See Figures 1, 2, 3, 4 and 5
Observe the following cautions when working on the radio:
- Always observe the proper polarity of the connections (positive to positive and negative to negative).
- Never operate the radio without a speaker, to prevent damage to the output transistors. If a new speaker is installed, make sure it has the correct impedance (ohms) for the radio.
If a new antenna or antenna cable is used, or if poor AM reception is noted, the antenna trimmer can be adjusted. Turn the radio to a weak station around 1400 kHz. Adjust the trimmer screw until best reception and maximum volume are obtained. The trimmer screw for the factory installed radio is located on the bottom in the left rear corner on 1970-71 models, in the lower left corner of the rear of the radio case 1972-78, above the left knob on the front of the radio in 1979, above the right station pre-set button on 1980-86 720D series models, and on 1986-88 D21D series models, either above the left station pre-set button or in the lower left corner of the facia.
Never turn the antenna trimmer more than1/2turn on 1980-88 models.
For best FM reception, raise the antenna to 31 in. For best AM reception, raise the antenna to its full height.
REMOVAL & INSTALLATION
See Figures 6 and 71970-79
- Disconnect the negative battery cable. Carefully pull the knobs off the radio control shafts.
- Remove the radio retaining nuts and washer from the radio control shafts.
- Remove the bezel plate from the front of the radio.
- Disconnect the antenna cable and the power and speaker wires from under the instrument panel.
- Remove the radio from the instrument panel.
- Install the radio in the instrument panel.
- Connect the speaker and power leads, plug the antenna in and then position the bezel.
- Slide the washers over the control shafts and then tighten the retaining nuts.
- Press the knobs back onto the control shafts.
- Disconnect the negative battery cable.
- Remove the ash tray and heater/air conditioner control panel.
- Disconnect the wiring plug at the back of the radio.
- Remove the plug covering the mounting screws, remove the screws and pull the radio from the dash.
- Disconnect the wiring harness and the antenna.
- Reconnect the wiring harness into the rear of the radio and then slide the radio into the instrument panel.
- Install and tighten the radio mounting screws and then press the plug into position.
- Reach through the control head opening and connect the antenna and any electrical leads.
- Install the control head and connect the battery cable. Adjust the heater control head if necessary.