Sony SL-8000
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This machine was the first Betamax recorder available to home users in the UK. Although it is less "industrial" than its wood and metal U-Matic cousins, and the original SL-7300, the family resemblance is clear in the overall layout. Thus it has a central top-loading mechanism with the main operating keys in front of the cassette lid, which does not completely seal the opening. Like U-Matic machines there is a sizeable gap, presumably to allow the cassette's label to be read. This is a curious peice of design, since it allows dust and even fingers to easily get into the machine's delicate mechanisms.
The green gas-discharge clock display is mounted so that it can be seen from both above and in front, allowing the machine to be used at different heights; to complement this the keys are also labelled twice to be seen from any angle. There is a mains power switch hidden away at the bottom right, with th enormal operating switch at the left. This selects between Standby (off), On, and Timer. To the right are switches to select aerial or AV input, and to control the output signal; curiously, although engaging PLAY automatically switches the output between TV tuner and tape replay (physically moving the switch) when the tape is stopped the switch has to be manually returned in order to see a TV signal!
The tape-transport keys operate as normal, although PLAY does not have to be pressed with REC to engage record, which is unusual for a mechanically operated machine. Normally the PLAY key performs all the mechanical operations required to start the tape moving, while REC simply switches the electronics from playback to record.
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The TV tuner uses rotary presets under a flap to
tune in the 8 available channels, and push-buttons on the
front to select them once tuned. Like many Sony machines the flap also holds a special tool for adjusting the presets; I have never understood why they did this when finger-adjustable tuners would have been simpler and wouldn't need this easily-lost gadget. |
A mechanical tape counter is provided, with a switch grandly marked APSS - "Auto Program Search System". This simply means that the machine will stop winding (FF or REW) when 0000 is reached, and is now more commonly known as counter Memory.
The clock and timer
controls are under a flap on the front. The buttons are
colour-coded into functional groups, and the pastel
shades used for this look surprisingly modern. The timer gives a single event up to 48 hours ahead, with recording length selectable from 15, 30 or 60 minutes, or to the end of the tape. Only the start-time itself is set on the main clock display, the DAY1 / DAY2 and recording length settings are indicated by LEDs on the programming buttons themselves. |
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The output modulator is removable, under a flap at the back. This allows the same machine to be used in different areas, where slight variations in the PAL format (particularly the audio carrier frequency) are used. This feature was common in professional machines at the time; today most VCRs are built for a specific area.
The first impression of the innards of the machine is
the tremendous size and weight of everything. The main chassis is made out of
thick steel, and steel bracing bars and struts abound. Everything except the head drum itself is driven by a single motor, which is almost large enough for a washing machine. This has cooling fans mounted on both the top and bottom, to dissipate waste heat, and its power is delivered to the various tape-transport mechanisms via a forest of belts, pulleys and gears. |
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The printed circuit boards contain a surprising number of ICs (chips), and are fully labelled - every area of the board is marked with its function, and every important signal and connection is annotated. This was very common with these older machines, which makes them much easier to work on, but as time went on less and less information was printed on the boards. Today there is usually no useful information at all, just a load of cryptic identity numbers.
The tape is laced up as soon as the casette is inserted, and remains in position for all operations - it is only returned to the casette when Eject is pressed. The lacing system, derived from U-Matic (though for some reason reversed) is similar in concept to the Philips VCR approach, using tape guides on a rotating ring to wrap the tape around the head drum. Unlike the Philips system, however, the head drum is not itself part of the rotating mechanism. This allows it to be firmly bolted to the chassis, which avoids any alignment problems caused by movement of the drum relative to the tape. Alignment is critical, and is also the reason for the machine's immensely rigid construction.
The loading ring carries the pinch roller and its
associated guides, which start off behind the tape. As
the ring rotates, they pull the tape out and around the
drum through about 270 degrees, to the capstan and audio/control
heads. A swinging arm pulls the tape out in the other
direction to meet the erase
head. The tape has to return all the way back around the drum to the cassette, of course; to prevent it from fouling, another arm mounted on the loading ring engages in a guide rack as it passes and pulls the tape to one side. |
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At each end of the tape path are the tape sensors. These are used to detect the ends of the tape, and prevent it from slamming into the end-stops when fast winding, which could easily stretch or snap it. The Betamax system uses strips of metallic foil on the tape to mark the ends; the Philips formats (and VHS) use transparent leader tape with optical sensors.
This machine came from a street market, and surprisingly works pretty well. A fault in the colour system, giving essentially monochrome playback, is its only real problem.
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