TUCoPS :: TV, Cable, Satellite :: mcrvisn.txt

Defeating Macrovision video copy protection

Reply-To: marc.klopert@factory.com (Marc Klopert) 
Date: Sun Apr 24 18:35:00 1994

The person who said that you can readjust a trimmer in your VCR to
defeat MacroVision is CORRECT.
The precedure is as follows..
1.get a service manual, or ask a repair shop to look up your model.
2.find the video AGC trimmer.
3.hook your machines together, video in to video out, audio in to audio
4.put the encoded tape in the machine that you are using to play the
tape(the one with the plugs in the output jacks)
5.hook up your tv to the OTHER machine
6.while playing the encoded tape, watch it on the tv..you should see the
picture changing brightness.
7.open up the machine that you would be recording ON(the one that the tv
is on now).
8.using the info derived from steps 4 & 5, find the video AGC trimmer.
9.using a non-metal tool(try Radio Shack),adjust this trimmer until the
brightness variations stop.
10.put the cover back on the VCR.
The reason this works...
The way MacroVision screws up your copies, is a variation of video
levels(not the whole signal, but a part of it).
This throws the recording machine into a tizzy because the
AGC(automatic Gain Control)circut can't keep up with the varying levels.
When you readjust the trimmer, you are lessening the effect of that
The result is that the signal goes right by with no problem.
In most cases, doing this will have no negitive effect on non encoded
inputs..this is because most signals are aprox. 1 volt peak-to-peak
anyway, so the video AGC is not really needed anyway.
If you have some source that overdrives your machine, then play with the
trimmer..you should be able to find a point that makes everyone happy.
If you don't want to open up your machine, then spend 30 to 50 $, and
buy a Macro eliminator box.
These work fine(Damarc often has a good rice on these)
If you buy a unit, make sure that it is DIGITAL.
There may still be a few analog units out there.
You can tell the difference very easily.
The DIGITAL units have NO CONTROLS on them(except prehaps for a power
The analog ones have 2 controls, 1 which says stablize,video lock, or
some other such term)the other control or switch will say in/out.
You do NOT want this type!
They do not work as well, and strip many other things out of the video
signal then are needed to defeat MacroVision(closed captions for
L8R all.......M.K.........

TUCoPS is optimized to look best in Firefox® on a widescreen monitor (1440x900 or better).
Site design & layout copyright © 1986-2024 AOH