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Sony SL-2700 Betamax

Discussion in 'Electronic Repair' started by Phoena, May 25, 2013.

  1. Phoena

    Phoena Guest

    I'm old enough to remember that only fags wanted to use Betamax.
     
  2. Guest

    Is there anyone here old enough to remember working on the Sony SL-2700 Betamax? I refurbish Beta's for resale and this one has a tough problem. TheVCR works fine except for hifi audio - put in a hifi tape, and the hifi indicator 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, perhaps one of my substitute boards had the same problem.
    Any ideas?
     
  3. 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...
     
  4. Guest

    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 bulk of the time was troubleshooting the 7 bad traces from acid destroying thecopper on the (coincidentally) audio processor board.

    Look for yellowish/brown 'mist' around the caps. By that time it's bad. EVERY 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 and clean the flux. It gets more 'interesting' with 4 layer boards if it destroys 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 doctor capacitor on occasion.

     
  5. Guest

    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. Most bad caps I encounter in these are in high-temperature areas like the power supplies, but on rare occasions I have found bad ones where I least expected it.
     
  6. Guest

    The one thing about Sony Beta HIFIs is that they have a very zealous mutingsystem. Another thing to remember is that each channel is processed separately, 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 which is rightly muted. (rightly muted means that between how it is decoded andthe DBX expansion applied on playback, we are talking speaker blowing noise 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 nice video carrier envelope, it does not necessarily follow that you have a perfect 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 problems. 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 valid synch.

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

    That's where I would go on this, and I did work on Betas, in fact I still have 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 youneed an IC or a hybrid, finding one.

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

    Yeah well first of all they want quality, second of all they can afford quality. They make good customers. They pay up and pick up their shit fast as soon as it's done, and they don't bother you with phone calls every three hours.

    They also won't **** your secretary.
     
  8. "Phoena" wrote in message
    Is this some sort of joke? If it is, I fail to see the humor.
     
  9. Guest

    If that were the case, Betamax would never have gone out of style.
     
  10. Guest

    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, anything 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 warmed 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.
     
  11. Archon

    Archon Guest

    VHS only took off because of the amount of porn movies available..........JC
     
  12. John-Del

    John-Del Guest

    LOL!! Poetry Jeff, poetry....
     
  13. Is there anyone here old enough to remember working on the
    What about niggers? How did they feel about Betamax? And the kikes? What about
    the chinks and wogs?
     
  14. Phoena

    Phoena Guest

    If your secretary is Dan Litov, then you can expect Paul Feaker to give
    your secretary's ass a pounding.
     
  15. Phoena

    Phoena Guest

    I'm sure any niggers who bought Betamax blamed whitey for VHS winning
    the format war, yo. If the kikes approved of Betamax then it would have
    been the dominant format at least in the U.S. anyway. I doubt the chinks
    could tell Betamax's superior picture with their fucking squinty eyes
    anyway. I'm not sure how the wogs feel about Betamax, because CNN tells
    us that they chant "Death to VHS" so the American public will accept
    U.S. troops being sent to the Middle East to fight more of Zionist
    Israel's wars.
     
  16. Phoena

    Phoena Guest

    I'm not saying anything that hasn't been already posted on various
    websites and usenet groups and shit like that. Sure, I'm not a genius
    but everything I said I had learned from legitimate trustworthy news
    sources. Not Commie News Network or Faux News or MSNBS because you won't
    hear the truth on those networks because they are controlled by the same
    Zionist cabal that controlls the government and the banks.
     
  17. Guest

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

    Oh quite probable. but if you intend to change every cap with marginally high ESR you are chasing your tail. The fact is that some are more critical than others. What's more the more ripple or delta current applied to each decreases it's lifespan. I a a pro and I will tell you now, DO NOT just change all the damn caps. It is a waste of time. You need to find the ones causing the problem. If you want to replace caps to restore original performancefind the ones in the audio path and **** all the rest, unless they cause aproblemm. 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 will 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. Itwill 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 call maybe. Maybe. If you do have a PDF of it send it to me and I can probablylocalize the problem to some extent.
     
  18. Guest

    I bet the Rabbi wanrs to uncircumcise you. Anyone who is not a Jew but knows all about them would never express themselves that way unless they were fucking nuts.

    Have a nice day schill.
     
  19. "Jeff Liebermann" wrote in message
    Absolutely untrue. I remember seeing Sony's first US Betamax, which was
    ensconced in a handsome console with a 19" display. The store (I think it was
    Luskin's) was playing a boxing match, and I was not aware that it was a
    recording.

    Most color TVs had no more than a 3MHz luminance bandwidth. Within that
    limitation, Beta could record and play back with only a slight loss of
    quality. This was a far cry from VHS, which was crap, crap, crap from the word
    "go".
     
  20. VHS took off because the European countries wanted to place quotas on VCRs.
    They really did not want people to own them, and even with very high taxes,
    they were selling well.

    So the VHS companies got together and decided it was better to sell NTSC
    VHS VCRs at a loss than it was to reduce production capacity. They
    limited the number of PAL or SECAM ones and no quotas were enacted.

    Eventually the sales of VHS outsripped BETA to the point that Sony could
    no longer sustain the home market and left it.

    Geoff.
     
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