Betamax PALsite: VTC-9300 : Technical

Technical

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Fault and repair guide

Because of its age spares are not easy to obtain for the VTC-9300.

Tape transport is sluggish or fails to rewind

Internally the VCR 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.

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!

Expand adjustment (click to enlarge)

Blurred picture

Here's a tip for Sanyo VTC 9300/9350/Fisher VBS-7000 users. These models are known for having poor playback resolution from when they were new. Adjusting the Expand (VR216) control in the luminance circuit will sharpen the picture.

Don't adjust it too much otherwise the picture will be too sharp and grainy. The factory specification is 1.35V measured in the base of the transistor Q258. A setting of 1.1V should make the picture look much better.

Many thanks to Fivos Sakellis for this tip

Quick fault guide

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Fault	Solution
Loss of colour or intermittent colour in playback	Adjust AFC(VR - 214). If that fails, replace Q204(IC, CX -150) and surrounding electrolytic capacitors. AFC may need to be adjusted after these components have been replaced.
Double vertical image	Adjust VR101 and VR102 on W1 till you get the best image. Use multiple tapes to confirm. You can also refer to page 10 of the Sanyo VTC9300 service manual for instructions. This requires an oscilloscope and alignment tape for best results.
Bad tracking at center position	Misaligned audio/control head position. Loosen the 3 screws that hold the ACE and then slide the ACE assembly forwards or backwards until you get a perfect picture with the tracking control at the center position. A known good tape and a scope is recommended for perfect adjustment.
Output image is black and white	(Possible, simple solution) Make sure that the "TEST SIGNAL SWITCH" is set to the "OFF" position (Bottom position). If this was the problem then the image should become coloured instantly.
Very slow lace up	Apart from replacing belts... very slow lace may be due to the lacing gears under the capstan flywheel seized up! There are three gears and the grease may have gone rock solid. Just one drop of oil on all shafts after clean and it will be a different machine.
Pinch roller not engaging	Incorrect holding current due to failure of Q810.
Tape counter increasing during rewind	Incorrect "down" command to TMS1070 due to leaky C1618 affecting the operation of Q1602.
Picture wobble on playback	This can be due to faulty servo damping capacitor C134.
No servo lock in record but playback is ok	Check C108.
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