Betamax PALsite: SL-8000 : Technical

Technical

SL-8000 rear connectors

Because of its age spares are not easy to obtain for the SL-8000.

Modification for 60Hz, 120V mains operation

Please note that for 60Hz, 200-240V operation, carry out steps 3 to 5 only.

Procedure

Set the voltage selector to 127V.
Remove and tie back the yellow and white wires from the power transformer T9501 which are soldered to the FS-1 board. Connect 2 leads to the terminals left free on the FS-1 board. The lead soldered to F9002 should be connected to Pin 4 of the voltage selector and the other lead should be connected to Pin 3.
Reduce the value of the motor capacitor C8102 from 3.7 microF to 2.5 microF by removing the jumper lead from the PE-1 board.
Remove D3101 from the PT-1 board.

The following pulleys should be changed:

	Former	New
Motor pulley assembly	X-3656-025-l/5	X-3656-350-l/7
	Select for correct drum free speed
Drum pulley	3-656-034-00	3-656-421-00
Capstan pulley	3-646-192-01/51	3-646-194-01/5l
	Select for correct tape speed

Thanks to Martin Imber for providing this information.

Fault and repair guide

Tape transport is sluggish or fails to rewind

Internally the SL-8000 contains many drive belts which are used in the mechanics of tape transport. With age these belts become slack causing malfunctions and when this happens the whole lot should be replaced. In particular for the rewind function you will need to replace a tyre on the supply reel.

Strange behaviour of capstan/drum servo

The first thing to check is the tantalum capacitors in the servo circuit.

Sluggish threading and capstan problems

The bottom bearing on the capstan motor is prone to wear and because this motor also drives the threading mechanism threading can become sluggish. When this happens you will hear a horrible squeaking noise!

Quick fault guide

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Fault	Solution
Colour streaking on playback of pre-recorded tapes	Check for poor contacts or contamination of the presets in the chroma circuit. If necessary clean and re-align.
Crackling or noise on sound	Suspect failure of the record/playback switch S601.
Intermittently stopping when warm	Check the plug and socket connectors to the end sensor coil. Then check presets RV701 and RV702.
Interference on picture	Suspect failure of the record/playback switch S101.
No Power	Main on/off switch
Tape jammed or lock up	Stop solenoid switch
Ejects Tape	Dry Joint on tape slack sensor
No AC motor drive	bad connections on 3 pin connector or AC motor open circuit
Picture slips in pause	Belts and/or brakes
Shuts down on Play	Static build-up on metal threading guide, earth guide
No Go	Board SY-1: Q701 & 702 2SC-1364, auto stop
No play or spool	Board SY-1: IC 701 CX-141
No Pause	SY-1: IC 702, 703 TC-4001
Tape Lock Up or Spool malfunctions	SY-1: RV701, 702 22k pots sensor osc.
Tape lock -up	SY-1 C701 .0033uf
Rewind only	SY-1 CN 6161--wire direct
No ctl pulse on Pause	IC 501 CX-138
No tracking	IC 502 CX-139
No rev	SY-11 change R1, C1 to 180k, .001uf, dirty contact cn4007
no audio rec	AS-1 Q605, 606
No buttons will lock	belts off
Rewind button will not stay down	check board connections on supply sensor board
Intermittent colour on play	Check AFC adjustment on Y/CE board RV14 bottom pcb
White streaks, b&w and possible vertical jitter	One head clogged, dirty contacts on S101 or faulty pre-amp
Throws loop off tape when going from rewind to stop	Replace or adjust supply/take-up of brake assembly
Auto stop when rew pressed	Check TP702 fro 3V p-to-p
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