Kenwood TK-790 Service Manual

Also see for FleetSync TK-790: Specifications Instruction manual Specifications Instruction manual

20TK-790/(B)/H(B)6-3. Modification to increase the audio output ofthe control headThe speaker output can be increased to 13W by movingjumper resistor (0 ohm) R628 on the control unit (X57-561B/3) to R627. In this case, the KCH-10 internal speaker can-not be used because the maximum input (3W) of the inter-nal speaker is exceeded. Therefore, use the KES-4.Note : Even if the KRK-6DH is modified in this way, the au-dio output of head 2 cannot be increased.To increase the audio output of head 2 of the KRK-8DBH,modify radio 2 in the same manner.6-4. Use as public address speaker1. Remove the short plug from the 9-pin accessory connec-tor on the rear of the radio. (Remove the jumpers as de-scribed in Section 5-1.)2. Insert the KES-4 speaker leads into pins 7 and 8.3. If you remove jumper shorting pins 3 and 6, the 20W PA(public address) voice signal is output from pins 7 and 8.(Only when the PA or SP switch is on.)4. If you use the radio with pins 3 and 6 shorted, the internalspeaker is available (when the KCH-10 is used). The KCH-11 does not contain a speaker.Note : Relation ship between accessory connector (9-pins)connection and speaker output.When pins 3 and 6 are shorted ; The 3W internal speaker isused (KCH-10 only).When pins 3 and 6 are open and output is from pins 7 and 8; The 20W external speaker is used.Default Modification 1 Modification 2R690 Present Present AbsentR691 Present Absent AbsentR692 Absent Present PresentStateTable 2 (Refer to page 21)8. Accessory Terminal Function8-1. 25-pin accessory terminal• Pin 13MI/DI (MIC Signal Input/Output or Data Audio Input)This pin has one of the two functions listed in Table 3 bysetting jumper resistors (0 ohm) R640 and R641 on thecontrol unit (X57-561 B/3) (Refer to page 21).1) MIC signal input/outputThis pin is directly connected to the MIC input pin of thetransceiver, so it has the same function as the MIC inputpin. When the input is 5mV/3 kHz, DEV (600 ohms)modulation is obtained. The MIC input is output from thetransceiver panel as it is.2) Data audio inputThe signal from this pin passes through the LPF (fc: about10kHz), is summed with the MIC AMP output, and goesto the modulator. Therefore, it is not preemphasized.• Pin 14SB (DC Power Output After Power Switch)The maximum output (13.6V : TK-790/(B), 13.4V : TK-790H(B) / 0.5A) can be obtained by modifying the controlunit as follows:Short the land of the print pattern near CN505 of the con-trol unit (X57-561 B/3).R640 R641 FunctionPresent Absent MIC signal input/outputAbsent Present DATA audio input : DefaultTable3 (Refer to page 21)9. Connection with the Remote KitWhen the KRK-5, KRK-6DH, KRK-7DB or KRK-8DBH isused, set chip resistors and transistors as shown in the tablebelow.KRK-5 KRK-6DH KRK-7DB KRK-8DBHRadio 1 UnnecessaryRadio 2 – Remove R546 and R661Move R602 to R705.Table 4 (Refer to page 21)INSTALLATION78Plug (9P)Crimp terminal(E23-0613-05)To KES-4Black leadBlack/White leadFig. 117. Horn Alert FunctionThe HR1 pin of the accessory connector (9-pin) on therear of the transceiver is an open collector and the maxi-mum current is 100mA. The maximum available current canbe increased to 1A by installing a relay.1. Remove the upper half of the case of the TK-790.2. Move jumper resistor (0 ohm) R691 on the control unit(X57-561 B/3) to R692. To make the HR2 pin, removeR692 (Refer to page 21).3. Remove screws and erect the PC board. Install and sol-der relay K501 (Part No. : S76-0407-05).4. Reinstall the PC board and the upper half of the case.HR1HR2HR1HR2HR1HR2