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Setting up sync with a older Grass Valley 100

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Will Lane
Setting up sync with a older Grass Valley 100
on May 12, 2009 at 4:12:43 am

I have a grass valley 100 series switcher. I also have a grass valley pulse sync generator. This is connected with 3 leads to the main box for the switcher.

That is:

Composite Blanking > Blanking In
Composite Sync > Sync In
Sub carrier Output > SC In

Now what I am trying to do is connect my equipment that has genlock to the sync system but I can't figure out where to connect this.

Anyone have any experience with this stuff that can shed some light about where the genlock for the cameras etc should go?

Also I am I need to have a color bar generator connected to the sync generator at all times?


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maurice jansen
Re: Setting up sync with a older Grass Valley 100
on May 12, 2009 at 8:17:20 pm


where do i start ;-)
i will try to explain it in 2way's the good way and a way that will do thejob but isn't that precise.

first just to explain the GVG100 has been produced in several setup's
with or without ProcAmp / Syncreplacer and with or without internal SPG
and in CVBS or Component <= i believe this was the GVG110.

if your model has a SPG just wire BlackBurst to the reference input. if not wire all the seperate syncpulses like sync blanking subcarrier. for ease use wire's of equal length when you have to do this. i have never worked with a GVG100 with seperate sync's (just AMPEXvista's ;-) )

of coarse give all your Source's Ref/blackburst from your SPG(syncPulseGenerator) and if you own one also your waveformmonitor/vectorscope.

as said earlier therse a good way of doing this and a less precise way of doing this i will start with the best way.

Connect a Waveformmonitor Vectorscope to the preview/preset output of the mixer if you own a model with a Procamp/syncreplacer this will not be inserted in this output that's why we measure here.
also connect a colorbar to 1 of the input of the mixer.

make sure that the waveform monitor and the vectorscope is switched to external ref. and switch on the magnify funtion on the waveformmonitor.
switch to the Colorbar on the presetbus.

change the Hposition and Vposition on the waveform monitor that the middle of the half amplitude point of the falling edge of the syncpulse crosses one of the vertical line's on the graticule.
this is important because in the standart there is a large tolerance for different syncwitdth's

also chance the phase of the vectorscope that the burst fall on there specific boxes.

from this point don't adjust phase and Hpos & Vpos anymore.

if your sources have a colorbar switch, switch it on and switch to the source you want to adjust on the presetbus. you will see a position shift on the waveform monitor and a phase shift on the vector scope.
adjust your sources with Hphase and Subcarier fase in a way that these shift's disapear. for precise checking switch rapidly between the colorbar and the source to see small differences. in the end time the internal colorgenerator/blackgenerator of the mixer it self.

to check if everything has gone well look at the program bus and look at shifts in colorfase and VideoPhase just before and after the busses flip after a transition.

as said earlier there is a other less precise way of doing this.
on your preset monitor run in externalsync and put the monitor on external sync and on HVdelay. when your sources are not timed well the blackbar will shift. By rapidly switching between colorbar and the source you are timing you can adjust Hphase so that this shift is gone. for subcarrier als switch rapidly and try to math the colors with SubcarrierPhase of coarse is this the poorman's way of doing this and the signal coming out of the switcher will not be on broadcast spec's use this way only in a situation were it's no big deal.

long story but i hope it helps


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Bob Zelin
Re: Setting up sync with a older Grass Valley 100
on May 13, 2009 at 2:46:12 am

aaaah Maurice, you can't train someone on how to time an analog system over a user forum - at least without pictures.

Maurice is correct. There were option boards available for the GVG100 - one was a black reference input board, that allowed you to put in NTSC black, instead of seperate sync/blanking/sc - so I can't answer what you have, or don't have in your GVG 100. You have also not told us what sync gen you have - if it is an antique, it wont' even have NTSC black, and may only have sync/blanking/sc.

Once you do this, you must perform a process called TIMING to get your cameras to lock up. This requires a waveform montior, and it requires you to disable the "proc amp" which replaces the sync interval on the GVG 100 switcher. I forgot if this was a switch, or a hairpin jumper on one of the boards (it's been A LONG TIME). But even if you find the switch, no one can tell you in words how to H and SC time different camera sources, using a switcher and waveform monitor, without actually showing you.

What you will find is that if you do not genlock all of your sources (cameras, and VTR's), you will get jumps and breakup when you switch or dissolve sources. And if you DO genlock, but don't have the H and SC adjusted on EACH source, you will still get horizontal jumps, and color shifts when you cut or dissolve.

See - it wasn't easy back then, you actually had to understand this stuff. Today, you buy a modern switcher, they have frame sync inputs, so you don't worry about genlocking, or timing with H and SC.

Without someone being there to show you, it's almost impossible to instruct you how to do this over a user forum.

Bob Zelin

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maurice jansen
Re: Setting up sync with a older Grass Valley 100
on May 13, 2009 at 6:22:59 am

i know bob

but at least i can try to help this guy.
knowing how to do this old stuff help's people understanding the new
stuff. i guess he will have a lot of question rising when he read's the replies.


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Tom Matthies
Re: Setting up sync with a older Grass Valley 100
on May 16, 2009 at 4:05:50 pm

On a GVG 100, the Proc Amp control is a jumper near the back of the Reference (or control? -it's been a long time) board. Years ago, while working with a 100, I wired a small toggle switch across the jumpers and mounted the toggle near the front of the board for easy access.
BTW, the GVG-110 isn't necessarily a component switcher. It's just an upgraded Model 100 where they added few new features including E-Mem's and a setup mode that made timing much easier. And they had a toggle switch to disable the Proc Amp...right in the same place where I mounted the make shift bypass on the older Model 100.

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Gary Reece
Re: Setting up sync with a older Grass Valley 100
on Jul 14, 2009 at 4:00:17 pm

You can time a GV100 with color bars and come very close to what you would do with a WF/Vector Scope.
If your do not have the regen option card you will need a sync generator that produces the external drive inputs to the GV100. With the option installed you only need color black to the ref input. Use the appropriate generator that also includes color bars.

Ideally you will run each input through something that will allow you to adjust gain, or the source will have such an adjustment.

You will need to run color black to all of your sources. It is best to take this sync signal into a DA and then fan out to each source from there. Other option is if each item has a loop through and you can chain the sync from one to the next.

Run color bars into one of the inputs and your sources to the others. Create a spit screen with the color bars on the bottom and one other source on top. Set your source (camera, etc.) to generate its internal color bars, or (deck) play content with color bars). Split the screen on the large white block at the bottom. Adjust your gain until the two halves of the white block match.

Reposition the split in the center of the upper bars.

Adjust the horizontal phase of the source until the bars align vertically. If one source has fatter bars and only one place will align pick one to the left, like between grey and yellow.

Adjust the coarse phase of your source until you get bars at the top that are as close as you can get to your standard on the bottom. Then adjust the fine phase until they match.

Adjust the color or EQ adjustment of your source until the bars blend as best possible with no visible split.

Repeat steps as needed to refine the adjustments.

You may never get it perfect. NTSC = Never Twice Same Color, but once you get it as close as you can you are good to go.

If your picture jogs at the end of a transition you need to fine tune the Horizontal phase.

Also, there are course and fine phase adjustments in the GV100. Use them only to calibrate the standard from your generator so that the standard appears correct. Without a waveform monitor you will have to decide with your eye if the colors are correct. With experience you will get close and without bars recorded to your master and a monitor to evaluate them, there will be few who could challenge your colors.

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Francisco Salas
Re: Setting up sync with a older Grass Valley 100
on Nov 10, 2010 at 4:35:43 pm


I have the possibility of acceding to a Grass Valley 100 (NTSC) but have a great doubt rather or a great problem.

The video to camcorder that I have is canon XL1, XL1s and XL2, which obvious does not have possibility of Genlock.

It is possible to use this to switcher with those chambers being used some generator of sync or genlock?

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Gary Reece
Re: Setting up sync with a older Grass Valley 100
on Dec 24, 2010 at 6:24:31 pm

Hi Francisco,

Depending on the GVG100 you are using you have some options.

What most professional installations did with non-synced sources for a Grass Valley switcher was to run the source into a Time Base Corrector (TBC). The TBC is locked to the house sync generator and can be timed into the switcher as you would any source that can lock to the house and be adjusted. The TBC has enough of a buffer to hold the field or frame until it is the right time to release it to the switcher. The one drawback in using a TBC is that you will add a frame of delay from the source to the switcher. You may need to add a frame of delay to the audio to be happy with the result. Used composite TBCs are plentiful and very inexpensive with many facilities having transitioned to digital.

Another way of dealing with this might be to use the un-synced camera as your house sync. Run the signal into the sync connector of the switcher and then extend the signal from the loop through to the selected input. This only works if you have one such camera and everything else can be locked. It also only works if your switcher can lock to a single video signal. Without the regen option you would have to have a generator that produces all three of the required drive signals.

The GVG SCB-200N provides all of the drive signals you would need to provide house sync to any GVG100 switcher configuration. In addition to all that the SCB-100 does, it can be locked to an external source. It could take camera video and provide house sync for the rest of the system.

I don't like using a consumer camera, or any camera for that matter, for house sync because of the risk of loosing sync with the loss of power or other camera changes. But it might be a way for you to get by with what you're doing.

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