Sony SL-2700 Betamax

Is there anyone here old enough to remember working on the Sony SL-2700 B etamax? I refurbish Beta's for resale and this one has a tough problem. The VCR works fine except for hifi audio - put in a hifi tape, and the hifi in dicator lights but the sound is mute, both on the output and the VU LED's. The linear sound works fine if switched to that. Tried swapping all boards related to audio, but got the same result, perh aps one of my substitute boards had the same problem. Any ideas?

Reply to
packrat1979
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I guess I'm stating the obvious, but...

If the Stereo light comes on, then the circuitry has detected the HiFi carrier.

Have you tried signal-tracing the HiFi path? The carrier is omnipresent, so it shouldn't be too hard...

Reply to
William Sommerwerck

etamax? I refurbish Beta's for resale and this one has a tough problem. The VCR works fine except for hifi audio - put in a hifi tape, and the hifi in dicator lights but the sound is mute, both on the output and the VU LED's. The linear sound works fine if switched to that.

rhaps one of my substitute boards had the same problem.

I spent most of last week working on a Sony DVW-A500 broadcast VTR machine replacing leaky (some VERY leaky - acid puddles) electrolytic caps. The bul k of the time was troubleshooting the 7 bad traces from acid destroying the copper on the (coincidentally) audio processor board.

Look for yellowish/brown 'mist' around the caps. By that time it's bad. EVE RY cap I pulled had some leakage under it. A 'mist' an inch in diameter is likely to require re-constructive surgery. So far I've replaced around 100 caps in this machine, most just simply remove, clean the residue, replace a nd clean the flux. It gets more 'interesting' with 4 layer boards if it des troys the plated through hole. 2 layer boards are much easier.

FWIW I buy thousands of caps every year for my employer(s) and am called do ctor capacitor on occasion.

Reply to
stratus46

Tracing any signal in these VCR's is a real pain, the circuits are quite elaborate and everything is packed in here extremely tightly. Poor-quality .PDF scans of the schematic diagrams don't help either. But if it comes to signal tracing, I suppose I'll have to. I'll try checking some caps with an in-circuit ESR meter first though. Mo st bad caps I encounter in these are in high-temperature areas like the pow er supplies, but on rare occasions I have found bad ones where I least expe cted it.

Reply to
packrat1979

The one thing about Sony Beta HIFIs is that they have a very zealous muting system. Another thing to remember is that each channel is processed separa tely, so usually any one bad component in the detectors should only affect one channel, unless it is a general failure of one of the ICs.

Find the muting circuit and disable it, you might find distorted audio whic h is rightly muted. (rightly muted means that between how it is decoded and the DBX expansion applied on playback, we are talking speaker blowing nois e here) Unlike VHS, Beta uses the same heads for the AFM (HIFI) carriers. H owever the difference in frequencies means that just because you have a nic e video carrier envelope, it does not necessarily follow that you have a pe rfect AFM carrier envelope.

You could have a severe dropout during vertical retrace time and it really depends on the monitor you use whether you will see any vertical sync probl ems. Most TVs had abandoned the countdown circuit but if it does use that, some units could stay in synch for quite a long time between periods of val id synch.

If you are using an LCD monitor, it is possible that the synch circuit is s o good that it will lock onto noise, I do not know. Things have changed, th ere is no vertical oscillator anymore.

That's where I would go on this, and I did work on Betas, in fact I still h ave one that works. The envelope and the muting. If nothing pans out there hopefully you can get enough info on the chipset. Then the fun part, if you need an IC or a hybrid, finding one.

I have a small selection of OEM Sony parts from that era so if you find you need a proprieary part let me know. Even if I don't have it I know people in the business who might.

Reply to
jurb6006

ng system. Another thing to remember is that each channel is processed sepa rately, so usually any one bad component in the detectors should only affec t one channel, unless it is a general failure of one of the ICs.

ich is rightly muted. (rightly muted means that between how it is decoded a nd the DBX expansion applied on playback, we are talking speaker blowing no ise here) Unlike VHS, Beta uses the same heads for the AFM (HIFI) carriers. However the difference in frequencies means that just because you have a n ice video carrier envelope, it does not necessarily follow that you have a perfect AFM carrier envelope.

y depends on the monitor you use whether you will see any vertical sync pro blems. Most TVs had abandoned the countdown circuit but if it does use that , some units could stay in synch for quite a long time between periods of v alid synch.

so good that it will lock onto noise, I do not know. Things have changed, there is no vertical oscillator anymore.

have one that works. The envelope and the muting. If nothing pans out ther e hopefully you can get enough info on the chipset. Then the fun part, if y ou need an IC or a hybrid, finding one.

ou need a proprieary part let me know. Even if I don't have it I know peopl e in the business who might.

This VCR was only used for a few hours and was stored for nearly 30 years , so I doubt it's an issue with worn heads. But now that I think of it, any thing that sat so long unused probably will need some caps. I still use an old CRT TV with a countdown circuit, as I never really war med up to LCD. I find older stuff like VHS tape looks terrible on LCD. Thanks for the offer on parts, if I need anything I will let you know.

Reply to
packrat1979

"anything that sat so long unused probably will need some caps"

Oh quite probable. but if you intend to change every cap with marginally hi gh ESR you are chasing your tail. The fact is that some are more critical t han others. What's more the more ripple or delta current applied to each de creases it's lifespan. I a a pro and I will tell you now, DO NOT just chang e all the damn caps. It is a waste of time. You need to find the ones causi ng the problem. If you want to replace caps to restore original performance find the ones in the audio path and f*ck all the rest, unless they cause a problemm. There are exception, like in the PS. You take them on a case by case basis. If you just change all of them that don't read like new you wil l have succeeded in wasting a bunch of tie and money.

So, in kooking for caps, find the muting line and everything that feeds it. It will have a feed from the servo for whenever it is switching speeds. It will have lines from both video and AFM detectors. If the video detects a loss of V sync, out goes the sound. any variance in signal level more than about 30 % at any time will trigger the muting.

There are capacitors used in the muting, if they go open what happens ? It will always be muted.

Did you get a print for the unit ? If you can't I have one person I can cal l maybe. Maybe. If you do have a PDF of it send it to me and I can probably localize the problem to some extent.

Reply to
jurb6006

SL-6200 perhaps? I've never seen one.

I will confess to not being an expert on video quality. I also didn't care much for TV in any form. However, the lady friend dragged home a brand new Betamax SL-8200(?) and assigned me the task of setting it up and making it play. I'm not sure of the model number but I do recall it was a top loader. It worked fairly well for about a month. Then, things started to fail. I don't recall the exact failures. Rather than tinker with it, we sent it to the authorized repair center (initially under warranty). It returned functional, but with a deteriorated picture. After about 3 additional repairs and no improvements, we parked it in the garage. I then bought her a no-name cheap VCR at the local department store. As I recall, it was about half the price of the Sony. It lasted about a year before it totally died. When we parted ways, she took both with her. It was 15 years later before I bought another TV.

I never did a side by side comparison between VHS and Beta, so I can't really be sure that Beta is really better. As I recall, I didn't see much difference. My uninformed impression was that both were mechanical nightmares, that were easily jammed and broken by mishandling and bad tapes. Perhaps if the VCR and TV were maintained to peak performance, Betamax might have shown it's superiority, but with the poor lifetime and generally miserable picture that I experienced, I suspect that "normal" operation would not have shown much difference.

Like I said, the superior technology doesn't always win. Sony may have had the edge in picture quality, but what the GUM (great unwashed masses) wanted was long play, and cheap, cheap, cheap, cheap, and cheaper.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

I hope the following doesn't sound unduly ad hominem. However, the differences are plain.

1 Betamax has more-stable tape motion. Without TBC, VHS has enough jitter to produce a sometime-ragged-looking picture. 2 Betamax appears to have slightly better luminance /and/ chroma bandwidth. 3 Sony's refusal to license its polarity-inversion chrominance-recording system forced JVC to use a quadrature system, which badly degraded color fidelity.

If you want conclusive proof, look for an article in one of the video mags (sorry, I don't remember which or when) where a source was repeatedly dubbed. Betamax held up for three or four dubs. VHS fell apart very quickly.

Betamax represents a "reasonable" compromise for a consumer product. I consider myself a critical viewer, but I could watch Beta tapes without getting unduly upset. VHS was another matter.

Reply to
William Sommerwerck

You do know that Ampex started the development of VHS before they sold out to a consortium of japanese companies to raise much needed funds for their financial survival? Ampex wanted to make a cheap, scaled down version of their existing 1% 2" tape systems, to sell at an affordable price for consumers but ran into cash flow problems.

Sears and a couple others attempted to develop and market Cartrivision, another failed system. The cartridge was huge, and rental tapes couldn't be rewound. They had to be put in a separate machine at the video store to be rewound before being rented again. That made them so unwieldy that no one want ed to handle them. Only blanks could be recorded, & played, after being rewound on a home machine. Avco was the company doing the development, at the site of a former W.W.II Crosley plant on Glendale-Milford Road in Cincinnati, Ohio. The testbeds were still sitting in the warehouse when it became the original location for Cincinnati Electronics.

The Betamax machines I worked on treated the tape a lot worse than VHS. Some had the tape sliding against itself to simplify they loading and unloading.

Having seen both in use in a broadcast station, the cheap VHS was much better than any beta, other than the overpriced ENG version that only got 20 minutes per tape. All Sony machines needed a TBC to meet FCC requirements, but I could feed a $79 VHS tape into our Vital Industries Squeezezoom and get a picture that was stable enough to broadcast.

We had a complete three deck 1" sony video editing suite, each with a TBC. The LaCarte video automation system had 12 sony U-matic players and a 'Striper' to record programs and read the time codes for the automation. That system had another TBC. We used a framestore to synchronize live video from the studio, rather than depend on not losing the feed over the 7 GHz STL. At times we used a second framestore to be able to crossfade between live feeds from two studios, in different cities.

Reply to
Michael A. Terrell

FCC requirements, but I could feed a $79 VHS tape into our Vital Industries Squeezezoom and get a picture that was stable enough to broadcast. "

I find that extremely hard to believe. I do believe it about the Sonys because of tape drag, but I find it hard to believe they let you broadcast right out of a VHS. You sure there might not have been another TBC downsteam ?

Some Sony pro equipment just incorporated the TBC, did someone turn it off or something ?

Reply to
jurb6006

of tape drag, but I find it hard to believe they let you broadcast right out of a VHS. You sure there might not have been another TBC downsteam ?

something ?

Believe whatever you want to. We all know that you think you know everything about everthing, and you've bragged about being the best in your field. The TBC were all external to the Sony 1" VTRs & third party equipment. The Squeeze Zoom was fed directly to the Vital Industries master video mixer & 3M video router. There was no TBC in that path. I know this because I was one of the two engineers who maintained that control room, and the million dollars plus worth of equipment. The three Sony 1" machines & TBCs were bought from Coors Brewing, and the RCA TK46A cameras came from the Nautilus Eliptical studio in Ocala, when it was closed. From the way you post, it would appear that you know more about Coors, than TV studios.

Reply to
Michael A. Terrell

The problem with you "beta was better" guys is you never admit that during the great vhs vs. beta wars, 99% of the people who bought them had crap televisions that probably couldn't produce 280 lines of resolution.

I'd bet most tv's in the late 70's when home video started to gain ground still had some vacuum tubes.

It was a coax hookup, not line outs.

If there was a difference on paper, thats where the difference ended.

The simple fact of the matter was, most people simply could not tell the difference from one to the other. People with trained eyes, possibly.

There was no day and night difference between them, there couldn't of been because few people owned any kind of set to watch them on, to notice the difference.

The only credit I give the beta format was when the copy protection shit came out (copyguard), what worked on vhs, didn't on beta. So if you needed to make an archival copy of something, doing it from beta worked better.

I'm with the other guys, mechanically, beta machines were built like shit and didn't last long in normal use. Transport problems were difficult to repair and usually didn't last. Being they were usually more expensive than the vhs counterparts, they were just a poor value for the money.

-bruce snipped-for-privacy@ripco.com

Reply to
Bruce Esquibel

That's new to me. I don't see why Japanese companies aren't capable of designing poor-quality products on their own. (RCA had been working on a consumer video recorder for years, but felt it wouldn't be marketable until it hit the same price point as color TV -- $500.)

That's not altogether surprising. Beta pulled the tape into an elongated loop around the drum, to isolate its motion -- which is why Beta has less line jitter.

I'm not sure I understand.

You are one of the most-knowledgeable people (about anything) I've ever met, but here I have to say "No way, José." VHS has serious time-base problems.

I first noticed this the early 80s when I was scanning a late-night show I'd recorded * -- why was the picture visibly sharper than in normal play? I looked closely and saw the reason -- severe line jitter. When scanning, there was either less of it (for the same reason analog recorders have less flutter at higher speeds), or the eye did a better job of averaging the errors.

Just as I judge audio equipment by what I hear, I judge video equipment by what I see. When VHS recordings have obvious time-base problems -- what am I supposed to conclude?

  • The machine was a high-end RCA-branded Panasonic.
Reply to
William Sommerwerck

I owned an NAD MR-20A at one time, and my SuperBeta HiFi machine made recordings that were //almost// indistinguishable from the broadcast. Obviously, if they were played on modern displays, the loss of quality would be more visible.

You don't need trained eyes to see the difference. It isn't at all subtle.

You're kidding, of course. One of the most-noticeable problems with VHS is the lousy color. Not only are hues sometimes off, but the chrominance doesn't always fill the luminance!

I can't speak for or against the quality of Beta transports. They were more-complex than VHS, so, in principle, they should have been less reliable. I never had trouble with my SL-HF900 deck. It still works.

Reply to
William Sommerwerck

the tape was wrapped around the drum, then around a guidepost. The back side of the film was dragged across the outside of the film on its way back into the cartridge. VHS pulled the tape around the drum from both sides, and didn't have some of the tape handling problems of the Beta machines.

We offered U-matic for our public access channel at United Video Cablevision in Cincinnati. One church paid to air their services but insisted on beta. They supplied a huge, Sony beta deck. It, and the video quality was crap. The chroma was unstable, and the sync levels didn't meet FCC specs, so I had to let the dark, muddy video go out. It was a minority church that had screamed racism, because 'Only a white church can afford U-matic!!!'

You don't understand what the SqueezeZoom was. It was the first broadcast quality Digital Video Effects system on the market. It sold for $250,000, and was made in Gainesville, Florida. It had two pages of digitized video, and built one while displaying the other. Considering that it used a Z80B processor and slower than dirt interleaved RAM, it was an amazing piece of equipment. It filled a full relay rack, and the

+5 volt power supply was a linear three phase monster with a clean 1,000 amp output. It could take the output of a good VHS machine with no problem, but I never saw a Beta that it liked.

You've likely seen one of it's best known uses at the end of the old Sonny & Cher show, when they walked out in each set of costumes from each skit, one after another. The images were combined into a video with all of them with no obvious degrading of the image. It was the first time it could be done in post production, with 2" video tape instead of shooting film and sending it to and outside company for optical work. Studios were begging for a chance to get one as fast as possible.

BTW: The custom video ADC was over $1400.

Reply to
Michael A. Terrell

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