WhitakerAudio 60 W Stereo Power Amplifier, Руководство пользователя и по сборке

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– Organize the wiring using the available tie-wraps.
6 Checkout
After the Automatic Protection option has been installed, operational tests should be run on the
unit prior to being put into service. Use extreme caution in the following steps as high voltages
may be present.
– Connect the amplifier to an ac power source and turn the amplifier on. Note that RYL202
will close immediately (the state of the unit is shown on the top cover). After about 30
seconds, RYL204 will close. Both relays should stay closed. If RYL202 drops out after
RYL204 closes, then there is a problem with the protection loop. The protection loop
consists of the following elements:
• Auto-off time delay = RYL201
• High-temperature thermostat = SW203
• Voltage sense 1 = RYL205
• Voltage sense 2 = RYL206
– Carefully measure the V+ voltage; this can be done at the anode of D203. A reading of
+25 V dc should be observed.
– Carefully measure the ac voltage at the ACneutral post on the PWB. A reading of zero V
ac (referenced to ground) should be observed.
– With a high-impedance voltmeter, measure the voltage at the junction of positive terminal
of C201. When the amplifier is first tuned on, the value will be in the neighborhood of
+1.5 V dc. Over time it will climb higher until if finally causes unijunction transistor Q201
to fire SCR Q203. This will end the auto-off time period and shut down the amplifier.
– Set the Delay Adj trimmer potentiometer for center of travel. This should result in a time-
out period of about 3 hours, which is a good starting point.
Installation of the Automatic Protection Option has now been completed. The PWB installed
in the 40 W Amplifier is shown in Figure 4.