The double jack at the left of the panel is used for making a connection between a non-synchronous turntable and the amplifier equipment.

At the center of the panel below the meter are four metering jacks. The jack on the left is for measuring the voltage of the storage battery. When using this jack press the meter push-button. The second jack from the left is for use in measuring the plate voltage of voltage amplifier No. 1. The third jack from the left is for measuring the plate voltage of voltage amplifier No. 2 and the jack on the right is for measuring the polarizing voltage of the photo-cell. The purpose of these measurements is to check the condition of the dry batteries.

In a row along the bottom of the panel are four snap-switches. The switch on the left is the battery switch for opening and closing the storage battery circuit, to the amplifiers and exciter lamps. The second switch from the left is used to switch the output of the photo-cells or turntables from the input circuit of one voltage amplifier to the input circuit of the other voltage amplifier. The third switch from the left is for changing the volume control connections from one voltage amplifier to the other. The switch on the right is for changing the connections between the output of the voltage amplifier and the input of the power amplifiers from one voltage amplifier to the other. These three change-over switches should all be in either the "No. 1" position or "No. 2" position, as indicated on the name plates beneath the switches.

190. Description of the PA-17A Power Amplifier Control Panel. -The rheostat knob for controlling the AC line voltage input to the power amplifiers is located at the center of the power amplifier control panel. The rheostat is in series with one of the AC power lines and allows adjustment of the voltage of the AC power input to 100 volts. The AC voltmeter in the upper right-hand corner of the panel indicates the alternating voltage supplied to the power amplifier units. The two switches below the meter are for switching "on" and "off" each power amplifier independently. The two jacks below the switches are monitoring jacks. One jack is provided for each amplifier, so that they can be monitored separately.

191. Operation of the PA-17A Voltage Amplifier Control Panel. -Before starting the equipment check the voltages at the voltage amplifier control panel, by means of the test meter and jacks. The reading obtained from the "FILAMENT VOLTAGE" jack, while pressing the meter push-button, should be 12 volts as read on the lower scale of the meter. Do not press the meter push-button when taking readings from any other than the "FILAMENT VOLTAGE" jack. A reading of 115 to 135 volts should be obtained when checking either the "NO. 1 PLATE V" or the "NO. 2 PLATE V" jack. A reading below 115 volts indicates that the "B" batteries are weak, and should be replaced. A reading of 170 to 200 volts should be obtained from the jack labeled "PHOTO CELL PLATE V" if UX-867 Photocells are used with the equipment. A reading below 170 volts is an indication that the photo-cell batteries should be replaced. If UX-868 Photocells are used, a reading of from 80 to 90 volts should be obtained when using the "PHOTO CELL PLATE V" jack. In this case a reading of less than 80 volts indicates that the photo-cell batteries should be replaced.

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