Sony BVH-2180-PS: Servo Error

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Re: Sony BVH-2180-PS: Servo Error

Post by PID_Stop » Tue Jan 05, 2016 3:49 pm

Oh, yeah, we know Studer! They were more of a presence in recording studios than broadcast facilities, at least in my part of the country. Of course, Ampex's largest distributor for pro audio east of the Mississippi River was less than a hundred miles from here... so nearly every station was filled with 601s, 350s, 440s, or an occasional ATR-700 (really a Teac clone, if I remember right). The exceptions were decks that came with automation systems (IGM, if I remember right) or special purpose machines like the huge Scully machines that took 14" reels and could auto-reverse.

I doubt that a Studer would have lasted very long in our shop, with all the people drooling over it. :lol:

-- Jeff

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Re: Sony BVH-2180-PS: Servo Error

Post by DolbySR » Wed Jan 06, 2016 10:16 am

PID_Stop wrote:I doubt that a Studer would have lasted very long in our shop, with all the people drooling over it. :lol:
Sure, that might be a bit of a problem... Quite understandable, though. The drooling especially, not the not lasting very long :wink:

My middle school had an entire language laboratory (well, a room with tape recorders at each desk to learn languages, interconnected with some great functions) equipped with those Studer-ReVox learning system. Really cool devices to learn a new language and to perfect it. We went there each week in our French classes.

Anyway, in the mean time, I managed to get the 1st volume of the BVH-2000 manuals as a PDF. This one certainly helps a lot in order to understand basic functions, especially all the edit functions. There are some really neat things you can do with them. Quite impressed.

But something else that came to mind: I watched a video about one of the latest AMPEX 1" C-type recorders and they apparently have an untreading function. Up until now, I always unthreaded a tape using the JOG function after the rewinding had stopped a few meters before the end of the tape. Is there something similar available with the BVH? Yeah ok, it might be in the manual, but I have to admit to having mainly concentrated on the video recording and editing theory... :roll:

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Re: Sony BVH-2180-PS: Servo Error

Post by PID_Stop » Wed Jan 06, 2016 1:03 pm

DolbySR wrote:I watched a video about one of the latest AMPEX 1" C-type recorders and they apparently have an untreading function. Up until now, I always unthreaded a tape using the JOG function after the rewinding had stopped a few meters before the end of the tape. Is there something similar available with the BVH?
Sony built several safeguards into the BVH-2000 to avoid having the tape end nailing the head. First, the system constantly watches timer 2 (the one you can't reset) and automatically slows down the tape when it approaches the end of the tape. Second, the EOT STOP switch on the SY-80 board will actually stop the tape before it runs off the end of the reel. And finally, when you continue rewinding, the guides automatically retract.

The last feature is probably the most important because the distance between the guides and the drum is very small; part of the mechanical setup when you replace the upper drum or the guides is to shut off the power and manually close the guides; there should be just enough clearance between the drum and the ceramic guide edge for two thicknesses of tape to pass. If the end of the tape passes through the closed guides, any wrinkles, folds, or zebra tape is very likely to score the drum surface or nail one of the tips.

In general, I prefer to use a fairly slow shuttle (maybe -5x) to unthread the tape, rather than jogging; that clears the tape end out of the tape path promptly without whipping it around.

The NBC station across town (where my dad was an engineer for more than 50 years, as it happens) had Ampex machines, VPR-80s and VPR-2Bs. They seemed to have far more instances of tip damage than we did; on the other hand, Ampex tips were individually replaceable on the drum. Breaking a tip on a BVH means you are in for several hours of fairly intricate work...

-- Jeff

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Re: Sony BVH-2180-PS: Servo Error

Post by DolbySR » Wed Jan 06, 2016 1:29 pm

Well, those safeguards are really handy and I noticed the very tiny tiny gap between the drum and the guides. I once tried to play a tape and a few minutes through the tape, there were wrinkles in the tape itself. I immediately hit stop to avoid any damage. But I can see why any major disturbance of tape thickness is increasing the risk of head damage. There isn't much tolerance at all.

Shuttle, yes, I actually meant shuttle not jog. This +/- 50 times shuttle is amazing every time I watch it. And I asked myself a few times whether you could prepare your salad with this machine. Cut up the vegetables for example :wink: A friend of mine actually tried this with a decommissioned film projector which had a single-blade shutter which, in order to achieve 24 frames per second which were projected twice each, rotated 48 times a second. Its edges were quite sharp because there was no finishing to preserve the straight edge for the shutter. The cucumber was all over the place, cut into very fine pieces :lol:

Concerning heads... Is there any method of telling how many hours my heads have on the clock? I know there is this small fuse-like hour counter, but this one is already maxed out. Do I have to assume that the head drum should be changed soon? For my rare use though, I guess it would be okay to just run until the quality decreases?

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Re: Sony BVH-2180-PS: Servo Error

Post by PID_Stop » Wed Jan 06, 2016 3:51 pm

DolbySR wrote:Concerning heads... Is there any method of telling how many hours my heads have on the clock? I know there is this small fuse-like hour counter, but this one is already maxed out. Do I have to assume that the head drum should be changed soon? For my rare use though, I guess it would be okay to just run until the quality decreases?
When you buy a new head, it comes with one of those little indicators... but it's not very accurate and if you refurbish the head, all bets are off.

The best way to estimate head life is by using the eccentricity gauge. This is a very precise tool similar to a dial micrometer that screws onto a threaded boss on the machine's deckplate and rests against the base of the lower drum assembly (the part with the slant guide).

Image

There's an adjusting screw that moves a nylon tip down onto the surface of the upper drum; if you are measuring tip projection, you move the drum to a spot between tips and adjust the gauge until the needle reads '0'. Then carefully turn the drum until the tip comes around under the gauge's nylon tip -- the needle will deflect to read how far out from the surface the tip is protruding. The measurement is is microns (0.001mm). A factory new head will have just over 90 microns on the play (DT) and R/P heads, around 50 on the erase head. A head will start showing problems when it approaches 50 microns.

It's hard to correlate the number of hours to tip projection: different tape formulations vary in abrasiveness, and the cleanliness of the environment also plays a part. At our station, we would get on the order of 2,500 hours or better on a drum.

Here's where it gets uncertain: several companies used to refurbish upper drums. They would polish the drum surface and reposition the head tips to stick out a bit more, to about where a new head's tip would be. That would solve the tip-to-tape contact problem, but gap width becomes an issue. A new Sony tip can wear down to the point where the projection becomes a problem, and the gap will remain about the same width; but after a certain point (another 40 microns or so of wear, in our experience), the gap starts to widen rapidly. That's what I was referring to the other day... and that's why tip projection alone doesn't necessarily tell the whole story. The best way to estimate useful life is to measure the tip projection, then pop the cover off the head assembly and look for a sticker from a refurbishing service (CMC did most of ours, and AheadTek also did a few).

Image

This is a snapshot of a spare upper drum on the shelf in my office; notice the CMC sticker, which tells you it has been refurbished.

You will have to remove the copper-plated amplifier assembly to see the sticker, if it's there. Make sure you note which way around the amplifier is mounted, because there are three possibly ways to mount it, two of them wrong. I'd use a sharpie to make corresponding marks on the amplifier and the inside of the drum.

Regards,

Jeff

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Re: Sony BVH-2180-PS: Servo Error

Post by PID_Stop » Wed Jan 06, 2016 4:21 pm

I had better add a couple of notes about the eccentricity gauge, just for the sake of safety.

1) Power to the machine should be off when you are measuring tip projection or drum eccentricity. We had a bright fellow in the school who thought you could make a rapid measurement by mounting the gauge and starting up the drum (normally that's impossible unless you get the machine into a special test mode). This would be a very efficient means of needing both a new drum and a new gauge... both of which were quite expensive 30 years ago. I can't imagine what the cost would be today!

2) When you install the gauge on the machine, the small adjusting screw (it's on the left side of the main bracket in the photo above, roughly where the needle is pointing) should be counterclockwise enough that the gauge tip is fully disengaged from the head surface. In practice, this would always the the case, but it's worth mentioning.

3) There's a black metal bracket under the nylon one (you can't see it in the photo); as you screw the gauge to the deckplate, the whole thing will rotate clockwise until the bottom black bracket rests against the lower drum. You really want the gauge against the stop, or else your measurements will tend to drift.

4) Once the gauge is firmly screwed down (don't go crazy, but it wants to be secure), you can grab the whole thing and swing it to the left; a spring normally holds it to the right, in position. If you swing it to the left, you will find that you can slide the whole thing in and out (toward the deckplate or toward you). Take a look at the shaft under the big mounting screw while you're doing this, and you will see an orange dot. If you slide the gauge all the way toward the deckplate so the dot is fully visible, the nylon tip will line up with the sync tips on the drum (these record a short portion of the vertical interval while the main head is in the no-tape space between the entrance and exit guides). If you slide the gauge out so that the orange dot is halfway covered, the tip lines up with the main head tips. And if you slide the gauge all the way out so the dot is covered, the tip misses the tips entirely. This is how you measure drum eccentricity.

5) All measurements start by positioning the drum so the nylon tip is between heads, resting on the drum surface. Slowly turn the adjusting screw clockwise until the tip actually contacts the drum; the needle will start moving to the left. Adjust it until the needle winds up at '0'. Then you can slowly rotate the drum toward the tip you want to measure.

5) Eccentricity is the measure of how uniform the drum's radius is as it rotates. If you set the gauge all the way up (orange dot hidden) and adjust the needle to the '0' mark, you should be able to slowly rotate the drum around the full 360°, and see only a minimal movement of the needle. If you are adept, you can generally get the eccentricity within one tick-mark (±0.002mm) of the average. There are tools to make the job easier (tapered screws, for example), and several tricks that I have learned over the years which would be a good subject for some later time. Ignore the manual when it calls for a plastic-tipped hammer (yes, really!). If you have the mounting screws just slightly loose, a slightly assertive tap on the inside of the drum with your fingertip is safer, and much more precise.

6) (This was added in the edit) When you have finished taking your measurements, unscrew the adjustment to lift the nylon tip back off the head.

7) If you don't have an eccentricity gauge, don't loosen the drum mounting screws or attempt to change the drum. It's very easy to install it with so much position error that it will hit the ceramic edge of the guides... and without a gauge, there's absolutely no way to eyeball such a small error.

That's enough about for that!

-- Jeff

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Re: Sony BVH-2180-PS: Servo Error

Post by DolbySR » Thu Jan 07, 2016 8:56 am

Hello Jeff

Thanks for the very detailed information about this neat measurement device :D

The chance for me to get a gauge for my own are quite small I presume, so I'll just stick with the heads I have for now 8) Even though I'd be quite interested in what state the heads are in. I picked up the machine from a film and video postproduction company, "CinePostproduction GmbH" near Munich, apparently only a few months before they went bust :roll: . I could have filled an entire truck with equipment there I guess. But where to put it... There was so much stuff around waiting to be sold or, the majority of it, thrown away.

So if I did the math correctly... If I buy a new head drum (currently about 6'300$ - holy F!), run the heads down to 50 microns, I have used about 40 microns of head material. I then refurbish this drum and there would still be another 40 microns of "head" to eat through before the gap would become an issue. So about 5'000 hours on one head drum with refurbishing. And one hour costs more than 1$ in pure head-wear :roll:

This sync head... I understood what the CTL track is used for now, but what exact purpose does the sync head have? I saw on a diagram in the 1st volume of the manuals that there is a sync "blob" just before a video track starts and this one sits within the CTL track. Do they have anything do to with each other? Something I didn't get until now?

A plastic hammer to align the drum? Okay... Maybe that guy was a bit of a Jeremy Clarkson type :lol:

Image

I read in my manuals that they suggest the rear of a screw driver to give light corrections to the inner ring of the drum. But a plastic hammer... Eccentricity is one thing, but what about balancing? Is this an issue to deal with or are the drums themselves already balanced well enough? After all, this drum rotates at quite some speed and has some diameter.

I just recently read about the first headwheel the AMPEX engineers designed which didn't cope with the centrifugal force and (almost) send heads flying though the room. :D Great stories.

Regards,
Patrick

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Re: Sony BVH-2180-PS: Servo Error

Post by PID_Stop » Thu Jan 07, 2016 11:03 am

DolbySR wrote:So if I did the math correctly... If I buy a new head drum (currently about 6'300$ - holy F!), run the heads down to 50 microns, I have used about 40 microns of head material. I then refurbish this drum and there would still be another 40 microns of "head" to eat through before the gap would become an issue. So about 5'000 hours on one head drum with refurbishing. And one hour costs more than 1$ in pure head-wear :roll:
Yup. Back when these were our primary machines (think 25 years ago), an upper drum cost about $1,200; the lower drum was about $6,000. And yes, your estimate is pretty accurate. Remember the context, though: the 2" quad machines these replaced were even more expensive to operate. And back then, syndicated shows were delivered on videotape, not via satellite -- so just the difference in shipping cost between an hour of 2" tape versus an hour of 1" tape was considerable improvement in a station's balance sheet.

Operationally too, 1" tape was much nicer to handle. Our station had three 2" machines, plus two film chains and the ACR-25 cassette commercial player. Between playing shows to air, producing shows and commercials, we kept all of the machines running pretty constantly -- and reel changes were hurried affairs, especially when you had 93 seconds to take down your previous show, thread, set up, and cue your next show on the same machine. One of our operators lost his grip on an hour reel of 2" tape in his hustle, and it managed to break his foot. He got the show up on time with no dead air, though. :shock:
DolbySR wrote:This sync head... I understood what the CTL track is used for now, but what exact purpose does the sync head have? I saw on a diagram in the 1st volume of the manuals that there is a sync "blob" just before a video track starts and this one sits within the CTL track. Do they have anything do to with each other? Something I didn't get until now?
Great question. A video signal is continuous: a succession of video lines punctuated by horizontal sync, followed by the vertical interval which tells your TV to begin scanning the next field. If you look at what the BVH's video head is doing, you will notice that it cannot record continuously: there's a gap on the right side of the drum between the guides, where no tape is in contact. If you think about it from the point of view of the record head, that means that for a few degrees of each drum rotation, the head isn't touching the tape and can't record anything.

Most helical tape formats like U-Matic, Betacam, DVC-Pro, and VHS solve this problem by wrapping the tape around just a bit more than half the drum, and positioning a pair of head tips directly opposite each other on the drum. This guarantees that there is always at least one head tip contacting the tape at all times. But the one-inch format has the so-called omega wrap, and the head scans a far longer diagonal track across the tape. If you have a copy of volume 1 now, take a look at the foldout pages 5-3 and 5-4 (it's the beginning of the theory of operation section). It shows exactly how the different tracks are arranged on the tape, and how they correlate to different portions of the video signal. The short version is that the main video tracks, which are a succession of slanted segments take up most of the space on the tape, only start recording before the start of active video, and end shortly after the beginning of the vertical sync interval. During the time the main head is flying past the open area between the guides, a second sync head, riding 30° ahead of the main head, has already come into contact with the tape and can record the portions of the vertical interval that the main head can't. The result is a second set of very short diagonal sync tracks that live between the control track and audio track 3 (which is generally used for time code).

The sync tracks just supplement the main video tracks, so that a complete video signal can be recovered from the tape. The control track's mission in life is to tell the drum servo where it should be positioned angularly in order to line up with the video tracks (and, by extension, the sync tracks as well).
DolbySR wrote:A plastic hammer to align the drum? Okay... Maybe that guy was a bit of a Jeremy Clarkson type :lol:

...I read in my manuals that they suggest the rear of a screw driver to give light corrections to the inner ring of the drum. But a plastic hammer...
Ha! Evidently they backed off a bit over time. Still, I really recommend using your fingers to do the tapping. Centering the drum is very touchy, and it's easier to control how much of a tap you're giving the drum when you actually feel it.
DolbySR wrote:Eccentricity is one thing, but what about balancing? Is this an issue to deal with or are the drums themselves already balanced well enough? After all, this drum rotates at quite some speed and has some diameter.
If you look at the inner rim of a drum, you will find spots of brown putty stuck on to balance the drum. There's also putty on the backside of the drum, along with brass weights:

Image
(This is the top surface of the drum, which you would see by removing the cover.)

Image
(This is the underside of the drum, which you only see when it's off the machine.)

The Sony instructor used to joke about a room full of elderly Japanese ladies chewing gum and balancing drums... but I have yet to find chewing gum that comes in that particular shade of brown (not that I have a desire to sample any!).
DolbySR wrote:I just recently read about the first headwheel the AMPEX engineers designed which didn't cope with the centrifugal force and (almost) send heads flying though the room. :D Great stories.
Yes, that was indeed a huge challenge for Ampex. Remember, their headwheel was spinning at 14,400 RPM, and the forces become a huge issue. The BVH head only makes one turn for each video field, so at 60 fields per second, that's a far more sedate 3,600 RPM. For you, running at 50 fields per second, it drops to a downright leisurely 3,000 RPM.

One last bit of Ampex trivia: the early quad heads used ball bearings, which imparted a certain amount of noise (which translates into time-base error and jitter in the picture), and sliprings to get the signal between the rotating headwheel and the rest of the machine. At some point, I'm guessing the early '60s, they replaced the sliprings with rotary transformers (which don't wear out, and don't require mechanical contact with the rotating parts), and replaced the ball bearings with frictionless air bearings, so the headwheel and shaft floated, like the puck on an air hockey table. Even ordinary reel-to-reel quad machines were highly dependent on compressed air and vacuum; if you want a jaw dropping treat, search in Youtube to see an ACR-25 operating. It combined two quad transports into one system to provide continuous playback from a series of cassettes. All of the cassette loading and unloading and tape threading were done using compressed air and high vacuum produced by a pair of large blowers driven by a three-phase motor. Wowza: life was exciting in our control room back then!

Regards,

Jeff

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Re: Sony BVH-2180-PS: Servo Error

Post by grich » Thu Jan 07, 2016 12:38 pm

DolbySR wrote:A plastic hammer to align the drum? Okay... Maybe that guy was a bit of a Jeremy Clarkson type :lol:...
Ahh, Jeremy Clarkson. With one drunken rage, he destroyed a great TV franchise. :(
PID_Stop wrote:...if you want a jaw dropping treat, search in Youtube to see an ACR-25 operating. It combined two quad transports into one system to provide continuous playback from a series of cassettes. All of the cassette loading and unloading and tape threading were done using compressed air and high vacuum produced by a pair of large blowers driven by a three-phase motor. Wowza: life was exciting in our control room back then!

Regards,

Jeff
When I was hired, the ACR-25 was gone, and a Panasonic MARC was playing commercials. I wish I had video of that running. I heard plenty of stories about the dreaded "thunk" when the ACR mis-loaded a tape. Excitement ensued when that happened.

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Re: Sony BVH-2180-PS: Servo Error

Post by DolbySR » Thu Jan 07, 2016 1:38 pm

Hello Jeff :)
PID_Stop wrote:Operationally too, 1" tape was much nicer to handle. Our station had three 2" machines, plus two film chains and the ACR-25 cassette commercial player. Between playing shows to air, producing shows and commercials, we kept all of the machines running pretty constantly -- and reel changes were hurried affairs, especially when you had 93 seconds to take down your previous show, thread, set up, and cue your next show on the same machine. One of our operators lost his grip on an hour reel of 2" tape in his hustle, and it managed to break his foot. He got the show up on time with no dead air, though. :shock:
Okay :shock: Tough guy! The show really had to go on in this man's mind! And it did.
I had a talk with a projectionist once who told me about some similar stories. They used to have film reel towers running in their cinemas to play the entire movie in one go without intermission or changeovers. At about 4'000 meters, one of those reels were heavy like hell. In one of their cinemas, they hadn't the space to have the reels as a sidewinder setup like you see here:

Image

Instead, they had the version with both reels stacked vertically. So the full reel had to be lifted up to quite a height in order to be mounted on the upper flange. That one time though, someone did not lock it down and so the reel slowly crept forward until it fell down, snapping this guy's leg in two. Unfortunately, the show didn't go on and the projector started yanking on the polyester film until it finally split and stopped the projection.
PID_Stop wrote:The sync tracks just supplement the main video tracks, so that a complete video signal can be recovered from the tape. The control track's mission in life is to tell the drum servo where it should be positioned angularly in order to line up with the video tracks (and, by extension, the sync tracks as well).
So the sync track fills in the missing gap where the main head won't touch the tape. Basically the information between two lines of video. But what if I record something on audio track 4?
PID_Stop wrote:If you look at the inner rim of a drum, you will find spots of brown putty stuck on to balance the drum. There's also putty on the backside of the drum, along with brass weights.
Oh, I see! Never saw this to be done with putty though. But with delicate heads, I wouldn't want to drill out material from a head in order to get it balanced. But do I see normal Phillips head screws holding the heads in? How did they align the heads to stick out 90 microns? Not with those screws I assume?
PID_Stop wrote:Even ordinary reel-to-reel quad machines were highly dependent on compressed air and vacuum; if you want a jaw dropping treat, search in Youtube to see an ACR-25 operating. It combined two quad transports into one system to provide continuous playback from a series of cassettes. All of the cassette loading and unloading and tape threading were done using compressed air and high vacuum produced by a pair of large blowers driven by a three-phase motor. Wowza: life was exciting in our control room back then!
I often wondered how they did commercials back in the days. I would have never guessed that they used 2" in cartridges... I mean, other cartridges like U-Matic or so, okay, but 2" tape. Just watched a commercial for the RCA TCR-100 cartridge system on YouTube. Man, that's something. Speechless! So! Speechless! ...

I'll be diving deeper into YouTube once more :lol:

Regards
Patrick

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Re: Sony BVH-2180-PS: Servo Error

Post by PID_Stop » Thu Jan 07, 2016 3:32 pm

Hi Patrick!

Broadcasting was much more mechanical and physical when I started; looking back, operating master control was remarkably like the circus clown spinning several dozen plates on wooden sticks, running like mad to keep them from slowing down and creashing.
So the sync track fills in the missing gap where the main head won't touch the tape. Basically the information between two lines of video. But what if I record something on audio track 4?
The sync tracks records about a dozen lines of video during the vertical interval. Without looking it up, I think the tape is in contact with the drums for about 343° of the drum's circumference. If you consider NTSC, which has 525 lines per frame or 262.5 lines per field, the result is that one sweep of the head can record (343/360)*262.5, or about 250 lines. That leaves a gap of about 12.5 lines that the sync head fills in. We don't want to have a headswitch during active video, but that's okay: there are more blank lines in the vertical interval than the gap that has to be filled... and the vertical interval tends to have less visually critical stuff like time code, test signals, and program identification data.
Oh, I see! Never saw this to be done with putty though. But with delicate heads, I wouldn't want to drill out material from a head in order to get it balanced. But do I see normal Phillips head screws holding the heads in? How did they align the heads to stick out 90 microns? Not with those screws I assume?
I'm not sure how they did it, but it's very likely they had some sort of tooling to hold the tip in place while it was being fastened down. Head refurbishing was something of a black art, and CMC was one of the better known practitioners.
I often wondered how they did commercials back in the days. I would have never guessed that they used 2" in cartridges... I mean, other cartridges like U-Matic or so, okay, but 2" tape. Just watched a commercial for the RCA TCR-100 cartridge system on YouTube. Man, that's something. Speechless! So! Speechless! ...
The TCR-100 was RCA's alternative to Ampex's ACR-25, and was quite a bit more primitive. The TCR had a caterpillar belt that held the cassettes, and they played in whatever order they were inserted in the belt. The tape handling was purely mechanical, with scads of levers and metal fingers to grab and thread the tape. In my town (Syracuse, New York), all of the stations had Ampex ACR-25's -- and they were quite a bit slicker. Instead of an external belt, the ACR had a metal carousel positioned between the two transports; it was driven by a very large motor, and could spin from wherever it was to any other point in about a second. You would program the logic to play whatever was in the bins, in any order; the programming could extend up to 40 events. Threading was entirely performed with air: a puffer would blow into the cassette while vacuum was applied to the transport; the supply reel motor would spin to allow tape to blow up into the transport, until it entered the takeup column; then vacuum would be applied to draw it into the supply column and across the surface of the audio and video head assemblies. A sub-deck would come forward, bringing the vacuum capstan up behind the tape. The high vacuum would be released, and lower vacuum would keep the tape in the columns; a photocell strip in each column, with a row of lamps on the other side, would send an analog signal to the reel motor servos so that just the right amount of torque would be applied to keep the tape in the middle of the columns. The capstan would rapid-cue the tape to the start of the video clip, and stop. Mind you, all of this would take about three or four seconds to accomplish... after the spot finished playing, the rewind and unthread process was just as fast. The ACR could run ten-second spots back-to-back indefinitely, and it was absolutely stunning to watch. My dad's station got their first ACR when I was a young teenager; I remember seeing it for the first time, and my jaw nearly hit the floor.

As impressive as it was when it was running properly, it could fail even more impressively. The massive torque needed to haul that big carousel around, or for the reel motors to fly the tape up into the transport, could be seriously self-destructive if an optical sensor or a microswitch failed at just the wrong moment. Sometimes a cassette would get its hubs welded to the rubber rings on the motor turntable, and have to be extracted; sometimes the carousel would try to move while the anti-rotation pin was still engaged, killing a drawerful of power transistors. Our station, regrettably, had only one ACR... so we got remarkably skilled at repairing it rapidly, and could tell from the sounds it was making if we were headed for trouble. You could be all the way back in the maintenance shop, and the "chick - chick - stoomp!" sound of a misthread was all it took to get people running.

Nowadays about the only running that happens is when someone brings in free food. :lol:

-- Jeff

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Re: Sony BVH-2180-PS: Servo Error

Post by DolbySR » Mon Jan 18, 2016 9:19 am

Hi Jeff!

Sorry for the major delay since my last response. There was simply far too much going on around here. At work and everywhere else as well... Which also meant that I still didn't manage to perform some tests on my recorder... This bothers me most right now to be honest.

But anyway...
PID_Stop wrote:Broadcasting was much more mechanical and physical when I started; looking back, operating master control was remarkably like the circus clown spinning several dozen plates on wooden sticks, running like mad to keep them from slowing down and creashing.
It really was. As a teenager, I used to produce little movies when we went on vacation or when there was something special going on at school. I always made them on Super8 film and due to the incompatibility with modern editing tools like Premiere Pro or Sony Vegas, at least not right out-of-the-reel, I had quite some trickery to do when I wanted to have nice titles and so on. There was really a big mechanical component involved everywhere. Later, in middle-school, I joined the AV-club. There, we used miniDV and edited on digital systems called "Casablanca". But the capabilities weren't exciting enough, so I often copied scenes onto SVHS and edited them at home to add some effects. I imported the footage via the Video-In card of my PC, edited the hell out of my machine, rendered it over the week-end and exported it back to SVHS via the graphics card :mrgreen:
PID_Stop wrote:The TCR-100 was RCA's alternative to Ampex's ACR-25, and was quite a bit more primitive. The TCR had a caterpillar belt that held the cassettes, and they played in whatever order they were inserted in the belt. The tape handling was purely mechanical, with scads of levers and metal fingers to grab and thread the tape. In my town (Syracuse, New York), all of the stations had Ampex ACR-25's -- and they were quite a bit slicker. Instead of an external belt, the ACR had a metal carousel positioned between the two transports; it was driven by a very large motor, and could spin from wherever it was to any other point in about a second. You would program the logic to play whatever was in the bins, in any order; the programming could extend up to 40 events. Threading was entirely performed with air: a puffer would blow into the cassette while vacuum was applied to the transport; the supply reel motor would spin to allow tape to blow up into the transport, until it entered the takeup column; then vacuum would be applied to draw it into the supply column and across the surface of the audio and video head assemblies. A sub-deck would come forward, bringing the vacuum capstan up behind the tape. The high vacuum would be released, and lower vacuum would keep the tape in the columns; a photocell strip in each column, with a row of lamps on the other side, would send an analog signal to the reel motor servos so that just the right amount of torque would be applied to keep the tape in the middle of the columns. The capstan would rapid-cue the tape to the start of the video clip, and stop. Mind you, all of this would take about three or four seconds to accomplish... after the spot finished playing, the rewind and unthread process was just as fast. The ACR could run ten-second spots back-to-back indefinitely, and it was absolutely stunning to watch. My dad's station got their first ACR when I was a young teenager; I remember seeing it for the first time, and my jaw nearly hit the floor.
Yeah, those systems really are amazing. Now that you mentioned the threading is done mechanically in the TCR-100, I realized how much effort Ampex went through to keep tape wear just by threading alone to an absolute minimum. After all, the RCA system claimed that it was capable of about 20 runs for each commercial until the quality would degrade. Was this the case with the Ampex system as well? If so, this meant that some guy was constantly re-copying cartridges from a master tape, assumingly quadruplex? Or 16/35mm film?
PID_Stop wrote:As impressive as it was when it was running properly, it could fail even more impressively. The massive torque needed to haul that big carousel around, or for the reel motors to fly the tape up into the transport, could be seriously self-destructive if an optical sensor or a microswitch failed at just the wrong moment. Sometimes a cassette would get its hubs welded to the rubber rings on the motor turntable, and have to be extracted; sometimes the carousel would try to move while the anti-rotation pin was still engaged, killing a drawerful of power transistors. Our station, regrettably, had only one ACR... so we got remarkably skilled at repairing it rapidly, and could tell from the sounds it was making if we were headed for trouble. You could be all the way back in the maintenance shop, and the "chick - chick - stoomp!" sound of a misthread was all it took to get people running.
Indeed. I believe that! But when something major happened to this machine, was there any kind of backup solution? Like a quad reel with commercials on it or one of those "please wait" signs which could be broadcasted? Maybe not the test pattern, but something nice... :wink:

Image
PID_Stop wrote:Nowadays about the only running that happens is when someone brings in free food. :lol:
Not even then...Well ok, it would get me running for sure. :wink: If it's cheese fondue: 100%!

Regards,
Patrick

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Re: Sony BVH-2180-PS: Servo Error

Post by PID_Stop » Mon Jan 18, 2016 12:54 pm

Hi Patrick!
DolbySR wrote:Yeah, those systems really are amazing. Now that you mentioned the threading is done mechanically in the TCR-100, I realized how much effort Ampex went through to keep tape wear just by threading alone to an absolute minimum. After all, the RCA system claimed that it was capable of about 20 runs for each commercial until the quality would degrade. Was this the case with the Ampex system as well? If so, this meant that some guy was constantly re-copying cartridges from a master tape, assumingly quadruplex? Or 16/35mm film?
I didn't know that about the TCR... some of our carts must have played thousands of times before we respooled them with new tape (I'm thinking particularly about cart 6007, the generic legal ID. Funny how some details get etched into one's memory, even 30 years later!). As it was, we kept reasonably busy dubbing new spots as they came in... I can't imagine having to redub existing spots that frequently.

Every spot that came in on a quad reel got dubbed to an ACR cart; we also dubbed most 16mm films. We also used to air a fair number of commercials that consisted of several slides and an audio cart (for some reason, these were mainly shoe stores), and those aired live. Our traffic department must have really hated me, because they always scheduled these slide-cart spots toward the end of breaks leading up to a show that was playing from a quad VTR; our Ampex VR-2000 quad machines needed an eight-second pre-roll. So every afternoon I had to switch a break that looked something like this:

3:58:00 Flip film chain 5's multiplexer to show the slide projector, light up the first Pearl Shoes slide
3:58:10 Load the Pearl Shoes cart in 5-spot player slot 1, the legal ID cart in player slot 2
3:58:46 General Hospital ends, play and take the ACR (two :30 spots)
3:59:46 Take film chain 5 and break audio away to the 5-spot, hit 'PLAY' on cart 1
3:59:49 Advance to Pearl Shoes slide 2
3:59:52 Start playback on the next show (usually VTR 2 for the 4:00 show)
3:59:53 Advance to Pearl Shoes slide 3
3:59:56 Advance to the legal ID slide, hit 'PLAY' on cart 2
4:00:00 Take VTR 2

This would be a fairly simple instance... we also used to live-tag some commercials (movie spots, Ronco stuff) with slides and audio carts. And if the ACR was down, things got really busy. The whole day was pretty much like that... things would quiet down a bit during network programming, but that's when we would do dubs and commercial production, so there was never really a calm time. For years I worked the sign-off shift, and would get home around 2am; it would take several hours for me to wind down enough to be able to sleep!
DolbySR wrote:Indeed. I believe that! But when something major happened to this machine, was there any kind of backup solution? Like a quad reel with commercials on it or one of those "please wait" signs which could be broadcasted? Maybe not the test pattern, but something nice... :wink:
The other stations in town had two ACRs, which gave them better backup; my station had one. When the ACR went down, we would immediately revert to airing spots directly from master reels. We had three reel-to-reel machines, and the worst case would be if we were ending a local show from one of them, had to play several spots from open reel masters, and the next show was also on VTR. It wasn't pretty, but it could be done. Murphy's law being what it was, this would happen while you had a tour group coming through the control room, or some salesperson was underfoot. Cigarette smoke wasn't the only thing turning the air blue back then.

If we knew the ACR was going to be down for a while, we would put together a work reel, editing spots together. If we were in network programming, we'd slap together as many breaks as we could, then spin the reel back to play the next break we needed for air, then go back to building up later breaks. We would stick slips of paper in the reels to mark where to rewind for the next break, and where to spin forward to pick up where we left off. (Unlike the BVHs, the quad machines had only a single mechanical timer that you would reset at the head of each break so you could spin the tape back eight seconds for the preroll. Time code was just an abstract fantasy you'd read about in the trade magazines!)

The ACR seemed to know when we had just hired a new operator, and would behave itself for a couple of days, waiting until the newbie was soloing before crashing. In my own case, someone doing maintenance on the digital time base corrector slipped with a scope probe, shorting the +12 volt supply to the +5 volt supply and taking out dozens of ICs on multiple boards. We were down for over a week, and I got pressed into some of the troubleshooting. We hired one fellow who lasted about a week until the ACR crapped out. He walked out at the end of the shift and never came back.
DolbySR wrote:If it's cheese fondue: 100%!
That sounds good! I haven't made that yet this winter...

Have a good one --

-- Jeff

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Re: Sony BVH-2180-PS: Servo Error

Post by PID_Stop » Mon Jan 18, 2016 1:06 pm

Thinking of ACR outages brought to mind one of our sign-on operators who was just a bit nervous, and who tended to panic at the prospect of running breaks by hand. It turned out that he would watch the station in the evening, and if it looked like the ACR was down (one telltale, even if we were otherwise keeping things smooth on the air, was running a slide-audio cart ID instead of the animated ID from the ACR) he would call in sick.

We strongly suspected there was some technically-induced hypochondria going on, and tested it for a few evenings by dubbing the slide-cart ID to the ACR... and sure enough, the guy kept calling in sick. Eventually the assistant chief engineer figured out what was going on, and told us, with barely suppressed amusement, to knock it off: he was tired of getting the phone calls at 4am.

-- Jeff

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Re: Sony BVH-2180-PS: Servo Error

Post by w9wi » Mon Jan 18, 2016 7:21 pm

PID_Stop wrote:In my own case, someone doing maintenance on the digital time base corrector slipped with a scope probe, shorting the +12 volt supply to the +5 volt supply and taking out dozens of ICs on multiple boards. We were down for over a week, and I got pressed into some of the troubleshooting.
Believe it or not, *precisely* that happened to us.

We had two ACRs, so it shouldn't have caused a problem.

Except that the guy was probing around the *good* ACR trying to find the voltage that didn't match the *bad* one.

He had to go without help, as the remainder of the engineering staff was stuck on spot reel duty:)
--
Doug Smith W9WI
Pleasant View, TN EM66

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