Shure SCM810 User Manual page 14

INTERNAL MODIFICATIONS
WARNING
All modifications must be performed by qualified
service technicians.
This section describes SCM810 modifications that can be
made using solder "jumpers" on the printed circuit board; the
pads where jumpers may be used are placed close together so
that a single solder drop functions as a jumper. Note too that:
(1) The only printed circuit board legends used for these modi-
fications are jumpers (X's) and resistors (R's).
(2) Where resistors are to be added, through-holes are present
on the board.
(3) For individual channel modifications, the first number of the
reference designation refers to its channel number, i.e.,
R1027 refers to a Channel 1 resistor, X7216 refers to a
Channel 7 jumper , etc. All references to Channels 1 through
8 in the following paragraphs use Channel 1 jumpers and re -
sistors as reference. Modifications affecting the Master sec -
tion are preceded by the number "9" (X901, etc.).
To gain access to the main printed circuit board, remove the
8 Phillips head screws securing the top cover, and remove the
top cover. Most modifications can be made from the top of the
main board.
15 dB Mic Preamplifier Pad
A microphone preamplifier channel gain can be reduced by
15 dB. This may be desirable with extremely high-output mi-
crophones.
Procedure: Remove resistor R1027.
Line-Level Output to Mic-Level Output
Procedure: Short jumper X901. Remove resistors R900 and
R909.
Disable Master Level Control
The Master gain control can be disabled so it cannot be tam-
pered with. The table indicates the resistor value to be used for
the desired gain.
Master Section Gain
-6 dB
0
6 dB
Procedure: Remove resistor R9230. Install new resistor at
jumper X914.
Change Limiter Threshold
All three threshold settings (+16, +8 and +4 dBm) can be
changed. To shift the threshold down by 6 dB, resistor R will be
82 kΩ. To shift the limiter thresholds up by 6 dB, R will be 330
kΩ.
Procedure: Remove resistors R9177 and R9180. Install
new resistor R at jumper X907.
Local Aux Operation
With linked mixers, the Aux input from a modified mixer does
not link.
Procedure: Remove resistor R9024.
Direct Out to Post-Fader
A channel's Direct Out phone jacks can be changed from
pre- to post-fader.
Procedure: Short jumper X106. Remove resistor R1011.
Resistance
5.1 kΩ
10 kΩ
20 kΩ
14
Direct Out to Post-Fader Send/Return (Insert)
1
Changes a channel's /
4-
insert point. Send is tip of phone jack; return is ring. Insert jacks
are useful for inserting line-level signal processors into a chan-
nel. For instance, a parametric EQ or compressor/limiter can
be inserted into a channel for additional processing.
Procedure: Short jumpers X101, X102, X105 and X106. Re-
move resistors R1011 and R1020.
Direct Out to Gated Direct Out
This post-fader, post-EQ channel output is gated, but with-
out NOMA. In this mode, if the Local/Global switch is in "Local",
a manual mix of channel inputs is present at the Line output.
The Off-Attenuation level of the Gated Direct Out signal is infi-
nite.
Procedure: Short jumpers X104 and X906 (in Master sec-
tion). Remove resistor R1011.
SCM810 Speech Gate for Mixing Console
The SCM810 can be used in conjunction with large mixing
consoles to provide automatic mixing for talk shows, panel dis-
cussions, and news shows. Large consoles have channel in-
sert jacks so that external signal processing devices can be
patched into individual channel signal paths. With this modifi-
cation the SCM810 can be placed into unbalanced insert
jacks, and the SCM810 used as a high-quality, external,
8-channel speech gate. This arrangement allows the operator
complete control of each channel via the console's input con-
trol strip, while the SCM810 keeps the number of open micro-
phones to a minimum.
In this operational mode:
1. The Direct Out jack tip is the input from the mixing console,
and the ring is the output to the mixing console.
2. The SCM810 channel inputs, faders and EQ do not function.
3. NOMA does not function, channel Off-Attenuation is infinite.
4. The front-panel channel overload indicators indicate gating
and overload for each input.
5. The "Local" operating mode provides a non-automatic audio
signal at the output for use in external mixes.
6. If the insert point on the mixing console is pre-fader, the gain
trims should be set such that all microphone levels are simi-
lar.
Procedure: Short jumpers X103, X107, X108 and X906 (in
the Master section). Remove resistors R1011, R1019, and
R1020.
MUTE IN Precedence to OVERRIDE IN Precedence
With this modification and when both MUTE IN and OVER-
RIDE IN logic are grounded for a channel, the Override mode
will take precedence (as supplied, the MUTE IN takes prece-
dence over OVERRIDE IN).
Procedure: Short jumper X114. Remove resistor R1046.
Dead Zone on MUTE IN Defeat
As supplied, MUTE IN is intended for use as a momentary
cough button or privacy function (mute when necessary).
However, if the MUTE IN is intended to be used so that the talk-
er must unmute microphones to enable speech pickup (un-
mute when needed), this modification is needed. This re-
moves the muted channel from the MaxBus which eliminates
"dead zones." A dead zone is an area in which a microphone
picks up a talker through a muted microphone and other micro-
phones do not activate for that talker.
Procedure: Short jumper X115.
inch Direct Out jack to a post-fader