SB-951 TS-940S ERRATIC DISPLAY 01/20/89 Intermittent control or display problems that are difficult to correct with the reset procedure may be caused by a faulty ROM socket. The socket should be checked to insure that it makes good electrical contact with each pin of the ROM. If it is found to be intermittent, remove the socket and solder the ROM directly to the board. It should be noted that units between serial numbers 701XXXX to 811XXXX and from 903XXXX to 909XXXX are not likely to have this failure. In addition, units with a serial number of 909XXXX and above do not incorporate a socket. CAUTION Removing the socket requires good soldering skills. The ROM is mounted on the Digital A unit and is designated as IC2. The board, being double sided, has solder connections on both component and foil sides. When the socket is removed, it is very important to insure that each pin is completely solder free. Having to pry up on the socket means that it is not completely desoldered and will cause the circuit foils to tear. When performing any work on the Digital A board, CMOS handling techniques must be observed. Such techniques include using a grounded or isolated soldering tip, avoid touching the pins of IC chips with your fingers, and ground yourself with a wrist ground strap. To remove the socket: 1. Disconnect the power cord and antenna coax. 2. Remove the top and bottom covers from the transceiver. 3. Remove the 2 flat head screws from each side of the front panel chassis. 4. Loosen the round head screw on each side of the front panel chassis. 5. Carefully rotate the front panel forward. It will be necessary to unplug the VS-1 cable from the transceiver. 6. Remove the 4 screws from the speaker mount. 7. Carefully pull up on the mount and rotate it toward the front panel. Swing the mount toward the right side of the transceiver and allow it to rest on the Digital B unit shield. 8. Remove the 8 screws from the Digital A unit shield plate. 9. Lift the plate and rotate it to the left side of the transceiver. 10. While avoiding contact with the pins, remove the ROM (IC2) and set it aside on anti-static foam. 11. Remove the 6 screws that mount the Digital A board. Rotate the board toward the front panel to expose the bottom side of the board. 12. Carefully desolder the socket and remove it from the board. Do not pry up on the socket. If it does not easily pull off the board, the top foils are still soldered to the socket. 13. Install the ROM in the board and solder it in place. 14. Assemble the transceiver by reversing steps 1 - 11. Do not pinch the power switch cables between the front panel and the body of the transceiver. Time required for this modification is 1.5 hrs or less. (C) 011189TKC Kenwood U.S.A. Service Bulletin Extract Amateur Radio Number: SB950 Subj: TS-440S Case Screws binding in the heat sink. Date: 01/20/89 Occassionally a case screw that fastens to the heat sink of the TS-440S will cross thread or bind when it is being inserted or removed. Binding may be caused by tooling marks on the screw or by burrs on the tapped threads in the heat sink. When a screw starts to bind, DO NOT TRY TO FORCE IT! as this may cause the head to shear off. If the screw is being removed and it starts to bind, return the transceiver to KENWOOD. Do not make attempts to remove the screw. In addition, if a transceiver is being brought to you with a scrw sheared off, return the unit to KENWOOD. Do not attempt to drill out the screw. If a screw starts to bind when it is being installed, carefully back it out. Inspect the screw for marks or burrs and replace it if it is questionable. Since the threads in the heat sink may be causing the screw to bind, they should be cleaned by running a 3 x 0.5 mm tap into each hole. The tap is inexpensive and can be obtained at may of the larger hardware stores. To avoid cross threading, make sure the covers are properly aligned when they are being installed. Proper alignment means that there is a clear path for the screw to turn into the heat sink. This assures that the screw does not rub against the case and result in it turning into the heat sink at an angle. SB-949 TS-440S PROTECTING Q33 01/20/89 If pin 7 (RL) of the remote connector is accidently connected to ground, current from the 14 volt line (14L) will damage transistor Q33 on the IF unit. This will prevent the radio from transmitting. To protect Q33, a 4.7 ohm resistor should be installed in series with the RL line on the foil side of the IF board. In the event that pin 7 is connected to ground, the resistor will open, but the transceiver will still be capable of transmitting. REQUIRED PART: 4.7 OHM, 1/6 WATT RESISTOR ........ RD14CB2C4R7J 1. Disconnect the power supply and antenna from the transceiver. 2. Using a #2 Phillips screw driver, remove the 9 screws from the top cover of the transceiver. Remove the cover and unplug the speaker wire. 3. Locate connector 19 on the IF unit. 4. Using a #1 Phillips screw driver, remove the 7 screws that secure the IF unit to the chassis of the transceiver. 5. Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board. 6. On the foil side of the board, locate the trace that is connected to pin 3 (brown wire) of connector 19. 7. Using a craft knife, cut the trace comming from pin three so as to open the foil trace. 8. Solder the 4.7 ohm resistor across the now open trace (i.e. in series with the trace). 9. Assemble the transceiver by reversing steps 1 - 5. This is an optional change that may not be covered under warranty. Time required for this modification is 0.5 hrs or less. (C) 112188TKC SB-948 TS-440S NOTCH FILTER LOW FREQUENCY IMPROVEMENTS 01/20/89 The low frequency attenuation characteristics of the notch filter can be improved by reducing the input level to the notch filter chip (IC1). To compensate for the loss of input level, the amount of negative feedback to the audio amplifier (IC7) will need to be reduced. This modification is already incorporated in all models beginning with serial number 704XXXX. REQUIRED PARTS: 120K OHM, 1/6 WATT RESISTOR ........ RD14CB2C124J 390 OHM, 1/6 WATT RESISTOR ........ RD14CB2C391J 1. Disconnect the power supply and antenna. 2. Using a #2 Phillips screw driver, remove the 9 screws from the top cover. Remove the top cover from the transceiver and unplug the speaker wire. 3. Locate resistors R86 and R229 on the component side of the IF board (Figure 1). 4. Using a #1 Phillips screw driver, remove the 7 screws that secure the IF unit to the chassis of the transceiver. 5. Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board. 6. Desolder and remove both resistors from the board. 7. Install and solder a 102K ohm resistor in place of R86. 8. Install and solder a 390 ohm resistor in place of R229. 9. Assemble the transceiver by reversing steps 1 - 5. This is an optional change that may not be performed under warranty. Time required for this modification is 0.5 hrs or less. (C) 110788TKC SB-947 TS-440S OPERATION WITH THE MC-85 01/20/89 With some TS-440S transceivers, insufficient modulation may occur when the MC-85 compression switch is turned on. This may be caused by too much of a voltage drop across resistor R172 on the IF unit of the transceiver . If this is found to be the case, change the resistor from 1K ohm to 100 ohms. REQUIRED PART 100 OHM, 1/6 WATT RESISTOR.......RD14CB2C101J PROCEDURE: 1. Disconnect the power supply and antenna from the transceiver. 2. Using a #2 Phillips screw driver, remove the 9 screws from the top cover of the transceiver. Remove the cover and unplug the speaker wire. 3. Locate resistor R172 on the component side of the IF board (Figure 1). 4. Using a #1 Phillips screw driver, remove the 7 screws that secure the IF unit to the chassis of the transceiver. 5. Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board. 6. Desolder and remove resistor R172 from the board. 7. Install and solder the 100 ohm resistor in place of R172. 8. Assemble the transceiver by reversing steps 1 - 5. This modification may be covered under warranty. Time required for this modification is 0.5 hrs or less. (C) 110888TKC