Macrovision Circuit not working - Page 1
Forum section: electronics / beginners

author: 97paul
author_rank: Contributor
timestamp: October 12, 2025, 12:50:54 pm
content: Hello everyone,I recreated this circuit (see link).https://hbo.tripod.com/VCR/en_macrovision.htmUnfortunately, I suspect a mistake in the circuit diagram.On the CD4053B, the voltage on pin 14 is much too high (10V). This is causing the transistors and resistors on the video output to overheat.There's no input signal on pin 3 of the LM324. Therefore, as far as I know, the LM324 outputs 10V. That's where the 10V comes from.So it seems like something is wired incorrectly on the CD4053B, but I've set everything up exactly according to the circuit diagram.Maybe someone has an idea and can help me.

author: Benta
author_rank: Super Contributor
timestamp: October 12, 2025, 01:45:18 pm
content: Just for your info: it won't work very well. It will allow VHS-to-VHS copy, but if you're trying to digitize tapes, the circuitry needed is much more involved.

author: fzabkar
author_rank: Super Contributor
timestamp: October 12, 2025, 03:36:34 pm
content: Quote from: 97paul on October 12, 2025, 12:50:54 pmLM324 is configured as a voltage follower, so whatever appears on pin #3 should also appear on pin #1.

author: 97paul
author_rank: Contributor
timestamp: October 12, 2025, 04:39:16 pm
content: This is very strange since there is no signal on pin 3.

author: fzabkar
author_rank: Super Contributor
timestamp: October 12, 2025, 05:23:51 pm
content: Quote from: 97paul on October 12, 2025, 04:39:16 pmWhat does "no signal" mean? What is the DC voltage on pin #3?

author: 97paul
author_rank: Contributor
timestamp: October 12, 2025, 07:39:33 pm
content: I received a tip from another forum. I grounded pin 1 of the 4053 via a 10K resistor. Now I have 2V at the output of the LM324. I reconnected the output transistors and now get a 2V signal at the video output (IMAG4335 before and IMAG4336 after). Here's a photo of the video signal before and after the circuit. Unfortunately, all I get at the output is junk.

author: Benta
author_rank: Super Contributor
timestamp: October 12, 2025, 08:35:56 pm
content: Like I said at the start: this circuit is no good.It's designed by someone who does not understand how the LM1881 works.Also with no understanding of how the Macrovision "copy protection" (read: signal mistreatment) works.It makes no sense to waste time on it.If you want an idea of what is needed to neutralize the copy protection, here's a schematic of a circuit that works:

author: tooki
author_rank: Super Contributor
timestamp: October 12, 2025, 08:51:43 pm
content: Quote from: Benta on October 12, 2025, 08:35:56 pmWhy would someone make a schematic with no part numbers on the ICs?!?

author: Benta
author_rank: Super Contributor
timestamp: October 12, 2025, 09:03:51 pm
content: Quote from: tooki on October 12, 2025, 08:51:43 pmBecause it's a legal minefield (yes, still). I only posted the schematic to illustrate the needed complexity vs. the OP's primitive circuit.

author: cunningfellow
author_rank: Regular Contributor
timestamp: October 12, 2025, 09:46:56 pm
content: All of that complexity of LSI counters and logic COULD be replaced with a PIC12C508 though

author: Benta
author_rank: Super Contributor
timestamp: October 12, 2025, 09:55:50 pm
content: Quote from: cunningfellow on October 12, 2025, 09:46:56 pmNo it couldn't.We're talking timing in the 10s of ns range coming in real time here. Even the fastest MCU I found could not provide reliable/replicable timing.I looked into CPLDs (which would do the job), but their excessive power consumption (>100 mA) made it a no-go.

author: Fraser
author_rank: Super Contributor
timestamp: October 12, 2025, 09:59:22 pm
content: This takes me back to my younger days. I wanted to make a personal copy of the Aliens VHS so I studied the Macrovision protection that was used. It was a large amplitude signal bouncing up and down in amplitude during the blanking period to mess up the VHS recorders AGC circuit and create a flashing image effect. I beat that system with a Sync separator IC, a 555 timer to set a delay after being triggered by the output of the sync separator and another 555 triggered by the output of the first after the desired delay duration. The second 555 was driving a transistor that clamped the video signal and it set the duration of the clamp. It was “down and dirty”, required an oscilloscope to set up the delay 555 and clamp duration 555 but it worked like a charmReal low tech, but it got the job done for my needs.Fraser

author: Benta
author_rank: Super Contributor
timestamp: October 12, 2025, 10:05:16 pm
content: @Fraser, yes. That would enable a VHS-to-VHS copy, no more. The video signal would be a little less corrupted, that's all. But far away from a standard CVBS signal. And the VHS copy would also be corrupted.

author: cunningfellow
author_rank: Regular Contributor
timestamp: October 12, 2025, 10:51:56 pm
content: I assure you that a 12C508 is more than capable of twiddling two analog switches to alternate between a sample and hold, black level and unaltered video. I probably would not have given the archaic 12C508 as an example of an MCU that could do it if I didn't know of a working example.The LM1881 extracts the syncs for you.Then frequency lock by dicking around with the 12C508 RC-Oscillator calibration values - Mostly what your 4066 is doing on page four of your schematic.Then all the stuff that is done by all those logic chips on page two is all software and cycle counting.Get rid of your ICL7660 on page 3 by just using an AC plug-pack/wall-wart to power it and I think it comes out at a total of three chipsThere is NO having to react to a signal in 10s of nS AFAIK. You have 1/60th of a second to get the timing right for the next field/frame.In fact I have been lead to believe that it is easy enough for a five year old tibetan spaniel to build.

author: Benta
author_rank: Super Contributor
timestamp: October 12, 2025, 10:59:43 pm
content: Quote from: cunningfellow on October 12, 2025, 10:51:56 pmGreat. Do it. Put your money where your mouth is.

author: cunningfellow
author_rank: Regular Contributor
timestamp: October 12, 2025, 11:06:42 pm
content: Did it in 1993.Can only find a reference to it on the broken web at the momenthttps://www.edaboard.com/threads/looking-for-macrovision-remover-schematics.3341/If the wayback machine starts working again, search for that bit about the tibetan spaniel and you will find the schematics and source code.Microcontrollers can do amazing things if you have the imagination to use their peripherals creatively.

author: Benta
author_rank: Super Contributor
timestamp: October 12, 2025, 11:37:18 pm
content: The link works fine, and I find nothing there to change my mind. 2003, BTW. Which of the users/links are you?

author: cunningfellow
author_rank: Regular Contributor
timestamp: October 13, 2025, 12:15:23 am
content: Wayback machine started working a bit and found this linkhttps://web.archive.org/web/20040606025407/http://home.quicknet.com.au/ANDREWM/macro/index.htmlSadly still does not find the final version of the project that had the NTSC/PAL switching software and the OSCAL PLL stuff (which would have been on my own domain not "quicknet").I am guessing this project was done 1993 as that is around when I bought a video projector that was upset by macrovision. If it had of been after 1996 it would have been using an AVR. In fact a later video jiggery circuit I made (SSAVI suppression approx 1998) got rid of the LM1881 by using the AT90S2313 analog comparator plus software to do sync separation with reduction in false positives.This comparator to replace the LM1881 was an idea I stole from "3Chip". If you really want to be amazed at what creative people can make a few chips do then look up "3Chip SSAVI". Not a 74LSxx or FPGA in site - Just creativity most people can't hope to match.