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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Fri 21, 2019 2:50 am 
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Location: Albion, CA, USA, 95410
I tried to contact the OP about this project but he hasn't picked up his mail. No worries, life is a busy place. Since I have some DVDs that have this problem I looked around for an off-the-shelf solution. I found this:

https://www.amazon.com/XDIMAX-GREX-7.../dp/B0096I2DNE

Ordered it and it works great, Eliminates the retrace lines completely on my Predicta.


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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Sat 22, 2019 2:40 pm 
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Location: Beaver Falls, PA. USA
30+ years ago, I built a similar unit from plans obtained from a company called Elephant Electronics. The circuit used some timing stages, and triggered on the first incoming interference pulse; each line containing the pulses was replaced with black level. The circuit did work well, after it was set up with a scope; all of the timing adjustments had to be just right. I will have to dig through my files for a schematic.

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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Sat 22, 2019 6:09 pm 
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Location: San Jose, CA USA
Here's another approach using good old analog design (with tubes, nonetheless!) to solve this problem: viewtopic.php?f=3&t=86186&start=20

As with most old links to this site, the pictures are all gone. Fortunately, somebody out there captured this with photos: https://www.boxcarcabin.com/blanking.html .

Not sure exactly what this second link is. It's a direct copy of my post from many years ago.

My approach involves modification of the receiving set, so not everybody is on board with that. But if you're OK to modify the set, it works well.

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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Mon 24, 2019 5:49 am 
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Joined: May Sun 07, 2017 11:35 am
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Location: Belrose, NSW, Australia
Sorry Madlabs, your contact request got lost in the stack of email I get! (it was put in the "unimportant" folder!)

I've replied, if it's not too late.

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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Tue 25, 2019 2:29 am 
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Joined: May Sun 07, 2017 11:35 am
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Location: Belrose, NSW, Australia
I built a similar circuit using 300v Vceo transistors into my Kriesler 79-2. No room for a tube to be added.

It worked fine, but I pulled it out when I fixed the sound (jammed slug in ratio detector coil). I don't need the blanking circuit now, my modulator does the job.

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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Tue 25, 2019 4:09 am 
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irob2345 wrote:
Sorry Madlabs, your contact request got lost in the stack of email I get! (it was put in the "unimportant" folder!)

I've replied, if it's not too late.


No problem! While I do have a solution I am still interested in your method. I'll answer your PM.


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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Tue 25, 2019 7:14 pm 
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Location: Martha's Vineyard, Mass.
Eric H wrote:
I have a "Black Box" that I picked up at a thrift store.

I know nothing about it but it absolutely does eliminate the retrace lines on DVD's, it does nothing for the white level buzz in the sound on certain sets though.
Also it runs on a 9 volt battery and has no on/off switch, i don't know if it shuts off automatically or if it'll kill the batter if I let it sit for a month.


Dumb question perhaps, but here it goes:

I have one of those combo VHS/DVD players with the 75 ohm coaxial output to run my TVs. Is it possible to connect this black box directly into the 75 ohm coax output then shoot the AV signal into the TV? 8)

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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Tue 25, 2019 8:43 pm 
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Location: Pewaukee, WI
I own that exact same box that Eric has and the answer is no.... that box is line level composite video only. To use it with your VCR/DVD unit you would need an extra device with an RF modulator or a schematic of your VCR and the patience to modify it to have a break in the video chain before it's internal modulator.


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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Wed 26, 2019 2:25 am 
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Location: Belrose, NSW, Australia
Most VCRs have composite video and audio input jacks. Just connect your box to those, select AV In instead of Tuner, and the signals will be routed to the RF output of the VCR.
The VCR itself doesn't even need to be in working order for this to work.

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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jun Wed 26, 2019 3:06 pm 
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irob2345 wrote:
Most VCRs have composite video and audio input jacks. Just connect your box to those, select AV In instead of Tuner, and the signals will be routed to the RF output of the VCR.
The VCR itself doesn't even need to be in working order for this to work.


You have not tried that scheme before have you? If you select input on the VCR it will feed the input video to both the video and RF output Jack's and you will have a video feedback loop ( video leaves video output on VCR goes to input no black box leaves output on black box and goes to input on VCR and is passed to video output on VCR where it started) if you just connect the box to the video input and output Jacks of a VCR....also if you play a tape the tape will go straight to the RF output and the video that leaves the black box won't do anything.

I suppose on some of the DVD/VHS combos where the DVD and VCR each have their own independent outputs you have a prayer of that scheme working for one of the recording formats, but the RF modulator is usually tied to the other as described in my previous paragraph....


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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jul Mon 01, 2019 3:03 am 
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I bought a blanker/ proc amp from China off eBay for about $25. Works a treat.


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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jul Mon 01, 2019 8:12 am 
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Location: Belrose, NSW, Australia
Quote:
You have not tried that scheme before have you? If you select input on the VCR it will feed the input video to both the video and RF output Jack's and you will have a video feedback loop ( video leaves video output on VCR goes to input no black box leaves output on black box and goes to input on VCR and is passed to video output on VCR where it started) if you just connect the box to the video input and output Jacks of a VCR....also if you play a tape the tape will go straight to the RF output and the video that leaves the black box won't do anything.


I have used this technique on many thousands of installations. You will only have a feedback loop if you go to some trouble to create one. Here is the video path, as you can see there is no loop.

DVD --> Black Box --> VCR Input --> VCR RF Output --> TV.

Now of course I am assuming that you are using a SEPARATE DVD player and VCR.

Penthode, I'd be interested to know if your proc amp solves the caption buzz issue when playing through a modulator or VCR under all conditions of light and dark backgrounds..

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 Post subject: Re: Playing copy-protected DVDs on old TVs - a solution
PostPosted: Jul Mon 01, 2019 4:17 pm 
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Location: Pewaukee, WI
irob2345 wrote:
Quote:
You have not tried that scheme before have you? If you select input on the VCR it will feed the input video to both the video and RF output Jack's and you will have a video feedback loop ( video leaves video output on VCR goes to input no black box leaves output on black box and goes to input on VCR and is passed to video output on VCR where it started) if you just connect the box to the video input and output Jacks of a VCR....also if you play a tape the tape will go straight to the RF output and the video that leaves the black box won't do anything.


I have used this technique on many thousands of installations. You will only have a feedback loop if you go to some trouble to create one. Here is the video path, as you can see there is no loop.

DVD --> Black Box --> VCR Input --> VCR RF Output --> TV.

Now of course I am assuming that you are using a SEPARATE DVD player and VCR.

Penthode, I'd be interested to know if your proc amp solves the caption buzz issue when playing through a modulator or VCR under all conditions of light and dark backgrounds..

It will work for just DVD that way but M3STR8 who we were responding to has a DVD/VHS all in one combo...so that method probably won't even work for DVD for him....also if you ever want to play a VHS tape that has macrovision your scheme isn't going to work.


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