Wersi DX 400 Assembly Manual page 58

Note: Even with the triac off, there is a small residual
voltage on the transformer primary through the RIC unit
(100 Ohms/0.1 uF). This voltage is stepped up by the
transformer and goes to the organ electronics, causing some
LEDs to glow dimly. This phenomenon is completely
harmless and consumes an insignificant amount of current.
The master switch on the AC panel plug can completely
switch off any current to the organ, but this is normally left
on.
b) Power Amplifier PC Board PA 10 (Fig. 36)
PC board PA 10 contains the power supply for the hybrid
power amplifiers, the speaker switch relay and the discrete
components for the hybrid amplifiers. The two hybrid
amplifiers are mounted separately on the LE 30 heat sink
and are connected to the PA 10 board via ribbon cables. Fig.
36 shows the circuit for only one hybrid amplifier since the
two circuits are identical. The corn-
AM 334-01-502
ponent designations of each circuit's discrete components are
shown together (ex., R7/14).
When the LE 30 is first turned on, capacitor C4 charges
slowly through R1 until the collector voltage of Q1 becomes
high enough to turn on Q1. This energizes the relay; the
relay's contacts close, completing the connection from the
amplifiers to the speakers. This delayed speaker turn-on
permits the electronic circuits to stabilize before the speakers
are connected, preventing a loud "Pop" or "blupp" at turn-on.
The audio signals coming in via input jack Plug 6 pass
through the stereo volume control pot to the hybrid
amplifiers, where they undergo voltage as well as power
amplification. The discrete components associated with each
amplifier determine its sensitivity and bandwidth. The output
signals go through the relay contacts and the switching
phone jacks to the external speakers.
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