Cheap Macrovision stripping unit tip--

[zenith2134]

I ordered an MCM 'Digital Video Stabilizer' for about 20$ just to see what it could do for my copy-protected VHS tapes. Keep in mind, I'm not digitizing or copying these tapes, I simply want to air them over my amateur NTSC channel without my old TVs brightening/darkening in unison with the AGC fluctuations caused by the Macrovision encoding.
Running the stabilizer off of a (freshly-installed by me) 9V battery since the one supplied looked like total garbage, the unit does a fine job of removing the copyguard on all tapes tried thus far. The VBI, as visible with my 1979 System 3 vertical hold control in between frames, maintains the sync pulses as normal, versus the light-and dark- strobing boxes which it contained without the unit. For instance, on my VHS copy of "Quiz Show" there was a distinct difference and the cheap MCM box worked 100%. Also on "Meet the Parents"--same situation. Not bad for the money.
However. This unit, since it isn't a proper TBC (which would cost real money), does nothing on tapes with stretch from previous VCR abuse, such as former rentals. The flagwaving is still present on badly damaged cassettes, even on a modern TV set. This is to be expected, since my VCRs do not contain any form of a skewing control.
Overall, for the money this box is definitely recommended if the copyguarding of your video library is throwing off the AGC in one or more of your TVs.

The attached pic shows the unit in my upstairs video closet, along with my Toshiba VHS deck and Philips DVD unit. It is feeding a Blonder Tongue AM-60-860 agile modulator with a freqency-specific dipole I built thanks to a helpful video on youtube. The Leader NTSC pattern gen. is there for good measure; I broadcast bars in between showings. Excuse my cellphone camera..it's dark in that room since it is also where I store my vinyl records and books.

[old_tv_nut]

I bought a cheap one years ago (can't remember the brand) that stripped the CG, but also distorted the color burst - my CTC-5 didn't like it. Have you tried putting a multiburst through this to measure the frequency response?

[zenith2134]

Well I brought the unit with me to work today since I have more test equipment here at my disposal. I found a Tektronix 1400 series signal generator with multiburst mode and it is warming up until later on (I just got here). The manual for the stabilizer actually lists some specs, although I doubt that it meets them.....Differential phase >2 degrees, diff. gain better than 2%, video bandwidth better than 4.5MC....I would prefer to see a +/- tolerance for bandwidth, much like audio equipment measurements..But I will perform my own tests.

[zenith2134]

Well, looking at my graticule, it seems as though the response is a bit blunted on the high end with the stabilizer connected....It goes to 4.5MHz and beyond with the multiburst of a Tektronix 1401 connected right to the scope but rolls off around ~~4.23MHz with the stabilizer in the chain. My measurements were done in a rush, since I'm not supposed to be fooling with this at work, but Old-TV_nut is right that there is some deviation in burst response
I suppose this is a decent compromise... If I put up a red raster, there is a tad more hash with the unit in the chain too..but it is negligible. My oldest COLOR daily watcher is only from the early 70s so I suppose on the 1950s color TVs it would be more of an issue(?) Not sure..

[Jeffhs]

Originally Posted by zenith2134

I ordered an MCM 'Digital Video Stabilizer' for about 20$ just to see what it could do for my copy-protected VHS tapes. Keep in mind, I'm not digitizing or copying these tapes, I simply want to air them over my amateur NTSC channel without my old TVs brightening/darkening in unison with the AGC fluctuations caused by the Macrovision encoding.
Running the stabilizer off of a (freshly-installed by me) 9V battery since the one supplied looked like total garbage, the unit does a fine job of removing the copyguard on all tapes tried thus far. The VBI, as visible with my 1979 System 3 vertical hold control in between frames, maintains the sync pulses as normal, versus the light-and dark- strobing boxes which it contained without the unit. For instance, on my VHS copy of "Quiz Show" there was a distinct difference and the cheap MCM box worked 100%. Also on "Meet the Parents"--same situation. Not bad for the money.
However. This unit, since it isn't a proper TBC (which would cost real money), does nothing on tapes with stretch from previous VCR abuse, such as former rentals. The flagwaving is still present on badly damaged cassettes, even on a modern TV set. This is to be expected, since my VCRs do not contain any form of a skewing control.
Overall, for the money this box is definitely recommended if the copyguarding of your video library is throwing off the AGC in one or more of your TVs.

The attached pic shows the unit in my upstairs video closet, along with my Toshiba VHS deck and Philips DVD unit. It is feeding a Blonder Tongue AM-60-860 agile modulator with a freqency-specific dipole I built thanks to a helpful video on youtube. The Leader NTSC pattern gen. is there for good measure; I broadcast bars in between showings. Excuse my cellphone camera..it's dark in that room since it is also where I store my vinyl records and books.

I have videocassettes that are at least 25 years old, which still play like new on my Panasonic PV-4022 VCR and flat-panel TV. These cassettes contain programs I taped from network broadcast TV in the '80s and '90s, long before DTV, the "500-channel universe" and everything else we take for granted today. I also have a few (very few) professionally recorded VHS videocassettes, but I don't know if they show any kind of distortion as I haven't played them yet. I would imagine they would play normally on an NTSC TV, but the Macrovision signals may cause distortion on modern flat screens. I'll have to dig out those tapes and try them, just for the ducks of it. Who knows, they may play just fine on a modern TV, even though the VCR is well over ten years old.