[marknorton]

To start, here are some images of the camera with the top cover and lens mount removed.

Camera Top Rear.jpg

From the back, you can see the Digital Signal Processing board protruding up into the top of the camera including the Analog Devices Black Fin DSP and 4 of the 5 Samsung memory chips which form the RAW data buffer.

Running along the top of the camera is the main control board of the camera. This is part of the camera which meters the scene, detects the lens in use and fires the shutter. It’s an M16C processor from Renesas, formerly Mitsubishi, who are the world’s largest supplier of microcontrollers. This processor, type M30624FGPGP, has 256k of Flash EPROM program memory and 20k bytes of RAM.

Because this circuit board runs right underneath the top cover of the camera you can see why there is not enough space for a larger LCD.

The connector to the immediate right of the processor is to the LEDs in the viewfinder, an astonishingly small connector with 30 pins. The circuit board changes level via the red flex print to make space for the shutter speed dial and shutter release and you can see three white connectors at the lower level. These connect to the light metering circuitry, the circuitry in the top cover and to the shutter/motor-wind controller.

Camera Front.jpg

Viewed from the front, you can see the familiar Leica M rangefinder and the vertical adjustment which is accessible through the Red Dot. The adjustment tool locates in the hole and the cam on the tool adjusts the slider up or down.

Sensor Vertical Alignment 2.jpg

The inverted U flex print at the back is the only connection between the “camera” electronics and the image processing electronics, more on this later.

The flex print at the left of the picture connects to the shutter and motor-wind controller and this is used both to supply power (notice the thicker tracks to handle the current required) and control signals to fire the shutter and monitor the wind-on process.

There are some thicker tracks in the DSP flex print as well. Those are probably for the backup battery because, as we’ll see, the DSP gets its own power directly from the battery.

The lens mount is shown removed here. A slot in the lens mount engages with the top cover front edge so it is intended to remove the top cover before removing the lens mount. The lens mount is screwed directly to the front machined face of the casting without using shims.

You can see the lens code detector which appears to be a small circuit board with IR LEDs and photo-diodes mounted on it. It fits into a recess milled into the back of the lens mount. This recess is also painted black to minimise stray reflections.

You can also see here the three metering cells in the floor of the lens throat, the central light metering cell and the flash metering cells (actually photo-diodes) either side.

Camera Top 2.jpg

Viewed from the top, you can see the centre white connector is vacant. This is where the electronics in the top cover of the camera connect.

To the right, you can see the tubular “blue dot” light sensor which appears to be a simple photo-diode behind a light pipe/lens.

M16C.jpg

Here’s a close up of the M16C processor. You can see that the LEDs in the viewfinder are connected directly to the microprocessor. Also interesting is the empty connector at the bottom which connects to at least 4 pins on the microprocessor. These pins are one of the M16C’s UARTS, meaning it would be possible to connect a PC serial port (via a suitable level shifting circuit – NOT directly which will cook the chip). It’s likely this connection is used for diagnosis and calibration during manufacture and repair.

Here’s the complete circuit removed from the camera and shown flattened:

M16C Circuit - Flat.jpg

So this is how this core part of the camera connects to the rest of the camera:

- Left-hand flex: Power, Lens Code detector, Frame Selector detector
- On-board Connector 1: Diagnostic Port
- On-board Connector 2: Viewfinder LEDs
- White Connector 1: Light Metering
- White Connector 2: Top Plate
- White Connector 3: Shutter/Motor Wind
- Right-hand flex: DSP Board