I have done a modification on my YAESU FT-757GX to solve a trouble in the
display. The segment VFO A VFO B and MR were always weak ligthed also when
not selected. The cause is the bad signal present on the pin 6 (R3) of
display processor TMS 2370.
This signal is not so negative to ligth off the segments not selected. The
modification is very easy and consist to connect a 1,2Kohm resistor between
pin 11 and 7 of the display (-30V. and G7). In this mode the signal is low
enough to ligthed off the segments. The best way to connect this resistor is
on the display terminals on the component side of the display board.

73 and have fun.

                     IK1EBG  Riccardo  QTH Sanremo n/w Italy.



FT-757 Filter modification

During RTTY/AMTOR operation it is usefull to have an narrow filter to reduce
QRM from other stations. It is possible to use the narrow CW filter of the
FT-757 for SSB, because of the shift/width system.

1.) Cut the connection between cathode of diode D 102 and a 150 ohm resistor
    on RF UNIT. This resistor is not shown in service manual, but it exists
    on all rigs later LOT 4.
2.) Take a new diode (1N4148 or similar) and solder the cathode to the open
    end of the 150 ohm resistor. Connect the anode to middle contact of a
    doubble pole toggle switch.
3.) Connect the OFF contact to pin 5 of J10 (SSB 8V) and ON contact to pin 8
    of J10 (TX 8V).
4.) Get another diode of the same type and solder it's cathode to pin 1 of
    J09 and the anode to ON contact of the second pole of toggle switch.
5.) Connect the switching (or middle) contact of second pole to pin 7  of J10
    (RX 8V). The OFF contact will be let free.

For the SPDT switch I am using the MOX switch on the front panel.
It is a 2 pole toggle switch and you habe to cut the PCB between the
contacts.
Further you have to remove all wirers to the MOX switch.
That's all.

Attention: There are some errors in the Service Manual. F.e the filter
connection is shown wrong. If you want to have a corrected circuit diagramm
or complete modification diagramm please write to:
Roland Robic OE6RCD
Augasse 15, A-8430 Leibnitz, Austria.
Please enclose an A4 SASE ( 2 IRC or 4 IRC outside Europe Airmail) 
  
This Modification should work also on FT-757GX/II.