Need Help - problem with Toshiba DR430

My guess is the flicker is caused my your Toshiba(which are known to be very trigger happy AFA CP detection) falsely detecting a CP signal(change in lighting would be a good example of a area that might trick the recorder).
As you noted, just routing your signal through your Toshiba can cause problems because of the design of the machine. I had the same thing happen when I first got a DVD player. Because my TV didn't have a video input(and that's all the DVD player outputted) I had my DVD player running through my Samsung VCR. Even though I wasn't recording with the VCR I got bright and dark flashes when playing a CP'd DVD Non CP'd DVDs played just fine.
In desperation I tried a older Samsung VCR I had and it allowed pass through just fine although as expected if I tried to record the DVD my output would start flashing dark and bright. I guess the point of my story is that depending on design, even pass through can exhibit the same signs of trying to record the signal.

I know you said your DVDs aren't CP'd but some machines(Toshiba, Sony and JVC jump to mind) are designed so fussy that they can detect a CP signal even when they aren't present.
A couple of choices for you would be: A) get another DVDR that isn't overly trigger happy(Panasonic or one of the Magnavoxes w/hdd come to mind) or B) purchase a video filter to remove CP(or what your Toshiba is thinking is CP). If you have the option my first suggestion would be to get another brand DVDR. Every filter I've ever tried messes with the black level a little. It sounds like you're a bit on the fussy side and you may not like the increased black level(blacks not being totally black) I know I don't like it
For a list of current and past Panasonics click my signature. For info on the Magnavoxes, check Wajo's sticky thread for a wealth of information.
For information on video filters you can check out any of the many threads talking about those.

Copy Protection, I know your tapes are homemade but as I said sometimes overly sensitive DVDRs like your Toshiba react to glitches on the tape like they are a CP signal.
If you can find a EA-18 my guess is your problems would go away. Panasonics do react to a real CP signal but aren't known for false detections, like what I'm thinking your Toshiba is.

Does your Toshiba DVDr have a recording setting called WHITE AGC that you can toggle on and off? If you have such a setting on your DVD recorder try setting it to the OFF position.

AGC stands for Automatic Gain Control and sometimes if there is a sudden change in the lighting level, especially in home videos - the AGC circuitry may get triggered causing a sudden change in the video level and this may look like a flash.

It is possible that your DVDr might have a similar setting and it might not be called WHITE AGC it might be called something else but similar.

You mentioned you are playing S-VHS tapes..don't know if that makes a difference. I know others here know if all VCRs can play the S-VHS tapes or whether they can only play standard VHS. My regular VHS tapes are fine on my Toshibas but I don't have any S-VHS ones to try. Maybe this is a clue?

Sorry for resurrecting an old thread, but I thought I'd check to see if anyone ever figured out a solution for this. I've got a DR430 and it very definitely has this exact same issue. It does it with different cables and different S-VHS players (tried a Sony S-VHS and a Panasonic S-VHS player - both with S-VHS tape sources and regular VHS sources), and constantly get this issue on ever single tape. Like the OP, it is a plainly obvious problem when just previewing video in passthrough, and when playing back recordings the DR430 made. Very, very annoying problem.

 

The MCM filter described here might help if the Toshiba is sensing anything "out of the ordinary" like false CP... only $26 to find out?