Dbx 160 Service Manual

Page 2

User/ Operator Description

Page 14

Page 4

,- '> 6.3) Turn power off and adjust the mechanical zeroes of
( M1 and M2. Turn power back on.

Ceyiro/ LOCAf/aM DIAszAA

[:5 E:
2123 .212:
:32: can 1:21:12! czar:
:2:

a 2:22:
(:3 E2! [:3 DC!

271 in? 21.11 21.11 211!
C21

2m 2 In

C: E35353 C:

.2122 2/24

AMZ

6.h) Mode switch ' input '. Apply 1 VEMS @ 1 khz to " both
channels. Adjust 312 a 31223 for odb on M1 C M2 3.

6.5) Step oscillator from - 30 db to + 10 db. Adjust 3115
K 3107! so that M1 K M2» track properly from - 30 to

+ 10 ib.

7) C.M.R.:

..._-_--

7.1) Set mode switch (F.P.) to " output". Set compression
control to (>9 . Apply 1 VRMS @ 1 khz to ' both "
channels. Step oscillator to - 30 db and adjust threshold
control until both LEDS go out.

7.2) Step oscillator to + 10 db and adjust front panel gain
control for a convenient reading on M1 N M2 8. Step
oscillator to - 30db and adjust 8132 a R133 D for
minimum change on M1 M2 3, from previously,set reading.

8) Gain Change M1:

8.1) Apply 1 VRMS @ 1 khz to " bothchannels. Set compression
control to 1 . Place mode switch to 3 gain change"
adjust 312 to obtain a "0' db reading on M1.

8.2) Place mode switch to " input'. Adjust 3125 (E.P.) for
"0" db on M1.

Page 15

11) Output Gain Check:

11.1)

11.2)

11.3)

Apply 1.00 VBMS at 1 khz to both" channels. Place
mode switch to ' output. Set compression control
to 3 1 ' Set front panel gain control to '0'. M1

and £2 should both read 0' as well as the external
meters.

Set front panel gain control fully clockwise. M1 and
?2 must read +20db. fChedk external meter both channels
g ldb

Set front panel gain control fully counter-clockwise.
M1 and M2 must read -20 db. Check external meter both

channels (1 1db)

12) Compression Check:

12.1)

12.2)

C, 12.3)

12.)

12.5)

Lo. .
13) Distort?§§#i§ingt%§n :

13.1)

13.2)

Apply 1.00 VRMS at 1khz to ' both " channels. Set mode
switch to ' output! Set compression control tocKD '.
Monitor channel 1 on the external metea. Step oscillator
to -30 db and adjust the threshold control so that both
L335 are off. Note reading on the meters. Step oscill-
ator to +10 db. Neither M1 or M2 or the external meter

should change, more than 1 ldb.

Repeat Step(12.l) while monitoringchannel 2 on the
external meters.

Set compression to '4". While still monitoring channel

2 on the external meters, step oscillator to -30 db and
adjust the front panel gain control for a convenient
reading on the external meter. 5.6. -30 db. Step
oscillator to +10 db. Reading should change iodb adjust
388, if necessary. '

After 388 is properly adjusted, step oscillator from

~30 db to +10 db in 10 db steps. External meter should
vary in 2.5 db steps.

Set threshold fully CH, apply 1,0_VRMS a: 11612 to both channels. Vary
Should be no change noted on external meters.

switch to " output '. Place compression control to "ac.
Set front panel gain control fully clockwise. Monitor
channel 1 and adjust the threshold control for a reading
of "O" on the external meter. Adjust the pot on the
channel 1 VGA for minimum distortion. Must be less than

.1%.

Apply 1.00 VBMS at 100hz to "both' channels. Place mode

Repeat step (l3;l)whilemon$tbring~channeEBZ'afid adjust
the pot on the channel 2 VGA.