Motorola VRS750 Service Manual Download Page 78

Page: 78 / 104

10. Press

Toggle Bias

again to disable the PA Bias softpot.

11. Program the Bias softpot into the radio’s codeplug via pressing

Program

12. Exit the PA Bias Low Power function.

NOTE: After tuning a transceiver, go back and tune the

interface board (details in this chapter) and then adjust
the output power and squelch settings (see Chapter 2).

Summary of Contents for VRS750

Page 1: ...1 VRS 750 Vehicular Repeater System Detailed Service Manual ...

Page 2: ... Motorola computer programs stored in semiconductor memories or other media Laws in the United States and other countries preserve for Motorola certain exclusive rights for copyrighted computer programs including but not limited to the exclusive right to copy or reproduce in any form the copyrighted computer program Accordingly any copyrighted Motorola computer programs contained in the Motorola p...

Page 3: ...na Installation 7 VRS750 Programming 7 3 VRS Operation 19 General 19 Control Unit 19 Vehicle Interface Ports 20 VRS Access 20 In Car Monitor 20 Mobile Audio Repeat 21 4 Operation of VRS Options 23 Base Repeater 23 Mobile Detector 23 VRS Transmit PL Generator 23 A Private Line and Motorola are registered trademarks of Motorola Inc Systems 9000 ASTRO Spectra Call Alert Private Conversation Single To...

Page 4: ...ansceiver 43 Interface Board 43 Power Regulation 43 Bus Translation Circuitry 43 Audio Routing Circuitry 44 Single Tone Encoder 45 Single Tone Decoder 45 Boot Control Circuitry 45 Program Sense 46 Mode Configuration 46 7 Maintenance and Troubleshooting 49 Troubleshooting Procedures 49 Disassembly and Reassembly Procedures 51 VRS Transceiver 56 VRS Tuning and Alignment 56 8 Troubleshooting Charts 6...

Page 5: ...Institute ANSI Institute of Electrical and Electronic Engineers IEEE C95 1 1992 Institute of Electrical and Electronic Engineers IEEE C95 1 1999 Edition International Commission on Non Ionizing Radiation Protection ICNIRP 1998 Ministry of Health Canada Safety Code 6 Limits of Human Exposure to Radiofrequency Electromagnetic Fields in the Frequency Range from 3 kHz to 300 GHz 1999 Australian Commun...

Page 6: ... requirements and may require additional compliance actions such as site survey measurements signage and site access restrictions in order to insure that exposure limits are not exceeded Electromagnetic Interference Compatibility NOTE Nearly every electronic device is susceptible to electromagnetic interference EMI if inadequately shielded designed or otherwise configured for electromagnetic compa...

Page 7: ... is placed in the air bag deployment area and the air bag inflates the radio may be propelled with great force and cause serious injury to occupants of the vehicle Potentially Explosive Atmospheres Turn off your radio prior to entering any area with a potentially explosive atmosphere Sparks in a potentially explosive atmosphere can cause an explosion or fire resulting in bodily injury or even deat...

Page 8: ...the notes on the schematic to find out whether or not you can insert or remove circuit modules with power applied to the unit and act accordingly 4 When servicing a circuit module avoid carpeted areas dry environments and the wearing of static generating clothing 5 Be sure that all electrically powered test equipment is grounded Attach the ground lead from the test equipment to the circuit module ...

Page 9: ... Cable Siren to VRS 2 2 2 6881094C84 VRS750 Detailed Service Manual X X X 2884606M01 Mini UHF crimp connector X X X YLN4480 VRS Pushbutton X X X HBN5086 Packing Kit 3085031D01 Cable VRS Programming accessory NTN4056 Adapter VRS Flash programming accessory NKN6460 y cable kit for dual controlhead w vrs accessory TLN5277 DC filter for excessive alternator whine accessory RLN5394 VRS750 Test Box acce...

Page 10: ...0 ms Typical Typically 5 W in 8 ohms Consult the product catalog sheets ECAT Price Pages for a list of disallowed frequencies GENERAL TRANSMITTER RECEIVER Model P2081 403 470 MHz P2082 450 512 MHz Number of Channels 1 T1 R1 Frequency Programmable Synthesized Frequency Channel Channel Spacing 12 5 20 25 kHz Operation Temp Range 30 C to 60 C Primary Power 13 8 VDC 20 Negative Ground DC Current Drain...

Page 11: ...h the VIP input off Enable The activation of the repeater Press the VRS button on the control head or switch the VIP input on Inhibit A condition that occurs when the countdown sequence of the logic circuitry of the repeater ends or anytime the repeater stops transmitting Non Priority Repeater A repeater in any delay state other than delay state zero This unit is inactive and does not repeat until...

Page 12: ...isecond PAC Portable Area Coverage PL Private Line PPI Portable Priority Interrupt P B Portable to Base RF Radio Frequency RX Receive SB Serial Bus SBEP Serial Bus Expanded Protocol TOT Time Out Timer TX Transmit VIP Vehicle Interface Port VRS Vehicular Repeater System VRS EP Vehicular Repeater System Expanded Protocol VRS750 Vehicular Repeater System Model 750 ...

Page 13: ...e signals to the base station on the mobile radio s transmit frequency NOTE These transmissions have the mobile s ID not the portable s Similarly base station signals received by the mobile radio are sent to the VRS and re transmitted to the portable radio The VRS does not provide local repeater capability received portable signals are not repeated on the portable receive frequency The VRS to port...

Page 14: ...is y cable allows the VRS to be connected to the ASTRO mobile with two control heads A separate antenna not included is necessary for use with the repeater Typically a one quarter 1 4 wave length antenna maximizes radiation efficiency when installed at the center of the vehicle roof If it is necessary to mount the antenna on the vehicle s trunk lid an appropriate 3 dB gain antenna should be used S...

Page 15: ...nformation refer to VRS750 Programming in Chapter 2 IMPORTANT NOTE All ASTRO Spectra VRS systems with the same VRS RF transmit receive frequency need to be CPS programmed identically to ensure proper operation Failure to do so could result in erratic system operation The VRS does not have to be installed in the system for programming only the mobile radio is programmed If the VRS is not connected ...

Page 16: ... Emergency Call the VRS cannot be activated NOTE When an Emergency Alarm is received the dispatcher may elevate that talkgroup to Emergency status Reprogram Request Trunking Repeater Access Control Conventional Mobile Single Tone Conventional Seven Tone Modat Conventional Motorcycle Consolette Digital Remote and Tone Remote The following mobile radio features may be received but may not be initiat...

Page 17: ... PA is to be used the G334AC option must be ordered which replaces the HKN6153A cable with a HKN6154A cable or a separate HKN6154A cable must be ordered To install plug the T side of the HKN6154A cable to the Siren PA Replace the mounting screw on the HKN4363B cable with the double length screw Plug this side into the T cable Plug the DB 25 end of the HKN6154A into the VRS see Figure 3 Figure 2 In...

Page 18: ...e mark the positions of the holes on the mounting surface 3 Center punch the spots you have marked and drill a 4 mm 0 16 inch hole at each 4 Secure the trunnion mounting bracket with the four screws provided see Figure 4 5 Connect the VRS to Mobile cable to the 25 pin connector on the bottom of the VRS750 6 Position the VRS750 in the trunnion 7 Secure the VRS750 with the two wing screws and the sp...

Page 19: ...rovided with each VRS750 unit for easier installation with a pre existing antenna Ensure that the antenna s cable connector is fully tightened An adapter should NOT be used between the antenna cable mini UHF connector and the VRS750 VRS750 Programming The user selectable operating parameters for the VRS750 reside in the ASTRO mobile EEPROM during normal operation The EEPROM located in the VRS750 h...

Page 20: ...active open or active closed Then use the Radio Configuration Radio Wide Radio VIP window see Figure 7 to select the VIP to be used However the VRS button must still be added to the control unit if it is desired to have the indicator light when the VRS750 is enabled See the ASTRO Spectra CPS user s manual for details concerning programming the VIP NOTE The ASTRO Spectra CPS user s manual does not ...

Page 21: ...ng type if one is being used If Mode Steering is set to Disabled the Access PL Freq and Access PL Code fields will become user selectable These fields specify the one PL frequency transmitted by the portable that will be used to access the VRS750 The VRS750 will treat that access PL in the same manner as a select mode mode steering PL To edit these fields click in the Access PL Freq or Access PL C...

Page 22: ...10 Figure 8 VRS Window Radio Configuration Radio Wide VRS Figure 9 VRS Private Line Window Radio Configuration Radio Wide VRS Private Line ...

Page 23: ...t to Fast 500 ms or Slow 2 seconds for conventional modes and Fast 500 ms or Slow 1 second for trunked modes NOTE When using Rptr PPI the receiver squelch setting of the portable must be programmed for CSQ carrier squelch The fourth window is the VRS Personality subsection see Figure 11 The VRS Personality sets the VRS Frequency Band Simplex Frequency Channel Spacing and TX Output Power for the VR...

Page 24: ...ow Radio Configuration Radio Wide VRS EP Mode Steering VRS EP Mode Steering List VRS EP Mode Steering 1 see Figure 12 is a table containing PL and mode steering information that can be edited Mode Steering must first be enabled in the VRS Private Line window before the mode steering PLs in the table can be edited To enter the PL codes used in mode steering and their corresponding destinations ente...

Page 25: ...be accessed by the VRS Mode Steering window is 20 Any Zone number greater than 20 will not be allowed in this window but is allowed for normal radio operation VRS750 Global Tuner The Tuner for Professional Radios Global Tuner can be used to adjust the VRS750 s Transmitter Output Power and Receiver Squelch Settings while in Normal Mode see Table 6 in Chapter 6 In order to program the VRS750 using t...

Page 26: ...able power level given in the table below must not be exceeded NOTE When checking the RF power output of the VRS750 always use an attenuator pad of at least 30 dB attached to the radio end of the RF cable This will avoid an RF mismatch and ensure a stable RF reading that will not change with varying lengths of connecting cable NOTE The VRS750 will be programmed from the factory with a high power s...

Page 27: ...3 To perform Transmit Low Power Tuning do the following 1 Under the Tx Align menu select Transmit Power then select Low 2 Press PTT Toggle This will key the radio up at F1 3 Adjust the power level by moving the slider spin control or keying in values in the edit control press ENTER to confirm selection after typing in the softpot value Figure 14 Transmit High Power Window in the Global Tuner Table...

Page 28: ...RF signal modulated with 1 kHz tone at 60 rated deviation see Table 10 in Chapter 7 for current frequency point F1 being the first of 110 dBm Make sure that the mobile mic is off HUB and the VRS is programmed for ICM BOTH mode so that the audio will be routed to the mobile speaker NOTE The 110 dBm squelch level was chosen so that each VRS750 would have the same squelch performance as other VRS750 ...

Page 29: ...l program all off the softpot values into the VRS750 s EEPROM VRS750 Upgrade Kit The VRS750 firmware can be reprogrammed reflashed using the VRS750 Upgrade Kit In order to use the VRS750 Upgrade Kit the VRS750 should be connected to a desktop or laptop PC via a COM port as indicated in Figure 13 The Flash adapter NTN4056A should be placed between the VRS750 programming cable 3085031D02 and the SRI...

Page 30: ...ill request which baud rate to use when flashing the first radio For the VRS750 the baud rate should not exceed 38 400 bps Contact Customer Resources for information on how to obtain this VRS750 Upgrade Kit Figure 16 Flashing Adapter ...

Page 31: ...utton may occupy any of the indicator button positions Field programming determines the exact position The VRS requires an ASTRO radio with a remote mount control head When the VRS is turned on the indicator illuminates and after transmitting the Single Tone burst the words VRS BOTH indicating the In Car Monitor mode will be displayed momentarily The indicator remains on for as long as the VRS is ...

Page 32: ...s the VIP option pressing the VRS button on the control head will only cause the display to change momentarily to the In Car Monitor Mode VRS BOTH It will not enable or disable the VRS as previously described It is still necessary however to select in CPS an indicator button for the VRS if it is desired to have the indicator light when the VRS is enabled VRS Access With the VRS on press the portab...

Page 33: ...sed to change modes If the mode rocker switch is used to change modes the portable user will not be made aware of this mode change With Ack Tones are enabled the portable user will hear a bad tone if the mode is changed during the transmission VRS Reception The VRS option has no effect on mobile radio squelch control or normal mobile radio reception The VRS portable unit s squelch setting is not u...

Page 34: ...22 Notes ...

Page 35: ...o s receive frequency to match that of its transmit frequency of the steered mode The non priority VRS will count down in priority if its corresponding mobile does not detect the repeated transmission on the Listen Around frequency When the portable is dekeyed the non priority VRS will send a second message to the mobile to disable Listen Around and return to normal operation This feature does not...

Page 36: ...hanges the selected mode using the mobile s mode rocker switch before pressing the mic PTT the mobile will now transmit on the new selected mode NOTE For the above type of steering the portable user will be able to steer back to the selected user mode on the control head by programming one PL destination for Sel Mode However the selected mode can be changed by the rocker mode switch Transmitter St...

Page 37: ...ventional respectively The VRS will only generate an Emergency not perform a portable to base audio repeat while the portable is transmitting on an Emergency request channel This feature is typically implemented in the portable using a one touch button that has been programmed for Emergency revert to a channel with the proper PL Although the portable generates MDC tones the VRS cannot decode MDC I...

Page 38: ...knowledged If the status selected is invalid either incorrectly programmed in CPS or not a valid status for the currently displayed mode the VRS will send a low pitched alarm tone to the portable To generate a status request the portable user would select the channel on the portable programmed for the status request momentarily press the PTT button wait for the confirmation tone and return the cha...

Page 39: ...yed every 6 seconds is determined by the temporary message display timer value This value from 250 to 6250 ms default 1000 ms can be programmed by the CPS To configure select Radio Configuration Display Menu Advanced screen Repeater PPI The Repeater Portable Priority Interrupt PPI when enabled causes a base to portable transmission to be interrupted every 1 second in trunked mode or 2 seconds in c...

Page 40: ...28 Notes ...

Page 41: ...it only the highest priority VRS will PTT its corresponding mobile for transmission to the base The other VRS units however will be able to hear the portable transmission and monitor for mobile channel activity Channel activity is verified by a squelch detect of the mobile For non priority units the portable s audio will be sent to the mobile s speaker unmuted from the VRS not from the mobile This...

Page 42: ...ssion in a trunking system would therefore be 5 8 seconds See the description of the Portable Priority Interrupt feature on page 34 for information on the self clearing feature used to re establish a single priority unit when multiple units are mistakenly in priority This condition may occur when a VRS unit is activated before arriving on a scene or in the unlikely case where several units stack u...

Page 43: ...unit B See Figure 20 A portable radio s transmissions solid arrows in Figure 20 go to all portable radios and VRSs in the area Because unit B is the priority repeater it repeats the portable s signal open arrows in Figure 20 to the base station and other mobile radios Unit A cannot countdown and repeat until the delay state one time delay elapses However because unit A detects the mobile carrier o...

Page 44: ... C s repeater transmits a Single Tone burst when its VRS option is turned on Unit C s repeater priority counter initializes in delay state zero making unit C the priority unit Unit A s repeater portable receives unit C s transmission which sets unit A s repeater to delay state two Unit B s repeater portable receives unit C s transmission which sets unit B s repeater to delay state one Transmission...

Page 45: ...ccur the unit in delay state one unit B in Figure 21 counts down to delay state zero and becomes the priority unit See Figure 22 IMPORTANT NOTE Non priority units those in delay state 1 or higher will not count down into priority if the portable user attempts to send a status or message If there is no priority unit on scene the request will be ignored Figure 21 Three VRS Unit Transmission Sequence...

Page 46: ... 500 ms for conventional modes There is also a random time factor added to the base interval to prevent two VRS units from interrupting at the same time This interrupt allows the receiver to monitor portable or other VRS activity for approximately 6 ms See the timing chart in Figure 23 Figure 22 Priority Unit Reassignment MAEPF 26083 O VRS REPEATER TRANSMITTER PORTABLE TRANSMITTER WITHOUT PL PORTA...

Page 47: ...itting begin i e the mobile receives a base signal both VRS units begin transmitting Figure 24 shows the unit B interrupt pulse occurring first due to the random time factor added to the interrupt interval When unit B is interrupted it detects another VRS unit transmitting and so unit B s transmitter remains inhibited Unit B is set to delay state one and unit A remains the priority unit since by t...

Page 48: ...Audio to the base The VRS RX Audio is routed to the mobile speaker TX PL Self Clearing As part of the multi unit resolution prioritization algorithm TX PL Self Clearing operates by adding the VRS transmit PL to the list of PLs that the VRS monitors If a VRS transmit PL is detected by a priority VRS delay state 0 it will indicate that another VRS is transmitting This feature will cause the original...

Page 49: ...o will be disabled 3 During a base to portable repeat operation the mobile user initiates a mic PTT The base to portable repeat operation will be interrupted Mic Hi line audio is not routed to the VRS transmitter The mobile will key up and transmit mic audio to the base When the mobile mic PTT is released the base to portable repeat will continue if the mobile is still receiving a base transmissio...

Page 50: ...e was cut short due to the mobile TOT being exceeded or the mobile channel being changed during the repeat a lower pitched tone sounds If the portable user does not hear a tone after completing a transmission the portable is either out of range of the repeater or there is no priority repeater in the area VRS Mobile Trunking Tones Trunking Only For trunked modes the VRS regenerates the standard tru...

Page 51: ...t the mobile cannot access the trunking system The system busy tone a telephone like busy tone indicates that at the time the portable user dekeyed the trunking system had no voice channel available If the user does not key the portable again after receiving a system busy signal a talk permit tone will be transmitted to the portable as soon as a voice channel is available Message Status Acknowledg...

Page 52: ...dispatch systems TX RX the Mobile Detector must be enabled for the prioritization routine to function properly 3 The VRS will determine if the mobile of another VRS system is repeating the portable signal by steering the mobile to the mode corresponding to the received PL If within one delay state at least 600 ms for conventional at least 900 ms for Base Repeater and at least 1 5 seconds for trunk...

Page 53: ...eature Summary An emergency alarm is initiated when the VRS receives a portable transmission which contains the Emergency Alarm PL as programmed in the mode steering screen of CPS Upon decoding the Emergency Alarm PL the VRS sends an enter emergency bus message to the mobile radio The mobile radio will respond as if the Emer button had been pressed on the control head and will proceed with the Eme...

Page 54: ...out receiving an Emergency ACK from the base The mobile receives an Emergency ACK from the base For silent Alarm any of the following will cause the mobile to exit Emergency Extended keypress of the Emer button on the mobile s control head Mobile mic PTT or a portable to base repeat 2 The mobile will not unmute due to base traffic during silent alarm and therefore the priority VRS will not attempt...

Page 55: ... and C137 are used to filter alternator whine from this signal before providing it as SWB to the interface board The VRS750 utilizes the mobile s analog P102 2 10 11 21 and digital grounds P102 18 U111 regulates the SWB down to 5 VDC This voltage provides power for several switching transistors and voltage dividers on the VRS750 board U118 i a micropower low dropout regulator used to provide 9 6 V...

Page 56: ...udio from any ground noise such as alternator whine before being routed to the mobile at TX_AUDIO P102 8 During portable to base transmissions the mobile routes TX_AUDIO to its transmitter Base to Portable The MIC_FIL_SEL J30 15 and TONES MOBILE_AUD J30 8 control signals are generated by the microcontroller and are used to control audio routing circuits U101 1 and U101 3 for Base to portable activ...

Page 57: ...essor is set to a High state when the VRS750 is in the Single Tone Decode mode receive mode When this signal is high U101 2 allows receive audio URX_SND J30 11 to pass to buffer U100 1 The output of the buffer drives the low pass filter that is also used in the encoder circuit U124 1 and the associated diodes D100 and D101 produce a square wave which is divided down to 3 3V by R172 and R173 This s...

Page 58: ...VRS750 Upgrade Kit refer to VRS750 Upgrade Kit in Chapter 2 To prevent mobile bus messages from corrupting the codeplug programming and or tuning of the transceiver the control signal to U105 1 pin 10 is driven to ground Mode Configuration There are various operating modes of the VRS750 The mode is selected at power up based on the settings of dipswitch S1 pins 1 2 and 3 Pin 4 is unused Table 6 sh...

Page 59: ...rposes Professional CPS Mode is available for when the user requires the transmit and receive frequencies to differ Operation during this mode is not advised and if required please contact your Motorola sales representative for details about this mode All other combinations of the dipswitch are not supported and will default to the Normal mode ...

Page 60: ...48 Notes ...

Page 61: ...ommon Power Up Problems section on page 50 for possible solutions ERR 12 81 Flash EPROM failure If re flashing the unit does not fix this problem the transceiver should be replaced ERR 12 82 Codeplug checksum error After verifying that both mobile and VRS have the correct software version checking the mobile to VRS connection and moving the cable away from any interference reprogram the VRS750 s c...

Page 62: ...tion for a channel spacing of 25 kHz NOTE Because of the short burst it may be necessary to verify the deviation on the modulation scope instead of the usual deviation meter Activation may be repeated by pressing the VRS button once to disable the unit and again to reactivate it Common Power Up Problems 1 ERR 12 10 message is displayed on power up The VRS mobile interface cable is disconnected or ...

Page 63: ... CMOS Integrated Circuit Devices section at the beginning of this manual prior to disassembling the radio Disassembly to Interface Board Level Remove Front Housing 1 Disconnect the Programming Connector Cover by squeezing the top and bottom of the connector together disengaging the bottom snap then the top and pulling straight out 2 Remove the gasket within the recessed area for the 18 pin program...

Page 64: ...clip by inserting a small flat blade screwdriver or like instrument between the clip and the top of the cavity wall as shown in Figure 27 Gently pry upwards 2 Remove the board screws with a T 10 Torx Driver 3 Carefully remove the interface board by rotating it out of the chassis Slowly lift the board on the front edge while pushing up on the board through the accessory connector opening Pull the b...

Page 65: ...nsceiver leaving the 30 pin end attached to the interface board 4 Loosen the screws for the two retainers holding the transceiver to the interface board Slide one of the retainers away from the edge of the transceiver to free it 5 Remove the transceiver from within the two retainers 6 Detach the RF cable from the RF adapter plug Unscrew the RF adapter plug from the transceiver Figure 27 Removing t...

Page 66: ...of the board 3 Add the conductive insulator to the back of the regulator 4 Insert the main board carefully at an appropriate angle approximately 30 into the chassis Start but do not torque down screw number 6 per Figure 29 and Table 8 5 Install the antenna retaining clip 6 Attach the nylon washer to the regulator at screw hole number 4 as indicated in Figure 29 7 Install the screws with 6 8 in lbs...

Page 67: ... in the front of the chassis 2 Place white remote retainer 4205395X01 over the 18 pin connector Figure 29 VRS750 Torque Sequence Table 8 VRS750 Torque Sequence Step No Screw P N Bit Torque Notes 1 6 0310907A20 Torx T10 Start Only 2 Place Antenna Conn Clip 3 4 8 0310907A20 Torx T10 8 in lb Number 6 Inclusive 4 1 3 0310907A20 Torx T10 8 in lb Figure 30 Cover Gasket Location 4 2 7 8 5 3 1 6 Cover gas...

Page 68: ... the VRS Setup ASTRO Spectra Station Cable Setup Ensure that the ASTRO Spectra B cable is disconnected from the power supply and the control head is off WARNING Never turn B power off with the control head still on Connect the VRS DB 25 cable HKN6153A into the accessory connector of the mobile Connect the other end of the VRS cable to the VRS Set the test station power supply to 13 8 Vdc and curre...

Page 69: ...abling Diagram Figure 32 Tuning Potentiometers Mobile Communication Analyzer DC Supply ASTRO Spectra Mobile W7 Control Head Speaker Mobile Microphone HKN6153A VRS750 VRS Communication Analyzer 4 2 7 8 5 3 1 6 R150 R148 R146 ...

Page 70: ...Hz tone 3 kHz deviation and any receive PL for which the VRS is programmed 750 Hz deviation If the receive PL for select mode is not used the Mobile Communications Analyzer frequency may need to be adjusted a Set the Mobile Communications Analyzer frequency to the current mobile mode b Switch on the VRS Communications Analyzer RF c Adjust R146 on the VRS board until 3 00 kHz deviation is obtained ...

Page 71: ...he VRS750 for ATE Test Mode Make the appropriate connections to the VRS750 test box for power and audio Once this is complete the VRS750 can be tested and tuned using the Global Tuner Front End Filter Tuning NOTE Tuning is normally not required for VHF radios It should only be performed if a radio has poor sensitivity VHF radios are only tuned at one softpot frequency F3 The values for the untuned...

Page 72: ... slider keying in the softpot values in the edit box press ENTER to confirm selection or using the spin control until the maximum RSSI voltage has been achieved 4 For UHF and VHF radios a UHF radios Choose the next frequency and repeat steps 1 to 3 until all seven tuning points are done b VHF radios Calculate the softpot offset by subtracting the default softpot value for F3 from the tuned softpot...

Page 73: ...cause of the impact of warp on signaling operations 1 Under Tx Align menu select Reference Oscillator Warp 2 There is only 1 frequency point shown which is always the last non 0 transmit frequency point which will normally be F7 3 Click on the slider thumb Press PTT Toggle to key up the radio at the corresponding frequency point 4 Monitor the transmit frequency 5 Adjust the slider spin or edit con...

Page 74: ...n send a softpot value 3 Inject a 1 kHz at 80 mVrms signal into the external mic connector on the test box VRS750 input 4 Note down the deviation obtained 5 Adjust the slider adjust the spin control or key in softpot values press ENTER to confirm for the frequency point until the deviation is within range as defined in Table 12 6 Dekey radio press the PTT Toggle button Choose the next frequency ke...

Page 75: ...med for both High and Low power for UHF and VHF radios Take note that Procedure 1 IS NOT TO BE PERFORMED for UHF low power level tuning Please refer to Procedure 2 1 Ensure that the radio s antenna output is terminated to a 50 Ohm load This is to prevent self destruction of the PA 2 Under Tx Align select PA Bias select High Power 3 Measure read the dc current drawn from radio specifications will v...

Page 76: ...s is to prevent self destruction of the PA STEP 1 1 Under Tx Align select PA Bias select Low Power 2 Measure read the dc current drawn from radio specifications will vary from radio to radio Call this X This value should typically range from 70 100 mA or 0 07 0 1 A 3 Press Toggle Voltage to enable the PA control voltage edit box spin control 4 Increase the Voltage softpot value and measure read fr...

Page 77: ...Low Power function STEP 3 1 Press Toggle Bias twice to reset the softpot value 2 Press Toggle Bias again to disable the PA Bias softpot 3 Measure read the dc current drawn from radio specifications will vary from radio to radio Call this X This value should typically range from 70 100 mA or 0 07 0 1 A 4 Press Toggle Voltage to enable the PA control voltage edit box spin control 5 Increase the Volt...

Page 78: ...gram the Bias softpot into the radio s codeplug via pressing Program 12 Exit the PA Bias Low Power function NOTE After tuning a transceiver go back and tune the interface board details in this chapter and then adjust the output power and squelch settings see Chapter 2 ...

Page 79: ...ber 1 VRS Enable Failure 68 2 Error 12 10 69 3 Error 12 81 69 4 Error 12 82 Codeplug Checksum Error 69 5 Error 12 84 Configuration Register Corruption 69 6 Error 12 88 HC11 RAM Failure 69 7 VRS 001 VRS Synthesizer Lock Failure 70 8 Single Tone Encode Failure 71 9 Single Tone Failure 72 10 Base to Portable Repeat Failure 73 11 Portable to Base Repeat Failure 74 12 VRS ICM Audio Failure 75 13 Serial...

Page 80: ...rogram mobile codeplug for VRS button operation Is VRS BOTH message displayed on button press VRS is now enabled Reset system and start over If CSQ is being detected the VRS will not enable Is the mobile codeplug programmed for VRS VIP active state Program mobile codeplug for VRS VIP Is switch in correct VIP Program mobile codeplug for proper VRS VIP active state Check VRS VIP switch input Move sw...

Page 81: ...ERROR 12 10 Chart 3 Error 12 81 START Reprogram the Flash Memory ERROR 12 81 Chart4 Error 12 82 Codeplug Checksum Error START Reprogram the VRS750 Codeplug ERROR 12 82 Chart 5 Error 12 84 Configuration Register Corruption Yes No START Reflash the VRS750 with the correct version firmware Reset the system Is the 12 84 error still displayed Replace the transceiver board Problem is corrected ERROR 12 ...

Page 82: ...ock Failure VRS 001 FAILURE Yes No Does the Freq Band field in ASTRO CPS match the freq Band of the VRS750 attached to the mobile Replace the transceiver board Correct the freq band field for the VRS750 in the ASTRO mobile codeplug START ...

Page 83: ...eiver Replace the flex cable START SINGLE TONE ENCODE FAILURE Yes Yes Yes Is 3 3VDC square wave at R114 during Single Tone burst Is 80mVpp sinewave at TP104 Is there continuity between J30 6 and J40 21 on the flex cable Is the sinewave present at TP101 Check and or replace U100 U124 Is the sinewave present at the negative terminal of C104 Verify that pin 10 of U101 is 0VDC during the Single Tonebu...

Page 84: ... when the volume button is pressed Does J30 21 pulse to 0VDC when the volume button is pressed Check the mobile to VRS cable Is there continuity between J30 21 and J20 9 on the flex cable Check and or replace U103 and Q103 Check and or replace the transceiver Replace the flex cable Verify that J30 20 boot control is 3 3VDC SINGLE TONE FAILURE ...

Page 85: ...o the VRS Is audio present U101 pin 4 Check U104 Adjust R150 if necessary Is audio present TP101 Verify that the local mic is not pressed Is audio present J30 19 Is pin 10 of U101 HIGH 9 6VDC Is there continuity between J30 19 and J20 7 of the flex cable Replace the transceiver Replace U101 Is there continuity between J30 8 and J40 23 on the flex cable Is pin 9 of U101 low 0VDC Repair replace U101...

Page 86: ...nd replace if necessary Is mobile transmit deviation 3kHz Check solder connextions for C132 C133 and T2 Replace if necessary Complete Adjust R146 to obtain 3kHz deviation from mobile Activate the VRS750 Is VRS BOTH displayed briefly Provide an on channel RF signal with an Access or Mode Steering PL to the VRS750 The VRS750 is not enabled and will not repeat Is audio present TP128 Is there continui...

Page 87: ...r replace U101 Check and or replace Q114 Activate the VRS750 Is VRS BOTH displayed briefly During Base to Portable communications is audio heard the portable Check C185 and C166 to make sure they have not been shorted to ground Verify that the MOBILE_MIC_HI line in the mobile to VRS is ok Is audio present pin 1 of U101 Is audio present pin 15 or U101 Is pin 9 of U101 a logic HIGH 9 6VDC Is pin 10 ...

Page 88: ...C when the volume button is pressed Does J30 21 pulse to 0VDC when the volume button is pressed Check the mobile to VRS cable Is there continuity between J30 21 and J20 9 on the flex cable Check and or replace U103 and Q103 Check and or replace the transceiver Replace the flex cable Verify that J30 20 boot control is 3 3VDC SERIAL BUS FAILURE ...

Page 89: ...ormal operation Is audio present at TP108 Repair and or replace U107 Adjust mobile volume on controlhead to level 7 Check solder connections for C183 C103 and T1 Activate the VRS750 Is VRS BOTH displayed briefly Provide an on channel RF signal with the proper Access or Mode Steering PL to the VRS750 The VRS750 is not enabled and audio will not be heard START Replace the transceiver Replace the fle...

Page 90: ... programming cable back in to the VRS750 and try again Reset the mobile radio Plug the programming cable back in to the VRS750 Is PROG VRS displayed on the mobile control head Try programming again A Connect the SRIB to the serial port of the computer using a null modem cable and make sure it is turned on Verify that the mobile is powered on If not power the mobile on and start over A Is the VRS75...

Page 91: ...the VRS750 Remove the Flashing Adapter and reset the mobile The Flashing adapter could be bad Place the switch in the B position and reset the mobile Is the cathode of VR121 grounded when plugged into the SRIB Replace the header block Verify that P101 7 is connected to J30 24 Replace the programming cable Is the Flashing Adapter being used A PROGRAMMING AND TUNING ISSUES CONT ...

Page 92: ...80 Notes ...

Page 93: ... and Parts Lists Description Page Number Printed Circuit Board Electrical Parts List 83 Printed Circuit Board Component Location Diagram 84 85 Printed Circuit Board Schematic Diagram 86 87 Exploded View and Exploded View Parts List 88 VRS to Mobile Cable 89 VRS to Siren Cable 89 VRS750 Programming Cable 90 VRS750 Programming Cable Schematic Diagram 90 VRS750 Flashing Adapter Schematic Diagram 90 ...

Page 94: ...82 Notes ...

Page 95: ...821A21 nchan_tmosfet_gsd Q114 115 4880141L02 NPN RESISTOR Ohms 5 1 8 W unless otherwise stated R101 0662057A93 68 k R102 0662057A73 10 k R104 105 0662057A25 100 R106 0662057A65 4 7 k R107 0662057A69 6 8 k R108 0662057A93 68 k R109 0662057A97 100 k R110 0662057A77 15 k R111 0662057A83 27 k R112 113 0662057A97 100 k R114 0662057B10 330 k R115 0662057A94 75 k R116 0662057A84 30 k R117 118 0662057A65 ...

Page 96: ...11 R112 R113 R114 R115 R116 R117 R118 R119 R120 R121 R122 R123 R124 R125 R126 R127 R128 R129 R130 R131 R132 R133 R136 R137 R138 R139 R140 R141 R142 R143 R145 R146 R147 R148 R149 R150 R151 R155 R156 R157 R158 R159 R160 R161 R162 R163 R164 R165 R166 R171 R172 R173 R174 R175 R180 R181 R182 R183 R184 R200 R210 R211 R212 R213 R215 R216 R217 R220 R221 R224 R225 R226 R227 R228 R229 S1 TP101 TP102 TP103 T...

Page 97: ...03 C132 C133 C137 C156 C157 C159 C162 C183 C195 C196 L101 P31 P32 P33 18 10 9 P101 25 14 13 P102 1 3 4 6 T1 1 3 4 6 T2 4 5 8 U111 W101 VRS750 Vehicular Repeater System Printed Circuit Board Component Location Diagram Sheet 2 of 2 ...

Page 98: ... C100 220pF S1 6 3 100 22 1K R130 1 220pF R104 R127 10K C161 220pF C112 R156 J30 10 1K R126 15K C175 D100 220pF R140 100K 4 7K SW7 5V R112 10K R211 P101 1 1K R210 4 7K R200 TP101 J30 3 C122 220pF U103 5 MC14106 11 10 1uF C103 100K R109 6 8K P102 3 J30 26 R119 C116 01uF U107 2 MC33072 6 5 7 0 1uF Q104 MMBT3906 10K C105 C107 R173 220pF 9 6V R216 C194 1 5MEG 13 MC14053B U102 3 9 4 5 3 1000pF MC14053B...

Page 99: ...F 5 6V U129 ADJ IN OUT P102 7 VR105 C136 220pF W102 3 U124 5 4 11 15K R157 U102 4 16 6 7 8 P102 21 C129 220pF U104 4 MC3303 13 12 14 5V 1uF C143 R160 15K 5V RADIO_SWB TP117 220pF C147 2K R165 VAG C158 220pF C140 0 1uF U104 1 MC3303 2 3 1 4 5 6 9 6V T2 1 3 5V SW7 5V R161 220pF C159 C149 10uF 820 220pF 01uF 5V C131 C141 56K R149 47K R145 U100 POWER POWER POWER POWER POWER POWER POWER POWER 8 4 W101 ...

Page 100: ...0M02 INSULATOR Nylon Heat Conductive for Regulator 16 TRANSCEIVER PMLD4196A VHF Transceiver PMLE4242A UHF R1 Transceiver PMLE4243A UHF R2 Transceiver 17 2885170D01 PLUG RF Phone to SMB 18 3085166D01 CABLE RF Coax 19 4285033D01 RETAINER Internal Radio 2 req d 20 0300139800 SCREW 6 32 x 5 4 req d 21 0200844628 NUT 6 32 2 req d 22 4285168D01 RETAINER Flex Connector 23 1485171D01 INSULATOR PC Board 24...

Page 101: ...14 Bus 15 N C 16 N C 17 N C 18 18 DGND 19 19 Reset 20 N C 21 21 Bus_GND 22 22 SWB 23 23 Busy 24 N C 25 N C VRS to Siren Cable HKN6154A Pin Number Signal Name VRS750 P102 Siren HLN1439A 39 pin J1 1 N C 2 15 FIL_Audio_GND 3 N C 4 N C 5 17 Bus 6 9 FLT_Audio 7 33 Rx_Audio 8 3 Tx_Audio 9 N C 10 11 AGND 11 14 Mic_Lo 12 27 Mic_Hi 13 N C 14 25 Bus 15 N C 16 N C 17 N C 18 19 DGND 19 4 Reset 20 N C 21 18 Bu...

Page 102: ... 4 N C 5 N C 6 N C 7 15 TXD 8 N C 9 2 Prog_Sense 10 N C 11 N C 12 N C 13 N C 14 N C 15 N C 16 N C 17 N C 18 N C VRS750 Programming Cable 3085031D01 Pin Number Signal Name VRS750 P101 SRIB DB25 Female VRS750 Programming Cable 3085031D01 VRS750 Programming Cable Schematic 3085031D01 VRS750 Flashing Adapter Schematic NTN4056A ...

Page 103: ... chassis or kit of which it is a part and sufficient description of the desired component to identify it Crystal and channel element orders should specify the crystal type or channel element type number crystal and carrier frequency and the model number in which the part is used Replacement Parts Test Equipment Manuals Crystal Service Items Motorola Inc United States and Canada Accessories and Aft...

Page 104: ...92 Motorola 8000 West Sunrise Boulevard Fort Lauderdale Florida 33322 68P81094C84 O 6881094C84 6881094C84 ...

Search results

Summary of Contents for VRS750

Reviews:

Related manuals for VRS750

Brands by name

Popular brands

Motorola VRS750, Service Manual

Search results

Summary of Contents for VRS750

Reviews:

Related manuals for VRS750

Brands by name

Popular brands