you are not going to get accurate meter readings because they deliver 1.5 volts instead of 1.35 volts. There are a number of solutions to this problem, but I think the simplest is to make an adapter out of a 625 Wein cell or a 625 alkaline cell.
If you look closely at the battery, you will see that it is a smaller cell that has been force-fit into a metal shell. If you dig or cut the smaller button cell out of the shell, ream the plastic insert a bit so you get a looser fit, and drill a small hole in the bottom of the shell, you can use it as an adapter that will let you use commonly available and cheap 675 hearing aid batteries in it. 675 zinc/air hearing aid batteries do supply the correct voltage.
If you are using an alkaline cell, be sure to discharge the battery overnight before cutting on it. Then use rubber gloves and eye protection. The cells contain a very caustic substance that can and will burn you. It is quite a lot stronger when the battery is not discharged.