Modifications for the Kenwood TS-940 Modifications for the Kenwood TS-940 TS-940S LCD Clock Display Erratic Operation We have received a few reports concerning erratic operation of teh LCD clock display when the Main dial is rotated, or the VBT or SLOPE TUNE controls are operated. This appears as if you had pressed the SET, SCROLL, or GRAPH switches. This erratic operation may be caused by improper timing of the input pulses applied to the auxiliary display microprocessor, IC1.

• This symptom is easily corrected by replacing IC2 MBM2764-30T1 with MBM2764-30T2, on Digital Unit A. Early models of the improved IC will carry the old nomenclature but will be distinguished by a white dot on the top of the chip. • After the IC has been changed reset the main microprocessor by pressing and holding the A=B key, and then turning the power switch OFF and then back ON. Then release the A=B key. • After this change is made the sub-display will not immediately track the main display. A slight delay has been introduced int he new IC to prevent any timing errors. It may take approximately 0.5 seconds for the LCD to track the main display.

The 940 was one of the best radios of the mid-80's. If you want to know its age, take a look at the serial number. The first digit is the year of manufacture, i.e. 5xxxxx was made in '85. Skip this section to the articles if you don’t care about my philosophy and human interest blathering. One of the best ways for the technically. TS940S serial numbers. Discussion in 'General Technical Questions and Answers' started by MM0XXW, Mar 22, 2008.

• Please return the old IC2 to the Service Department along with the WSR for Credit. Perform this modification only if the symptom occurs, as a repair. This change is not required otherwise. Time required for this modification is 1 hour or less.

TS-940S SSB Talk Power Improvement TS-940S's in the serial number range of 601XXXX through 708XXXX may be limited n SSB peak power as compared to full CW output. The level may be increased by changing the value of capacitors C182 and C183 in the ALC circuit on the Control board. The recommended replacement value for each capacitor is 0.0022 uF, 50v (CK45B1H222K).

Procedure: • Disconnect the power cord and antenna from the transceiver. • Remove the top and bottom covers (16 screws). • Locate the Control board on the bottom of the transceiver. • Locate transistor Q37 on the board (toward the back right hand side.) The two capacitors are mounted on the foil side of the board underneath Q37.

• To access the bottom of the board remove the 8 screws that mount the board and heat sink to the chassis (See figure 1.) • Carefully lift the board/heat sink fomr the right hand side and pivot it toward the front of the transceiver. • Replace C182 and C183 with 0.0022 uf, 50v capacitors.

• Lower the board back into its original position (don't pinch any wires!) and re-install the 8 mounting screws. • Put the covers back on the TS-940S and secure them with the 16 case screws.

• Connect the antenna and power cord then test the transceiver for normal operation. This is an optional change and may not be performed under warranty. Time required for this change is 1 hour or less.

TS-940S erratic display 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. Software Id Card Gratis. 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: • Disconnect the power cord and antenna coax. • Remove the top and bottom covers from the transceiver.

• Remove the 2 flat head screws from each side of the front panel chassis. • Loosen the round head screw on each side of the front panel chassis. • Carefully rotate the front panel forward.