DVR620KU Makes Background Noise When Dubbing

Question

Hi, I recently purchased a DVR620KU.  I started dubbing VHS tapes to DVD+R.  The VHS tapes sound good when I play them alone, but as soon as I begin dubbing to DVD I can hear background noise, like a persistent light tapping sound.  Thus the DVDs end up with this background noise that isn't present in the original tapes.  I tried different DVD speeds.  I also removed the machine completely, plugged it into a different wall socket, and tried dubbing without the unit connected to any other devices.  The noise was still present when I played back the new DVD.  The noise is not present in DVDs that were not dubbed by this machine.  At this point I am convinced that the Toshiba DVR620KU is the root cause of the background noise.  Do you know what Toshiba's explanation is, and what is the recommended solution?  Thanks.

Answer 1

The noise is initiating from the VHS playback, and then being written into the DVDs.  The noise only occurs when the DVD is either dubbing or recording the L1 circuit (even when the L1 circuit is empty, the VCR playback is still affected while L1 is being recorded to DVD).  When the DVD player is off, the noise is not present in the VCR playback.  I'm not sure how to determine whether the noise is originating mechanically or eletronically.  But it ends up as part of the sound transmission through the speakers.  I'm not hearing something banging inside the machine, if that's what you mean.  If you tapped on a microphone repeatedly while it was recording, this is what the output would sound like.
So far I've identified 7 VHS tapes that are affected by this problem, and 8 VHS tapes that resulted in excellent DVDs.  I just burned a perfect DVD this morning.  All the tapes are T-120 cassettes that were originally purchased as blanks.  Several different brands and grades are represented.  All of the "bad" tapes weigh more than 240 grams (average 257g), and all of the "good" tapes weigh less than 230 grams (average 204g).  I know that blank T-120 cassettes generally become lighter over time, which means the "heavy" cassettes are probably generally older than the "light" cassettes.  This also implies that the material was generally recorded with older VHS players on the "heavy" cassettes.  The transition between the "heavy" and "light" tapes was probably around early-90's based upon the material on the tapes and when I think the data was originally recorded.  So I don't know whether or not the weight actually means anything, although it could because mass can obviously impact mechanical vibrations.  But the difference could also be that different tracking technologies were involved with the older, or heavier, cassettes and/or the machines they were involved with at the time the material was recorded.
I read on a different forum that VHS cassette tracking imperfections may be present all along, but they don't become audible until the digitization process amplifies some of frequencies involving the imperfections.  I don't know much about that, but to me, it's plausible that the frequency processing and flow path out of the machine changes when the DVD player is recording.  I'm not sure about that either, but something is definitely happening when the DVD recorder is on that affects the VCR playback on these heavier, older cassettes.
So, at this point, I can carry on knowing which tapes will be useful, and which will be problematic with this Toshiba dubbing process.  The problem is what to do about it.  Perhaps if I purchased another unit and ran the VHS output from the "slave" unit to the L1 circuit on the Toshiba, the problem might be fixed.  Or, maybe this unit is defective, and if I exchanged it for a new Toshiba, the problem will be fixed.  Or, maybe the Toshiba design includes this sensitivity, and the only solution may be to return it for cash refund and purchase a competetive product.  Or, maybe the digitization process is what it is, and these old tapes are what they are, and there is no solution.
You said you have a DVR620KU and you've never experienced this problem.  I don't suppose you have any old VHS T-120 cassettes that weigh ~250-260 grams?  If you do, I would be curious to know whether you have the same issue.  Thanks.