SLO-1700
Sony 1984
Betamax SLO-1700


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711A CHASSIS

Technical

Betamax SLO-1700 Fast wind buttons
Fast wind controls

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 inside 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, also found on Sanyo models.
Betamax SLO-1700 rear connectors
Rear of the SLO-1700

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.

Betamax SLO-1700 record current control
Record current control

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 practise 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.
Upper Drum without brass
Upper drum

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. Click to see full replacement instructions.
Betamax threading gear
Threading gear

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.
hall effect sensors with glue
Hall effect sensor attached with glue

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 by a blob of glue. Full details on how to fix this can be found on the head motor page.
VU meters
SLO-1700 VU meters

No illumination in the VU meters

This happens when the 12V tungsten lamp fails. Replacement involves dismantling the meters.
Betamax SLO-1700 tracking control
Tracking control

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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FaultSolution
Erractic lacing with no motor driveIf the tape won't lace automatically when a tape is inserted, or partially/intermittently laces and the motor isn't turning this may help.
There's a microswitch at the back left of the mechanism (as viewed from above) which might be intermittently depressed when it should be fully depressed during lacing. The metal mount on which the switch is fixed can get pushed a little too far back over time and is easily bent back to restore function.

If the motor is turning but similar issues occur, check the lacing belt.