Marantz SR-3000 Service Manual Download

Page: 40 / 77

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.
Requirement : < -25 dB

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
Requirement : < -25 dB

Test 12b :

Select track 4 :
For 3 kHz in Right channel and measure the crosstalk in Surround, Left, Center
Requirement : < -25 dB

Test 13b :

Select track 5 :
For 3 kHz in Centre channel and measure the crosstalk in Left, Right, Surround
Requirement : < -25 dB

Test 14b :

Select track 6 :
For 1 kHz in Surround channel and measure the crosstalk in Left, Center, Right
Requirement : < -25 dB

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

; R

inputs.

(in phase 0

∞

)

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

input, but in reverse phase to the R

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