Troubleshooting the BVU-870

[captain18]

So, some time back I wrote an article about my attempts to obtain higher-quality video output from my old warhorse 3/4" deck (see Stupid U-Matic Tricks). The one thing about documenting my efforts is that it pulled together a lot of useful information I simply didn't have before. Like information on other gear out there that was available on eBay

Comments

[johnr2]

Hi Captain,

Very interesting posts on U-matic decks and dub connection. I picked up a Sony VO-9850 with TBC card in order to digitize some U-matic tapes. After reading your posts I figure that I cannot just plug in to the composite BNC and get the best transfer. From your expert experience what is the best route to get the best transfer out of a deck such as mine? My original thought was to connect the composite BNC to a Canopus ADVC 300 and then firewire to a PC.

Looking forward to your thoughts.
John

[captain18]

Hi John,

I may be wrong but I do not believe that the VO-9850 came with a built-in TBC option. I believe what your deck has is a built-in Time Code card (the BKU-704 reader or BKU-705 reader/generator option) -- unless your unit has a third-party add-on or you mean a separate TBC was included with the deal.

My understanding is that tht BVU-9xx series (BVU-900, BVU-920, BVU-950) were the only U-Matic decks which could take a built-in TBC card (the BKU-901A option).

Even if it did include a TBC, there's a strong possibility it only provided time base correction for the composite output and the YC-688/Dub signal is not processed. This would need to be tested and verified prior to use as we really want to source our signal there since it contains greater signal bandwidth.

If you can confirm what gear you have, I can give you more precise direction.

[johnr2]

Hi Captain,

The VO-9850 I have comes with the BKU-705...I gather this is not a TBC.

John.

[captain18]

You're correct. The Time Code (TC) board lets the deck read and write time code from tapes which were recorded with it -- some were, some weren't. This can be useful if you're doing linear editing or if you have RS-422 deck control from the computer you'll be using for video capture but otherwise makes no difference

[captain18]

I blew the 5V fuse again tonight on my BVU-870. Annoying, but I finally discovered why.

PROTIP: When Sony says to only connect and disconnect the Dub cable when the power is off, they mean it!

[jvraines]

Hey Captain, thanks for the tip and all the great info on using the U-matic dub output. I finally got a UTP-2 (DPS-210) for my 9850 and built myself a dub cable. I run s-video through my little AVT-8710 frame sync and the picture looks great!

Do you have any suggestions about where I could find a service/setup manual for the transcoder? The color balance is a little too far off to correct with the front trim pots. I think I need to tweak the pots on the board.

[jvraines]

Never mind. The board labels were sufficiently explanatory to find the right adjustments.

[captain18]

I'm glad you were able to get the unit adjusted! It looks like a copy of the service manual can be backordered at Union Electronic Distributors if anyone else is looking for it.

[erwagr]

Hello Captain

[captain18]

Thanks for your kind words!

The simple answer is, you have to run two cables instead of one. Not a big deal, it just feels somewhat redundant and inefficient.

The Dub cable carries the chroma signal at 688 kHz. Rather than taking that signal and upconverting it to 3.58 MHz at the TBC, most TBCs "cheat" and have you run a regular composite video cable in addition to the dub cable. This way they take the luma from the dub and the chroma from the composite, since it's already at 3.58 MHz.

In detail, this is how you will want to connect your VTR to the a DPS-295 (or one of its siblings):

VTRTBC
Dub OutDub Y Input
Video OutNTSC-2/Dub C Input
Sync InAdv Sync Output
SC InSubcarrier Output

If your VTR has a Mode Select switch (labeling may vary by model), set it to TBC.
On the front panel of the DPS-295, set the Input Format to DUB and the Input Mode to DIRECT.

Good luck!

[erwagr]

Captain,

Thanks mightily for the chart, which couldn't be more clear. One last thing, 8th Man is out of those cables so it looks like I'll be going the Markertek/solder route. Based on your other post, I take it that I only need a two-wire cable and then I wire up pins 1 and 2 on the SVHS-7M connectors. Please confirm or correct. Is it obvious on the connectors which pins are 1 and 2? I know on XLRs they print on the plastic, but maybe these others aren't so helpful...

Thanks,
Eric

PS. I re-posted this since my initial post was marked as spam by livejournal, I think because I copied the url of your eariier post in the message. I've deleted it on this one and hope this message posts normally...

[captain18]

Absolutely, if you're going to use a solution which requires both the dub cable and a composite line, you can get by with wiring only the two pins for the luma.

If you're rolling your own, be aware that you'll need a SVHS-7M and a SVHS-7F. One suggestion would be to get a pair of BNC bulkhead jacks and effectively build yourself a pair of 7-pin to BNC adaptors and you could use a regular cable to go between.

The pins are well labeled so you shouldn't have any trouble if you've worked with XLRs before.

[ext_1686162]

Hi, Captain.

I've been having some trouble digitizing some tapes from U-Matic in Final Cut Pro. There are times when the audio ends up out of sync. It's not a case of audio drift because some of the tapes end up just fine. It happens when there's a glitch in the tape and the picture and audio go out. When they come back the picture ends up about 3 frames ahead of the audio. This adds up, so if it's a particularly old and/or damaged tape, you can end up quite a few seconds off by the end of it.

I'm noticing this with Hi-8 and VHS transfers as well, but Beta SP's don't seem to have this problem. Any insight would help.

Thanks in advance.

-Greg

[captain18]

Do you have a TBC or at least a framesync between your U-Matic/VHS/Hi-8 and your capture card?

If not, then when your deck is hitting the glitch, the capture card is losing sync -- which it was probably struggling to maintain anyway if it was an old tape or multigenerational dub.

You're not seeing this with Beta SP for two reasons. 1) Most Beta SP decks have onboard TBCs; 2) The greater robustness of the Beta SP format is giving your capture card higher quality video to capture.

If you do have a TBC in the middle then I would make sure it's either generating a proper reference signal or receiving one from a stable source. I had a sync problem once that drove me crazy; it turned out the camera I was using to generate my "house" sync had failed and was no longer generating a valid video signal.

[ext_2198288]

Oh captain my captain---

We are digitizing 16mm films with a Elmo TRV-16H (S-VIDEO and composite outputs) running to a DPS-295 then into a Blackmagic SP Card. We used to get color using routing the S-Video through the DPS-295, but a staff member swapped all the cables out and we only get a B&W signal now. Any ideas?

[captain18]

Given that you're getting luma but no chroma, the connections can't be too far off... So I have a bunch of questions:

Are you using the DPS-295 for time base correction and signal adjustment, or are you using it to transcode from S-Video to Component?

How does the video get from the Elmo to the 295, and from the 295 to the Blackmagic? Is it a 4-pin mini-DIN S-Video cable, or something else?

Can you bypass the 295, and if so do you get color or B&W at the capture board?

With those questions in mind, if you're using S-Video cables, check to make sure you don't have bent pins on the connectors. Also, throw the 295 into TSG mode on 00 and make sure your Blackmagic is seeing color bars in color, that will help pick out whether your problem is going into or coming out of the unit.