Yaesu FT-901DM Maintenance Service Manual page 71

SERVICING
POWER SUPPLY PROTECTION MODIFICATION
Beginning with production lot No. 6, the following
modification was adopted, in order to provide pro-
tection for the filter capacitors, screen grid supply,
and mode switch. These might be subject to
damage in the event of flashover between the
electrodes inside the final amplifier tubes.
Modification Procedure:
(1) Fix a three-terminal soldering post to the
chassis, using a self-tapping screw, as illus-
trated in Fig. 1 .
(2) Solder a 10D10 diode to the post as shown,
being careful to observe proper diode polarity.
(3) Remove the yellow wire previously connected
to the circuit board, as shown in Fig. 1.
Solder it to the anode of the diode, as shown
in the drawing.
(4) Connect a lead from the cathode end of the
diode to the circuit board, in the position pre-
viously occupied by the yellow wire.
(5) The modified schematic is shown below.
PB-1715A
PB-1715A
Fi
R1705 0.01
100
300 V
igure 2
3-16