Inside a Leica CL Metering Device

The meter needle of my Leica CL wasn’t moving at all, so I decided to take it apart and see what the problem was.

As it turns out the metering device, a galvanometer, is broken. When measuring the resistance of the coil, which should be around 3.8kΩ, I get an open circuit. This means that somewhere inside there is a wire that is disconnected, and I decided to take the galvanometer apart and try to repair it. Here are some pictures of the disassembling process and of what’s inside the galvanometer.

 

We want to remove the linkage for the shutter speed indicator. Put the shutter dial on the B position and unscrew that top screw that holds the spring in place.

Before you remove the arm, loosen the screw in the red box, till you can move the metal piece on the right. Then gently remove the arm.

Remove the two screws that keep the metering device arm in place

Notice that there are two metal pieces that come off

Gently remove the arm

Unscrew the two screws that you see on the left of where the galvanometer was, and gently remove that device (you will need to desolder the wires from it)

If you unscrew one of the screws on the side of the galvanometer, you can pop the lid off

Before you can remove the coil from its inner housing (that C shaped brass piece with the silver magnet in the middle) you will have to desolder the two hairsprings

This hairspring, and the other on the other side of the coil, provide the spring action for the coil, while also functioning as the electrical contact between the ends of the coil and the outside contacts

As you can see, the hairspring is very small, you will need tweezers, a loupe (or better a microscope), a good soldering iron and a lot of patience

The red arrow points to one of the ends of the coil that attaches to the contact. In my case, both the ends of the coil had to be re-soldered to their contact. It’s a painful and slow process, and if like me you don’t have a microscope and a good SMD soldering iron, it is very much a difficult and trial-and-error process. You will need time and patience.

After several attempts, the coil is connected to both contacts, and the contacts are connected to the hairsprings. As you can see, that soldering spot where the hairspring connects is NOT a good joint, but that’s as good as it gets with my limited tools. To have a nicer and more secure joint you will need a microscope, good tin, flux, and a SMD iron.

The coil back in its frame! After hours of work the galvanometer is finally working again, and can be reassembled and reinstalled on the camera.

The whole process is a delicate and painful one, unless you own a stereo microscope and a good SMD soldering iron. If you contact Leica they can send you the spare part, but it takes 3 weeks to come from Germany (they don’t repair Leica CLs in  USA) and it costs more than $80.