How to tell if TBC is working?

[Hellbore]

I have an I.DEN IVT-7 TBC I bought on Ebay. The proc amp in it definitely works. However, I don't know how to tell if the TBC / frame synchronizer is working.

Is there any easy test to see if it is working?

One thing that was a little worrisome for me: Hooked straight up to my capture card, if I press Pause on the VCR, I get a still image on my capture display. However, run through the TBC, the image pause flickers and jumps all over the screen. While the video is playing though, it looks fine.

Any ideas? How can I test a TBC for correct functioning?

[davideck]

Hellbore -

Sounds to me like its working fine. If the picture out looks as good as the picture in during normal playback, then that is an indication that all of the signal paths are in order.

Since you notice a difference in pause and with the proc amp, you can assume that you are not just looping through or bypassing the TBC function.

The flickers and jumps indicate that the TBC's input sync detection is not as tolerant as your capture card when it comes to non-standard vertical blanking intervals which are typical during VCR still frame. That's not unusual.

The TBC may have its own freeze button to capture great stills...

If you connect a Monitor to the TBC output and it remains locked with no TBC input, then that is further confirmation of proper operation.

[Hellbore]

Thank you for your advice. It does indeed have Frame Freeze button and a Field Freeze button. The Frame Freeze worked great for a still image.

It also passed the other tests you mentioned.

Thanks, now I know I can give the seller positive feedback

However, I am still wondering... How can I see the TBC doing something, i.e. correcting some flaw? What kind of problem would I see it fixing on a tape?

[davideck]

How can I see the TBC doing something, i.e. correcting some flaw? What kind of problem would I see it fixing on a tape?

Look closely at vertical lines within the picture content; they may appear straighter at the output than at the input.

If there are any vertical edges that appear to bend at the top of the picture, then the TBC may straighten these out as well.

Chroma impurities at the input may be reduced at the output. Look for large areas of red or blue that are non uniform at the input.

A bypass button is great for these tests; if the TBC has one, then you can quickly switch between input and output while you keep your eyes focused on the picture.

[Hellbore]

Yeah, this TBC has a bypass button. I remember now that my tape of Ocean's Eleven (commercial tape I purchased, a real one, not a copy or ripoff) has vertical lines in some scenes that were WAVY... I definitely remember this... I will have to run it through the TBC and see if they straighten up