If any of the heat-sink-mounted parts (voltage regulatorsSHR-02 HI-Z INPUT BOARD
U1408, U1409 and U1410, or silicon rectifiers D1423 and D1424)To remove SHR-02, remove the six 1/2-inch nuts on the input
is replaced, be sure to apply a small amount of Wakefield Typejacks. Disconnect the four 3-pin connectors from the SHR-01
120 Thermal Joint Compound between the component and theLO-Z INPUT BOARD and the two 3-pin connectors from the
heat sink to allow maximum heat transfer.SHR-03 AUX/MIC BOARD. Pull the board straight back to
A number of components on SHR-14 are mounted on spacingdisengage the jacks from the rear panel: SHR-02 can then be
insulators to keep them a measured distance from the board,completely separated from the 1200.
e.g., R1460, D1422. If any of these parts is replaced, be sure to
remount them the required distance above the board on spacingSHR-01 LO-Z INPUT BOARD
insulators as originally supplied.Remove the twelve screws (two per input) connecting the
XLR-type connectors to the rear panel. To remove SHR-01 without
VR1401 POWER AMPLIFIER LIMITER THRESHOLD ADJUSTMENTfirst removing SHR-02 HI-Z INPUT BOARD, remove the four
This adjustment is made under the following conditions.Phillips screws that hold the rear panel to the chassis bottom.
Rest the unit on its side while performing this operation. Then
1. Terminate the Speaker Output in a 4-ohm resistive load.swivel the rear panel away from the chassis (it is still held by the
2. Set the Master control and trimpot VR1401 on SHR-14 fullypower cord). This allows SHR-01 to be pulled straight back and
clockwise.away from the rear panel without being stopped by the interior
3. Set the Limiter switch to Out.vertical metal shield. Disconnect the four 3-pin connectors (two
4. Connect the unit to a 120 Vac, 60 Hz power source andfrom SHR-03 and two from SHR-04 CHANNEL BOARDS) and
switch the unit on.the four 4-pin connectors (from SHR-02 and SHR-04). (Be sure
5. Drive one low-impedance input channel at 1 kHz with itsto label all removed lead-connector assemblies.) Unsolder from
channel control fully clockwise. (Turn all the other inputpoint AA the yellow lead from SHR-10 REAR PANEL INPUT-
channel Volume Controls fully counterclockwise.) IncreaseOUTPUT BOARD: SHR-01 is now completely free of the 1200.
the input signal until the signal at the Speaker Output just
visibly clips.SHR-13 SPEAKER OUTPUT BOARD
6. Reduce the input signal level such that the output voltageTo remove SHR-13 SPEAKER OUTPUT BOARD:
drops 1.5 dB.
7. Switch the Limiter In. Slowly turn trimpot VR1401 counter-1.Disconnect the 3-pin connector from P1301.
clockwise until the output voltage drops an additional 0.2 dB.2.With a 1/2-inch nutdriver or wrench, remove the nuts holding
the speaker output jacks to the rear panel.
REAR-PANEL BOARDS AND COMPONENTS3. Unsolder the leads from AA and AB.
The following printed circuit boards and components are4.The SHR-13 board is now free of the 1200.
mounted on the rear panel.
B1 FAN
SHR-10INPUT-OUTPUT BOARDTo remove the fan:
SHR-03AUX/MIC BOARD
SHR-02HI-Z INPUT BOARD1.Remove the four screws, nuts, and starwashers at the four
SHR-01LO-Z INPUT BOARDcorners of the fan grille. This frees the fan from the rear
SHR-13SPEAKER OUTPUT BOARDpanel.
B1FAN2. Unsolder the black fan leads from pins AE and AG on SHR-14.
S3+24 VDC PHANTOM POWER SWITCH3.If necessary to remove the fan from the 1200, slide the fan
W1POWER CORDleads out of the insulating tubing and separate the fan from
J1AC CONVENIENCE RECEPTACLEthe unit.
XF1EXTERNAL FUSEHOLDER
For access to or replacement of any of these parts, turn
the 1200 on its side (power transformer down) and remove theCAUTION
When replacing the fan, be sure to slide the leads through
four Phillips screws that hold the rear panel to the chassis
bottom. The rear panel then can be separated sufficiently fromthe insulating tubing before soldering them to the pins on
the chassis bottom to permit access to these boards andSHR-14.
components.
SHR-10 INPUT-OUTPUT BOARDS3 PHANTOM POWER SWITCH
To remove SHR-10, use a 1/2-in. nutdriver to remove the nutsRemove the two screws that fasten the Phantom Power Switch
on the five phone jacks. Carefully pull the board straight backto the rear panel. This will free the switch from the panel. to
until the connectors are free of the rear panel. To separate theseparate the switch completely from the 1200, unsolder the red
board completely from the rear panel, remove the 6-pin andand green leads from the switch terminals.
4-pin connectors from P1001 and P1002. Unsolder the green
and red leads from the Phantom Power switch, and unsolderFRONT-PANEL BOARDS AND COMPONENTS
from SHR-10 the yellow lead that connects AC on SHR-10 toThe following printed wiring boards and components are
AA on SHR-01. SHR-10 can now be completely separated frommounted on the front panel.
the 1200.
SHR-04CHANNEL BOARD (6)
SHR-03 AUX/MIC BOARDSHR-05MASTER CONTROL BOARD
To remove SHR-03, disconnect the four connectors from AA,SHR-07HEADPHONES CONTROL BOARD
AB, BA, and BB to P201 and P202 of SHR-02 and from AC, AD,SHR-06HEADPHONES OUTPUT BOARD
BC, and BD to P102 and P104 of SHR-01. Remove the fourSHR-09LIMITER BOARD
Phillips screws that hold the switches to the rear panel; SHR-03SHR-08INDICATORS BOARD
can be completely separated from the 1200.S2POWER ON/OFF SWITCH
7 |
ACEC
