Marantz SR4000 Service Manual - Page 40

8-3

8-3

Test 13a :

Select track 5 :

For 1 kHz in Center channel and measure the crosstalk in Left, Right, Surround.

Requirement : < -25 dB

Test 14a :

Select track 6 :

For 1 kHz in Surround channel and measure the crosstalk in Left, Center, Right.


2-

Centre mode “normal” (use 3 kHz or 1 kHz tone)

Test 11b :

Select track 3 :

For 3 kHz in Left channel and measure the crosstalk in Center, Right, Surround


Test 12b :

Select track 4 :

For 3 kHz in Right channel and measure the crosstalk in Surround, Left, Center


Test 13b :

Select track 5 :

For 3 kHz in Centre channel and measure the crosstalk in Left, Right, Surround


Test 14b :

Select track 6 :

For 1 kHz in Surround channel and measure the crosstalk in Left, Center, Right


Inputs overload test (headroom to visible clipping)

General :

Before starting these tests set Master Volume -15 dB lower to make a new output reference (1W on loudresistors).

Requirement : check on scope for no visible signal clipping or measure THD <1,5 %

Test 15 :

Select track 7 :

Check the Left output signal between 20 Hz ... 20 kHz

Test 16 :

Select track 8 :

Check the Right output signal between 20 Hz ... 20 kHz

Test 17 :

Select track 9 :

Check the Center output signal

CENTER “SMALL” between 100 Hz ... 20 kHz

CENTER “LARGE”

between 20 Hz ... 20 kHz

Test 18 :

Select track 11 :

Check the Surround output signal between 50 Hz ... 7 kHz

Test 19 :

Center Mode Check

Select Center size “SMALL”.

a - Select track 5 at 1 kHz :

Adjust the Center output again with master volume for 1W output as 0 dB reference.

b - Select on track 5 the 100 Hz :

Signal to check the roll-off behaviour at -3 dB on the Center output

c - Select on track 5 the 50 Hz :

Signal and measure on the Left and Right output channels.

The lost 50 Hz signal on the Center output is equally splitted and added to the L and R channels.

Test 20

:

Center Mode Check

Select Center size “LARGE”

Repeat test 19 a,b and c

The difference is no roll off behaviour at 100 Hz (Center) and no splitted bass (50 Hz signal)

added to L and R.

Test 21 :

Center Mode Check

Select Center mode phantom = Center speaker “No”

Select track 5 (20 Hz ... 20 kHz) :

No output signals on the Center output or at least minimum -40 dB related to 1W outputs.

Measure now

on the Left and Right output channels : the lost Center signals are equally splitted and added to these

left and right channels (- 3 dB)

Test 22

:

3 CH mode control

Select Front 3 stereo (Rear speaker “No”)

Select track 6 (100 Hz ... 7 kHz):

No output signals on the Surround output channel or at least minimum -40 dB related to 1W output.

Measure now at the Left and Right output channels : the lost Surround signals are equally splitted and added to the

Left and Right output channels (-3 dB)

Test 23 :

2 CH mode control (stereo)

Select Surround “OFF”

Select track 5 :

No output on Centre output channel

Select track 6 :

No output on Surround output channel

Test 24

:

Time delay

control in Surround channel

-

Principle description encoded burst signal spots (see fig. 1)

1- Tone burst 1 kHz during 1 msec with interval time at 20 msec are given at the same time to the L

t

; R

t

inputs.

(in phase 0

∞

)

2- The next tone burst is given at the same time to the L

t

R

t

input, but in reverse phase to the R

t

input (180

∞

).

These 2 tone bursts are repeated continuously during 2 minutes.

-

Principle description decoded signal spots in Center/Surround channel

-

In case of 20 msec time delay

mode the results are shown in fig. 1 in Center and Surround channel.

The center spots in Center channel can be used as ìMarkerî spots (trigger signal)

→

repeated

every 40 msec.

The delayed surround spots occur at the

same time as the center spots (markers)

-

When time delay mode is changed to 15 msec the delayed surround spots move to the left with respect to the centre

mark spots.

-

When time delay mode is changed to 25 msec or 30 msec the delayed surround spots move to the right with respect

to the center spots.

- In

case of no time delay ! (faulty condition) the surround spots fall

just between 2 center markers spots (20 msec)

-

How to check with a double beam scope

WARNING:

Be sure that the ground connection (-) of each instrument is

not connecteded

with the safety

earth

⊥

connection. To avoid damage to output amplifiers (balance type) Use only cinch (input)

ground connection

-

Select Pro Logic size “LARGE” or “SMALL” (phantom in case of no Center output.)

-

Select 20 msec time delay in Surround channel.

-

Adjust scope at 5 msec/division and trigger at A input

-

Connect input A to Center channel (or L or R in case of phantom mode)

-

Connect input B to Surround channel

-

Adjust trigger level and the X position to set pulse A in the middle of the scope . see fig.2 (if

L or R used in

phantom mode choose the largest (amplitude) pulse. see fig 3

Select track 24:

Pulse A = 20 msec marker

Pulse B = delayed surround signal pulse

marker = A

(adjust with X position)

marker = A

20msec time delay

20msec in case of phantom mode

Fig 2

Fig 3

A

B

A

B

Marantz SR4000 Service Manual - Page 40

msec time delay, 20msec in case of phantom mode

Page 40 highlights