Modifications for the Kenwood TS-950

Picture(s) of Kenwood - TS-950

19-07-1998 TS-950SD general coverage transmit mod English language
19-07-1998 Kenwood TS-950 Power On Funktions English language
30-05-1999 Kenwood TS-950-SDX Allows sub-rcvr to be on different band than Main receiver English language
20-04-2000 TS-950SD Speech processor noise English language
20-04-2000 TS-950SD N.B. Gate switching noise English language
20-04-2000 TS-950SD Early protection with TL-922A English language
20-04-2000 TS-950SD RX digital noise English language
20-04-2000 TS-950SD Two second TX power delay with MONI on English language
20-04-2000 TS-950/SD Receiver noise English language
21-04-2000 TS-950S/SD TX image on 18.115 MHz English language
21-04-2000 TS-950S/SD 80 meter spurious emission English language
21-04-2000 TS-950S Final bias circuit change English language
21-04-2000 TS-950S Rear panel cooling fan English language
22-04-2000 TS-950SDX Mode switching English language
22-04-2000 TS-950SDX No beep in headphones English language
22-04-2000 TS-950SDX Distorted DRU-2 TX audio English language
22-04-2000 TS-950SDX w/K1EA Ver. 8 Program (Revised) English language
22-04-2000 TS-950SDX Speech processor English language
22-04-2000 TS-950SDX 3rd order IMD standardization English language
22-04-2000 TS-950SDX Key click w/bug type keyer English language
23-04-2000 TS-950 Hum with monitor ON English language
23-04-2000 TS-950 Noise with Sub-Band noise blanker ON English language
23-04-2000 TS-950 14.200 MHz transmit spur English language
23-04-2000 TS-950 Low power output after temp. protection English language
23-04-2000 TS-950 Infinite SWR at beginning of transmission English language
23-04-2000 TS-950 Smoke from antenna tuner unit English language
23-04-2000 TS-950S/SDX Transmit spur English language
23-04-2000 TS-950SDX "click noise" with NOTCH ON English language
23-04-2000 TS-950SDX YG-455S-1 Installation note English language
23-04-2000 TS-950SDX No VFO B after "split" English language
23-04-2000 TS-950SDX Carrier point adjustment English language
23-04-2000 TS-950SDX Sub band residual noise English language
23-04-2000 TS-950SD 18.115 MHz spur English language
23-04-2000 TS-950SDX Change of Gate resistor type English language
20-01-2001 Countermeassure against cold solder joint at the resistor block; CP1-CP4 in the PLL unit. English language

19-07-1998
TS-950SD general coverage transmit mod

1. Remove power and ant.

2. Remove top and bottom covers.

3. Locate the digital unit.

4. Cut diode d-17

5. Reassemble radio.

6. Reset cpu.

This modification is read 408 times.

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19-07-1998
Kenwood TS-950 Power On Funktions

Please notice that all functions only work if you switch off radio first.
Please push the named buttoms to start function when switching on the radio:

SUB : SUB receiver capable of scanning,to SUB-scan push and hold the SUB-key and press than the scan key

ENT : Set up ch. 90-99 as amateur band vfos 160-10 m band possible.each memory vfo will accept direct frequencie entry.(like ICOM band stack memory)

5+M-VFO : set up ch.80-89 to accept any memory data

RX/A : Turn ON/OFF SUB receiver marker on SM 230 Monitor in 100 kHz/250kHz and 25kHz sweep mode.

IC+COMP : stop transmit if Ic exceeds 1,7 A. Power output limited to 10 Watt

8.83 + RIT : Both 8.83 MHz and 455 kHz IF Filters are selectable on transmit. Each memory channel is also capable of storing this setting.

Memory protect: Cutting D 129 on control unit protects memory contents from beeing erased.

Write protect : Cutting D 18 on Control Unit write protects all memory channels.

from Hanno DG8JZ

This modification is read 754 times.

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30-05-1999
Kenwood TS-950-SDX Allows sub-rcvr to be on different band than Main receiver

Allows sub-rcvr to be on different band than Main receiver.
This is a Power On function mod.
Start with radio turned off.
Hold down buttons SUB, M/S, RX/SUB while turning on the power ON. Now you can listen to 15M on sub-rcvr with Main rcvr on 20M. or any other band or visa-versa. Both receivers will be in the same mode USB, LSB, CW etc.
73,
George, K5GH

This modification is read 1061 times.

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20-04-2000
TS-950SD Speech processor noise
Author: Trio-Kenwood Communication, inc.


Service Bulletin no. 959 (12-1-1990)

When the Processor-In control is set to some level below 10 dB of compression, a crackling noise can be induced on the transmit signal. The following modification will reduce the noise. After the modification has been performed, the noise can only be heard when the Processor-In control is set too low to be functional.

Note: This modification has already been performed on models starting with serial number 0120441.

Required parts:

Transistor (PNP)                      (2SC2458Y)
4.7 ohm, 1/6 watt resistor            (RD14CB2C4R7J)
10 ohm chip resistor                  (RK73FB2A100J)
39 ohm chip resistor                  (RK73FB2A390J)
10 Kohm chip resistor                 (RK73FB2A103J)
  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Locate the Signal board on the bottom of the transceiver. This is the front right board of the 4 boards on the bottom of the transceiver.

  4. Disconnect the 3 flex cables and remove the 6 mounting screws from the Signal board.

  5. Carefully lift the board and rotate it toward the AF unit (front left board) to expose the foil side of the Signal board. Loosen the wire harness as necessary to rotate the board.

The following will be performed on the foil side of the Signal board.

  1. Cut the foil between pin 3 of CN18 and chip resistor R229.

  2. Desolder and remove R229.

  3. Solder a 10 ohm chip resistor across the cut foil.

  4. Solder a 39 ohm chip resistor in place of R229 (it will be slightly offset due to the installation of the 10 ohm resistor).

  5. Solder a 4.7 ohm resistor to the collector of a 2SC2458(Y) transistor. Shorten the lead length to accommodate the following installation and insulate the leads with shrink tubing.

  6. Solder the exposed end of the 4.7 ohm resistor to chip capacitor C167.

  7. Solder the base and emitter leads as shown in the accompanying diagram.

  8. Solder a 10 Kohm resistor to the circuit as shown.

This modification is covered under the 1 year warranty.
Time required to perform the modification is 1 hour or less.

This modification is read 1318 times.

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20-04-2000
TS-950SD N.B. Gate switching noise
Author: Trio-Kenwood Communication, inc.


Service Bulletin no. 961 (11-1-1990)

Switching noise from the main band noise blanker circuit may be induced on the 15V line and pass through the AF amplifier to the speaker. The following modification will correct this condition.

Note: This modification has already been performed on models starting with serial number 104xxxx.

Required parts:

120 ohm, 1/8 watt resistor             (RD14BB2B121J)
100 F, 16 V electrolytic capacitor    (CE04EW1C101M)
  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Locate the AF board. This is the front left board of the 4 boards on the bottom of the transceiver.

This work will be done on the component side of the AF board.

  1. Cut the foil shown in the accompanying diagrams.

  2. Add a 120 ohm resistor between the emitter of Q48 and the 15 V line.

  3. Add a 100 F, 16 V capacitor between the 15 V line and ground.

  4. Reassemble the transceiver.

This modification is covered under the 1 year warranty.
Time required to perform the modification is hour.

This modification is read 1564 times.

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20-04-2000
TS-950SD Early protection with TL-922A
Author: Trio-Kenwood Communication, inc.


Service Bulletin no. 962 (17-1-1990)

The TS-950SD RX to TX switching time in semi break-in is approximately 10 mS. At the key down, the transceiver momentarily sees an open circuit because the linear's keying relay has not engaged. As a result, the transceiver's protection circuit turns on, causing the output power to be reduced. The following modification will make the RX to RX switching time, in semi-break-in, approximately 30 mS. This modification does not affect full break-in switching. Increasing the switching time to 30 mS may restrict certain long distance high speed communications.

Required parts:

Digital transistor (QTY 2)                     (DTC124ES)
100 Kohm,  resistor                           (RD14BB2E104J)
2.2 F, 50 V electrolytic capacitor            (CE04EW1H2R2M)
  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Remove the top screw from each side of the front panel assembly.

  4. Loosen the bottom screw on each side of the front panel assembly.

  5. Pull the front panel assembly forward to expose the Digital and Control boards.

  6. Remove the two screws that secure Control board B/3 to the top of the chassis and swing the board out of the way.

  7. Remove the 4 screws from Control board A/3 and rotate the board down. Disconnect the right hand plugs as necessary to expose the foil side of the Control board.

  8. Install the circuit shown in figure 1 on the foil side of Control board A/3.

  9. Assemble the transceiver by reversing steps 1 - 7.

This modification is covered under the 1 year warranty.
Time required to perform the modification is 1 hour or less.

This modification is read 1825 times.

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20-04-2000
TS-950SD RX digital noise
Author: Trio-Kenwood Communication, inc.


Service Bulletin no. 963 (17-1-1990)

Some early TS-950SD transceivers may exhibit a low Signal to Noise ratio on ten and fifteen meters. In addition, rotating the encoder may allow the user to hear a crackling noise in his headphones. The following modification will correct this condition.

Note: This modification has already been performed on model from serial number 101xxxx.

  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Open the subchassis as shown in figure 1 (remove 4 top screws, remove 3 back panel screws, unplug the RX ANT OUT and DRIVE IN connectors).

  4. Remove the cover from the subchassis (12 screws). Figure 1.

  5. Remove the 9 screws from the Filter board.

  6. Desolder the antenna connector wires at the antenna connector. Do not damage the surge absorber.

  7. Rotate the Filter unit to expose the foil side of the board. Disconnect coax cables as necessary to rotate the board and remove the mesh plate as the board is rotated.

  8. Cut the two foils as shown in figure 2.

  9. Assemble the transceiver by reversing steps 1 - 7. Remember to install the mesh plate, resolder the antenna connector, and plug in the two connectors on the back panel.

This modification is covered under the 1 year warranty.
Time required to perform the modification is 1 hour or less.

This modification is read 2086 times.

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20-04-2000
TS-950SD Two second TX power delay with MONI on
Author: Trio-Kenwood Communication, inc.


Service Bulletin no. 964 (22-1-1990)

When the MONI switch is turned on, transmit power may not develop for two seconds after key down. During this time, the ALC meter will pin and the SWR meter will read high. This will more likely develop on 18 MHz and 21 MHz bands. The following modification will correct this condition.

Note: This modification has already been performed on model from serial number 0120441.

Required parts:
2.2 Kohm chip resistor (RK73FB2A222J)

  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Locate the RF unit on the bottom of the transceiver. This is the back left board of the four boards on the bottom of the transceiver.

  4. Remove the RF board shield plate (4 screws).

  5. Remove the 3 remaining screws from the RF board.

  6. Remove the black screw that secures the DRIVE OUT/RX ANT IN jack to the back panel.

  7. Disconnect the right hand coax cables from the RF board and unplug connector #2.

  8. Slide the RF board forward and then rotate it towards the front of the transceiver to expose the foil side of the board.

  9. Locate chip resistor R135 as shown in figure 1.

  10. Replace R135 with a 2.2 Kohm chip resistor.

  11. Assemble the transceiver by reversing steps 1 - 8.

This modification is covered under the 1 year warranty.
Time required to perform the modification is 1 hour or less.

This modification is read 2336 times.

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20-04-2000
TS-950/SD Receiver noise
Author: Trio-Kenwood Communication, inc.


Service Bulletin no. 971 (29-5-1990)

About 1 mV noise is present at the speaker or headphone jack in the receive mode with the AF GAIN control set to minimum. If the transceiver is in the CW mode, a faint tone might also be heard through the headphones (sidetone leakage). The following modification will reduce the level of the noise and the tone.

Required parts:
2SD1257K(S)

  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Locate the RF unit on the bottom of the transceiver. This is the back left board of the four boards on the bottom of the transceiver.

  4. Remove the screws from the AF unit and disconnect the plugs as necessary to turn the board over to expose the foil side of the board.

  5. Replace Q6 with a 2SD1757K(S).

  6. Solder a 22 AWG jumper wire as shown in figure 1.

This modification may be covered under warranty.
Time required to perform the modification is 1 hour or less.

This modification is read 2587 times.

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21-04-2000
TS-950S/SD TX image on 18.115 MHz
Author: Kenwood Communication, inc.


Service Bulletin no. 982 (6-2-1991)

Some TS-950SD owners have reported a transmit image at 18.115 MHz that cause the receiving station to hear distortion on the carrier. If the operating frequency is shift 3 KHz above or below 18.115 MHz, the image disappears. This modification will lower the image level from -30 dB (worse case) to better then - 40 dB by installing a trap on the 455 KHz I.F.

Required parts:

4 pF Trimmer capacitor              C05-0308-05
40 pF Trimmer capacitor             C05-0309-05
2.2 H coil                         L40-2292-14

Modification:

  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Locate the I.F. board on the bottom of the transceiver. This is the back right board of the 4 boards on the bottom of the transceiver. Figure 1.

  4. Locate L36 by connector CN17 on the I.F. board. Figure 2.

  5. Install and solder into place a 4 pF trimmer capacitor across L36. Figure 3.

  6. Install a 2.2 H coil and 40 pF trimmer capacitor in series from the output of L36 to ground. The can of L31 can be used for ground. Figure 3.

Alignment:

  1. Connect the TS-950S/SD to a power meter and 50 ohm load.

  2. If you are working on the TS-950S digital, connect the DSP cables on the bottom cover to the back panel.

  3. In the CW mode, adjust the front panel power control for 150 Watt while the ALC level is just at the starting point on the meter. This will create the highest image level condition.

  4. Using a monitor receiver with narrow filters installed and AGC set to off, tune the receiver to the image frequency.

  5. Alternately adjust the two trimmer capacitors until the image cannot be heard. This procedure may need to be repeated several times.

  6. Push the wire harness around the I.F. board toward the chassis of the transceiver.

  7. Assemble the transceiver.

This modification may be covered under 1 year warranty.
Time required to perform this modification is 1 hour or less.

This modification is read 2836 times.

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21-04-2000
TS-950S/SD 80 meter spurious emission
Author: Kenwood Communication, inc.


Service Bulletin no. 984 (6-2-1991)

Some TS-950S/SD owners have reported a transmit spurious emission between 3.500 MHz and 3.520 MHz. The modification will reduce the spurious emission to - 65 dB.

Required parts:

10 pF capacitor           CC73FCH1H100J     QTY. 1
16 pF capacitor           CC73FCH1H160J     QTY. 1
12 H coil                L40-1201-17       QTY. 1
2.6 X 4 mm screws         N09-0650-05       QTY. 4
  1. Disconnect the power cord and antenna.

  2. Remove the top and bottom covers (18 screws).

  3. Open the subchassis to expose the PLL board (figures 1-3). To open the subchassis remove 4 top screws, remove 3 back screws, and unplug the RX ANT OUT and DRIVE In connectors.

  4. Replace the four VCO shield plate screws with the type listed above. Figure 3.

  5. Close the subchassis and secure it with the screws removed in step 3.

  6. Locate the A.F. board on the bottom of the transceiver. Figure 4.

  7. Remove the board's mounting screws and disconnect the necessary connectors to expose the bottom of the board.

  8. Locate the foil pattern area shown in Figure 5. This area is below IC11.

  9. Cut the foil pattern and add the components shown in Figure 6.

  10. Assemble the transceiver. Remember to plug in the two connectors on the back panel.

This modification is covered under the 1 year warranty.
Time required to perform this modification is 1 hour or less.

This modification is read 3076 times.

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21-04-2000
TS-950S Final bias circuit change
Author: Kenwood Communication, inc.


Service Bulletin no. 990 (28-1-1992)

It is possible to exceed the maximum Vcbo rating of the MRF429 transistors used in the TS-950S/SD if the unit is operated at excessive transmit power levels (greater then the normal factory output power setting). This results in a collector to base short on the MRF429. This causes excessive current to be drawn thru R17 and or R18 of the final bias circuit. This can cause a large amount of smoke from the overloaded resistors. It does not normally cause damage to surrounding components. (You might wish to check Q7, VR2, Q8 and the fuse just as a precaution!)

R17 and R18 are carbon type resistors (27 ohms w). Carbon resistors can emit quite a bit of smoke when overload in this manner and can be the cause of considerable concern by the operator!

In order to case operator concern we recommend replacing R17, and R18 on the final unit (X45-3330-00) with ceramic resistors whenever replacing the final transistors. These special resistors have been designed to open quickly if the current rating is exceeded. This prevents smoking and the odors associated with burning resistors.

Parts required:
27 ohm watt ceramic resistor, (R92-1286-05)

Precautions:

  1. The MRF-429 transistors generally fail one of two ways:

    1. The collector/base junction opens. R17 and R18 are not damage when this occurs.

    2. If the MRF-429's are operated at RF power levels higher then the absolute maximum Vcbo rating the collector/base junction fails. This causes excessive current to flow thru the base circuit.


  2. If the MRF-429's short collector to base with ceramic resistors there will be very little smoke before the resistor opens. The outward appearance of the resistors will not change, so you must make sure to check the resistors with an ohmmeter before installing new finals.

  3. If R17 or R18 should open there will not be an appreciable change in the base circuit current. It is essential, however, that these resistors be in good working order as they ensure stable operation of the final amplifiers.

  4. R17 and R18 must be replaced whenever you replace the final transistors. The ceramic resistors are easy to identify. They are rectangular and white in color.

Replacement Procedure:

  1. Replace the bad MRF-429 transistors.

  2. Remove R17 and R18 from the component side of the Final circuit board.

  3. Solder the ceramic resistor directly to the base and emitter of the final transistors. The stability of the circuit is improved by soldering R17 and R18 directly to the base and emitter of the finals. Do not install them in the old locations!


This modification is read 3345 times.

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21-04-2000
TS-950S Rear panel cooling fan
Author: Kenwood Communication, inc.


Service Bulletin no. 991 (24-1-1992)

The 50 watt power down circuit will begin to operate if the cooling fan on the rear panel fails to operate after 15 minutes of continuous transmission in order to protect the final amplifier circuit. Failure of the fan will prevent the power down circuit from returning transmit power to normal levels since the transformer temperature remains high. This trouble can sometimes be traced to a pinched/burnt wire near resistor R17 of the AVR unit (X43-3070-01).

Causes:

If the red wire attached to the connector CN2 of the AVR unit is pinched between the chassis and ground the insulation might be damage and allow this line to be short to the chassis. This wire supplies 15 Vdc to the fan motor thru resistor R17. Excessive current is drawn thru R17 under this circumstance, approximately 1.5 A rather then the normal .5 A. This can cause the resistor to become red hot and damage the surrounding circuit board, since R17 is a metal oxide film resistor.

Corrective action:

R17 should be replaced with a ceramic resistor if this symptom is encountered. Replacing the metal oxide film resistor with a ceramic resistor will prevent damage to the circuit board should the red lead become shorted.

Parts required:
10 ohm 2 watt ceramic resistor, R92-1285-05


This modification is read 3604 times.

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22-04-2000
TS-950SDX Mode switching
Author: Kenwood Communication, inc.


Service Bulletin no. 998 (3 August 1992)

Occasionally the TS-950SDX will transmit instantaneously when the mode is switched from SSB to CW with the VOX turned on. The frequency of occurrance depends upon the setting of the VOX GAIN and DELAY controls.

Cause:

A small amount of RF feedback is felt on analog switches IC5 and IC6 in the AF unit. This RF causes the timing circuit to actuate briefly when the mode is changed with VOX ON.

Warning: This radio uses micro-sized surface mount component, and/or multi-layer circuit boards. If you are not familiar with the techniques for service of this type of equipment do not attempt this modification yourself. You will invalidate your warranty if you attempt to modify the equipment and damage the radio. If you are at all in doubt about your qualification to perform this modification you should seek qualified assistance.

Required parts:
C191: 4.7 F, 25 V electrolytic capacitor (CW04EW1W4R7M)

Procedure:

  1. Unplug the DSP unit from the rear of the transceiver.

  2. Remove the top and bottom covers (18 screws).

  3. Turn the units so the bottom is up.

  4. The AF unit is located in the front left hand corner.

  5. Remove the 8 screws securing the AF unit to the chassis.

  6. Add C191 in the position indicated in figure 2.

  7. Reverse steps 1 - 5 to reassemble.

This modification may be covered under warranty.
Time required for this modification is 1 hour or less.

This modification is read 3870 times.

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22-04-2000
TS-950SDX No beep in headphones
Author: Kenwood Communication, inc.


Service Bulletin no. 999 (4 August 1992)

Several owners of the TS-950SDX have reported the absence of an audio confirmation tone when using monaural headphones. The tone is present when listening with stereo headphones but only from the right hand speaker element.

Cause:

In this design the SUB AF PA circuit supplies audio when using a monaural headphone, and the MAIN AF PA supplies audio to the right speaker of a stereo headphone. The audio confirmation tone is not applied to both the SUB AP PA and the MAIN AF PA. To simplify circuit design the tone is only routed to the MAIN AF PA. Unfortunately this left monaural users without a confirmation tone and stereo headphone users with a confirmation tone only in the right side of the headphones.

Correct action:
The following modification permits the user to hear the audio confirmation tone from both sides of a stereo headphone and from a monaural headphone.

Warning: This radio uses micro-sized surface mount component, and/or multi-layer circuit boards. If you are not familiar with the techniques for service of this type of equipment do not attempt this modification yourself. You will invalidate your warranty if you attempt to modify the equipment and damage the radio. If you are at all in doubt about your qualification to perform this modification you should seek qualified assistance.

Required parts:
R138: 100 Kohm radial lead watt resistor, (RD14BB2C104J)

Procedure:

  1. Unplug the DSP Unit from the rear of the transceiver.

  2. Remove the top and bottom covers (18 screws).

  3. Remove one screw from each side of the front panel and tilt the front panel forward.

  4. Add R138 from the wiper arm of VR1 to the negative side of C39 as shown in the accompanying diagram.

  5. Reverse steps 1 - 3 to reassemble.

This modification may be covered under warranty.
Time required for this modification is 1 hour or less.

This modification is read 4113 times.

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22-04-2000
TS-950SDX Distorted DRU-2 TX audio
Author: Kenwood Communication, inc.


Service Bulletin no. 1001 (4 November 1992)

We have received several reports of minor distortion of the DRU-2 transmitted audio when used with the TS-950SDX. Recordings made from incoming received sources do not appear to be distorted.

Cause: This characteristic is caused by an impedance mismatch between the DRU-2 output and the input of the microphone amplifier circuit in the TS-950SDX. The following modification will correct/improve this characteristic.

Procedure:
On the Microphone Amplifier Unit (X59-3710-01), which is part of Switch Unit (A) (A41-3240-00) (H/10): (The Microphone Amplifier Unit is a small daughter board located on the switch assembly that has the Microphone Gain/Power Output Control and the Speech Processor IN/OUT controls).

  1. Change chip resistor R257 from 4.7 Kohm to 8.2 Kohm (RK73FB2A822J)

  2. Change chip resistor R262 from 4.7 Kohm to 1.5 Kohm (RK73FB2A152J)
Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 30 minutes or less.

This modification is read 4360 times.

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22-04-2000
TS-950SDX w/K1EA Ver. 8 Program (Revised)
Author: Kenwood Communication, inc.


Service Bulletin no. 1003 (1 June 1993)

We have received several reports of the transmitter unkeying when using the K1EA Contesting program. This symptom only occurs when the TS-950SDX is used with version 8 of the K1EA program. Apparently some of the more advanced control features of this new version of the program cause the radio to think the program has unkeying. A new EPROM is available that corrects this transmitter drop out.

Parts required:
IC-19 Microprocessor, (27C512RJDVF), QTY. 1

Procedure:

  1. Remove the top and bottom covers of the TS-950SDX.

  2. Carefully unplug the two DSP units cables from the rear of the transceiver.

  3. The front panel of the radio is designed to allow it to be tilted forward for ease of service. To tilt the front panel forward remove the screw at the top of the brackets that secure the front panel to the chassis. (Please refer to the Accompanying diagram). There is one screw on each side of the front panel.

  4. Next loosen the remaining screw at the bottom of each bracket.

  5. Gently pull the bottom of the front panel forward until it reaches the end of the slot in the bracket and gently pull the top of the front panel down.

  6. Now look at the circuit board mounted vertically on the main chassis. This is the Digital Unit (X46-3130-11). Near the center of this board you will find the lithium battery for memory backup and a large IC installed in a socket. This is the EPROM.

  7. Carefully remove the IC from the socket. Use an IC pull or very gently pry it out by slipping a small flat tool between the IC and the socket. Do not use excessive pressure as you can damage the circuit board if you pry too hard!

  8. Take the new EPROM and carefully install it in the now vacant socket. Note that the notch on the end of the EPROM should be down.

  9. Reverse steps 1 - 5 to reassemble. Make certain you do not pinch any wires when you return the front panel to its vertical position.

  10. You will need to reset the microprocessor after the radio is reassembled. This is done by pressing and holding the A=B kay while the power is turned on, and then release the key.

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 30 minutes or less.

This modification is read 4607 times.

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22-04-2000
TS-950SDX Speech processor
Author: Kenwood Communication, inc.


Service Bulletin no. 1007 (25 January 1993)

Symptom:
Reports of low COMP meter sensitivity, or noise on the transmitted audio when using the speech processor is normally a result of misadjustment of the PROC IN control. This control is very sensitive and is difficult to adjust properly.

Parts required:
150 ohm chip resistor, (RK73FB2A151J)

Procedure:
Change the value of R258 in the SIG unit (X57-4130-00) from 68 ohm to 150 ohm. This will increase the available adjustment range of the PROC IN control. This will make it much easier to properly adjust the control and thus avoid overdriving the speech processor circuit.

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 30 minutes or less.

This modification is read 4882 times.

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22-04-2000
TS-950SDX 3rd order IMD standardization
Author: Kenwood Communication, inc.


Service Bulletin no. 1009 (25 January 1993)

Symptom:
3rd order IMD figures have been noted that do not meet out standard value of -32 to -35 dB.

Cause:
We have found that this symptom can be caused by either improper blas to the final transistor and/or because of distortion inducted by the 73.05 MHz IF mixer circuit.

Parts required:
R195, R197, R198    150 ohm chip resistor   RK73FB2A151J     QTY. 3
R204                4.7 Kohm chip resistor  RK73FB2A472J     QTY. 1
R19, R20            22 ohm carbon resistor  RC05GF2H220J     QTY. 2

Procedure:

  1. On the Final unit (X54-3450-00) change R19 and R20 from 10 ohm to 22 ohm. Figure 1.

  2. On the IF unit (X48-3100-00): Figure 2.
    1. Change R195 from 56 ohm to 150 ohm.
    2. Change R197 from 220 ohm to 150 ohm.
    3. Change R198 from 220 ohm to 150 ohm.
    4. Change R204 from 10 Kohm to 4.7 Kohm.


    No additional adjustment or modification will be required.

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 1 hour or less.

This modification is read 5130 times.

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22-04-2000
TS-950SDX Key click w/bug type keyer
Author: Kenwood Communication, inc.


Service Bulletin no. 1012 (3 May 1993)

Symptom:
A "bug" type keyer used at high keying speeds might cause a key click or chattering noise on the transmitted signal. When the internal electronic keyer is used no such chattering noise is encountered.

Cause: The internal chatter absorption filter circuit incorrectly tries to remove noise from the external keyer.

Procedure:

  1. Press the MENU key one time.

  2. Select MENU no. 12 by tuning the M.CH knob.

  3. Press the UP key until OFF appears in the display.

  4. Press the MENU key one time to exit the MANU mode.

  5. Turn off the POWER SW.

  6. Turn ON the POWER SW while depressing the MENU key.

  7. Select MENU 69 by tuning the M.CH knob.

  8. Press the DOWN key until OFF appears in the display.

  9. Press the MENU key one time to exit the MENU mode.

This operation turns off the internal chatter absorption filter circuit.

Time required for this modification is 15 minutes or less.

This modification is read 5369 times.

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23-04-2000
TS-950 Hum with monitor ON
Author: Kenwood Communication, inc.


Service Bulletin no. 1016 (12 May 1993)

Symptom:
On early versions of the TS-950 series (below serial number 106xxx) a hum might be heard when the MONI function is active and headphones are connected to the PHONE jack. No hum is experienced when the MONI circuit is OFF

Cause:
This noise can only be found in the monitor circuit itself and not on the transmitted signal. We have found that the VCO shield cover for the PLL unit might be contacting the shield plate for the filter unit. This physical contact can allow a slight amount of vibration to be felt in the sub-receiver section. This vibration, combined with too much gain in the sub-receiver section contributes to the hum.

Parts required:

Qty    Description                          Kenwood Part No.    Circuit description
 4     Low profile PLL Unit cover screws    N35-2640-05         NA

Procedure:

  1. On the IF unit (X48-3060-00) adjust VR-1 to the point the audio output just decreases when the MONI circuit is activated.

  2. Replace the screws on the VCO unit shield case with the new low profile screws.

Time required for this modification is 15 minutes or less.

This modification is read 5603 times.

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23-04-2000
TS-950 Noise with Sub-Band noise blanker ON
Author: Kenwood Communication, inc.


Service Bulletin no. 1017 (13 May 1993)

Symptom:
Noise is generated when NB1 is switched on for the sub-receiver.

Cause:
Switching noise from the noise-blanker gate enters the AF amplifier via the +15 V line causing the noise.

Parts required:

Qty   Description                          Kenwood Part No.     Circuit description
 1    100 F, 16 V electrolytic capacitor  CE04KW1C101M         NA
 1    120 ohm resistor                     RD14BB2B121J         NA

Procedure:

  1. Cut the pattern of the 15 V line on the IF unit (X48-3060-00) component side, near Q34's emitter and add the 120 ohm resistor as shown in the accompanying diagram.

  2. Add the electrolytic capacitor as shown in the diagram. Quickly solder the negative lead to the metal shield of L28.

Time required for this modification is 15 minutes or less.

This modification is read 5832 times.

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23-04-2000
TS-950 14.200 MHz transmit spur
Author: Kenwood Communication, inc.


Service Bulletin no. 1018 (14 May 1993)

Symptom:
A close-in transmit spur might be present on early model TS-950(S) (serial number 1010xx and below) transceivers when operating at a dial frequency of approximately 14.200 MHz. This spur is seen approximately -40 to -50 dB down from the fundamental.

Cause:
The output from the mixer (IC12) which generates the final PLL loop comparison frequency for the AF unit contains harmonic radiation at approximately 36 to 68 MHz.

Parts required:

Qty   Description                          Kenwood Part No.  Circuit description
 1    Broad band transformer               L19-0346-05       L15
 1    .001 F 50 V capacitor               CK45B1H103K       C127

Procedure:

  1. Solder the primary of the transformer to pins 3 and 13 of IC12. You will have to bend the terminals slightly.

  2. Solder the secondary of the transformer to pin 1 and 14 of IC12.

  3. Remove chip capacitor C127 from the foil side of the board.

  4. Connect pin 14 of IC12 to the ground pattern.

  5. Add the new C127 from pin 1 of IC12 to L10 as shown in the accompanying illustration.

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 30 minutes or less.

This modification is read 6066 times.

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23-04-2000
TS-950 Low power output after temp. protection
Author: Kenwood Communication, inc.


Service Bulletin no. 1019 (14 May 1993)

Symptom:
After transmitting for approximately 2 hours at 50% duty with 150 watts output the temperature protection circuit activates reducing the output power to about 50 watts. Normally, full output power will be restored after the fans have had a chance to cool things down. Occasionally the power output will not return to normal, even after extended receive operations.

Cause:
The temperature sensor is attached to the main transformer and is set to activate at 80C. This setting was selected to reduce power before the internal fuse on the transformer opens.

Correct action:
After through testing, we have found that the temperature sensor should be set to 90C to allow proper return to full power transmit. This setting will also allow the radio to be used at higher ambient room temperatures without worrying about the power output dropping in the middle of a QSO.

Parts required:

Qty   Description                          Kenwood Part No.  Circuit description
 1    90C Thermal switch                  S59-1416-05       S1

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 30 minutes or less.

This modification is read 6307 times.

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23-04-2000
TS-950 Infinite SWR at beginning of transmission
Author: Kenwood Communication, inc.


Service Bulletin no. 1020 (14 May 1993)

Symptom:
During "Full Break-in" operation the SWR meter shows infinite SWR at the beginning of transmission. This results in a reduction of the transmitter power, followed by a gradual increase to normal full power. This symptom does not occur with the antenna tuner set to "THRU".

Cause:
Normally the RCB line should be 0 Vdc at the beginning of transmit operations. We have found that this does not always occur. The length of time required for transmit power to return to normally is directly related to the time constant of capacitor C128 on the RXB line.

Correct action:
Removing this capacitor corrects the above symptom, but might affect the receiver sensitivity at a dial frequency of 100 KHz. This action is only recommended if the symptom is actually present. Do not modify the unit if the symptom is absent.
Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.
Time required for this modification is 30 minutes or less.

This modification is read 6557 times.

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23-04-2000
TS-950 Smoke from antenna tuner unit
Author: Kenwood Communication, inc.


Service Bulletin no. 1021 (14 May 1993)

Symptom:
When tuning into an antenna with high SWR the SWR meter reading becomes unstable and a small amount of smoke is seen coming from the antenna tuner.

Cause:
One of the 3 x 4 self tapping screws that is used to secure the AT unit hinge can occasionally damage the insulation on the brown lead wire. When the tuner is then load into a high SWR the high reflected voltage causes the lead to head up, which further damages the insulation. Eventually the insulation breaks down completely and the wire shorts to the screw causing the lead to overheat and smoke to emanate from the area.

Correct action:
Cut a 12 cm long piece of the fiberglass insulating sleeve and install it over the brown lead wire to prevent shorting.

Parts required:

Qty   Description                          Kenwood Part No.  Circuit description
12 cm Fiberglass insulating sleeve         212-3502-05       W101
(Note: The insulating sleeve must be ordered in increments of 1 meter or greater).

Time required for this modification is 30 minutes or less.

This modification is read 6821 times.

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23-04-2000
TS-950S/SDX Transmit spur
Author: Kenwood Communication, inc.


Service Bulletin no. 1024 (27 May 1993)

Symptom:
A transmitter spur might be present at a dial frequency of xx.xx1 MHz. This spur (fo +/- 1 KHz) is quite small (-55 dB relative to fo) but might become noticeable when the transceiver is used with a linear amplifier.

Cause:
The transmitted signal enters pin 5 of IC11 which is in the last PLL loop in the AF unit due to RF feedback. This pin is the input for the 10 MHz Ref. Osc. signal from the CAR unit. IC11 is the source of the spurious signal since both the band and 10 MHz frequencies are divided by the 500 KHz comparison frequency supplies by IC11.

Correct action: To reduce this RF feedback increase the Ref. Osc. level from .2 V to .7 V ms by adding the accompanying circuit to the input of IC11.

Parts required:

Qty   Description                          Kenwood Part No.  Circuit description
 1    12 H Ferri-inductor                 L40-1201-17       NA
 1    10 pF Chip capacitor                 CC73FCH1H100J     NA
 1    16 pF Chip capacitor                 CC73FCH1H160J     NA

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 30 minutes or less.

This modification is read 7085 times.

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23-04-2000
TS-950SDX "click noise" with NOTCH ON
Author: Kenwood Communication, inc.


Service Bulletin no. 1026 (7 June 1993)

Symptom:
A click noise might be generated when receiving a strong signal (S-0 or above) when the NOTCH is ON and the Notch Control is turned away from the notch point.

Corrective action:
Lengthening the AGC release time of the IF Amp just before the NOTCH circuits will correct this symptom. The enclosed modification has been designed to change the time constant only when the NOTCH circuit is activated. Do not install this modification on sets that do not exhibit this symptom as the AGC FAST time constant affected by this change.

  1. Cut the printed circuit foil pattern between the test point (TP) and gate 2 of Q2 as shown.

  2. Install the 47 Kohm chip resistor from TP tp gate 2 of Q2.

  3. Add a 0.047 F ceramic capacitor as shown in the accompanying illustration.

  4. Add the DTC124ES transistor as show.

    Note: The .047 F capacitor and the digital transistor must be connected together as shown and installed so that they do not touch the sorrounding board patterns.

  5. Install a jumper wire from the base of the digital transistor to pin number 6 of CN14.

Parts required:

Qty   Description                          Kenwood Part No.  Circuit description
 1    0.047 F capacitor                   CK45B1H473Z       NA
 1    Digital transistor                   DTC124ES          NA
 1    47 Kohm chip resistor                RK73FB2A473J      NA

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 30 minutes or less.

This modification is read 7325 times.

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23-04-2000
TS-950SDX YG-455S-1 Installation note
Author: Kenwood Communication, inc.


Service Bulletin no. 1043 (28 March 1994)

Symptom:
When the YG-455S-1 is installed, the LSB audio is slightly off pitch. This characteristic is corrected using the "Service Adjustment" menu. Early models of this transceiver did not make this adjustment available the individual operator unless they had access to a service manual.

Countermeasures:
A menu option has been added to Menu 07 on late versions of the transceiver which allows the individual operator to "correct" this audio shift. This has been accomplished by changing the program of the ROM chip IC-19 on the Digital unit X46-3130 1/2, and by updating the operators manuals. Installing the new ROM on early versions of this transceiver will allow the operator the same convenience as provided on later serial numbered sets.

Parts required:

Qty   Description           Old part No.      New Part No    Circuit Description
 1    ROM                   27C512BJDUF       27C512BJDUG    IC-19
                                or
 1    ROM                   27C512RJDVF       27C512BJDUG    IC-19
 1    Instruction manual    B62-0229-30       B62-0229-40

Time required for this modification is 30 minutes or less.

This modification is read 7580 times.

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23-04-2000
TS-950SDX No VFO B after "split"
Author: Kenwood Communication, inc.


Service Bulletin no. 1045 (28 March 1994)

Symptom:
Using the following key sequence will result in a failure to receive on VFO B.

  1. Select different frequencies for VFO A and B. (Example: 14.019 for VFO A and 14.018 for VFO B. Mode SSB, 2.7 KHz FILTER for 455 KHz and 8.83 MHz).

  2. Select VFO A to RX and VFO B to TX. The press the TF-W key.

  3. Press the ENT key and select a frequency in the 7 MHz band. (For example: 7.018 MHz for VFO A and 7.019 for VFO B).

  4. Press the ENT key and reselect the 14 MHz band.

  5. Change VFO B from TX to RX. The FILTER display for 8.83 dissapears and reception is disabled on VFO B.'

Countermeasure:
Press the 8.83 MHz FILTER select key one time, or replace the ROM chip.

Parts required:

Qty   Description              Old part No.   New Part No    Circuit Description
 1    ROM                      27C512BJDUG    27C512BJDUJ    IC-19
                                   or
 1    ROM                      27C512BJDVG    27C512RJDVJ    IC-19

Time required for this modification is 30 minutes or less.

This modification is read 7820 times.

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23-04-2000
TS-950SDX Carrier point adjustment
Author: Kenwood Communication, inc.


Service Bulletin no. 1047 (28 March 1994)

Symptom:
The background audio tone is different between the LSB and the USB mode, when no signal is present, i.e. the carrier point is incorrect. Occasionally, this tone is still different after adjustment per the service manual, specifically Item 9 on page 196.

Countermeasure:
Change the adjustment procedure for Item 9 as follows:

Test Equipment

  • Two RF signal generators with good frequency accuracy.
  • A two-signal combiner.
  • An oscilloscope.

Preparation:

  1. Adjust the two signal generators for equal output levels.

  2. Connect the test equipment as shown in the accompanying diagram.

  3. Set the frequency of SSG1 to 1.850.2 MHz.

  4. Set the frequency of SSG2 to 1.852.8 MHz.

  5. Fine tune the output levels of the two SSG's for a good two-tone output on the oscilloscope (Figure 3).

Adjustment Procedure:

  1. Connect the transceiver and the test equipment as shown in figure 2.

  2. Select the adjustment Mode on the transceiver by pressing and holding the 3 and 9 keys on the keypad while the POWER is turned on.

  3.  
    • Set the output of the two signal generators for a - 73 dBm level.
    • Set the SSB SLOPE TUNE control to the NORMAL position.
    • Set the AGC to AUTO
    • Select MENU 00 using the M.CH/VFO knob.
    • Select USB mode.
    • Press the 8.83 MHz filter key until there is no indicator illuminated (no filter).
    • Press the 455 KHz filter key until 2.7 K appears in the display.
    • Set the frequency to the transceiver to 1.850.0 MHz.
    • Adjust the TX VFO/SUB encoder control until the waveforms displayed on the oscilloscope cross as shown in figure 3.


  4.  
    • Switch to LSBV.
    • Press the 8.83 MHz filer key until 6 KHz appears in the display.
    • Leave the 455 KHz filter set at 2.7 KHz.
    • Select a dial frequency of 1.853.0 MHz.
    • Adjust the TX VFO/SUB encoder control until the waveforms displayed on the oscilloscope cross as shown in figure 3.


  5.  
    • Select MENU 01.
    • Switch to USB.
    • Press the 8.83 MHz filter key until 2.7 KHz appears in the display.
    • Leave the 455 KHz filter set at 2.7 KHz.
    • Select a dial frequency of 1.850.0 MHz.
    • Adjust the TX VFO/SUB encoder control until the waveforms displayed on the oscilloscope cross as shown in figure 3.


  6.  
    • Select LSB.
    • Select a dial frequency of 1.853.0 MHz.
    • Both filters should remain at 2.7 KHz.
    • Adjust the TX VFO/SUB encoder control until the waveforms displayed on the oscilloscope cross as shown in figure 3.

    Note: This completes the adjustment.

  7. To return to the normal display and save these setting you should press the CLR key one time.

Time required for this modification is 60 minutes or less.

This modification is read 8085 times.

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23-04-2000
TS-950SDX Sub band residual noise
Author: Kenwood Communication, inc.


Service Bulletin no. 1050 (28 March 1994)

Symptom:
The level of residual noise (AF VOL at Min) on the SUB band is slightly higher than that of the MAIN band. This is especially true at audio frequencies of around 50 Hz, as viewed on a spectrum analyzer. As a result the SUB receiver is more susceptable to motor noise, such as might be generated by fans, refrigerators, etc.

Countermeasure: Replacing the Control unit electrolytic capacitors (C33, C34, and C39) with Tantalum capacitors, and adding the bypass capacitor to the Switch unit reduces or eliminates this symptom.

Parts required:

Qty   Description                          Kenwood Part No.  Circuit Description
 1    0.1 F 35 V Tantalum capacitor       C92-0001-05       C33
 1    1.0 F 16 V Tantalum capacitor       C92-0004-05       C34
 1    10 F 16 V Tantalum capacitor        C92-0505-05       C39
 1    .01  disc capacitor                 CK45B1H103Z       NA

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).

Time required for this modification is 60 minutes or less.

This modification is read 8326 times.

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23-04-2000
TS-950SD 18.115 MHz spur
Author: Kenwood Communication, inc.


Service Bulletin no. 1052 (28 March 1994)

Symptom:
Transmitting on 18.1145 MHz causes a spur to appear at 18.1150 MHz with the antenna tuner on.

Corrective Action: Add the low pass filter shown in the accompanying diagram to the input circuit of mixer Q41 on the IF unit (X48-3060-00). This filter will increase the attenuation by approximately 20 dB.

Parts required:

Qty   Description                          New Part No.      Circuit Description
 1    220 H inductor                      L40-2211-14       NA
 1    220 pF chip capacitor                CC73FSL1H221J     NA

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).

Time required for this modification is 60 minutes or less.

This modification is read 8568 times.

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23-04-2000
TS-950SDX Change of Gate resistor type
Author: Kenwood Communication, inc.


Service Bulletin no. 1053 (28 March 1994)

Symptom:
If the final amplifier is operated at excessive transmit levels (over 150 watts output) the final FET's may fail and short from Source to Gate. If this occurs, the bias resistors used in this circuit may be damaged and cause a large amount of smoke to be emitted from the final compartment.

Corrective Action:
Change the carbon type resistor used for R17 and R18 to the fuse type resistors specified below. This will prevent an unpleasant odor and smoke from the final compartment.

Parts required:

Qty   Description                          New Part No.      Circuit Description
 2    100 ohm  watt fuse resistors        R92-1310-05       R17, R18
Procedure:
Remove the old resistors from their locations an the circuit board and install the new resistors directly between the Gate and Source of the final transistors. (see the illustration below).

Caution: This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).

Time required for this modification is 60 minutes or less.

This modification is read 8815 times.

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20-01-2001
Countermeassure against cold solder joint at the resistor block; CP1-CP4 in the PLL unit.

Phenomenon:
  1. Sub-band reception is deteriorate or receiving audio is intermittent distortion.

  2. Transimission monitorring audio is distorted.
    If you find the malfunction at stated above, take the following procedure.

Cause:
Cold solder joint od resistor block; CP1-CP4 in the PLL unit (X50-3170-00). In the manufactoring process, the temperature in the reflow soldering furnace was lower than specified and the connection was insufficient.

  1. Temporary: Add more solder to the resistor block; CP1-Cp4 (at all pins) in meassure the PLL unit (X50-3170-00).

  2. Permanent: review the whole temperature control system of the reflow furnace to manufacture the Printed Circuit Board at more adequate temperature.

PC Board (Component side view).
PC Board (Component side view).

This modification is read 9062 times.

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