SVHS Mitsubishi HS-U746 produces artifacts on bright scenes.

[digicube]

https://drive.google.com/drive/folders/1h5FRorpBudMMjRMiux82OOo9P17EFOpp?usp=sharing

Artifacts appears via both composite and s-video direct output to capture device. I have cleaned the video heads. Is it a bad dropout compensator or worn out heads?

[davexnet]

Never seen that before. If you plug the VCR into the TV directly, do you see the same issue?

[digicube]

yes.

[dellsam34]

Is the tape S-VHS? It seems like it tries to playback a S-VHS tape but the S-VHS detection switch is malfunctioning and it plays it back as VHS, The DOC is trying hard to fix the luma signal clipping because it thinks it's a missing signal.

Does the S-VHS logo appears when you insert a S-VHS tape?

[digicube]

It's a VHS tape. I'm leaning towards worn heads and the dropout compensator doesn't work well on bright scenes, only in dark scenes.

[dellsam34]

That's not an artifact of low RF signal, I could be wrong. I've seen low RF signal from worn heads as uniform streaks all across the screen not just bright areas.

[digicube]

Maybe the streaks are dropouts and the dropout compensator is converting it to artifacts?

[oln]

I've observed the JVC VCRs I have causing black streaking on sharp transitions on some tapes to varying degree (while other VCRs don't do this on the same tapes.) From what I've seen Mitsu often used JVCs video ICs in their newer decks (tho will have to re-check) so maybe it's related in some way. The JVCs don't seem to have any way of adjusting it for standard VHS which is frustrating.

You can also get the effect on a vcr where the frequency response/rf Q adjustments are off in one direction, though that's not adjustable on many newer VCRs, not sure about this one.

I've also observed it when working on vhs-decode, one cause is that the transition from a very high frequency (white) to a low frequency (black) results in the signal amplitude at that point ends up very low and can end up being misinterpreted by the demodulation circuit as a different frequency. (VHS is FM-modulated on tape, i.e instead of white being higher voltage, white is higher frequency, and black is lower frequency, similar to FM radio.) The de-emphasis circuit then ends up turning the short "spike" into a "streak". This can also trigger the dropout compensator causing these weird effects (I've seen that effect in a Panasonic VCR.) The VCR will have filtering to compensate and eq the signal coming off the tape to reduce this to a degree but it's possible it can drift or be insufficient. A worn tape with a weak signal will be more suspect to this than one with a strong signal, head wear or damage may also have some impact but as noted that may cause different effects.