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-   -   Use two TBCs, or only one? (https://www.digitalfaq.com/forum/video-restore/11610-two-tbcs.html)

jose carlosv 03-15-2021 01:30 PM

Use two TBCs, or only one?
 
Well this is my doubt.
I have a JVC hm dr10000 and a refurbished Panasonic NV hs1000.
Both vcr has their own TBC and i have both vcr plugs to my denon avr3312ci
Looking the denon técnical specs i found It has two chips for upscalling, de interlacing and convert analog into digital Signal, the adv8002 and the adv7844.
This last chip has digital TBC, is made on 2011 so are da newer than JVC and panny TBC circuits.
Is recomendable to use both TBC, the vcr one and the denon one or only the TBC in denon?.
I say to let the denon tbc on because is the newer of there decks.
Many thanks

bookemdano 03-15-2021 02:08 PM

Those are two different types of TBC. Both are needed.

The VCRs have a "line TBC" that cleans up the picture.
The Denon is likely a "frame TBC" that cleans up the signal to stabilize it for capture without dropped frames.

jose carlosv 03-15-2021 02:13 PM

Many thanks sir you ask my doubt

lordsmurf 03-15-2021 02:20 PM

Quote:

Originally Posted by bookemdano (Post 75962)
The Denon is likely a "frame TBC"

Nope, highly doubt it. :no2:

Denon is usually just a home theatre appliance.

The presence the certain AD chips means nothing. While it has an optional line TBC ability, it's never been implemented properly by anything. Even when attempting to make it work, it really doesn't. Poor documentation is part of the reason. But even with those AD chips, it's line TBC. The frame TBC ability is pathetic. Actual frame TBC will require FPGA, there's no way around it.

hodgey 03-15-2021 02:21 PM

The adv7844 features both actually (if enabled), though I don't know if it is able to do any better than the in-vcr ones.

lordsmurf 03-15-2021 02:23 PM

Quote:

Originally Posted by hodgey (Post 75965)
The adv7844 features both actually (if enabled), though I don't know if it is able to do any better than the in-vcr ones.

The AD's TBC is really just a placebo, very narrow real-world uses.

jose carlosv 03-15-2021 03:02 PM

Ok so the TBC in vcr are the most important in my particular situación and in the other people with ad chips in the avr.
Is a shame because JVC works well but panny TBC has problem and i dont know where to look
I have check the caps, i have resolder some components but the TBC is not working properly
I know there are many post in the forum with this particular problem but i dont know if anyone has found the real problem to fix it.
I mean, bad heads are bad heads, you must to change It and this is clear but TBC problems are more difficult to find and repair.
I wish someone could Tell me, look this CAP or that chip or this component in the board but as i say i have read many post and i cant find any clearly way to fix It or yo check if TBC woks ok and the problem are the tapes

latreche34 03-15-2021 03:24 PM

1 Attachment(s)
The datasheet diagram suggests that it has a line TBC and a field TBC (half frame, Not sure if it stores two fields in the SDRAM or just one) as you can see it creates new H and V signals in addition to the field video data. It has a separate process for de-interlacing and upscaling, So it can provide an interlaced SD signal depends on how the menu works and what features are enabled. SoC are awesome if the needed features are functional.

http://www.digitalfaq.com/forum/atta...1&d=1615839648

lollo2 03-15-2021 05:33 PM

Off topic!

Quote:

SoC are awesome ...
Thanks! Finally some visibility for ASICs and ASSPs designers! :wink2:

hodgey 03-15-2021 07:20 PM

Quote:

Originally Posted by jose carlosv (Post 75967)
Is a shame because JVC works well but panny TBC has problem and i dont know where to look

What issue does it have? I had a bad cap in the TBC module causing a distorted image on one of these but that may have been caused by me accidentally shorting something so idk if that's a normal issue.

jose carlosv 03-16-2021 01:39 AM

Jitter and flikering sometimes.
As i say i know is a common faulty in this vcr and hard to found and fix

lordsmurf 03-16-2021 12:10 PM

Quote:

Originally Posted by latreche34 (Post 75968)
The datasheet diagram suggests

Ah, yes, but the bigger question is whether you've actually tried to make it work as it suggests. I'm currently working with somebody for something, and AD chips simply do not work as suggested. Very weak, problems. Interesting, but not feasible.

Again, a TBC is not a chip. More complex than that.

latreche34 03-16-2021 12:33 PM

Because the features are not always implemented in the final product that uses the chip as I stated in the same post. It's not the chip manufacturer's fault, it's the product's designer.

lordsmurf 03-16-2021 03:27 PM

No, that's not it at all. You're still missing what I'm saying. We've been trying to make the chip do what it claims. It simply will not work. Theory vs. practice, again.

Formica 03-16-2021 04:40 PM

Quote:

Originally Posted by lordsmurf (Post 75994)
No, that's not it at all. You're still missing what I'm saying. We've been trying to make the chip do what it claims. It simply will not work. Theory vs. practice, again.

I say a prayer for this project from time to time...


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