English, Block diagram of the cmit 5 u – SCHOEPS CMIT 5 U Benutzerhandbuch
Seite 26
DC generator
regulator
micro controller
, LEDs
preamp
impedance
converter
filter 1
push-
buttons
filter 2
filter 3
output
stage
RFI
filter
[1] +Phase: an excursion of the diaphragm towar
ds the back electr
ode
(positive pr
essur
e phase) leads to a positive signal at this pin
[2] Matched (i.e. matching tolerance of only 0.7%), see page 19
[3
]
Her
e ar
e thr
ee simple methods for verifying corr
ect phantom powering.
These measur
ements should be made at an unused input. Reduce the
channel gain to the minimum to pr
otect the loudspeakers, etc. If micr
o-
phones ar
e connected to other inputs at the same time, no substantial
dif
fer
e
nce should occur in the r
e
sults.
1. Measur
e the open-cir
cuit voltage between gr
ound (pin 1) and either
pin 2 or pin 3 of the XLR input. Given the permitted tolerances, this
voltage should be between 44 and 52 VDC for P48. Then, measur
e the
short-cir
cuit curr
ent between gr
ound (pin 1) and either pin 2 or pin 3 of
the XLR input. Given the permitted tolerances, this curr
ent should be
between 5.9 and 8.5 mA DC for P48.
Note: W
e
ll-designed phantom power supplies must tolerate at least a
temporary short cir
cuit without damage; an unbalanced connection
(w
h
ic
h
i
s
o
cc
a
sionally necessary) would cause the same curr
ent to be
d
ra
w
n
.
To
be safe, however
, do not leave the short cir
cuit closed for any
longer than necessary
.
2) Measur
e the DC voltages on the modulation leads with a micr
o-
phone connected, e.g. by opening the connector shell of the cable. The
tw
o
voltages (fr
o
m pin 2 and pin 3 to pin 1) must be identical. Th
e
y
should be about 33 V
olts (minimum = 29 V
olts).
3) For P48, use a
SCHOEPS
PHS 48 tester
. Plug it in; if the LED glows and
stays lit, all is well.
3
1
2
Phantom-
powering
[3]
U
s
= +48 V
R
s
[2]= 6.8 k
Ω
R
s
[2]= 6.8 k
Ω
Preampli
-
fier
,
recorder
or mixing
desk
∼ ∼
scr
een
-phase
+phase
XLR-3
connector
XLR-3
connector
Pin 1:
scr
een (GND)
Pin 2:
+phase[1]
Pin 3:
–phase
Bottom view
(as the pins ar
e seen)
1
2
3
Microphone
-
cable
[3]
SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: +49 721 943 20-0 · Fax: +49 721 943 2050
www.schoeps.de · [email protected]
Block Diagram of the CMIT 5 U
26
English