viewfinder – Experimental Engineering

Posted on November 22, 2016October 16, 2019 by The Engineer — 1 Comment

Panasonic NV-M5 CRT Viewfinder Hack

The old Panasonic NV-M5 has the standard for the time CRT based viewfinder assembly, which will happily take a composite video signal from an external source.

This viewfinder has many more connections than I would have expected, as it has an input for the iris signal, which places a movable marker on the edge of the display. This unit also has a pair of outputs for the vertical & horizontal deflection signals, I imagine for sync, but I’ve never seen these signals as an output on a viewfinder before.

Luckily I managed to get a service manual for the camera with a full schematic.
This unit takes a 5v input, as opposed to the 8-12v inputs on previous cameras, so watch out for this! There’s also no reverse polarity protection either.

Making the iris marker vanish from the screen is easy, just put a solder bridge between pins 15 & 16 of the drive IC. The important pins on the interface connector are as follows:

Pin 3: GND
Pin 4: Video Input
Pin 5: Video GND
Pins 6: +5v Supply

Posted on April 12, 2015October 16, 2019 by The Engineer — Leave a comment

Another Viewfinder CRT

Here’s another viewfinder CRT, removed from a 1980’s vintage VHS camera I managed to get cheap from eBay.

This unit is very similar to the last one I posted about, although there are a few small differences in the control circuitry.

Viewfinder Schematic – Click to Embiggen

Here’s the schematic, showing all the functional blocks of the viewfinder circuitry. An integrated viewfinder IC is used, which generates all the required scan waveforms for the CRT.
On the left is the input connector, with the power & video signals. Only pins 2 (GND), 3 (Composite video), & 4 (+8v) are needed here. Pin 1 outputs a horizontal sync signal for use elsewhere in the camera, while pin 5 fed the recording indicator LED.

To make connection easier, I have rearranged the wires in the input connector to a more understandable colour scheme:

Red & Blue for power input, & a coax for the video. For the video GND connection, I have repurposed the Rec. LED input pin, putting a shorting link across where the LED would go to create a link to signal ground. Keeping this separate from the power GND connection reduces noise on the CRT.

Here’s the complete assembly liberated from it’s plastic enclosure.

Closeup of the control PCB. The 3 potentiometers control the CRT brightness, focus & vertical size.

The tiny CRT. Only ~60mm in length, with an 18mm screen size. This tube runs on +2294v final anode voltage. Much higher than I expected.

The electron gun assembly, with the cathode, focus & final anode cups.

This screen is just a little bigger than a UK 5p piece! A marvel of precision engineering.

Posted on September 14, 2011October 16, 2019 by The Engineer — 10 Comments

Camcorder CRT Viewfinder

Here are the viewfinder electronics from a 1984 Hitachi VHS Movie VM-1200E Camcorder. These small CRT based displays accept composite video as input, plus 5-12v DC for power.

Here is the front face of the CRT, diameter is 0.5″.

Closeup view of the PCB, there are several adjustments & a pair of connectors. Socket in the upper left corner is the power/video input. Pinout is as follows:

Brown – GND
Red – Video Input
Orange – +12v DC
Yellow – Record LED

The potentiometers on the PCB from left:

H. ADJ
V. ADJ
BRIGHT
FOCUS

PCB Part Number reads: EM6-PCB

This unit utilises the BA7125L deflection IC.

Reverse side of the PCB, very few SMT components on this board.

Here is an overall view of the CRT assembly with scan coils. Tube model is NEC C1M52P45.

Closeup view of the CRT neck, showing the electron gun assembly.

The old CCTV camera used to feed a composite signal to the CRT board. Sanyo VCC-ZM300P.

Connections at the back of the camera. Red & Black pair of wires lead to 12v power supply, Green & Black pair lead to the CRT board’s power pins. Seperate green wire is pushed into the BNC video connector for the video feed. video ground is provided by the PSU’s ground connection.

Finally the connections at the CRT drive board, left to right, +12v, Video, GND.

Display taking video signal from the CCTV camera.

Posted on March 4, 2011February 11, 2011 by The Engineer — Leave a comment

Vivicam 5190

A 5 megapixel digital camera from Vivitar. Visible here is the lens, viewfinder & flash.

Rear of the unit showing the LCD & user control buttons.

Front frame removed showing some of the internals. Shutter assembly & lens in centre, battery compartment at left.

Rear frame removede, showing the LCD module & tactile switches.

LCD module removed from the PCB

Flash PCB removed. Transformer is fed with the 4.5v from the 3 AA cells & steps it up to ~300v DC for the flash capacitor. A pulse transformer energizes an electrode next to the Xenon flash tube with ~5kV to ionize the gas.

Main PCB removed. Internal flash ROM & RAM IC visible above the SD card socket. USB connector is at the top right, next to the piezo buzzer.

Main processor on reverse side of the PCB.

Closeup of the CMOS image sensor with the lens assembly removed.