Denon DCM 27 Service Manual

Page 2

SAFETYPRECAUHONS

LEAKAGECURRENTCHECK

cord is less than 460 kohms, the unit is defective.

LASERRANAHON

The following check should be performed for the continued protection of the customer and service technician.

Before returning the unit to the customer, make sure you make either (1) a leakage current check or (2) a line to chassis
resistance check. If the leakage current exceeds 0.5 milliamps, or if the resistance from chassis to either side of the power

Do not stare into beam or view directly with optical instruments, class 3A laser product.

©Heed the cautions!

Spots requiring particular attention when servicing, such as
the cabinet, parts, chassis, etc, have cautions indicated on
labels or seals. Be sure to heed these cautions and the cau-
tions indicated in the handling instructions.

©Caution concerning electric shock!

(1) An AC voltage is impressed on this set, so touching inter-
nal metal parts when the set is energized could cause
electric shock. Take care to avoid electric shock, by for ex-
ample using an isolating transformer and gloves when
servicing while the set is energized, unplugging the power
cord when replacing parts, etc.

(2)There are high voltage parts inside. Handle with extra care
when the set is energized.

© Caution concerning disassembly and assembly!

Though great care is taken when manufacturing parts from
sheet metal, there may in some rare cases be burrs on the
edges of parts which could cause injury if fingers are moved
across them. Use gloves to protect your hands.

©0n|y use designated parts!

The set's parts have specific safety properties (fire resis-
tance, voltage resistance, etc). For replacement parts, be
sure to use parts which have the same properties. In particu-
lar, for the important safety parts that are markedAon wiring
diagrams and parts lists, be sure to use the designated parts.

©Be sure to mount parts and arrange the
wires as they were originally!

For safety reasons, some parts use tape, tubes or other insu-
lating materials, and some parts are mounted away from the
surface of printed circuit boards. Care is also taken with the
positions of the wires inside and clamps are used to keep
wires away from heating and high voltage parts, so be sure to
set everything back as it was originally.

CAUTION Please heed the points listed below during servicing and inspection.

© Inspect for safety after servicing!

Check that all screws, parts and wires removed or discon-
nected for servicing have been put back in their original posi-
tions, inspect that no parts around the area that has been
serviced have been negatively affected, conduct an insulation
check on the external metal connectors and between the
blades of the power plug, and otherwise check that safety is
ensured.

(Insulation check procedure)

Unplug the power cord from the power outlet, disconnect the
antenna, plugs, etc., and turn the power switch on. Using a
500V insulation resistance tester, checkthat the insulation re-
sistance between the terminals of the power plug and the ex-
ternally exposed metal parts (antenna terminal, headphones
terminal, microphoneterminal, input terminal, etc.) is 1M0 or
greater. If it is less, the set must be inspected and repaired.

CAUTION Concerning important safety parts

Many of the electric and structural parts used in the set have
special safety properties. In most cases these properties are
difficult to distinguish by sight, and using replacement parts
with higher ratings (rated power and withstand voltage) does
not necessarily guarantee that safety performance will be pre-
served. Parts with safety properties are indicated as shown
below on the wiring diagrams and parts lists is this service
manual. Be sure to replace them with parts with the designat-
ed part number.

(1) Schematic diagrams Indicated by the A mark.
(2) Parts lists Indicated by the A mark.

Using parts other than the designated parts
could result in electric shock, fires or other
dangerous situations.

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Page 17

BA6392FP (IC 102)

DOM-390/290/27/500AE

ca-nourr GND
CHtOUTR cmourr
norm omourn
CHtFth VBlN
GHtFtN VSIN
VREFlN VBIN
VREFOUT Vcc
THERMAL
saw DOWN
crncurr
GND Voc
CH2FIN ct-BFIN
cream cream
new RGINS
crlzourn mourn
cuzomr cmourr
GND MUTE
Pin Description
Pin No. Pin name Function
1 CH1 OUT F Driver channel 1 fonniard output
2 CH1OUT Fl Driver channel 1 reverse output
3 RC IN1 Connect to attached resistor/capacitor (1)
4 CH1 FllN Driver channel 1 reverse input
5 CH1 FlN Driver channel1 forward input
5 VREF IN Internal reference amplifier input
7 VREF OUT internal reference amplifier output
8 GND Ground fer internal reference and internal power circuit
9 CH2 FIN Driver channel 2 forward input
10 CH2 FlIN Driver channel 2 reverse input
11 FIG lNZ Connect to attached resistor/capacitor (2)
12 CHZOUT Ft Driver channel 2 reverse output
13 CHZOUT F Dnver channel 2 forward output
14 GND Ground
15 MUTE Driver mute control input
15 CH30UT F Driver channel 3 forward output
17 CH3OUT R Driver channel 3 reverse output
13 RC INS Connect to attached resistor/capacitor (3)
19 CH3 RIN Driver channel 3 reverse input
20 CH3 FIN Driver channel 3 forward input
21 Vcc Power supply
22 Van: Power supply
23 VBlN Driver channel 4 bias input
24 VSIN Driver channel 4 input
25 VBIN Driver channel 4 bias input*
26 CH4OUT Fl Driver channel 4 reverse output
27 CH4OUT F Driver channel 4 fomard output
28 GND Ground

:tl Pin 23 and pin 25 are shorted Internally.

17