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 Post subject: [CLD-D704] CLV Smear
PostPosted: 03 Oct 2021, 00:20 
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Has anyone attempted to figure out how to disable the filter that causes CLV smear on the CLD-704 (and similar players)?

There’s an output line from the PD0226A (IC101), labelled XCLV. It appears to drive some analogue NR circuitry. High means CAV and Low means CLV. I wonder if forcing it high might disable the smear?

Anyone tried it before?

Note : I mistakenly posted this in the wrong location at first. Not sure if it's possible to move, so I deleted and reposted - hope that's not breaking any rules.
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 Post subject: Re: CLV Smear on CLD-D704
PostPosted: 03 Oct 2021, 01:41 
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Interesting. At some point I meant to look into this. Made a subpar compilation of CLD-D703 info:
Attachment:
XCLV.jpg
XCLV.jpg [ 66.18 KiB | Viewed 198 times ]


It seems low risk to try it out.

The optimal solution to min/max video quality might be to just tap the video going into that IC, bypassing it as well as the DVP, memory, and comb filter. Video goes into IC400 at .9Vp-p (#21 in image) and comes out 1.7Vp-p.
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 Post subject: Re: [CLD-D704] CLV Smear
PostPosted: 11 Oct 2021, 05:22 
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So I had a go at performing this mod today. It does reduce the CLV smear. I've not spent time to see if there are other issues with it (the filter is probably there for a reason), but it works in my environment.

The smear effect is pretty subtle on my Sony PVM CRT and on my OLED calibrated Laserdisc settings. Using a non-calibrated profile (with higher brightness) shows the issue (and noise) more clearly, and is easier to to photograph.

First an image of the CLV smear from Star Wars opening sequence:

Attachment:
File comment: Original Output with CLV filter
Smear.jpeg
Smear.jpeg [ 43.2 KiB | Viewed 154 times ]


Same scene with bypass enabled (disabling CLV specific noise filtering):

Attachment:
File comment: Output with CLV filter bypass
NoSmear.jpeg
NoSmear.jpeg [ 43.64 KiB | Viewed 154 times ]


On to the mod details. Pin 50 of IC101 is XCLV, which passes through W497. I didn't want to remove the whole motherboard for testing the mod, so I cut W497 instead:

Attachment:
File comment: Pin 50 of IC101 is XCLV, which passes through W497.
W497 cut.jpeg
W497 cut.jpeg [ 209.92 KiB | Viewed 154 times ]


Wire these with a three pin, two way switch, to toggle between +5v and XCLV to the output;

Attachment:
File comment: Solder points for switch. +5v, XCLV from IC101, and output.
Switch Wiring Points.jpeg
Switch Wiring Points.jpeg [ 221.95 KiB | Viewed 154 times ]


I drilled a hole between the COAX and the Optical outputs, and mounted the switch on the rear.

Attachment:
File comment: Mounted switch interior.
Mounted Switch.jpeg
Mounted Switch.jpeg [ 179.86 KiB | Viewed 154 times ]


Overall, it's to early to tell whether this mod is worthwhile or not. The smearing is usually pretty subtle on my TV set, and the extra noise on CLV discs might make this mod pointless. Looking forward to finding out though!
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 Post subject: Re: [CLD-D704] CLV Smear
PostPosted: 11 Oct 2021, 15:59 
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Nice job!

deckard wrote:
The smearing is usually pretty subtle on my TV set, and the extra noise on CLV discs might make this mod pointless. Looking forward to finding out though!

Eagerly awaiting your observations!
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