JVC KD-R491 Schematic Diagrams page 36

4.2 Production Test Mode
In during power off, pressing and holding [1] key and [3] key, then power on the +B power supply.
4.2.1 Test Mode Defaults
During Production Test Mode, the following settings defer from the Normal Mode.
The settings will change immediately after mode activation.
Period to prohibit TEL/LINE MUTE function (Normal Mode: 10 secs)
Mecha Initialize Action
Writing-in to E2PROM when DC error is detected
"DEMO" item in Setup Menu
Power supply during ACC OFF (Back Up On)
"BEEP" item in Setup Menu
Volume range
Source change interval timer
When 0-bit mute is detected
Default Volume
"BASS BOOST"
"LOUDNESS"
"TEL MUTING"
Initial Source
Language
EQ
Fader / Balance
Digital Track Expander(K2) / Sound Reconstruction Set
1.Space Enhancement
2. Volume Link EQ
3. Sound Response
4. Sound Lift
"VOL ADJUST" / "VOLUME OFFSET"
DEMO Mode Setting
Tweeter : Speaker Size
5. SETUP > Audio > Speaker / X'over > Front/Rear > X'over > HPF FREQ
6. SETUP > Audio > Speaker / X'over > Subwoofer > X'over > LPF FREQ
7. SETUP > Audio > Speaker / X'over > Front/Rear/ Subwoofer > X'over > SLOPE
8.SETUP > Audio > Speaker / X'over > Front/Rear/Subwoofer > X'over > GAIN
9.SETUP > Audio > Speaker / X'over > Subwoofer > X'over > PHASE
Sub-woofer/ Rear (For L/O switchable models)
Difference in action
Various setting item
(No.MA665<Rev.001>)17/33
Setting value
1 second
Prohibited
Prohibited
OFF
MUTE terminal turns OFF after 2 seconds
ON
0 to 33
0 seconds
Mute off
Setting value
33
OFF
OFF
ON
CD
English
FLAT
Center
OFF
OFF
OFF
OFF
OFF
0
OFF
None
Through
Through
-12dB/ OCT
0dB
Normal
Rear