2 RMX0002
3. With long-nose pliers, hold one of the lead remnants. Melt the solder with the iron, then pull the lead out of the circuit
board. Use braid or desoldering equipment to remove excess solder from the hole. Repeat for the three other lead remnants.
4. Twist the anode lead of a new 4.7-volt zener diode with one lead of a 180Ω
resistor to form a “V” and solder them together; trim the excess. Then trim
the cathode lead and the other resistor lead so they fit into place on the
board without short-circuiting anything. Repeat for the other three diodes
and resistors. See Figure 3.
5. Insert the zener/resistor combinations. Pay attention to their correct orientation:
the cathode (the banded end) of D107 should point toward the front of the amp,
while the cathode on D110 should point to the back. Solder them in place (Figure 3).
6. Repeat for diodes D207 and D210. D207’s cathode should point away from
the heat sink, while D210’s should point toward it.
7. Continue with bias and current limiting adjustments.
RMX 850 and RMX 1450
1. At the front panel, pull the two gain control knobs straight off.
2. Underneath the amplifier, remove the four screws that secure the heat sinks
to the chassis.
3. Remove the eleven screws that fasten the two channel modules to the
chassis (six screws on channel 1's module, and five on channel 2's).
4. Detach the input ribbon cable from channel 2's module.
5. At the front of the channel module boards and in front of the
heat sink tunnel, disconnect one end of the ribbon cable that
connects between the two channel modules.
6. On the rear panel, loosen the four screws on the fan enough to
allow you to remove the fan shroud (Figure 2). Lift the shroud
straight up to remove.
7. Slide the two channel module boards straight back to clear the
LEDs and gain control shafts of their chassis front panel
openings. Lift the boards up to gain access to the undersides.
8. Locate diodes 107 and 110 (Figure 4). Unsolder and remove them
from the board.
Fan shroud
Figure 1. Components D107, D110, R131, R139, R140, R146, D207, D210, R231, R239, R240, and
R246 in the RMX 2450. Note that in this model, the positions of channel 1 and 2’s channel
modules are the reverse of where they are in the RMX 850 and RMX 1450.
R239
R240
R231
D207
D210
R246
(behind
ribbon
cable)
D107
D110
R146
(under
ribbon
cable)
R139
R140
R131
Figure 2. Removing the fan shroud makes
it easier to remove the channel module
boards on the RMX 850 and RMX 1450
Figure 3. Soldering the zener diode and resistor to
the circuit board. On the RMX 2450, the components
can be soldered on the top side of the board as
shown; on the RMX 850 and 1450, they are soldered
on the underside.
Solder
Soldering
iron
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