MA 6S SERVICE INFORMATION
CAUTION: THESE SERVICING INSTRUCTIONS ARE
FOR USE BY QUALIFIED SERVICE PERSONNEL
ONLY. TO AVOID ELECTRIC SHOCK DO NOT OPEN
THE CHASSIS UNLESS YOU ARE QUALIFIED TO DO
SO. REFER ALL SERVICING TO QUALIFIED RANE
WARRANTY SERVICE STATIONS.
Disassembly Procedure
CAUTION: WAIT ABOUT 15 MINUTES AFTER THE
AMPLIFIER HAS BEEN POWERED DOWN BEFORE
BEGINNING DISASSEMBLY, TO ALLOW THE
POWER SUPPLY CAPACITORS TO DISCHARGE.
1. Remove the bottom cover: 4 each #6 x 3/8" phillips
screws on the bottom of the side rails and 12 each #6 x 1/4"
phillips screws on the bottom cover.
2. 80 Hz High Pass Internal Jumpers: To access the jumper
on each amplifier card, locate J2 (LOW FILTER). The
MA 6S is shipped with these jumpers in the OUT position
(filters defeated). Moving this jumper to the IN position
activates the filter.
In the event that 80 Hz is not a high enough cutoff
frequency, a table of resistor values is provided below that
replace R9, R10, and R11 on each amplifier card.
d. To remove a module, first de-solder the wires running to
the adjacent card. Be sure to note the location of all wires
for later reassembly (A to A, B to B). Then remove 7 ea.
of the #4-40 machine screws holding the output, driver
and bias transistors to the heatsink. Now pull firmly
straight up to disengage the module from the connector–
use a rocking motion to ease removal, as the connector is
very tight. NOTE: Be sure that all of the transistor sil
pads (insulators) stay on the heatsink–some of these may
stick on the transistor and be inadvertently lost or
thrown away with the defective component. New pads
should be used whenever possible.
4. Module replacement: Factory supplied amplifier modules
are pre-tuned and ready for installation. If you have made
repairs on a module, be sure that ALL diodes are measured
and replaced as necessary prior to installation.
a. Be sure that all heatsink sil pads (insulators) are in place.
b. Be sure the nylon shoulder washers are in place on
transistors Q2, Q4 and Q8 (TO-220 cases). Install the
#4-40 screws in these and snug up only: Do not overtighten these driver screws as this may damage the thin
shoulder washers and cause a short.
c. Install the remaining 4 ea. #4-40 screws on the output and
tighten these firmly to ensure proper heat transfer to the
heatsink.
Frequency
R9
R10
R11
80 Hz
14.3k
97.6k
5.62k
100 Hz
11.5k
78.7k
4.53k
125 Hz
9.09k
61.9k
3.57k
160 Hz
7.15k
48.7k
2.8k
e. Slide the heatsink assembly forward so that all LEDs are
properly aligned in the front panel holes. Install and
tighten the 8 heatsink mounting screws.
200 Hz
5.76k
39.2k
2.26k
f. Replace the 7 screws on the front panel.
250 Hz
4.53k
31.6k
1.78k
315 Hz
3.65k
24.9k
1.43k
3. To remove a module (PCB card):
a. Remove the input/output plate on the rear panel by
removing 7 phillips screws and 12 ea. #8 tapping screws
from the Euroblocks.
b. Remove the 7 phillips screws on the front panel just
below the Level controls.
c. Remove the 8 ea. #6/32x¾" machine screws from the left
and right edges of the heatsink mounting flange. Now
the entire heatsink/module assembly is free to slide to
the rear–this will provide the clearance necessary to
remove any of the six amp modules.
d. Resolder the black & white wires. Be careful to connect
them properly.
g. Replace the input/output plate and bottom cover (don’t
forget the 4 screws holding the bottom to the side rails).
5. Power supply repairs.
a. Power supply PCB: Do not attempt removal of this card.
Instead, remove amplifier modules #1 and #2 as necessary to allow clear access to the foil side of the power
supply PCB, then replace any defective components by
de-soldering.
b. Transformer removal: The transformer is held in place by
one ¼" bolt securing the transformer to the flat mounting
plate. Pull all transformer spade plugs from the power
PCB and lift the transformer out of the chassis. To
replace the transformer, reverse the above procedure.
Reconnect all transformer spade plugs as shown on the
power board designator diagram on the next page.
MA 6S AMP CARD
MA 6S POWER SUPPLY
MA 6S BUS CONNECTOR