From: wa2ise
Subject: TS940s erratic display or control fix

Date: 8 Dec 91 19:23:45 GMT

Sender: news




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 Msg# TSF  Size #Rd  Date  Time From   MsgID        To

 8594 BF   3105   0 01-Dec 2326 KD2EJ  27873_WB2QJA INFO
 Sb:TS-940 ERATIC DISPLAY INFO.



SB-951

TS-940S ERRATIC D  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:





1Disconnect the power cord and antenna coax.



2Remove the top and bottom covers from the transceiver.



3Remove the 2 flat head screws from each side of the

front panel chassis.



4Loosen the round head screw on each side of the front

panel chassis.



5Carefully rotate the front panel forward. It will be

necessary to unplug the VS-1 cable from the transceiver.



6Remove the 4 screws from the speaker mount.



7Carefully 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.



8Remove the 8 screws from the Digital A unit shield

plate.



9Lift the plate and rotate it to the left side of the

transceiver.



10While avoiding contact with the pins, remove the ROM

(IC2) and set it aside on anti-static foam.



11Remove the 6 screws that mount the Digital A board.

Rotate the board toward the front panel to expose the

bottom side of the board.



12Carefully 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.



13Install the ROM in the board and solder it in place.



14Assemble 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. ©

 011189TKC

==================================================================

Note:you might find it easier to break apart the plastic of the

socket and remove the pins one by one. And/Or use a better grade of

socket.

Try just removing and reinserting the Rom in its socket to see

if this fixes the problem before you go to all this trouble. This

might clean a dirty socket contact.    Anyway....

I haven't tried or verified this, proceed at your own risk. WA2ISE



Kenwood TS-940S

---------------

I'm afraid I've deleted the original request from a 'VK' from a month

or so ago regarding general coverage Tx on a Kenwood TS940S.  Out of

interest I've done some invesigation and an experiment and it seems to

produce the required result.



Here goes..

Remove the bottom cover Locate the 'Control' PCB. (The rearmost

board).  Find PL17/SK17 - a 5 pin 'harmonica' type - about midway along

the forward edge of the board.  Remove the connector and release the

individual socket that connects to pin 5 (nearest to the front edge of

the board). This can be done by depressing the barb on the socket

through the hole in the 'harmonica' moulding and pulling gently on the

wire.  Once removed replace the connector and insulate the, now

floating, removed wire and socket.  Replace the bottom cover.  (To

remove the mod - just replace the socket into the moulding).  In the

experiment the rig produced full output power ( >100W into 50ohm dummy

load) over the range 1.5 to 29.999 Mhz without use of the tuner. When

the tuner was enabled it managed to 'tune' the rig into the same 50ohm

load over the full range. How it would perform into any other load is

unknown.  Not suprisingly, I haven't managed to get it to Tx down to

73kHz in fact below 1.5Mhz the Tx is disabled.  I hope this reaches the

originator of the request.  Regards, Roger.  



G8IUC


Msg created 21:19 (local) on 20 Aug 96 using WinPack V5.4