Stopping the blinking OSD (on-screen-display) on Panasonic WV-F15 camera

The page describes modifying the circuitry of a camera, the risk of doing this is all yours, do not attempt this if you're not proficient at electronics.

Do you still use Panasonic's F15 cameras from 1991, and are annoyed by the blinking OSD (on-screen-display)?  Then here's several ways to deal with it:

Rather obviously, you could simply put an AAA battery into the side hatch, and you won't see “BACKUP” blinking at all you all the time.  You'll still see the other status messages, which might be useful to you.  But then you'll be faced with replacing the battery every few months, and cleaning up the mess when you forget.  And a few of those status messages are more annoying than they're useful.

Quite why they put that memory battery in there, I don't know.  It can only hold the white balance memory while the camera is on standby.  As soon as the power is off, it loses the memory.  So why bother to put a battery in?  The memory circuitry could have remained powered on in standby.  Other cameras have a battery that keeps the white balance memory all the time, even when the camera is fully powered down, so you only need to re-white-balance when the lighting conditions change.  Only the badly designed cameras need to be re-white-balanced for other reasons (temperature drift, or general instability in the camera).

You could, possibly, if you worked out the right value, run a resistor from the 12 volt supply to the battery terminals, or the output from a 1.5 voltage regulator, to make the camera think that there was a battery in there.

You can modify the camera or the viewfinder, and disable the OSD completely, but then you lose the other status messages (SES for the high speed Strobe Effect Shutter, low light warning, white balance warning, recording and tally).  You might not care about them, so I've written two ways of doing that, below.

The OSD is a separate signal that will be mixed with the picture, outside of the camera head.  The zebra pattern is supplied in two ways:  It's added to the video signal in the camera head, and supplied to the viewfinder, ready-made.  It's also supplied as a separate signal, mixed with a vertical blanking pulse, and the tally signal voltage (I can't see the point in separately adding the zebra to another pin, since it's already inserted in the viewfinder's video signal).  I presume that the small one inch eyepiece WV-VF02 viewfinder has a mixer circuit in it to combine the video and superimposition signals, in a similar manner as the WV-VF01 viewfinder does with the F10 camera.  The five inch WV-VF65BE viewfinder has an interface box between it, and the camera, as part of the WV-Q39AE mounting bracket that holds the viewfinder, that mixes video and OSD characters.

Firstly, the difficult way.  You'll need to do this if you can't modify the viewfinder, or the interface box between the camera and the viewfinder.  Open up the side of the camera with the viewfinder socket so you can get to the back of the viewfinder's socket, and cut the OSD signal track leading to pin 6 of the socket.  But, modifying the camera head is rather hard to do, and even more difficult to undo.  Since that thick film circuit track is next to impossible to repair, you'd have to run a wire from the viewfinder socket's pin 6 to the fifth pin down on the edge connector for the thick film ribbon track (trace the tracks visibly, and test with a meter, to work out from which end I'm talking about).

The alternative is to modify the box on the WV-Q39AE mounting bracket.  It's much easier to get into, and easier to undo the modification, later on.  In this case, remove the interface from the bracket, and locate the 7-pin header that has the cable leading to the camera head.  Cut the orange wire that's adjacent to the shielded video cable, and insulate the ends.  If you want to be able to turn the OSD on and off, then put a switch between them.

Starting from the end nearest the captive lead going out to the camera head, the 7-pin header carries the following signals:

  1. +12 volt supply (green wire)
  2. OSD signal [82Ω terminated] (orange wire)
  3. Video signal [82Ω terminated] (clear plastic covered wire)
  4. Shield for video signal (black insulation)
  5. Vertical Pulse, zebra, & tally signals (white wire)
  6. Standby signal [+3.5V standby/0V operate) (blue wire)
  7. Ground (grey wire)

NB:  I don't know if your wiring will use the same colours as in our unit.  Count the pins, and measure the signals.

The circuit board is doubled sided, there are mixing amplifiers underneath to merge the pin 2 (OSD) and pin 3 (video) signals, a filtered buffer to separate out the DC voltage on pin 5 to drive the tally lamp signal, and a transistor to buffer the standby signal (to power down the viewfinder, as well, when the camera is in standby mode).  On the top are various capacitors and a 9 volt regulator for this interface.  The viewfinder runs on 12 volts, the regulator is just for the circuitry on that small circuit board.

The WV-Q39A mounting bracket is a bit simpler, and doesn't include the mixing amplifers to overlay the OSD signal, at all.  The camera video signal goes straight through to the viewfinder, albeit with a 75Ω terminating resistor to ground (since the viewfinder doesn't have a terminator in it).

There doesn't appear to be a way to stop a blinking display from blinking, to make it a static display (which would be somewhat of an improvement—being able to see important information, without it being so annoying).  The text is controlled by a microprocessor, and it seems to be the thing that blinks it, rather than there being a separate flasher circuit.


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