Sony VO-9850 colour outputs B&W?
 

Hi all,

I've been working on transferring U-Matic tapes at my archive and noticed one of our VO-9850 decks has been outputting only black and white even when we use colour tapes. Typically we use the dub output through a DPS transcoder, although the black and white issue persists in the video out output also. I've taken a look at the APC switch as the service manual indicated this can impact colour signals but that is where it should be. Before I get into the meat of electronics, I was wondering if anyone here knows of any other 'easy' fixes or places to look? Thank you!

Was it outputting normally before and it stopped? I believe all that it would take for color not to come through is a poor connection on one of the connectors as it's kind of an older form of S-Video. Sounds like you also have multiple units, so I would think you'd have tried swapping Dub cables and DPS units? Which DPS TBC are you using? My understanding is that to use DUB IN you need to also connect Composite to the DPS unit as well as chroma actually comes through the composite plug. Not an expert by any means and haven't used an actual device that outputs DUB, but I have some TBCs with DUB-in and I'd like to see it in action one day haha. I hear even the plain DUB Cables are hard to find....

Howdy! Unfortunately we weren't keeping track of what equipment was used for transfers until recently, so I'm not sure if it ever gave us colour output or not. As for the signal path, we go VO-9850 dub output -> dub input to a DPS-210 transcoder -> S-video output to a DPS-235 TBC -> S-video output to BlackMagic Analogue-to-SDI convertor -> BlackMagic capture card. We only have one of all of these things, and two VO-9850s, so both are hooked up the same way for transfers. One gives us colour output, the other doesn't. I'm not sure its our cables, but it could well be the outputs on the machine!

Sounds like everything is the same after the players including the cables, so that does limit it to the players most likely. I'd probably look to make sure the connectors are not dirty looking and have good continuity using a basic multimeter from the inside of the machine to the other end of the dub cable.

I actually hadn't seen a DPS-210 - I honestly thought DPS only made TBCs, but I guess that doesn't contain a TBC as far as I can tell which is why I see you have the DPS235 afterwords.

Not that you probably want to spend more on your setup, but that Umatic deck has RF-out (means you can do dropout compensation on an equipped TBC), and Sync in (which means you can have the TBC control the rate at which the tape plays to get the fields/frames per second output by the VTR to be what the TBC says it should be without having to insert/drop frames. If you're going to archive, I would personally use those features as they could visibly improve the quality - particularly the dropout compensation.

TBCs that have advance sync, DOC, and DUB-in include the DPS-275 and ForA FA-300.

The I.Den IVT-7 TBC is missing the advance sync, but does have DUB-in and DOC.

I do have an FA-300 that I'd sell for much less than the ones currently listed on ebay, but it does have an issue where it doesn't like turn on the first flip of the power switch (you have to turn it on/off until the switching power supply starts up, but once it's powered up and running, it stays running fine. It's not the power switch itself because you can do the same thing by disconnecting AC and reconnecting with the power switch left on, so it's absolutely something in the power supply that initiates the switching circuitry. Someone who rebuilds power supplies (beyond recapping) could probably figure it out pretty easily, but that's not me haha. I actually didn't replace any of the caps on it since they tested fine in-circuit, but a full recap might fix it also. PM me if interested in that.

Hi, thanks for the detailed reply! I've definitely narrowed it down to the machine itself, and will be going over that in detail to see if I can pinpoint what exactly isn't working right.

We use the dub output to get the highest possible quality as we're ideally only transferring the material once to digital. From what I understand, while the RF output has those perks for controlling drop-out, its one of the lowest quality video outputs on the deck, although if I'm wrong please let me know! Unfortunately a new TBC isn't on the cards for us right now, anyway, but I'm interested to hear how our signal path could be improved to get the highest quality transfers.

RF out does contain the raw video data straight from the heads (this the only input VHS_Decode needs to fully reconstruct the image actually), but the TBC is not trying to decode any of the actual information there. All it does is check if the amplitude (height) of the raw waveform drops below a certain threshold (hence why they call it a dropout). By getting to tap into that amplitude, the TBC knows exactly when a dropout is occurring in real time, and the TBC starts replaying the last good line of video it has stored in its buffer over and over until the signal goes back above the threshold level. You actually get to adjust the specific "threshold" of what you want the TBC to consider a dropout to be which essentially lets you set the sensitivity. You definitely can't do that on VTRs with traditional dropout compensation.

Most newer tape players have built-in DOC, but most don't work the same way as a standalone TBC would. With a standalone TBC, the data replayed comes from a digital buffer and is perfectly replayed each time, whereas traditional internal dropout compensation comes from some sort signal stored in a crystal or IC (in a non digital form) that gets weaker each time the line is replayed from it (including even the first replay) hence you get those sort of horizontal purple discolorations which is what I personally would like to avoid. Better than looking at static or pure black lines I guess.

This info is all about reading from it, I've got several TBCs with DOC inputs, but no players that have RF output to actually see it in action unfortunately. It is possible that tapping the RF test point separately would then essentially "overwrite" the VTRs internal DOC, but that may be theoretically possible. Again, the hope would be that it gets rid of the purple horizontal lines during dropouts.

You should always use external DOC and ADV SYNC (synchronizes the playback speed to what the TBC is expecting to receive) if it's an option for the reasons above. Not saying that you *have* to buy a new TBC or anything, but if you do want the highest quality captures, Using DOC/RF out should be a given, but I wouldn't take my word for it (since I've never had the opportunity to see it in action), probably would ask someone who has done it both ways to see what advantages they saw or didn't see.

Fun Fact (I think - at least if the TBC-IV manual is correct) - Looks like the DPS-235 that you have does support both DOC and ADV Sync, but you'll need to make a cable that goes from that 9 pin Multi/IO port to two BNCs.

I have a DPS-235, but I can't confirm that those features work since I don't have any machines with RF Out/Sync In.

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