The price was right. Assuming the lot I'm getting tests and works correctly, there may be extra units available.
The units arrived today, and I have run them through a very basic test with color bars. I will be posting video clips of each unit (5 total) later on.
My first test was to see how "transparent" each TBC was to video. To test this I first recorded the color bars generated by the AVT-8170 TBC when hooked up directly to my ATI All-in-Wonder. I connected it up to each TBC channel using strictly S-Video input and output. I than reset the internal proc-amp on the TBC cards to their default or unity setting. To check levels without a real scope, I used the Video Tools Virtualdub
plug-in on each clip I captured. There is quite a bit of variation on output to say the least!
Unit 1, Channel 1: Levels way too hot, this was evident in the video preview
Unit 1, Channel 2: (no card installed)
Unit 2, Channel 1: Levels about right, color balance correct
Unit 2, Channel 2: Same as channel one. Note that this is the newest unit of the bunch as its labeled Leitch instead of DPS
Unit 3, Channel 1: Levels are low, video is slightly "dull", color balance is slightly off
Unit 3, Channel 2: Levels are low like above, color balance is slightly off
None of the units introduce RF interference into the video path. There is no pulsing or herringbone noise.
The proc-amp controls are about "medium" in their correction range. More then the AVT-8710's proc-amp, but less then a Elite Video BVP4+. In addition to linear hue adjustment, there is a "color balance" to adjust R-Y and B-Y levels. I can easily compensate for the output problems in the units using the built in proc-amp. Optionally there is a serial interface that can be utilized with PC or Amiga based software to adjust all the parameters on these units. There are also pots on the cards themselves to adjust static calibration. Of course I would need a real vectorscope and waveform monitor to do the calibration. That is if one even notices the color or level changes to begin with. Of the tests, I only noticed the one with the hot video levels. The rest were mostly correct to my eye.
This leads to an answer to the question on why old professional TBCs aren't good for VHS-to-DVD work. These older units are very fickle. They are affected by temperature changes and require adjustment from time to time. This was expected for this equipment as its target market was to be installed in an equipment rack in a studio with the proper scopes and where procedure dictated regular calibration checks. To put it simply, they aren't idiot proof "plug it in and forget it" devices like the Datavideo TBC-1000 and AV Tool AVT-8710.
Expect to see more tests in the coming days of this unit's ability to actually time-base correct video(line TBC functionality). I'll also try and stress its composite comb filtering ability as the daughter card for the function is present.