Betamax PALsite: SLO-1700 : Technical

SLO-1700

1984

Technical

Fast wind

This VCR had something which is unique among the Sony Betamax VCR's and that is the ability to unlace the tape and wind with the tape in side the cassette shell. This was the so called fast wind feature. To avoid the risk of tape damage it did not operate near the beginning or end of a tape. This is signalled by the orange LED on the front panel. Fast wind is now something that is common among VHS VCR's these days.

REC remote jacks

These are the two phono connectors on the rear of the machine. By shorting either one of them the recorder can be switched from stop to record mode. By opening the circuit a cassette tape will be ejected when the VCR stops. For REC remote operation an internal wiring change is required:
Cut out the jumper wire between 2 and 3 terminals on the CN615 connector on the 22-29 board. slo rear

Rear of the SLO-1700

Video head record current adjustment

The SLO-1700 has a user adjustment to vary the head record current. This is located under the flap on the top cover. The recommended practice is to adjust so that the replayed hi-fi sound level, as measured on the test point on the front of the VCR, is 300mV peak to peak in amplitude. In principle this adjustment should be made periodically or when changing the brand of tape used for recording.

Fault and repair guide

Irregular tape transport during rewind/review.

This is cause by the tape which sticks to the upper drum when it is worn. It can be fixed by replacing the upper drum.
The diagram opposite shows the upper drum

Grating noise during tape threading/unthreading.

This is caused by a split threading gear. Sony now supply an improved type which does not contain the inside metal bush. In the original design this would expand and cause the plastic to crack. It is also advisable to replace the threading belt at the same time.

No head drum rotation

You may find that the head drum fails to rotate. This is due to a problem with the Hall effect device on the head drum motor which is secured in place by a blob of glue which tends to become conductive especially if it absorbs moisture. The best remedy is to remove the glue from the device. To do this first remove the rotor from the bottom of the drum by undoing the lock-nut. Sometimes, however, it is enough to wait for the damp to dry out.

No illumination in the VU meters

This happens when the 12V tungsten lamp fails. Replacement involves dismantling the meters.

Incorrect tracking

If the tracking control appears to do nothing then check the front PCB which could be cracked. This often happens when the tracking control is knocked severely. Repair with care!

Quick fault guide

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