Kenwood TKR-750 Service Manual

Also see for TKR-750: Brochure & specs Service manual Function reference Service manual Instruction manual

15TKR-7501. Modification for Sinking the Collector Current UpAuxiliary output 1 and 2 can each be modified to sink up600mA of the collector current. The following modificationshould be installed when Auxiliary output 1 or 2 is used tocontrol external equipment.1. Remove D625, R755, and R769 for Auxiliary output 1(D624, R756, and R770 for Auxiliary output 2) on thecomponent side of the control section for TX-RX unitPCB.2. Install $Q608, $Q612, and $R761 for Auxiliary output 1($Q607, $Q611, and $R759 for Auxiliary output 2) on thecomponent side of the control section for TX-RX unitPCB.$Q607, $Q608, $Q611, $Q612 : DTD114EKA$R759, $R761 : 3.9kΩ (RK73GB1J392J) chip resistor.3. Change R801 for Auxiliary output 1 (R797 for Auxiliaryoutput 2) from 1kΩ (RK73GB1J102J) to 0Ω (R92-1252-05).By making this modification, Auxiliary output 1 and 2 cannow sink up to 600mA each.TX-RX unit (B/2)Component side$Q607$Q608 $Q612$Q611$R759 $R769CN605R755 R769R756 R770IC623IC602C681Add $Q608($Q607)DTD114EKAAdd $Q612($Q611)DTD114EKARemoveR755 (R756)0ΩRemoveR769 (R770)0ΩAdd $R761($R759)3.9kΩRemoveD625 (D624)DA204UShiftregisterIC6235V 5VTEST/SPKR2. DC Source SwitchTo prevent the power supply from turning off due tomisoperation of the DC source switch on the front panel oraccidents (tampering) after installation, the main unit can bekept on regardless of the on/off of the DC source switch onthe front panel.Short the PSW land near K1 relay by soldering.CF1WIDECF2NARROWPSWK1TX-RX unit (A/2)Component sideMODIFICATIONFig. 1Fig. 2Fig. 3