GEM SK760 Service Manual

SERVICE MANUAL
Index
2
Opening and Keyboard Disassembling Instructions & NOTICE
3 Layout SK760
4 Layout SK880
5
Assembly & Wiring Connections SK760 (TRF version)
6
Assembly & Wiring Connections SK760 (SWT version)
7
Assembly & Wiring Connections SK880 (TRF version)
8
Assembly & Wiring Connections SK880 (SWT version)
9 Block Diagram (TRF and SWT versions)
10 Power Supply (TRF Version), Phones, Midi & Controls I/O and
11
Power Supply (TRF Version), Phones and Midi & Controls I/O
12 Mixer Board (SWT Version) Schematic and Pcb Layout
13 Timings Table
14 76 Notes L/R Contact and Keyboard Interface Board Schematics
15
88 Notes L/R Contact and Keyboard Interface Board Schematics
16
Controls Interface & Controls Panel Board (TRF) Schematics
17
Controls Interface & Controls Panel Board (TRF) Pcb Layout
FOURTH EDITION APRIL 2000
Warnings
Address
CODE: 270216
Analog I/O Board Schematics
Pcb Layouts
Notice
Service must be carried out by qualified personnel only.Any tampering carried out by unqualified personnel during the guarantee period
will forfeit the right to guarantee.
For a correct operation of the instrument, after having switched off, be careful to wait at least 3 seconds before switching on again.
To improve the device's specifications, the schematic diagrams may be subject to change without prior notice.
All components marked by this symbol have special safety characteristics, when replacing any of these components use only
manufacturer's specified parts.
The (µ) micro symbol of capacitance value is substituted by U.
The (Ω) omega symbol of resistance value is substituted by E.
The electrolytic capacitors are 25Vdc rated voltage unless otherwise specified.
All resistors are 1/8Ω unless otherwise specified.
All switches shown in the "OFF" position. All DC voltages measured to ground with a voltmeter 20KOhm/V.
Soldering point. Supply voltage.
Male connector. Test point.
Female connector. Flag joined with one or more flags
M/F faston connector. with the same signal name inscribed.
ATTENTION
Observe precautions when handling electrostatic sensitive devices.
GENERALMUSIC S.p.A. Sales Division: 47842 S.Giovanni in Marignano (RN) ITALY - Via delle Rose, 12 - tel. 0541/959511 - fax 0541/957404
GENERALMUSIC on the NET: http://www.generalmusic.com
18
Controls Interface & Controls Panel Board (SWT) Schematics
19
Controls Interface & Controls Panel Board (TRF) Pcb Layout
20 Cpu & Sound Generator Schematic (Part 1/2)
21 Cpu & Sound Generator Schematic (Part 2/2)
22
Cpu & Sound Generator Pcb Layout
23
Cpu & Sound Generator Map
24
A/V Interface Board Schematic (Optional Accessory)
25 A/V Interface with Vocal Processor Board Schematic
(Optional Accessory)
26 A/V Interface and Vocal Processor Board Pcb Layouts
27
Test & Adjustment Procedure
28
Spare Part List
NOTE: The SK series is manufctured in two versions:
The TRF version has a traditional supply (transformer and pow-
er supply board with mixer).
The SWT version has a switching supply (switching unit and mix-
er board).
All the specifications remain the same, unless the mains voltage:
The TRF version has two nominal mains voltages 115Vac-60Hz
for U.S.A. or 230Vac-50Hz for CEE & other countries.
The SWT version accept all mains voltages into the range of
100-230Vac and 50-60Hz.
Logic supply ground.
Analog supply ground.
Chassis ground.
Earth ground.
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