• Broadcasting

  Leader waveform monitor, Vectorscope, JVC KM-1200 and Sony BetaCam sp Deck.

  Posted by Mat Cav on January 5, 2012 at 3:08 pm

  Not Sure if this is the right place to post this but here goes..
  I am sure this is simple but I am having issues. I have a JVC KM-1200u, signal coming from a BetaSP deck, Color bars look fine when bypassing the JVC, but once it goes though the JVC while connected to the test equipment the color turns rather green.

  Here is the mixer https://www.jvc.ca/en/pro/archived-product-detail.asp?model=KM-1200U

  There is no camera. Just encoding BetaCam SP tapes. The way it is running is like this:

  2 BNC Composite out to JVC KM-1200, one going to the In5/ gen Lock, the other goes to the BNC Composite IN 1.

  Program out goes to the Leader 5860c waveform monitor In A, then Loop Through out to the Leader 5850c Vectorscope In A, loop through out to the computer encoder or monitor for testing. The vectorscope also has an SG-2 Black burst generator connected to the Ext. Ref IN.

  The idea was that I wanted to use one Program out of the JVC KM-1200 to go to the testing equipment and the other Program out to the encoder. The reason we need the JVC KM-1200 is just to fade to black at the end of the encode, to do this I set input A to 1 and input B to 5/color- black, then just hit EFF and Auto Take, this fades the Beta Deck with the internal Black of the JVC KM-1200.

  I just dont understand why if I run one program out from the JVC KM-1200 to a TV and the other Program out to the test equipment, the TV bars look green as in the picture below.

  I dont have formal training, maybe I am missing something with color sync?

  
  

  Tom Matthies replied 14 years, 6 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Tom Matthies

  January 12, 2012 at 5:32 pm

  It would appear that the subcarrier phase or at least the hue is getting shifted as the video goes through the switcher. In looking at the specs for the switcher, it looks like it can either take a reference from an external source or generate it’s own reference signal. The specs say that it has two Black Burst outputs for genlocking external equipment. Try this. Remove the second cable that goes from the deck (what model deck is it also?) to the reference in to the switcher. It’s not a good idea to use a vtr as a reference source. Run the cable you just removed from the deck (ref to the switcher) to one of the BB outputs on the back of the switcher. Run the other end to the reference input on the Beta deck. Click the 75 ohm terminator switch on the deck to ON. This will lock the playback deck to the switcher. Also, depending on the model of the deck, make sure it is set to accept an external reference signal. Now, make sure the switcher reference is set to internal and not external lock. You color bars should look better. Depending on your Beta deck, you may still meed to adjust your Subcarrier Phase and your H-Phase. Each model of Sony Betacam decks is a little different. This will lock the correct color phase when you fade from the deck to black. It will be two small screwdriver “pots” somewhere on the deck. Send the other BB output from the switcher to the reference inputs to your waveform and vector scopes. You can loop it through the two devices and then terminate it on the vectorscope. If you now set the waveform/vector scopes to external, you will be able to set the correct phase on the deck color bars using the scopes. You can probably get it pretty close by just eye-balling it by switching between the switcher output and the deck output. Another thing to note. I can’t tell from the specs if the switcher incorporates a blanking processor, but if it does, you may be able to get by just by adjusting the Hue controls on the deck. It’s kind of cheating, but it will work just for fading to/from black. If the deck is a BVW or a PVW series, there are controls right on the deck for this. If it is a UVW series, you will need an external control box that plugs into the 15-pin connector on the back of the deck in order to control the Hue, Chroma, Set-up and so on.

  Pretty straightforward in all. Lock the deck to the switcher. Lock the scopes to the switcher. Set the switcher to internal reference. Adjust the H/Sub phase (or HUE) on the deck until the settings are correct and your bars should look good on the way to your encoder.

  E=MC2+/-2db

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