Luxman pd 121 service manual

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L SERVICE MANUAL

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MODEL: PD-121,13l

Features of Black light by using a small
Cold Cathode Ultra violet light tube

This small discharge type tube was developed for use in our turntable. As its features far out
weighed that of the conventional Orange Neon as strobo-scope timing light.

It differs in operation from the usual fluorecent tube in that it has no starting filaments, but
instead has a small electrode near each main cathode at each end of the tube. So discharge is
enabled by a high firing voltage (250 volts).

However, since mercury is used as the gaseous medium in the sealed tube operation at very low
temperatures eg. below 5°C is very difficult. But with the special firing circuits used in the

PD-121, operation is guaranteed from above 0°C.
This tube is characterized by

1) Low power consumption (0.7W)
2) Low operating temperature

3) Small-size

4) Long-life (20,000 hours)

5) Ultra Violet light at 3650 Z.

So to make the strobo-scope pattern very clear as if to appear stationary, the tube is fired by
short duration pulses, and to make for a high visibility "dayglo" type paint is used for the strobo

markings, this type of paint converts Ultra violet light into visible coloured light.
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ALIGNMENT PROCEDURE

1) PB-650 D.C. voltage adjust

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