Unplug AC Power and Speaker plugs from chassis.
Remove the four screws securing chassis to cabinet and remove chassis. Do not remove any
printed circuit boards from the chassis! Be careful of the tubes
– you may wish to remove them.
Orient bottom of chassis as shown in Figure 1a.
Unplug the
ribbon cable
from P5 and the DSP board and set aside (it is no longer needed).
Figure 1a
– Orientation of Chassis
The
“Breakaway” board with all controls is hidden by chassis lip above but shown in here in
Figure 1b.
Figure 1b
– Orientation of Breakaway Board
On the Breakaway board, there are 3 thru-hole points (A, B, C, in photo below) of contact for
R84
(GAIN)
and
R85 (VOLUME 1)
. The blue wires and jumpers come later so ignore them for now.
After making the following cuts in the traces, the trace should be checked with an ohm-meter to
verify it is indeed “open”; if the meter indicates zero ohms, the trace hasn’t been completely cut.
Figure 2
– R85
FOR R85 ONLY (the left-most control next to
INPUT jack when oriented as in Figure 1): cut
PCB trace where circled, between R85
terminal A and the via (thru-hole in PCB) as
shown in Figure 2.