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From what I've read, VCRs are supposed to have some degree of internal dropout compensation, but I am seeing it more than I thought I would on commercial VHS releases even when viewed directly on a CRT. The specific frames where I get horizontal line dropouts is consistent when playing back on each of three different JVC HR-VS30U's, but happens relatively frequently - seemingly around once every 20 seconds or so and to various degrees.
Just as a reminder, the SR-VS30U is essentially a newer 7600 variant on the VHS side with 2MB line TBC/Digital NR that can be activated in the OSD menu. Each of the VCRs have the dropout in the same frames as each other, so I do not believe this is due to anything wrong with the specific units I have hardware-wise since the results are repeatable across multiple VCRs of that same model.
However, when I try the same tape on a consumer Panasonic deck (DMR-EZ48V) and I see maybe 1/5th or less of the horizontal line dropouts and the ones I can see are much less severe.
Question is whether any of the other recommended JVC series with line TBCs handle horizontal line dropouts any better than the others? Is the 7600 series typically known for more dropouts than say the 9600 series? I assumed the dropout compensation would be fairly advanced on these since dropout compensation had existed for over 15 years at the time these were made.
I understand that some external TBCs have dropout compensation and I actually have one of those odd variants (Hotronic AP41-SF-DOC - DOC stands for drop-out corrector/compensator, though this isn't mentioned as an option in the AP41 manual PDF, but is listed in some marketing as an option). It does have a "DOC" BNC input on the back which I understand from looking at other TBCs with DOC that this is supposed to be connected to the Video RF signal from the heads so that the unit can compare the raw RF and see the dropouts slightly in advance of the processed signal - which interestingly enough is what the Domesday Duplicator accesses, so there's actually good information out there on what that would need to connect up to assuming there is no special attenuation required. Not sure if the internal dropout compensation will conflict with this, but as mentioned above, the dropout compensation does not seem to be doing much anyway. I'll eventually try to report back on if hooking up the DOC line the way that I think it is supposed to be hooked up actually does anything.
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