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View Full Version : Help on identifying the cause of this VHS artifact


Alex-Kid
17th November 2022, 07:57
Hello everybody, I started digitizing my old VHS tapes and found that many of them have these ugly artifacts.

https://www.mediafire.com/convkey/2efb/is5xuzndmyrotos9g.jpg

It looks like the overlays (text and logo) were the reason, more likely on high contrast edges. The strange thing is that this only happens with tapes recorded from this particular channel, the others doesn't have this problems.

So I don't know what to do here, it could be the tape, something in the signal recorded on the tape or even the equipment, why not? I hope someone can tell me why does it happen.

Here some more info to help with the diagnostic:

TAPE
-Year: 1997
-System: NTSC
-Rec mode: SP (also have EP recordings, they have less artifacts)
-VCR it was recorded from: Sony SLV 393 DA Pro 4 head mono (1993).
-Artifacts are present on recordings from channel 2. I have other recordings from channels 4 to 13 that doesn't have these artifacts and looks ok.

EQUIPMENT
-Tested in 2 VCRs with same results: 1) Panasonic NV-HD630 Hi-Fi Stereo 6 head, and 2) Sony SLV-D350P VHS+DVD Hi-Fi Stereo 4 head. Both use composite video output.
-Panasonic DMR-ES10 as TBC, using composite video input and s-video output.
-Hotronics AP41 TBC/Frame synchronizer. It does nothing as TBC or frame sync, but have good picture controls. s-video input and composite video output.
-USB Capture Stick MyGica, using composite video input
-Capture software: Virtualdub2 64bits.

SAMPLE VIDEO: 16 secs (114.23 MB, Cedocida DVCPRO50)
https://www.mediafire.com/file/0r3tv5ddsb3qegs/dinamo97.avi/file

lollo2
19th November 2022, 19:09
https://www.avartifactatlas.com/artifacts/scratches_and_tape_wear.html

https://www.avartifactatlas.com/artifacts/time_base_error.html

Emulgator
19th November 2022, 20:34
Overmodulation which threw off following circuitry ?
If only restricted to that particular channel it could even have been an overmodulated transmitter.

Rec tuner/deck: Might have been slightly misadjusted tuner while recording,
or the recording deck itself not tolerating out-of-bounds WTW video voltage.

Neither tape nor repro VCR should be guilty, that damage had been done before the recording head wrote it on tape.

Alex-Kid
22nd November 2022, 07:04
Overmodulation which threw off following circuitry ?
If only restricted to that particular channel it could even have been an overmodulated transmitter.

Rec tuner/deck: Might have been slightly misadjusted tuner while recording,
or the recording deck itself not tolerating out-of-bounds WTW video voltage.

Neither tape nor repro VCR should be guilty, that damage had been done before the recording head wrote it on tape.

By what you are telling me, I think the channel could be the reason. It was a young channel (2 years) at that time, had very young people working there and little money to spend, maybe they had this problem and couldn't fix it, though on TV the picture looked fine. I don't think the VCR or the tape were the problem because the other channels recordings have good picture and the other tapes with channel 2 recordings from that time (some of them are quality ones) they all have that artifact, especially when recorded on SP mode.

Pity can't be fixed from the analog world, but thank you for your help and guidance :thanks: